Optimization, Characterization and Fundamental Biological Relationships of Polysaccharides From Bergera Koenigii (Curry Leaves) as Antioxidant, Antidiabetic and Antihypertensive Agents

Polysaccharides have been widely known to exhibit various biological effects. This study explored the potential health benefits of polysaccharides extracted from Bergera koenigii leaves (BKLP) as antioxidants, antidiabetic, and antihypertension agents. Bergera koeniigi leaves were dried and ground to form a fine powder. The extraction of polysaccharides was conducted by using microwave-deep eutectic solvent-assisted extraction. After extraction, various biological activities, physicochemical, and structural characterizations of polysaccharides were further investigated. The extraction was optimized using a response surface approach, resulting in a yield of 18.21% at 30% microwave power, 2 min extraction time, 1% DES concentration, 1:20 g/mL solid-to-buffer ratio, and employing DES-BUD (citric acid monohydrate:1,4-butanediol-based deep eutectic solvent). Following optimization, an extensive physicochemical and structural analyses were performed. BKLP showed a low molecular weight (28.14 kDa), highly water-soluble due to its high amorphous, low-methoxy polysaccharide (DE = 21.50%), and exists in β-configuration. It is largely composed of glucose, galactose, and xylose, which are considered glucose-rich polysaccharides. BKLP had a non-triple helix configuration and minimal branching. The biological activities of BKLP revealed high dose-dependent antioxidant, antidiabetic, and antihypertensive properties. BKLP demonstrated DPPH, ABTS, and FRAP activity, exhibiting IC 50 values of 0.53 mg/mL, 0.27 mg/mL, and 1.23 mM FeSO₄ at 1 mg/mL, respectively. BKLP also inhibited α-amylase and Angiotensin-converting enzyme (ACE), with IC 50 values of 0.62 mg/mL and 0.70 mg/mL. BKLP has been shown to exhibit strong antioxidants, antidiabetic, and antihypertensive activities, which potentially could be applied as a natural health benefit for diabetes and hypertension management.