Planta Med 2025; 91(03): 89-108
DOI: 10.1055/a-2494-9020
Reviews

Plants with Hair Growth Activity for Alopecia: A Scoping Review on Methodological Aspects

1   Department of Pharmacy, Laboratory of Pharmaceutical Biology, Palafito, Universidade Estadual de Maringá, Maringá, Brazil
,
1   Department of Pharmacy, Laboratory of Pharmaceutical Biology, Palafito, Universidade Estadual de Maringá, Maringá, Brazil
,
2   Department of Pharmacy, Universidade Federal do Paraná, Curitiba, Brazil
,
3   Course of Pharmacy, Centro Universitário Ingá, Maringá, Brazil
,
3   Course of Pharmacy, Centro Universitário Ingá, Maringá, Brazil
,
1   Department of Pharmacy, Laboratory of Pharmaceutical Biology, Palafito, Universidade Estadual de Maringá, Maringá, Brazil
› Author Affiliations

The authors would like to thank the Laboratory of Pharmaceutical Biology (Palafito) at Universidade Estadual de Maringá. This work was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Scholarship Finance Code 001 for S. B.Galende) and CNPq (grant #310 407/2022 – 2 for J. C. P. Mello).
 

Abstract

Alopecia is a common dermatological disorder of patchy hair loss with substantial patient burden. Phytotherapeutic compounds are increasingly used as a source of new therapeutic options. This review aimed to synthesize the evidence on plant species in hair growth and the methodological aspects of in vivo experimental models. The systematic scoping review was conducted following the PRISMA checklist, the Joanna Briggs Institute, and in accordance with Cochrane. A systematic search was carried out in the Pubmed, Scopus, Web of Science, and SciELO databases. In vivo experiments that evaluated hair growth activity using natural substances of plant origin were included. Data collection and analysis: a total of 1250 studies were identified, of which 175 were included for qualitative synthesis. Of these, 128 used mice, 37 rats, 10 rabbits, 1 guinea pig, and 1 sheep as animal models. The methodologies mapped were as follows: hair growth analysis, histological analysis, immunohistochemistry, gene expression analysis, Western blot, enzyme-linked immunosorbent assay, and biochemical analysis. Minoxidil and finasteride were the most commonly used positive controls. The studies evaluated plant species (166), algae (11), or isolated substances (31). Overall, 152 plant species and 37 isolated substances were identified. This is the first systematic scoping review on the methodological aspects of in vivo hair growth activity. We created a checklist to be completed by authors to allow data comparison and reproducibility, facilitate data interpretation by readers, and ensure better quality of evidence. This work may become a valuable tool for future research and contribute to significant advances in hair growth studies.


Introduction

Hair loss or alopecia is a common multi-etiological dermatological disease. Alopecia is classified as scarring and nonscarring, with nonscarring being more frequent [1]. The main types of nonscarring alopecia are androgenetic alopecia, alopecia areata, trichotillomania, and telogen effluvium, with androgenetic alopecia being the most frequent [2].

Although hair loss is not life-threatening, it greatly impacts self-image and mental and emotional health, reducing social interactions and patientsʼ quality of life [3]. Several studies show that alopecia is associated with psychiatric comorbidities such as anxiety, depression [4], [5], [6], [7], and suicide risk [8], [9], as well as chemotherapy treatment due to cancer and stress for various reasons. In Australia, there were four deaths of young people aged 14 to 17 years old affected by alopecia areata, which the coroner recorded as suicide [10].

Clinical treatments for alopecia include surgical and medical therapies that are constantly expanding, reaching billions of dollars worldwide [11]. Although hair transplant surgery has reliable effects, there are still some limitations, including invasive surgical processes, high prices, and limited sources of donor follicles, and the risk of infection after surgery cannot be ignored [12], [13].

Minoxidil and finasteride are drugs approved by the United States Food and Drug Administration (US-FDA) [14]. However, the application of these drugs is limited due to their adverse effects, toxicity, high recurrence rate, non-adherence to treatment, and limited and transient effects [15], [16]. In June 2022, the US-FDA approved the use of baricitinib for the systemic treatment of severe alopecia areata in adult patients [17], [18]. In this context, the search for herbal products with greater efficacy and safety, less toxicity, and fewer adverse effects has been widely promoted in developing new substances against hair loss [19]. Thus, this study aimed to synthesize the available evidence of the methodological aspects to assess the hair growth activity of natural products of plant origin through a systematic scoping review of in vivo studies.


Methods

This research was designed according to the recommendations from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) [20] (Table 1S, Supporting Information), Cochrane Handbook for Systematic Reviews of Interventions, [21] and the Joanna Briggs Institute, [22] with Open Science Framework (OSF) register DOI: doi:10.17605/OSF.IO/Z5VQG.

Search strategy

A systematic search was performed in the electronic databases PubMed, Scopus, Web of Science, and SciELO with no restriction for publication, date, or language (updated in December 2023). The main descriptors used were ʼhair follicleʼ, ‘hair growthʼ, ‘animal modelʼ, ‘herbal medicineʼ, and ʼnatural productsʼ. The full search strategy can be found in Supporting Information. Grey literature and manual search in the reference list of the included studies was also conducted.


Inclusion and exclusion criteria

We have included in vivo experimental studies that used animal models (of any type) to evaluate hair growth activity using extracts, fractions, or isolated compounds of plant origin.

In vitro studies, clinical trials, reviews of any kind, letters to the editor, abstracts, cohort studies, editorials, and book chapters were excluded. Studies that analyzed allopathic medicines, phytotherapics, formulations, and substances of mineral or animal origin and articles written in non-Roman characters were also excluded.


Eligibility and data extraction

The selection process of the studies involved two steps: reading the titles and abstracts to exclude irrelevant records and reading the full text to select eligible studies for data extraction. A standardized form was then used to collect data on the characteristics of the animal model, natural substance, and methodological aspects. All the results were described qualitatively. Two reviewers conducted all steps independently, and a third reviewer was consulted in case of disagreements.


Data synthesis

Data were extracted using structured tables containing the general characteristics of the studies such as authors, year of publication, and country, the characteristics related to the animal model such as lineage, sex, age, and weight, the characteristics related to plant species, and the methods used to evaluate hair growth in each study. Based on the extracted data, we created a checklist to guide future authors.



