Phytochemical screening and in-vitro evaluation of Free Radical Scavenging Activity of Pistia stratiotes extracts

Medicinal plants have been identified and used throughout human history and many of the pharmaceuticals currently available to physicians have a long history of use as herbal remedies A large number of trado-medical uses were attributed to the Pistia stratiotes particularly the leaves. The root was applied as emollient and diuretic, while leaves infusions have been used for treatment of dropsy, kidney afflictions, dysentery, anaemia, eczema, leprosy, piles and syphilis and when boiled in coconut oil was applied externally in chronic skin infections. Current study was aimed at investigating the phytochemicals and antioxidant activities of methanol and n-hexane extracts of the leaves of Pistia stratiotes. Antioxidant activity was determined by spectrophotometric at 517 nm using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical mechanism with Vitamin C as reference standard. Phytochemical analysis confirmed the presence of flavonoids, tannins, alkaloids, steroids, reducing sugars, glycosides, deoxy sugars, resins and saponins. However, anthraquinones and volatile oils were not detected, while detection of phenolic compounds in extracts was confirmed by the positive test for flavonoids. From calibration curves, linearity of absorbance and % inhibition with concentration of Vitamin C was 0.9687 and 0.9685 respectively. Also, the linearity of absorbance with concentration of methanol and n-hexane extracts was 0.9528 and 0.9263 respectively. Also the linear correlation between the % inhibition and concentrations of methanol and n-hexane extracts were 0.9554 and 0.9520 respectively. In this study, hexane shows a better antioxidant activity (32.5-53.1%) than methanol extracts (31.5-43.4%) at 20-200μg/ml. Optimum inhibition of n-hexane extract (60.3%) was lower when compared to Vitamin C (93.4 %) at 300.0μg/ml. The IC50 for methanol and n-hexane extracts were 203.1 and 155.7μg/ml respectively, indicating a moderate antioxidant activity when compared to Vitamin C (13.9μg/ml). The results of this study confirms that the aquatic plant contain some natural compounds that could be used as antioxidants.