The study evaluated the effect of extracts of the seeds and pod parts of Lessertia montana on diabetes and free radicals. 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 assessed via the inhibition and kinetics of alpha-amylase and alpha-glucosidase. The pod decoction extract revealed the best radical scavenging activities in DPPH, ABTS and metal chelating (with IC50 values 1371, 730, 798 µg/mL respectively) compared with other extracts and control having IC50 (3094, 4125 and 523 µg/mL respective) values. While the Aq.ethanolic extract for both parts exhibited highest reducing capabilities of 2.969 (pod) and 3.457 (seeds) at 1 mg/mL, the aqueous extract of the seed showed the 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 Aq.ethanolic extract of the pod was competitive and non-competitive respectively while the two enzymes were uncompetitively inhibited by ethanolic extract of the seed. The investigation corroborated the antioxidative and antidiabetic potentials of the leaf as previously established from our group.
Key words: Antihyperglycaemic, free radicals, modes of inhibition, L. montana
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