Results

A total of 1218 records were retrieved from the databases after removing duplicates. Of these, 970 were excluded during screening (title and abstract reading). Of the remaining 248 studies, 93 were excluded after full-text evaluation (Table 2S, Supporting Information). Twenty articles were added by manual search. Finally, 175 studies that met the eligibility criteria had their data extracted and analyzed as shown in [Fig. 1] [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100], [101], [102], [103], [104], [105], [106], [107], [108], [109], [110], [111], [112], [113], [114], [115], [116], [117], [118], [119], [120], [121], [122], [123], [124], [125], [126], [127], [128], [129], [130], [131], [132], [133], [134], [135], [136], [137], [138], [139], [140], [141], [142], [143], [144], [145], [146], [147], [148], [149], [150], [151], [152], [153], [154], [155], [156], [157], [158], [159], [160], [161], [162], [163], [164], [165], [166], [167], [168], [169], [170], [171], [172], [173], [174], [175], [176], [177], [178], [179], [180], [181], [182], [183], [184], [185], [186], [187], [188], [189], [190], [191], [192], [193], [194], [195], [196], [197].

Zoom
Fig. 1 Flow diagram of the systematic scoping review. Adapted from Page et al. [198].

The main characteristics of the included studies are presented in [Table 1]. The studies were published between 1980 and 2022. These studies were conducted in the following countries: South Korea (n = 67; 38.29%), India (n = 35; 20%), China and Japan (n = 19; 10.86%), Indonesia (n = 12; 6.86%), Thailand (n = 4; 2.29%), and Pakistan and Iran (n = 3; 1.71%), as well as in the following countries: the United States of America, Nigeria, Malaysia, and Taiwan (n = 2; 1.14%) and Bangladesh, Brazil, Jordan, the Philippines, and South Africa (n = 1; 0.57%).

Table 1 Main characteristics of all the studies included in the systematic scoping review.

Methodology

Number
of studies

Country

Animal
Model

Treatment

Reference

1- Hair growth analysis

170

South Korea (n = 67)
India (n = 35)
China (n = 18)
Japan (n = 17)
Indonesia (n = 11)’
Thailand (n = 4)
Pakistan (n = 3)
Iran (n = 2) Nigeria (n = 2)
Taiwan (n = 2)
USA (n = 2)
Malaysia (n = 2)
Bangladesh (n = 1)
Brazil (n = 1)
Jordan (n = 1)
Philippines (n = 1)
Southern Africa (n = 1)

Mice, Rat, Rabbit, Guinea pig, Sheep

Plant species, Algae, Isolated substance

[23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100], [101], [102], [103], [104], [105], [106], [107], [108], [109], [110], [111], [112], [113], [114], [115], [116], [117], [118], [120], [121], [122], [123], [124], [125], [126], [127], [128], [130], [131], [132], [133], [134], [135], [136], [137], [138], [139], [140], [141], [142], [143], [144], [145], [146], [147], [148], [149], [150], [151], [152], [153], [155], [156], [157], [158], [159], [160], [161], [162], [163], [164], [165], [166], [167], [168], [169], [170], [171], [172], [174], [175], [176], [177], [178], [179], [180], [181], [182], [183], [184], [185], [186], [187], [188], [189], [190], [191], [192], [193], [194], [195], [196], [197]

2- Histological analysis

107

South Korea (n = 50)
India (n = 22)
China (n = 18)
Japan (n = 4)
Thailand (n = 3)
Iran (n = 2)
USA (n = 2)
Brazil (n = 1)
Indonesia (n = 1)
Malaysia (n = 1)
Nigeria (n = 1)
Philippines (n = 1)
Southern Africa (n = 1)

Mice, Rat, Rabbit

Plant species, Algae, Isolated substance

[23], [24], [27], [28], [29], [30], [31], [32], [33], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [46], [47], [50], [52], [53], [55], [56], [59], [60], [64], [65], [66], [69], [75], [77], [78], [79], [80], [81], [84], [87], [89], [90], [93], [94], [95], [97], [98], [99], [104], [105], [106], [110], [115], [116], [117], [119], [122], [123], [124], [125], [126], [127], [129], [130], [131], [133], [134], [135], [136], [137], [138], [140], [141], [142], [144], [145], [146], [149], [150], [153], [154], [156], [158], [161], [162], [164], [165], [166], [168], [169], [171], [172], [174], [175], [176], [180], [181], [183], [184], [186], [187], [188], [192], [194], [195], [196], [197]

3- Immunohistochemistry

34

South Korea (n = 24)
China (n = 5)
Japan (n = 2)
India (n = 1)
Taiwan (n = 1)
Indonesia (n = 1)

Mice, Rat

Plant species, Isolated substance

[36], [43], [55], [56], [59], [60], [74], [80], [87], [90], [92], [98], [99], [104], [105], [106], [116], [119], [122], [123], [125], [130], [131], [145], [150], [155], [166], [169], [172], [173], [177], [178], [192], [196]

4- Gene expression analysis

24

South Korea (n = 16)
China (n = 5)
Indonesia (n = 1)
Japan (n = 1)
Iran (n = 1)

Mice

Plant species, Algae, Isolated substance

[24], [41], [47], [48], [53], [56], [60], [84], [87], [104], [115], [124], [126], [131], [132], [140], [145], [153], [168], [169], [175], [187], [188], [195]

5- Western blot assay

19

South Korea (n = 12)
China (n = 6)
Indonesia (n = 1)

Mice

Plant species, Isolated substance

[24], [27], [31], [47], [56], [69], [78], [80], [84], [87], [104], [106], [115], [116], [126], [131], [140], [150], [166]

6- Enzyme-linked immunosorbent assay

8

South Korea (n = 3)
China (n = 4)
Indonesia (n = 1)

Mice

Plant species, Isolated substance

[24], [32], [80], [104], [116], [149], [186], [197]

7- Biochemical analysis

2

South Korea (n = 2)

Mice

Plant species, Algae

[27], [149]

Methodological aspects

Most studies used more than one methodology to assess hair growth in animal models. The methodologies mapped in this systematic scoping review were hair growth analysis, histological analysis, immunohistochemistry, gene expression analysis, Western blot, ELISA, and biochemical analysis.

