Advanced glycation end-products (AGEs) are linked to several pathological events which include diabetes and other age-related diseases. Inhibition of AGEs formation and breakage of established AGEs-protein cross-links are two strategies employed for combating the devasting effect of AGEs. Although some anti-glycation agents exist, most are not clinically approved because of their harmful side effects. There is therefore a need to explore the option of medicinal plants for this challenge. 

Four medicinal plants with scientifically proven blood glucose reducing property were investigated for their ability to prevent the formation of various types of AGEs or reverse AGEs-protein cross-links. The hexane, ethyl acetate, methanol and water extracts of Murraya koenigii (curry leaf) leaf, Psidium guajava (guava) leaf, and Sclerocarya birrea (cider tree) stem-bark as well as water stem-bark extract of Cinnamomum cassia (cinnamon) were incubated for 40 days at 37oC with bovine serum albumin (BSA)-glucose mixture. Aminoguanidine, an established antiglycation agent was used as control.  

All curry leaf extracts, the hexane, ethyl acetate and methanol extracts of guava leaf, hexane stem-bark extract of cider tree and cinnamon stem-bark water extract were more effective than aminoguanidine against total immunogenic AGEs formation. For fluorescent AGEs, the cider extracts and guava leaf polar extracts were more effective than aminoguanidine in preventing the formation of this type of AGEs. The guava leaf and cider tree stem-bark extracts were most effective in uncoupling AGEs-protein cross-links. Phytochemical evaluation of the selected plants and extracts revealed the presence of various secondary metabolites which may have contributed to the anti-AGEs properties observed. Further work is required to identify and isolate specific compounds from the most effective extracts and plants which may then be utilised as nutraceuticals or highly effective anti-glycation drugs.