Inhibitory effect and cross-link breaking activity of Moringa oleifera leaf crude extracts on fructose-derived advanced glycation end-products

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Background Leaf extracts of Moringa oleifera ( M. oleifera ), have been shown to have hypoglycaemic effects in both human and animal models of type 2 diabetes. However, the research on their anti-glycation effect is limited to only a few reports, and there is less knowledge in their cross-link breaking properties. We investigated the inhibitory effect of M. oleifera leaf (MOL) extracts on the formation of various types of advanced glycation end-products (AGEs) in vitro as well as their ability to break established AGE-protein cross-links. We compared these effects with that of aminoguanidine, a known inhibitor of AGEs. We also screened the extracts for their phytochemical composition. Methods Inhibitory effect of MOL extracts on AGEs formation was determined using spectrofluorimetry and enzyme-linked immunosorbent assays (ELISA). ELISA was also used to determine their cross-link breaking abilities. Standard techniques were employed for phytochemical screening. Results The polar extracts (methanol and water) showed higher percentage yields and the presence of more phytochemical constituents than the less polar extracts, hexane and ethyl acetate . After 20 and 40 days, the polar MOL extracts showed greater activity than aminoguanidine against fluorescent AGEs. For total immunogenic AGEs (TIAGEs), hexane extract showed higher inhibitory activity than aminoguanidine at 20 days. Significantly higher inhibitory activity was observed with MOL methanol extract at 40 days against TIAGEs formation. No significant improvement over aminoguanidine against N Ɛ -(caboxylmethl)lysine was observed for both time periods. As expected, all of the extracts showed greater cross-link breaking effect than aminoguanidine but there were minimum differences across the different extracts. Conclusion The results of this study suggest that MOL crude extracts have both anti-glycation and AGE-protein cross-link breaking activities.