Hair growth analysis

One hundred and seventy studies (97.14%) performed this analysis to assess hair growth. The references of studies that carried out this analysis are presented in [Table 1]. The following [Table 2] describes the evaluations using this methodology.

Table 2 Hair growth activity measured in studies.

Hair growth analysis

Studies (n)

%

Visual observation (skin color)

120

70.59

Hair length

68

40.00

Hair growth score

43

25.29

Hair growth % area

19

11.18

Hair growth initiation time and completion time

17

10.00

Hair weight

16

9.41

Hair density

15

8.82

Hair thickness

13

7.65

Percentage of anagen induction

4

2.35

Diameter of shaved area

2

1.18

Anagen/Telogen ratio

2

1.18

Growth activity

2

1.18

Reverse side skin evaluation of anagen induction

1

0.59

Hair tensile strength

1

0.59

Percentage growth

1

0.59


Histological analysis

Overall, 107 studies (61.14%) performed histological analysis ([Table 1]). All criteria evaluated in the studies are described in [Table 3].

Table 3 Histological analysis performed in studies.

Histological analysis

Studies (n)

%

Number of hair follicle

61

57.01

Anagen/Telogen ratio

46

42.99

Length of hair follicle

39

36.45

Observation of follicular phases

43

40.19

Skin thickness

16

14.95

Depth of hair follicle

10

9.34

Thickness of hair follicle

7

6.54

Bulb hair size

5

4.67

Number of master cells

3

2.80

Melanogenesis

3

2.80

Shape of hair follicle

2

1.87

Thickness of hair shaft

2

1.87

Number of basal cells

2

1.87

Roots of hair follicle

2

1.87

Number of hair shaft

1

0.93

Length of hair shaft

1

0.93

Shafts differentiation

1

0.93

Thickness of hair roots

1

0.93

Number of bulb hair

1

0.93

Number of blood vessels

1

0.93

Distance between hair follicle and dermis

1

0.93

Distance between hair germ and subcutaneous layer

1

0.93


Immunohistochemistry

Thirty-four studies (19.43%) performed immunohistochemical analyses ([Table 1]). The studiesʼ analyses evaluated the expression of fibroblast growth factors (FGF-5 and FGF-7), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF-1), transforming growth factor-β2 (TGF-β2), tumor necrosis factor (TNF-α), β-catenin, caspase-3, caspase-8, pro-caspase-9, protein (p53, p63), Bcl-2-associated X protein (Bax), B-cell lymphoma-2 (Bcl-2), Bcl-xL, cleavage-activating protein (SCAP), dickkopf-1 (DKK-1), telomerase reverse transcriptase (TERT), interleukin (IL) IL-1β, IL-4, IL-13, bone morphogenetic protein 4 (BMP4), sonic hedgehog (Shh), Ki-67 keratinocytes, keratin 19 (K19), K15, cluster of differentiation (CD34), p-JNK, p-IKB, SPTLC, cytokeratin 19 (CK19), substance P (SP+), calcitonin gene-related peptide (CGRP+), high-mobility group box 1 (HMGB1), stem cell factor (SCF), wingless-related integration site (Wnt) 3, Wnt3a, Wnt10b, alkaline phosphatase (ALP), and 5α-reductase.

The studies evaluated the detection of apoptotic cells by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method and the proliferation of keratinocytes by bromodeoxyuridine labeling.


Gene expression analysis

Twenty-four studies (13.71%) analyzed gene expression ([Table 1]). The markers evaluated by the real-time polymerase chain reaction (PCR) technique were keratinocyte growth factor (KGF), VEGF, hepatocyte growth factor (HGF), transforming growth factor β (TGF-β), TGF-β1, IGF-1, DKK-1, FGF-5, FGF-7, bax, Wnt10b, Wnt10a, Wnt3, Wnt3a, Wnt5a, low-density lipoprotein receptor-related protein 5 (LRP5), frizzled receptor 1 (FZDR1), frizzled 7, lymphoid enhancer factor 1 (LEF1), cyclin D1 (Cyc-D1), fas cell surface death receptor (fas), p53, matrix metallopeptidase 2 (MMP2), MMP9, disheveled 2, glycogen synthase kinase 3β (GSK-3β), β-catenin, and ALP.


Western blot

Nineteen studies (10.86%) performed Western blot analysis ([Table 1]). The markers evaluated in this methodology were β-catenin, cleaved caspase 3, caspase-3, -8 e − 9, active caspase-3, procaspase-9, extracellular signal-regulated kinase (ERK), phosfo (p)-ERK, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (SAPK/JNK), p- SAPK/JNK, p38, p-p38, p53, bcl-2, bcl-xL, bax, NF-kB, IkB-α, p-IkB-α, IGF-1, TGF-β, TGF-β1, TGF-β2, MMP2, MMP9, phospho-Akt (Akt phospholylation), jun proto-oncogene, AP-1 transcription factor subunit (c-Jun), FGF-5, FGF-7, LEF-1, Shh, smoothened (Smo), GLI family zinc finger 1 (Gli-1), Cyclin D1, Cyclin E, Wnt3a, Wnt5a, Wnt 10 b, frizzled 7, disheveled 2, GSK-3β, and ALP.


Enzyme-linked immunosorbent assay

The expression levels of KGF, VEGF, HGF, transforming growth factor α (TGF-α), TGF-β, TNF-α, IL-1β, IGF-1, FGF-7, EGF, p21, β-catenin, and Shh were measured by ELISA (n = 8; 4.57%).


Biochemical analysis

Only two studies (1.14%) measured the enzymatic activity of γ-glutamyl transpeptidase and ALP.



Animal models

Studies retrieved from the databases reported strain, sex, age, and use of guidelines.

Mice

Of the 175 studies selected in our systematic search, 128 (73.14%) used mice as an experimental model to assess hair growth. The strains identified in studies were C57BL/6 (n = 96; 75%), C3H/He (n = 12; 9.38%), Swiss (n = 7; 5.47%), Balb/c (nu/nu) (n = 4; 3.13%), Balb/c (n = 4; 3.13%), Kunming (n = 2; 1.96%), B6CBAF1/j (n = 1; 0.78%), Balb/Black (n = 1; 0.98%), dd-K (n = 1; 0.78%), and ICR (n = 1; 0.78%). Four studies (3.13%) did not report the strain used, and five studies used two different strains.

