One of the main objectives of pursuing research on medicinal plants is to identify the active principle(s). The plants, with which we are intimately associated in our everyday life, possess the major active constituents of many medicines. Most of the currently used important drugs contain active ingredients from plants. This information demonstrates the importance of natural products in drug discovery. The beneficial effects of plants of whatever origins are usually due to the secondary metabolites present in it.Induced by this state of affairs, the present investigator decided to undertake the systematic chemical investigation of one or two important plants, preferably endemic to Southern Assam where the present investigator hails from and also pursues his academic activities, and to screen the plant extracts or the pure secondary metabolites for certain types of bioactivities. Tree fern, Cyathea gigantea, belonging to the family. Cyatheaceae, is on the verge of being extinction. This warning motivated the present investigator to select two plants, Cyathea gigantea and Cyathea brunoniana. for their systematic chemical analysis and screening for biological activities.