During the last few decades, research into chemistry of natural products has advanced tremendously thanks to contributions from the fields of chemistry, life sciences, food science and material sciences. Comparisons of natural products from microorganisms, lower eukaryotes, animals, higher plants and marine organisms are now well documented. This book provides the detail study of isolation, structure elucidation and In-vitro antioxidant activity of Actiniopteris radiata Linn. In this, the chemical constituents isolated from different extracts of actiniopteris radiata (whole plant) namely, Stigmasterol, ?-sitosterol palmitate, hentriacontanol, ?-sitosterol ,Quercetin and rutin. further these extracts were screened for antioxidant acitivity, from which ethylacetate extract and isolated compound RUTIN shows significance response of antioxidant activity. This book is dedicated to new and important research in the field of phytochemistry which is in the strict sense of the word the study of phytochemicals.