Seventy-three studies (57.03%) used male mice, 37 (28.91%) used females, 8 (6.25%) used both sexes, and 11 (8.59%) did not report the sex. Among the studies that reported the age of the animals, the age ranged from 5 to 36 weeks, with 7-week-olds being the most used (n = 54; 42.19%). One hundred and two studies (79.69%) used guidelines and/or institutional protocols on animal management. The other studies did not report this information (n = 26; 20.31%).


Rats

Thirty-seven studies (21.14%) analyzed rats. The strains were Wistar (n = 24; 64.86%), Sprague–Dawley (n = 5; 13.51%), and Swiss (n = 3; 8.11%), and five studies (13.51%) did not report the strain used. Sixteen studies (43.24%) used male rats, six studies (16.22%) used female rats, five studies (13.51%) used both sexes, and ten studies (27.03%) did not provide data on the sex of the animals. The age of the animals ranged from 5 to 36 weeks, with the most-used mean age being 12 weeks (n = 7; 18.92%). However, most studies did not report this information (n = 21; 56.76%). Thirty studies (81.08%) used guidelines and/or institutional protocols on animal management.


Rabbits

Ten studies (5.71%) used rabbits in experiments to evaluate hair growth. The strains were Angora (n = 3; 30%) and New Zealand (n = 1; 10%); however, most studies (n = 6, 60%) did not report the strain. In nine studies (90%), the animals were males, and only one study (10%) used females. The age of the animals ranged from 3 to 5 weeks (n = 6; 60%). Four studies (40%) did not report this information. Eight studies (80%) use guidelines and/or institutional protocols on animal management.


Other models

Only one study (0.57%) used guinea pigs, and another (0.57%) used sheep as animal models. The study with guinea pigs did not provide any information about the lineage, sex, and age of the animals used in the experiments, and the sheep study reported using 1- to 2-year-old female animals of Lohi lineage. Neither study reported the use of guidelines.



Induction of alopecia

Thirty-four studies (19.43%) induced alopecia in animals by administering the following hormones: testosterone (n = 25; 14.29%), dihydrotestosterone (n = 4; 2.29%), or hydrocortisone (n = 1; 0.57%), or the antineoplastics cyclophosphamide (n = 3; 1.71%) and bleomycin (n = 1; 0.57%). Hormones were administered subcutaneously, topically, or intramuscularly, and antineoplastics intraperitoneally.

The remaining studies performed mechanical depilation of animals with electric hair clippers (n = 82; 46.86%), depilatory cream (n = 23; 13.14%), shaved+cream (n = 21; 12%), and wax (n = 10; 5.71%).

Four studies (2.29%) used nude mice, and one study (0.57%) used old animals (spontaneous hair loss). Two studies (1.14%) did not report the method used. One study carried out two methods for depilation (cream and shaved+cream), and one carried out three methods (shaved, cream, and wax).


Treatments

The plants and algae analyzed in the studies were prepared as crude extracts (n = 128; 73.14%), fractions (n = 16; 9.14%), or oils (n = 16; 9, 14%). Two studies (1.14%) did not report this data. Forty-nine studies (28%) did not report the part of the plant used, and 53 (30.29%) did not report the extraction method and solvent used (n = 22; 12.57%).

Plant species

From the 175 studies selected in our systematic scoping review, 166 (94.86%) evaluated plant species. We identified 152 different plant species, corresponding to 64 families. We report the complete list of plant species and families in [Table 4]. However, 20 studies (11.43%) did not report or make clear the plant species used. The most frequent plant species in the studies were Phyllanthus emblica L. Hibiscus rosa-sinensis L., Panax ginseng C. A.Mey., and Polygonum multiflorum Thunb. Four plants were not completely identified: Espinosilla, Aconiti Ciliare Tuber, Longanae Arillus, and Polygonati Rhizoma. They are suggested to be Loeselia mexicana Brand, Aconitum carmicarnichaelii Debeaux, Dimocarpus longan Lour, and Polygonati rhizome, respectively.

Table 4 Plant species, respective family, organ, extraction method, and solvent used in studies.

Plant species

Family

Organ

Extraction Method

Solvent

NE = not evaluated; NR = not related

Abrus precatorius L.

Leguminosae

Seed, Leaf

Maceration, Soxhlet

CHCl3: H2O, H2O, Petroleum ether: EtOH

Acorus calamus L.

Acoraceae

Root, NR

NR, Reflux

EtOH 30%, EtOH : H2O

Adiantum capillus-veneris L.

Pteridaceae

Aerial part

Maceration

EtOH 95%

Albizia julibrissin Durazz.

Fabaceae

NR

Reflux

EtOH 75%

Allium tuberosum Rottler ex Spreng

Amaryllidaceae

NR

NR

EtOH : Hex : DCM

Aloe vera (L.) Burm.f.

Asphodelaceae

Leaf

Blended

NR

Anemarrhena asphodeloides Bunge

Asparagaceae

Rhizome

NR

NR

Angelica dahurica (Hoffm.) Benth&Hook.f. ex Franch&Sav.

Apiaceae

NR

Reflux

EtOH 75%

Angelica gigas Nakai

Apiaceae

NR, Root, Root, NR

Reflux, NR, NR, Reflux, Reflux

EtOH : H2O, EtOH 30%, EtOH 98%, Hot water : EtOH

Angelica sinensis (Oliv.) Diels

Apiaceae

Root

Maceration

EtOH 70%

Angiopteris evecta (G.Forst) Hoffm.

Marattiaceae

Root

Maceration, Soxhlet

EtOH, EtOH : H2O

Apium graveolens L.

Apiaceae

Root, Leaf

Reflux, Maceration

EtOH

Asiasarum heterotropoides (F. Schmidt) F. Maek.

Aristolochiaceae

Root

NR

EtOH

Asiasarum sieboldii (Miq.) F. Maek

Aristolochiaceae

Root

NR

MeOH 95%

Astragalus spp

Fabaceae

NE

NE

NE

Bacopa monnieri (L.) Wettst.

Plantaginaceae

Whole plant, Leaf, Leaf, Entire herb

NR, Direct boiling, Boiling, NR

NR, Olive oil, NR, NR

Bergera koenigii L.

