Inhibition of advanced glycation end product and lipid peroxidation by extract and fractions of Newbouldia laevis

Newbouldia laevis is generally known for its significant antidiabetic potentials. Advanced glycation end-products (AGEs) and lipid peroxidation contribute significantly to the pathogenesis of diabetic complications through oxidative stress and protein damage. This study evaluated the inhibitory effects of extract and fractions of Newbouldia laevis leaves on AGE formation and lipid peroxidation. The leaves were extracted using 70% aqueous ethanol and partitioned into n-hexane, ethyl acetate, butanol, and water fractions. In vitro assays revealed the ethyl acetate fraction with the highest total phenolic content and exhibited the strongest ferric reducing antioxidant power and inhibition of lipid peroxidation. The formation of AGEs and glycation-induced protein carbonylation were significantly suppressed in a concentration-dependent manner, with the ethyl acetate fraction demonstrating the most potent activity in weeks 2 – 4 at 0.4 – 1.6 mg/ml concentrations, comparable to aminoguanidine, a standard AGE inhibitor. The butanol and water fractions also showed notable inhibitory effects, whereas the n-hexane fraction exhibited the least activity. The inhibitory potential of the fractions correlated with their phenolic content, suggesting a phenol-mediated mechanism. These findings support the therapeutic potential of N. laevis, particularly its phenol-rich fractions, in mitigating oxidative stress and protein glycation associated with diabetes mellitus and its complications.