Evaluation of In vitro Antioxidant and Antidiabetic Activities of Stem Bark Extracts of Nothopegia racemosa Dalz

Background: The stem bark of Nothopegia racemosa (Dalz). was collected from Dandeli, Tinaighat, 
and Malsang forests in Karnataka, identified by a taxonomist. The stem bark is shade-dried, 
powdered, and successively extracted with solvents of increasing polarity. Extracts were screened for 
phytochemicals and evaluated for antioxidant activity (DPPH and hydroxyl radical scavenging) using 
ascorbic acid and gallic acid as standards, and for antidiabetic potential (α-amylase and α-glucosidase 
inhibition) using acarbose as the standard. All assays were performed in triplicate, and IC₅₀ values 
were determined. Results: Phytochemical analysis confirmed the presence of tannins, flavonoids, 
glycosides, and polyphenols. Antioxidant evaluation showed that ethanolic and aqueous extracts 
exhibited better activity in both DPPH (IC₅₀ = 172.36 and 71.18 µg/ml) and hydroxyl radical 
scavenging assay(IC₅₀ = 169.35 and 89.9 µg/ml), though less potent than standards (IC₅₀ = 20 µg/ml). 
Ethyl acetate extract showed moderate activity in both DPPH and hydroxyl radical scavenging (IC₅₀ 
= 366.52 and 330.8 µg/ml). Antidiabetic assays revealed that ethanolic and aqueous extracts 
displayed marked inhibition of α-amylase (IC₅₀ = 22.53 and 18.03 µg/ml) and α-glucosidase (IC₅₀ = 
2.642 and 1.961 µg/ml), compared to acarbose (IC₅₀ = 3.039 and 0.316 µg/ml). Among all, the 
aqueous extract showed the highest potency as antidiabetic and antioxidant property. Conclusion: 
The study highlights the significant antioxidant and antidiabetic potential of N. racemosa, attributed 
mainly to its phenolic and flavonoid constituents. The aqueous extract shows better activity, 
supporting its traditional use and a promise as a natural therapeutic source for managing oxidative 
stress and postprandial hyperglycemia.