Objective: To assess the phytochemical contents and antioxidant activities of crude extracts from selected Tulbaghia species.
Methods: Standard methods were used for preliminary phytochemical analysis. The total phenolic acid contents of the plant extracts were determined using the Folin-Ciocalteu method, and the total flavonoid contents were determined using the aluminum chloride colorimetric method. 1,1-Diphenyl-2-picrylhydrazyl and 2,2'-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) assays were used to evaluate the antioxidant activities.
Results: Phytochemical screening showed flavonoids, glycosides, tannins, terpenoids, saponins, and steroids were present in the Tulbaghia species. The total phenolic acid and flavonoid contents varied in the different plant extracts, ranging from 4.50 to 11.10 mg of gallic acid equivalents per gram of fresh material and 3.04 to 9.65 mg of quercetin equivalents per gram, respectively. The IC50 values determined for Tulbaghia alliacea and Tulbaghia violacea based on 1,1-diphenyl-2-picrylhydrazyl (0.06 and 0.08 mg/mL, respectively) and 2,2'-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (0.06 and 0.03 mg/mL, respectively) were low and showed they had potential antioxidant activities.
Conclusion: Our results suggest that individual compounds from Tulbaghia species should be isolated for analysis of their antioxidant activity because some compounds may work best when pure.
Keywords: Antioxidants; Phenols; Phytochemicals; Tulbaghia.