Investigative studies on the inhibition of amyloid-like fibrils formation by the extracts of Vernonia amygdalina Del. leaf

Secondary metabolites from medicinal plants have been reported to inhibit the formation of glucose-induced protein aggregation. This study investigated the inhibitory potential of Vernonia amygdalina leaf extracts on amyloid protein aggregation. Prevention of glycation-induced amyloid-beta fibril formation was evaluated through the assessment of anti-glycation capacities of the extracts, inhibitions of glycation-induced oxidation of protein thiol groups and protein aggregation. Colorimetric methods were used for the estimation of aqueous and methanol extract of V. amygdalina. Luteolin, luteolin-7-O-beta-glucuronoside, and luteolin-7-O-beta-glucoside were identified through a previous study and evaluated for their binding energies with amyloid-beta and amyloid-beta fibril. The results showed that aqueous extract had higher amounts of phenolics while methanol extract had higher amounts of flavonoids contents. The aqueous extract exhibited higher albumin glycation inhibitory potential with the IC50 value of 65 mu g/ml. The methanol extract possessed higher protective effects on the total thiol groups of the glycated albumin and also exhibited higher inhibition of aggregates formation when compared with the aqueous extract. Luteolin-7-O-beta-glucuronoside had the highest binding affinity with the amyloid beta-peptide (1-42) and amyloid-beta (1-42) fibrils with the mean values of - 5.63 kcal/mol and -6.48 kcal/mol respectively. However, it was observed that luteolin exhibited the highest binding free energy of - 20.43 kcal/mol and - 8.67 kcal/mol with both proteins respectively. The ADMET properties revealed all the phytochemicals possess drug-like properties. These results demonstrated that phytoconstituents of V. amygdalina could act as highly potent inhibitors of protein aggregation and could be a promising candidate for the management of hyperglycaemia-induced protein aggregation.

Automated summary

The study revealed that extracts from Vernonia amygdalina leaves have inhibitory effects on amyloid protein aggregation, with aqueous extract showing stronger anti-glycation potential and methanol extract demonstrating better protection on protein thiol groups and inhibition of aggregate formation. Different compounds within the extracts exhibited varying degrees of binding affinity with amyloid beta proteins, suggesting their potential as potent inhibitors of protein aggregation.