Pharmacologically tested aldose reductase inhibitors isolated from plant sources-A concise report

Aldose reductase (AR), a cytosolic, monomeric oxidoreductase, is a key enzyme in the polyol pathway which controls the conversion of glucose to sorbitol. The accumulation of sorbitol by the activation of AR enzymes in lens, retina, and sciatic nerves leads to the cause of diabetic defects resulting in various secondary complications, viz. retinopathy, neuropathy, nephropathy and Alzheimer's disease. Thus, reduction of the polyol pathway flux by AR inhibitors could be a potential therapeutic opening in the treatment and prevention of diabetic complications. At present, the AR inhibitors belong to two different chemical classes. One is the hydantoin derivatives, such as Sorbinil, Dilantin, and Minalrestat, and the other is the carboxylic acid derivatives, such as Epalrestat, Alrestatin, and Tolrestat. However, it is known that most of these synthethic compounds have unacceptable side-effects. Well known medicinal plants like Chrysanthemum indicum, Chrysanthemum morifolium, Prunus mume, Myrcia multiflora, Centella asiatica, and Salacia reticulata, Salacia oblonga, and Salacia chinensis exhibited potent AR inhibitory activity. The present review summarizes the list of plant material, and their isolated phytoconstituents which have been tested for their AR inhibitory activity. This litreature review covers the period to 2011, and a total of 72 plants are listed.