Rutaceae

NR

NR

NR

Biota orientalis (L.) Endl. (Platycladus orientalis)

Cupressaceae

NR

Reflux

EtOH 75%

Bletilla striata (Thunb.) Rchb.f.

Orchidaceae

Tuber

Reflux

MeOH

Blumea eriantha DC.

Asteraceae

NR

NR

EtOH

Boswellia carteri Birdw.

Burseraceae

NR

Reflux

EtOH 75%

Brassica hirta Moench

Brassicaceae

Seed

Reflux

MeOH

Brassica juncea (L.) Czern.

Brassicaceae

Seed

NR

EtOH

Brassica rapa L.

Brassicaceae

Seed

NR

NR

Buxus wallichiana Baill.

Buxaceae

Bark

Soxhlet

Petroleum ether, CHCl3, MeOH, H2O

Calotropis gigantea (L.) W. T.Aiton

Apocynaceae

Leaf

Maceration

NR

Camellia oleifera C.Abel

Theaceae

Seed cake

NR

EtOH 60%, CaO

Camellia sinensis (L.) Kuntze

Theaceae

Leaf, Leaf

NR, 50 °C/3 h

EtOH 30%, MeOH 50%

Carthamus tinctorius L.

Asteraceae

Flower

Maceration (2×), Decoction, NR

EtOH 50, 95%, H2O, EtOH 30%

Centella asiatica (L.) Urb.

Apiaceae

Leaf

Soxhlet

EtOH

Chamaecyparis obtusa (Siebold & Zucc.) Endl.

Cupressaceae

NR

Vapor

H2O

Chrysanthemum indicum L.

Asteraceae

NR

Reflux

EtOH 75%

Chrysanthemum zawadskii Herbich

Asteraceae

Whole plant

Reflux

EtOH 95%

Chrysanthemum zawadskii var. latilobum (Maxim.) Kitam.

Asteraceae

Whole plant

Ultrasonic

EtOH 70%

Chrysanthemum zawadskii var. latilobum (Maxim.) Kitam.

Asteraceae

Aerial parts

NR

MeOH 95%

Cinchona succirubra Pav. ex Klotzsch

Rubiaceae

Bark

NR

EtOH

Cinnamomum osmophloeum Kaneh.

Lauraceae

Leaf

Gasheating cryogenic distillation

H2O

Cistanche tubulosa (Schenk) Wight ex Hook.f.

Orobanchaceae

NR (2×)

NR (2×)

H2O, EtOH 80%

Citrullus colocynthis (L.) Schrad.

Cucurbitaceae

Fruit

Soxhlet

Petroleum ether after EtOH 95%

Clitoria ternatea L.

Fabaceae

Flower

Flowers crushed and filtered

NA

Cnidium officinale Makino

Apiaceae

Root

NR

EtOH 30%

Cocos nucifera L.

Arecaceae

Fruit

NR

NR

Coix lacryma-jobi L.

Poaceae

NR

Maceration

EtOH 70%

Commiphora molmol (Engl.) Engl. ex Tschirch

Burseraceae

NR

Reflux

EtOH 75%

Corydalis ternata Nakai

Papaveraceae

NR

Reflux

EtOH 75%

Crataegus cuneata Siebold & Zucc.

Rosaceae

Fruit

Reflux

MeOH

Crataegus pinnatifida Bunge

Rosaceae

Fruit

NR

H2O

Crinum asiaticum var. japonicum Backer

Amaryllidaceae

NR

NR

EtOH 95%

Cucumis melo var. makuwa Makino

Cucurbitaceae

Leaf

Reflux

H2O

Cucurbita pepo L.

Cucurbitaceae

Seed

NE

NE

Cuscuta reflexa Roxb.

Convolvulaceae

Stem

Soxhlet

Petroleum ether

Cynanchum wilfordii (Maxim.) Hemsl.

Apocynaceae

NR

Decoction, Boiling, Fermented by Bacillus subtilis

H2O

Cyperus rotundus L.

Cyperaceae

Rhizome

Soxhlet, NR

EtOH, NR

Dicerocaryum senecioides (Klotzsch) Abels

Pedaliaceae

Leaf

Shaker

EtOH

Dictamnus dasycarpus Turcz.

Rutaceae

Root bark

NR

EtOH

Eclipta alba (L.) Hassk

Asteraceae

Leaf, Stems, and Flower, Aerial parts, Whole plant

NR, Reflux, Soxhlet

MeOH 95%, Petroleum ether
MeOH, MeOH 95%

Eclipta prostrata L.

Asteraceae

NR, NR

Sonication, Boiling

MeOH, H2O

Equisetum hyemale L.

Equisetaceae

Stem

Maceration

Hexane, Ethyl acetate, MeOH, H2O

Erica multiflora L.

Ericaceae

NR

Maceration

EtOH 70%

Eriobotrya japonica (Thunb.) Lindl.

Rosaceae

Leaf

NR

NR

Erythrina variegata L.

Fabaceae

Leaf

Maceration

EtOH 96%

Geranium sibiricum L.

Geraniaceae

NR

NR

MeOH

Ginkgo biloba L.

Ginkgoaceae

Leaf

Maceration, Decoction

H2O, EtOH

Glycine max (L.) Merr.

Fabaceae

Bean

NR

NR

Glycine max subsp. soja (Siebold & Zucc.) H.Ohashi

Fabaceae

Bean

Shaker incubator

EtOH 20%

Glycyrrhiza glabra L.

Fabaceae

Root (4×)

Soxhlet (3×), Maceration

H2O : EtOH, Petroleum ether (2×), EtOH

Glycyrrhiza uralensis Fisch.

Fabaceae

Root, NR

NR, Reflux

EtOH 30%, Hot water : EtOH

Vitis vinifera L.

Vitaceae

Fruit

NR

NR

Hibiscus rosa-sinensis L.

Malvaceae

Leaf (4×), Leaf Flower (3×)

Soxhlet (3×), Percolation, Maceration

EtOH (3×), Petroleum ether (2×)

Hordeum vulgare L. var. distichon Alefeld

Poaceae

Seed

Maceration

H2O 75%:Acetone

Houttuynia cordata Thunb.

Saururaceae

NR

Boiling at 96 – 100 °C/4 h

H2O

Hura crepitans L.

