The antimicrobial and antioxidant potential of Lithops lesliei, a South African medicinal plant

The Mesembryanthemaceae account for approximately 63% of the southern African succulent flora [1]. Lithops, known as “living stones” represents one of the most popular and widespread genera of the family. Lithops lesliei (N.E. Br) has gained prominence for its use as an ornamental and in traditional medicine [1]. This study investigated the antimicrobial and antioxidant properties of whole plant crude extracts. The antimicrobial activity of plant extracts on a range of Gram-positive and Gram-negative bacterial and fungal species was determined using the broth microdilution assay [2]. Antioxidant activity was determined by DPPH radical scavenging activity, β-carotene-linoleate bleaching assay and the ferric reducing antioxidant power (FRAP) assay using extracts obtained via soxhlation and sonication [2]. Antimicrobial activity was obtained in chloroform and methanolic extracts, particularly against Pseudomonas aeruginosa, Escherichia coli and Streptococcus pyogenes (MIC values of 0.625 mg/mL). All extracts exhibited poor antifungal activity against Candida albicans and Cryptococcus neoformans. The antioxidant activity of soxlation-derived, methanolic plant extracts was appreciable when compared to BHT (83.5% and 71%, respectively in the β-carotene linoleic acid assay). Dose dependent FRAP activity was obtained for both sonicated and soxhlation-derived methanolic extracts at comparable levels to BHT and ascorbic acid. This study supports the use of L. lesliei as an antibacterial and antioxidant agent in several applications and strengthens the use of this succulent as a source of novel, biologically active phytocompounds.

References:

[1] Smith GF, Crouch NR. Mesembs in the muthimarket: Lithops lesliei as an ethnomedicinal plant. British Cactus & Succulent Journal 1999; 17: 133 – 137

[2] Ndhlala AR, Mulaudzi R, Ncube B, Abdelgadir HA, du Plooy CP, Van Staden J. Antioxidant, antimicrobial and phytochemical variations in thirteen Moringa oleifera Lam. cultivars. Molecules 2014; 19: 10480 – 10494