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.