Natural Product Research Vol. 25, No. 7, April 2011, 760–763 SHORT COMMUNICATION Aldose reductase inhibitory, anti-cataract and antioxidant potential of selected medicinal plants from the Marathwada region, India R.N. Gacche * and N.A. Dhole School of Life Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606 (MS), India (Received 16 February 2010; final version received 19 October 2010) The water, ethanol and chloroform extracts of selected plants such as Adhatoda vasica (L.) (Acanthaceae), Caesalpinia bonduc (L.), Cassia fistula (L.) (Caesalpiniaceae) and Biophytum sensitivum (L.) (Oxalidaceae) were evaluated for rat lens aldose reductase inhibitory (RLAR) potential, anti-cataract and antioxidant activities. All the samples inhibited the aldose reductase considerably and exhibited anti-cataract activity, while C. fistula (IC 50 , 0.154 mg mL À1 ) showed significant RLAR inhibitory activity as compared to the other tested samples, and was further found to be more effective in maintaining sugar-induced lens opacity in the rat lens model. The antioxidant potential of plant extracts was determined using DPPH (2,2-diphenyl-1-picryl hydrazine), hydroxyl (OH), nitric oxide (NO) and hydrogen peroxide (H 2 O 2 ) scavenging activities, along with determination of reducing power, ferrous ion chelating ability and inhibition of polyphenol oxidase (PPO). The extracts of the tested plant showed significant free radical scavenging activities and inhibited the activity of enzyme PPO, a model oxidising enzyme. The plant samples were found to possess considerable amounts of vitamin C, total polyphenols and flavonoids. Keywords: aldose reductase; enzyme-inhibition; anti-cataract; antioxidants; medicinal plants; diabetic complications 1. Introduction Aldose reductase (AR) inhibition has been identified as one of the targets for the development of novel antidiabetic agents. AR (EC 1.1.1.21) is the rate limiting enzyme that catalyses the reduction of glucose to sorbitol in the polyol pathway. Sorbitol, a sugar alcohol, is then further converted to fructose by sorbitol dehydrogenase. Normally, approximately 3% of glucose enters the polyol pathway (Morrison, Clements, Travis, Oski, & Winegrad, 1970), but in the hyperglycaemic condition more than 30% of glucose goes through the polyol pathway, which results in various metabolic imbalances in the cells (Gonzalez, Barnett, Aguayo, Cheng, & Chylack, 1984). Excess sorbitol accumulation in the lens causes osmotic swelling, which is linked to the formation of cataracts and other related diabetic complications *Corresponding author. Email: rngacche@rediffmail.com ISSN 1478–6419 print/ISSN 1029–2349 online ß 2011 Taylor & Francis DOI: 10.1080/14786419.2010.536951 http://www.informaworld.com