ABSTRACT
The study evaluated the effect of extracts of the seeds and pod parts of Lessertia montana on diabetes and freeradicals. Free radical scavenging activities of the extracts was tested against 1,1-diphenyl-2-picrylhydrazyl (DPPH),nitric oxide, 2,2-azinobis (3-ethylbenzothiazoline-6) sulphonic acid (ABTS), hydroxyl radical and reducing power,metal chelating assays, while the antidiabetic activity was assessed via the inhibition and kinetics of α-amylase andα-glucosidase. The pod decoction extract revealed the best radical scavenging activities in DPPH, ABTS, and metalchelating (with IC50 values 1,371, 730, and 798 µg/ml, respectively) compared with other extracts and control havingan IC50 (3,094, 4,125, and 523 µg/ml, respectively) values. While the aqueous ethanolic extract for both parts exhibitedthe highest reducing capabilities of 2.969 (pod) and 3.457 (seeds) at 1 mg/ml, the aqueous extract of the seed showedthe best inhibitory activities in two of the six tested assays, namely, hydroxyl radical (717 µg/ml) and metal chelating(59 µg/ml). The kinetics of inhibition of α-amylase and α-glucosidase by aqueous ethanolic extract of the pod wascompetitive and non-competitive, respectively, while the two enzymes were uncompetitively inhibited by ethanolicextract of the seed. The investigation corroborated the antioxidative and antidiabetic potentials of the leaf as previouslyestablished from our group.
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.