Editorial [Hot topic: Natural Products (Guest Editors: Wei-Shuo Fang and Junzeng Zhang)]

Natural products have been used for thousands of years in human history for prevention and treatment of diseases, or for maintaining general wellness. Bioactive natural products are also the important sources of many current therapeutic agents, either in original forms or derivatives made from the natural lead compounds. During the past decades, new tools and strategies such as the combinatorial chemistry, high-throughput screening and computer-aided drug design have been introduced into drug discovery and development process and this certainly helps accelerating the pre-clinical studies in pharmaceutical industry. On the other hand, however, pharmaceutical industry is still in great need of the unique chemical diversity and biological relevancy observed in the natural products, resulting from millions of years' evolution. The chemical diversity of natural products comes from the biodiversity of organisms on earth. As such, the topics for these two themed issues on bioactive natural products (issues 16 and 17) would reflect this type of diversity and cover natural products from microbes to higher plants and from marine to terrestrial environment. As a continuation to issue 16, we are delighted to offer the CTMC readers another five reviews as follows. For the microbe-derived natural products, Zhan provided overview on the recent progress in biosynthesis research of bioactive aromatic polyketides from microorganisms with a focus on new enzymes or methods used in building the novel polyketide biosynthetic machinery. Natural products and herbal remedies for treatment of allergic inflammation, such as allergic rhinitis are reviewed by Kulka with discussions on their molecular mechanisms. This unique pharmacological perspective of bioactive natural products emphasizes the importance of biological activity - novel chemical structure is exciting, but new therapeutical applications are equally valuable. Bioactive natural products are important lead for drug discovery, and many therapeutic agents actually come from the chemical derivation and synthesis based on the natural leads. Dai provided in-depth coverage on a chemo-enzymatic transformation of taxanes, and the reversal activity towards multidrug resistance (MDR) tumor cells. These works demonstrate a powerful approach for natural products-based lead compound discovery by combining biotransformation with chemical conversion in structure diversification of natural products. In the review by Chen, the synthesis as well as biological activity of nordihydroguaiaretic acid and its derivatives, which have been extensively explored for their potential uses in the treatment of cancers, diabetes, viral, bacterial infections, and inflammation, are comprehensively documented. In closing this issue, Chang et al. reviewed the synthesis and biological activity of Wuweizisu C and analogues, lignans from a popular Chinese medicinal herb, illustrating this successful drug discovery strategy of combining ethnopharmacological knowledge and modern medicinal chemistry technology. Finally, we would like to thank Dr. Allen B. Reitz, for the invitation to be the Guest Editor of this special issue. We wish to offer our sincere appreciation to all the contributors for their dedication and hard work.