Evaluating the stability and quality of commercially available tinctures of Scutellaria lateriflora L.

American skullcap, (Scutellaria lateriflora L.) belongs to the Lamiaceae family and is one of 300 Scutellaria species worldwide. It’s been traditionally used by Native Americans for its sedative and diuretic properties. The anxiolytic properties of the Scutellaria species have been attributed to the flavonoids present. The main constituents baicalin and baicalein bind to the benzodiaspine site of the GABAA receptor. While baicalin is considered the main active constituent within S. lateriflora, baicalein has shown higher affinity to the benzodiaspine site, exhibiting a stronger anxiolytic effect. S. lateriflora preparations are sold as commercial tinctures and hydroalcoholic solutions, for their practicality in storage and dosage. A key challenge is validating the stability and quality of herbal products, due to their complex nature. Source material, solvent to solute ratio, and type of extraction can dictate the quality, safety, and efficacy of the preparations. Key constituents, baicilin and baicalein, are pH and temperature sensitive which may cause change in composition over time.

In this study, a significant difference was found between commercial tinctures prepared with fresh and dried plant material of S. lateriflora. Comparatively, levels of baicalin were lower (48 – 58%) in fresh plant tinctures, potentially due to hydrolysis by glucuronidases enzymes present in fresh plant tinctures. Additionally, fresh plant tinctures were placed under accelerated storage conditions (25°C/RH 45%), resulting in an observable change over the 6-month period ([Fig. 1]).

Fig. 1 HPLC-PDA chromatograms of S. lateriflora tinctures. a: Fresh-plant tinctures at initial timepoint. b: Fresh-plant tinctures after 6 months. c: Dry-herb tinctures. 1-internal standard (4-hydroxybenzoate), 2-baicalin, 3-wogonoside, 4-baicalein, 5-wogonin, 6-oroxylin A.

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Artikel online veröffentlicht:
16. November 2023