Euphorbiaceae

Bark

NR

EtOH 70%

Hydrangea macrophylla (Thunb.) Ser.

Hydrangeaceae

NR

NR

NR

Indigofera suffruticosa Mill.

Fabaceae

NR

NR

Coconut oil

Lawsonia alba Lam.

Lythraceae

NR

NR

Coconut oil

Leea indica (Burm.f.) Merr.

Vitaceae

Leaf

Maceration

MeOH

Leonurus sibiricus L.

Lamiaceae

Lespedeza bicolor Turcz.

Fabaceae

Leaf

Maceration

MeOH 80%

Ligusticum striatum DC.

Apiaceae

NR

Boiling/Reflux

H2O/EtOH

Ligustrum lucidum W. T.Aiton

Oleaceae

NR

Reflux

MeOH

Liriope muscari (Decne.) L. H.Bailey

Asparagaceae

NR

Under pressure at at 100 °C/3 h

H2O

Loranthus parasiticus (L.) Merr.

Loranthaceae

NR

Boiling at 100 °C/2 h

H2O

Lycium chinense Mill.

Solanaceae

NR

Maceration

EtOH 70%

Solanum lycopersicum L.

Solanaceae

Fruit

NR

NR

Lygodium japonicum (Thunb.) Sw.

Lygodiaceae

Spore

Maceration

EtOH 50%

Malvaviscus arboreus Dill. ex Cav.

Malvaceae

Leaf

Maceration

EtOH 70%

Mangifera indica L.

Anacardiaceae

Leaf

Reflux

H2O

Martynia annua L.

Martyniaceae

Fruit, Leaf

Decoction, Fine paste

H2O

Melandrium firmum Rohrb.

Caryophyllaceae

Whole plant

NR

H2O

Miscanthus sinensis Andersson

Poaceae

Flower

NR

MeOH

Morus alba L.

Moraceae

NR

Reflux

EtOH 75%

Murraya koenigii (L.) Spreng.

Rutaceae

Leaf

Cloth pouch boiling

NR

Musa paradisiaca L.

Musaceae

Fruit

Soxhlet

MeOH, H2O

Myrica rubra (Lour.) Siebold & Zucc.

Myricaceae

NR

Maceration

EtOH 50%

Nardostachys jatamansi DC.

Caprifoliaceae

Rhizome

Soxhlet

Hexane

Naringi crenulata (Roxb.) Nicolson

Rutaceae

Leaf

Maceration

H2O, CHCl3, Acetone

Nigella sativa L.

Ranunculaceae

Seed

Boiling

Coconut oil 60%

Nothopanax scutellarius (Burm.f.) Merr.

Araliaceae

Leaf

Maceration

EtOH 96%

Ocimum gratissimum L.

Lamiaceae

Leaf

Hydrodistillation

H2O

Oryza sativa L.

Poaceae

Bran

Supercritical

CO2

Paeonia lactiflora Pall.

Paeoniaceae

Root

Boiling

H2O

Panax ginseng C. A.Mey.

Araliaceae

Dried root, Root

NR, NR

MeOH 95%, EtOH 30%

Perilla frutescens (L.) Britton

Lamiaceae

NR

Boiling at 96 – 100 °C/4 h

H2O

Perilla L.

Lamiaceae

NR

NR

NR

Phyllanthus emblica L.

Phyllanthaceae

Dried fruit

Fried

Sesame oil

Phyllanthus niruri L.

Phyllanthaceae

NR

Maceration

EtOH 70%

Phyllanthus urinaria L.

Phyllanthaceae

Whole plant

Reflux

EtOH 50%

Pinus densiflora Siebold & Zucc.

Pinaceae

NR

Reflux

H2O : EtOH

Pinus thunbergii Parl.

Pinaceae

Bark

Reflux

H2O

Piper nigrum L.

Piperaceae

Leaf

Reflux

MeOH 50%

Platycarya strobilacea Siebold & Zucc.

Juglandaceae

NR

NE

NE

Platycladus orientalis (L.) Franco

Cupressaceae

Leaf

Reflux

EtOH 70%

Polygara senega var. latifolia Torr. et Gray

Polygalaceae

Root

NR

MeOH

Polygonum multiflorum Thunb.

Polygonaceae

Root

NR

MeOH 95%

Prunus mira Koehne

Rosaceae

Seed

Pressing seeds

NA

Prunus persica Batsch

Rosaceae

Seed

NR

EtOH 30%

Psoralea corylifolia L.

Fabaceae

NR

Boiling at 100 °C/2 h

H2O

Pueraria thomsonii Benth.

Fabaceae

NR

Reflux

EtOH 50%

Punica granatum L.

Lythraceae

Leaf

Soxhlet

EtOH: H2O

Rehmannia glutinosa (Gaertn.) DC.

Orobanchaceae

NR

Boiling

H2O

Ribes nigrum L.

Grossulariaceae

NR

NR

NR

Rosa multiflora Benth.

Rosaceae

Fruit

NR

NR

Rosa rugosa Thumb. var. plena Regl.

Rosaceae

Flower

Maceration

EtOH 50%

Rosmarinus officinalis L.

Lamiaceae

Leaf

Reflux

EtOH 50%

Rubus coreanus Miquel

Rosaceae

NR

Boiling at 100 °C/2 h

H2O

Rumex japonicus Houtt.

Polygonaceae

Root

NR

EtOH 95%

Russelia equisetiformis Schltdl. & Cham.

Plantaginaceae

Whole plant

Cold extraction

MeOH

Salvia miltiorrhiza Bunge

Lamiaceae

Root

NR

EtOH 30%

Salvia plebeia R.Brown

Lamiaceae

Whole plant

Maceration

MeOH

Sanguisorba officinalis L.

Rosaceae

Root

NR

NR

Schisandra nigra Maxim.

Schisandraceae

Fruit

Maceration

EtOH 85%

Schisandra Michx.

Schisandraceae

Fruit

Decoction

H2O

Schizandra chinensis (Turcz.) Baill.

Schisandraceae

NR

Boiling at 100 °C/2 h

H2O

Scrophularia buergeriana Miq.

Scrophulariaceae

Root

NR

EtOH 30%

Serenoa repens (W.Bartram) Small

Arecaceae

NE

NE

NE

Sesamum indicum L.

