V. K. GUPTA 
Comprehensive Bioactive Natural Products (Efficacy, Safety & Clinical Evaluation I) 

Natural product preparations in the past and even today have been the major source of numerous highly potent pharmaceutical agents, and indeed, more than 90% of current therapeutic classes have been derived from a natural product prototype. Interestingly, even today, roughly two-thirds to three-quarters of the worlds population relies upon medicinal plants for its primary pharmaceutical care. This is due to their greater potency and lesser side effects. During the past two decades, traditional systems of medicine have become a subject of global importance and about thirty per cent of the worldwide sales of drugs is based on natural products. Majority of the population in most developing countries continue to use bioactive natural products for their common health needs has resulted in increased concern about efficacy, safety and clinical evaluation of these products.