Although the use of bioactive natural products as herbal drug preparations dates back hundreds, even thousands, of years ago, their application as isolated and characterized compounds to modern drug discovery and development only started in the 19th century, the dawn of the chemotherapy era. It has been well documented that natural products played critical roles in modern drug development, especially for antibacterial and antitumor agents.1 More importantly, natural products presented scientists with unique chemical structures, which are beyond human imagination most of the time, and inspired scientists to pursue new chemical entities with completely different structures from known drugs. Medicinal chemistry has evolved from the chemistry of bioactive compounds in early days to works at the interface of chemistry and biology nowadays. Medicinal chemistry of bioactive natural products spans a wide range of fields, including isolation and characterization of bioactive compounds from natural sources, structure modification for optimization of their activity and other physical properties, and total and semi-synthesis for a thorough scrutiny of structure activity relationship (SAR). In addition, synthesis of natural products also provides a powerful means in solving supply problems in clinical trails and marketing of the drug, for obtaining natural products in bulk amounts is often very difficult.