Pedaliaceae

NR

Reflux

EtOH 75%

Sophora angustifolia Siebold & Zucc.

Fabaceae

NR

Reflux

H2O : EtOH

Sophora flavescens Aiton

Fabaceae

Root

NR

EtOH

Stemona japonica (Bl.) Miq.

Stemonaceae

NR

Under pressure at at 100 °C/3 h

H2O

Sterculia urceolata Sm.

Malvaceae

Leaf

Maceration

EtOH

Theobroma cacao L.

Malvaceae

Fruit peel

Maceration

EtOH 96%

Thuja orientalis L.

Cupressaceae

Leaf

NR

Hot water

Thuja occidentalis L.

Cupressaceae

NR

Reflux

EtOH 95%:Ethyl acetate

Trichosanthes cucumerina L.

Cucurbitaceae

Leaf

NR

H2O

Tridax procumbens L.

Asteraceae

Entire aerial part

NR

NR

Trigonella foenum-graecum L.

Fabaceae

Seed, Seed

Direct boiling, Paste cloth method (boiling)

Olive oil, NR

Vernonia anthelmintica (L.) Willd.

Asteraceae

Seed

NR

EtOH 60%

Vitex rotundifolia L.f

Lamiaceae

Fruit

Reflux

MeOH

Wikstroemia retusa A.Grey

Thymelaeaceae

Bark

NR

EtOH 70%

Wrightia tinctoria R.Br.

Apocynaceae

Leaf and bark

Maceration

Coconut oil

Zanthoxylum schinifolium Siebold & Zucc.

Rutaceae

Bark

NR

EtOH 30%

Ziziphus mauritiana Lam.

Rhamnaceae

Root

Maceration

EtOH

Zizyphus jujuba Mill.

Rhamnaceae

Seed

Hydrodistillation

H2O


Isolated substances

Thirty-one articles (17.71%) used isolated substances. A total of 37 different substances were identified and are depicted in [Table 5].

Table 5 Isolated substances found in all evaluated articles.

Number of isolated substances

Chemical class

References

(1) Oleuropein

Iridoid

[104]

(2) Cedrol

Sesquiterpenoid

[66], [183]

(3) Baicalin

Flavonoid

[114], [115]

(4) Lycopene

Carotenoid

[153]

(5) Ginsenoside Rb1

Saponin

[173]

(6) Ginsenoside Rd

Saponin

[173]

(7) Ginsenoside F2

Saponin

[99], [172]

(8) Procyanidin B-3

Proanthocyanidin

[68]

(9) (+)-Catechin

Flavonoid

[68]

(10) Stigmast-5-en-3-O-glucopyranosidetriacetate-51-ol

Steroid

[110]

(11) Shikimic acid

Carboxylic acid

[79]

(12) 2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-glucoside

Polyphenol

[87]

(13) 6-Gingerol

Ketone

[24]

(14) Astragaloside IV

Saponin

[116]

(15) Ginsenoside Ro

Saponin

[151]

(16) Formononetin

Isoflavone

[106]

(17) Linoleic acid

Fatty acid

[31], [41]

(18) Policosanol

Alcohol

[41]

(19) γ-Oryzanol

Sterol Ferulate

[41]

(20) γ-Tocotrienol

Tocotrienol

[41]

(21) β-Sitosterol

Phytosterol

[31]

(22) Bicyclo(10.1.0)tridec-1-ene

Cyclic olefin

[31]

(23) 6,7-Epoxy-5-hydroxyresiniferonol-14-(2,4-tetradecadienoate)

Diterpenoid

[31]

(24) Capsaicin

Alkaloid

[121]

(25) Nardin

Terpenoid

[57]

(26) Jatamansic acid

Terpenoid

[57]

(27) α-Terpineol

Monoterpene alcohol

[178]

(28) L-Menthol

Monoterpene alcohol

[132]

(29) Stevioside

Diterpene glycoside

[132]

(30) Cyanidin 3-O-arabinoside

Anthocyanin

[125]

(31) Apocynin

Acetophenone

[125]

(32) WGBP-A2b

Polysaccharides

[32]

(33) Fisetin

Flavonoid

[169]

(34) Resveratrol

Polyphenol

[169], [196]

(35) Physcion

Anthraquinone

[56]

(36) Decursin

Coumarin

[150]

(37) Timosaponin BII

Saponin

[55]


Algae

Eleven studies (6.29%) analyzed algae to verify hair growth activity. The algae were Ecklonia cava Kjellman, Ishige sinicola (Setchell & N. L.Gardner) Chihara, Undariopsis peterseniana (Kjellmann) Miyabe & Okamura, Sargassum kjellmanianum f. muticum Yendo, Sargassum glaucescens J.Agardh, Fucus vesiculosus, Laminaria japonica Areschoug, Eucheuma cottonii Weber Bosse, and Undaria pinnatifida (Harvey) Suringar.



Safety assessment

Less than 20% of the studies (n = 34) performed a primary skin irritation test on the animals. Only nine studies (5.14%) investigated the presence of acute or chronic inflammatory processes, six studies performed toxicity tests (3.43%) of the investigated substances, and only one study (0.57%) evaluated clinical manifestations and animal behavior.

Reproducibility is a fundamental pillar of scientific research, being essential to validate and consolidate discoveries. During data extraction, we identified that many studies lack clarity and completeness in data presentation. The omission of essential information compromises not only the robustness of the results obtained, but also the ability of other researchers to replicate and expand knowledge.



Discussion

This is the first systematic scoping review to synthesize the evidence of over 170 experimental in vivo studies on the effects of plants on hair growth activity. Our study mapped the methods, the animal models, and alopecia induction and reported the plant species, algae, and isolated substances investigated.

Although we were able to gather the evidence mentioned above, we observed that several studies had “flaws” because they were unclear or did not report all the necessary information about the models, methods, and study results, such as lineage, sex, weight, age of animals, name of the plant species used or the correct and accepted scientific name of the plant species, part of the plant material used, extraction and partition method, the solvent used, and others. This information is paramount to allow data comparison and scientific reproducibility [199], [200]. In addition, due to the heterogeneity between the studies (different animal models, methods of inducing alopecia, methods of evaluating hair growth, and markers used), it was not possible to compare them. Therefore, based on the information reported in the studies included in our review, we created a checklist that researchers should complete when evaluating natural compounds with hair growth activity ([Table 6]). This checklist aims to standardize the conduct and reporting of studies in this area, thus allowing the comparison of studies and the establishment of firm conclusions. Furthermore, it will direct the investigation of the mechanisms of action of the compounds.

