Phytochemical analysis and antioxidant activity of methanol extract and betulinic acid isolated from the roots of Tetracera potatoria

Aim

This study was designed to assess the antioxidant property of crude methanolic extract of Tetracera potatoria roots (MeTp); a bioactive constituent isolated from it, betulinic acid (BA) and a combination of BA with ascorbic acid.

Methods

The crude extract was obtained by cold extraction. Phytochemical screening of the crude extract was carried out using standard methods. Isolation of betulinic acid (BA) was effected by Accelerated Gradient Chromatography (AGC) fractionation of MeTp. Structural elucidation of the isolated BA was done with ¹H and ¹³C NMR spectroscopic technique. MeTp, isolated BA and BA plus ascorbic acid mixture (1:1) were evaluated for their antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl, (DPPH) method.

Results

The phytochemical analysis showed the presence of alkaloids, flavonoids, cardiac glycosides, saponins and tannins. Anthraquinones were absent. The ¹H and ¹³C NMR data obtained for the isolated BA were in accordance with published data. Antioxidant activity (IC₅₀) of tested materials ranged from 18 to 148 μg/ml, with MeTp having the highest value relative to ascorbic acid, the reference standard. The radical scavenging activities of MeTp and that of BA plus ascorbic acid mixture were greater than that of ascorbic acid alone, indicating synergism between ascorbic acid and betulinic acid.

Conclusion

The findings established the antioxidant property of methanolic root extract of T. potatoria. The combination of betulinic acid and ascorbic acid could be useful for the development of new antioxidant drug.