Cytotoxic, kinetics of inhibition of carbohydrate-hydrolysing enzymes and oxidative stress mitigation by flavonoids roots extract of Dicoma anomala (Sond.)

ABSTRACT

Objective: To investigate the free radical scavenging, antidiabetic, kinetics and cytotoxic potentials of flavonoids extract of Dicoma anomala root by using standard methods. Methods: Antioxidant activity of the flavonoids was investigated at scavenging free radicals such as 1,1- diphenyl-2-picrylhydrazyl, nitric oxide, hydroxyl radical, reducing capabilities, 2,2-azinobis (3-ethylbenzothiazoline-6) sulfonic acid as well as metal chelating capability at different concentrations (0.125-1.000 mg/mL) while the antidiabetic activity was evaluated via the inhibition and kinetics of carbohydrate digestive enzymes including, alpha glucosidase, sucrase and maltase. Brine shrimp lethality assay was also employed to examine the cytotoxic effects of the extract by using different range of concentrations (0.125-2.000 mg/mL). Results: The study revealed the best antioxidant activity of the extract in 1,1-diphenyl-2-picrylhydrazyl, 2,2-azino-bis (3-ethylbenzothiazoline-6) sulfonic acid and nitric oxide having IC50 values of (386.90±4.91), (736.00±38.12), (629.30±9.62) g/mL respectively compared with quercetin (standard) with IC50 [(522.20±12.38), (1 021.00±15.61) and (1 075.00±29.35) g/mL] respective values while it was insignificantly (P>0.05) at par with quercetin for reducing power. Similarly, the extract exhibited a moderate inhibition of alpha glucosidase (43.1%), sucrase (33.4%) and maltase (29.9%) activities which were significantly (P<0.05) better than acarbose (18.4%, 12.7% and 24.9% respectively) although acarbose (46.1%) inhibited the higher activity of alpha amylase than the extract (13.7%). The kinetics of mode of inhibition of alpha amylase, alpha glucosidase, sucrase and maltase by flavonoids extract of Dicoma anomala revealed an uncompetitive, non-competitive, competitive and non-competitive inhibition respectively. The result of the lethality assay showed a potent cytotoxic effect of the flavonoids with LC50 value 0.510 mg/mL. Conclusions: The results obtained from this study are suggestive of the antioxidative, antidiabetic and cytotoxic potentials of flavonoids root extract of Dicoma anomala.