Table 6 Checklist for conduct and reporting experimental in vivo studies.

Checklist Item

Reported on page nº

Animal model

Strain

Sex

Age

Weight

Guidelines – Committee approved

Induction of alopecia

Hormonal

Antineoplastics

Other type

Plant specie

Complete, correct, and accepted scientific name of the specimen

Date of plant collection (day, month, year)

Place of plant collection (city, state, country)

Coordinates of plant collection (latitude and longitude)

Voucher specimen number

Name of the Herbarium code (Index Herbarium)

Name of the person responsible for the collection and identification of the species

Isolated Substance

Complete, correct, accepted scientific name of the compound and chemical structure

If purchased, mention the name of the industry/
laboratory

Crude extract production

Part of the plant used, ground, and fresh or dried

Solvent and volume used

Plant and solvent proportion (w/v)

Method of extraction

Time and temperature of extraction

Yield of crude extract

Fraction production

Solvent and volume used

Method of extraction

Time and temperature of extraction

Yield of fraction

Safety evaluation

Primary skin irritation test

Toxicity tests

Investigation of inflammatory infiltrates

Observation of animal behavior

Duration of treatment

Methodology

Hair growth analysis

Qualitative

Visual observation/photography (skin color)

Hair growth initiation time and completion time

Quantitative

Hair length

Hair growth score

Hair density

Hair weight

Hair growth % area

Hair thickness

Others Yes ( ) No ( )

Which

Histological analysis

Number of hair follicle

Anagen/Telogen ratio

Length of hair follicle

Observation of follicular phases

Depth of hair follicle

Thickness of hair follicle

Others Yes ( ) No ( )

Which

Immunohistochemistry

Yes ( ) No ( )

Which

Real-time polymerase chain reaction

Yes ( ) No ( )

Which

Western blot assay

Yes ( ) No ( )

Which

ELISA

Yes ( ) No ( )

Which

Biochemical analyses

Yes ( ) No ( )

Which

Previous studies have shown that several plant metabolites, such as polyphenolic compounds, fatty acids, phytoestrogens, capsaicin, procyanidin B2, and epigallocatechin-3-O-gallate, have hair growth activity [201], [202], [203], [204]. Plants and their active compounds can induce hair growth via stimulation or inhibition of growth factors, cytokines, hormones, and enzymes or through modulation of signaling pathways [205]. In our review, a survey of 152 different plant species and 37 isolated substances evaluated in in vivo models of hair growth are depicted in [Tables 4] and [5], respectively. We also present the chemical structures of the isolated substances identified in the studies (Figure 1S, Supporting Information).

This review identified that 73.14% of the studies used mice as an experimental model, especially the C57BL/6 strain. This strain is the most used in in vivo models [174], [206] because it allows the visual assessment of hair growth since the animalsʼ skin color changes from pink to black as the hair cycle progresses from telogen to anagen [207]. This is because truncal pigmentation in animals is dependent on their follicular melanocytes. Melanin production in hair follicles is associated with the anagen phase of the hair growth cycle [208].

Hair growth and histological analyses were the most frequently performed methods in the included studies. However, these techniques lack information about the probable mechanism of action of the substances. Furthermore, we identified that only one-third of the included studies conducted molecular biology analyses. These methodologies contribute to investigating the probable mechanism of action of the substances in hair growth, as they allow the identification of levels and expression of cytokines, growth factors and signaling pathways involved in the hair cycle [209], [210], [211], [212]. Understanding and clarifying the mechanisms of action of plant species in promoting hair growth is important and should be further investigated in future research so that new herbal products that are effective against hair loss are available on the market [19].

Our review also found that very few studies conducted tests to assess the safety and irritation potential of the extracts or tested substances, such as primary skin irritation tests, toxicity tests, investigation of inflammatory infiltrates, and/or observation of animal behavior. These tests are important and must be performed to have reliable and safe herbal products for patients, minimizing risks and ensuring the protection of human health [213], [214].

This study has some limitations. It was not possible to find 12 of the studies, although we contacted the authors and requested information from colleagues from other countries and institutions. Another limitation was the heterogeneity between the studies, making it impossible to compare them. Thus, filling out the checklist that we developed should be considered.

However, it can be stated that the most widely used animal model was the mouse. Histological analyses accompanied by immunohistochemistry, gene expression analysis, and Western blot assay were the most commonly used.

Finding a product of natural origin for the treatment of alopecia will improve patientsʼ quality of life and help prevent people from taking their lives due to this situation, which we understand is not merely about esthetics but is a public health problem.


Conclusion

The treatment of alopecia remains a challenge for modern medicine. Although many natural drugs have been studied and discovered, it is still necessary to search for new hair-promoting agents. Furthermore, the underlying mechanisms of many compounds have not been studied or explained in detail.

The data synthesized in this review and the checklist can support and guide the development and execution of more robust future research that will contribute to an effective and safe natural product being approved and included for the treatment of alopecia. In addition, it will allow the comparison, reproducibility, and standardized reporting of results.

Contributorsʼ Statement

Conceptualization: JCPM; Methodology: SBG, MNP, MMF, DCMA, DC; Formal analysis and investigation and Writing – original draft preparation: SBG, MMF; Writing – review and editing, Funding acquisition, and Supervision: JCPM.




Conflict of Interest

The authors declare that they have no conflict of interest.

Supporting Information


Correspondence

Prof. Dr. João Carlos Palazzo de Mello
Laboratory of Pharmaceutical Biology
Universidade Estadual de Maringá
Avenida Colombo 5790, Palafito
87020-900 Maringá
Brazil   
Phone: + 55 44 30 11 46 27   
Fax: + 55 44 30 11 50 50   

Publication History

Received: 12 August 2024

Accepted after revision: 29 November 2024

Accepted Manuscript online:
02 December 2024

Article published online:
20 January 2025

© 2025. Thieme. All rights reserved.

Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany


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Fig. 1 Flow diagram of the systematic scoping review. Adapted from Page et al. [198].