This volume is a comprehensive compilation of contributions on the state of the art knowledge about bioactive compounds including their sources, isolation methods, biological effects, health benefits and potential applications. These bioactive compounds could serve as alternatives in the prevention or treatment of multifactorial diseases for vulnerable population groups. Chapters in the book incorporate the knowledge based on traditional medicine with recent findings on bioactive molecules and their pharmaceutical implications in neurodegenerative diseases, cancer, COVID 19, diabetes, immunomodulation and farm animal diseases. The book also highlights the latest breakthroughs in the field of screening, characterization, and novel applications of natural bioactive compounds from diverse group of organisms ranging from bacteria, algae, fungi, higher plants, and marine sources. Authors from renowned institutions of India, Japan and China have shared their expertise in the contributed chapters with the goal of enhancing readers' knowledge about the significance of use of bioactives in therapeutics and nutraceuticals. It is an informative reference for researchers, professors, graduate students, science enthusiasts, and all those who wish to gain insights into various aspects of bioactive compounds, and the development of new pharmaceutical constituents and nutraceuticals.