The need to higher stereo- and/or regio-selectivity control, milder reaction conditions, decreased waste generation, and fewer reaction steps, biotransformation and biosynthesis approaches have become powerful alternatives to chemical synthesis and diversification of structures of bioactive natural products. In this issue, a total of 10 articles that report recent progresses in natural products biotransformation and biosynthesis are compiled. Therein, whole-cell biotransformation of bioactive natural products by microorganisms or zebrafish (Xiang-Ge Tian and colleagues, Xiao-Ling Lu and Xiao-Yu Liu et al., Di-an Sun et al., Bin Chen and Dao-Quan Tang et al.), glycosylation by promiscuous glycosyltransferase (Min Ye et al., Jian-Qiang Kong et al., Jun-Gui Dai et al.), metabolic engineering of lipopeptide production (Tian-Hua Zhong et al.) as well as biosynthesis of plant natural products (Lu-Qi Huang and Xia-Nan Zhang et al., Lin-Guo Zhao et al.) are main topic in this issue.
Xiang-Ge Tian and Shan-Shan Huang’s group reported the investigation on biotransformation of imperatorin and its analogs, a family of natural products with linear furanocoumarin skeleton, by Aspergillus niger or Cunninghamella blakesleana. Hydroxylation or deprenylation occurred when the cultures was supplied with imperatorin and its analogs. Ten products were obtained from the biotransformation efforts and some of them showed moderate anti-osteoporosis activities. Xiao-Ling Lu, Xiao-Yu Liu and colleagues reported the biotransformation of total coumarins of Radix Glehniae by Lecanicillium attenuatum to give three new products. Hydrogenation, dealkylation, glycosylation, and methylation were some of the reactions that took place during biotransformation. Di-An Sun’s group investigated the transformation of pseudoprotodioscin by fungus Gibberella fujikuroi, and a total of 12 steroidal saponins including three new ones were obtained. The transformational sequence of pseudoprotodioscin by G. fujikuroi was also proposed.
Glycosylation is a powerful approach to improve water solubility, bioavailability, transport, and excretion of natural products. Different from biotransformation using microorganism, where reactions by different cellular enzymes can occurs and is typically unpredictable, enzymatic glycosylation catalyzed by recombinant glycosyltransferases can provide more precise modifications and lead to predictable products. Three articles in this issue reported different glycosyltransferases that catalyzed the glycosylation of diverse substrates. Min Ye’s group reported YjiC1 from Bacillus subtilis that catalyzed the glycosylation of oleanane-type triterpenoids and increased the anti-HIV activities of products. Jian-Qiang Kong’s group showed OcUGT1, a multifunctional glycosyltransferase from O. caundatum, was able to catalyze the 8-O-glycosylation of flavonoids via both glycosylation and trans-glycosylation reactions. To decorate two neurological active agents, Jun-Gui Dai’s group successfully utilized three plant UDP-dependent glucuronosyltransferases in the biosynthesis of O-glucuronosylated products.
During investigation of the biosynthesis of steroids from Paris polyphylla, a traditional Chinese herb medicine, Lu-Qi Huang, Xia-Nan Zhang, and their co-workers identified and functionally characterized two sterol-C24-methyltransferase enzymes. Lin-Guo Zhao and his colleagues investigated the differentially expressed genes in different cultivar Osmanthus by RNA-Seq, and verified enzymes involved in ionone biosynthesis. These research findings provide foundation for further elucidation of the biosynthetic pathway of steroids and ionone in plants.
By metabolic engineering and optimization of fermentation conditions, Tian-Hua Zhong and his co-workers were able to significantly increase the yield of enduracidin A, a nonribosomal peptide that has activity against Gram-positive bacteria, in Streptomyces atrovirens CGMCC No. 3365. Bin Chen and Dao-Quan Tang’s groups investigated the biotransformation of ginsenosides F4 and Rg6 in zebrafish, and found that this two main bioactive ingredients in steamed notoginseng or red ginseng could be metabolized via desugarization, glucuronidation sulfation, and dihydroxylation and led to the multiple metabolites, which provide foundation for further study on their druggability.
Overall, we hope the diverse articles in this issue provide our readers a general scope and new knowledge of biotransformation and biosynthesis of natural products.