The first chapter deals with the extraction, phytochemical screening and acute toxicity studies of the ethanol and chloroform extracts of Polyalthia longifolia leaves. The second chapter deals with the in vitro antioxidant activity of the extracts. Chapter three covers the in vitro xanthine oxidase inhibitory activity. In the fourth chapter, details of the inhibition exhibited against 12-lipoxygenase enzyme is provided.The anti-cataractogenesis activity was studied using goat lens and the details are dealt in the fifth chapter. The in vitro alpha amylase and alpha glucosidase enzyme inhibitory effect and the enzyme kinetics have been discussed in the sixth chapter. Streptozotocin was used to induce type 1 diabetes in rats and the anti-diabetic were tested in the type 1 diabetic rats. The details of the same are explained in the seventh chapter.Effect against streptozotocin-nicotinamide-induced type 2 diabetes in rats and protection against peripheral neuropathy were also studied. The eighth chapter deals with the same.This book will be a useful guide to medical, pharmacology, pharmacy and other allied science researchers.