A green and cost-effective process for the convenient synthesis of acylphloroglucinol 3-C-glucosides from 2-O-glucosides was exploited using a novel C-glycosyltransferase (MiCGTb) from Mangifera indica. Compared with previously characterized CGTs, MiCGTb exhibited unique de-O-glucosylation promiscuity and high regioselectivity toward structurally diverse 2-O-glucosides of acylphloroglucinol and achieved high yields of C-glucosides even with a catalytic amount of uridine 5′-diphosphate (UDP). These findings demonstrate for the first time the significant potential of a single-enzyme approach to the synthesis of bioactive C-glucosides from both natural and unnatural acylphloroglucinol 2-O-glucosides.

The microbial transformation of 14-anhydrodigoxigenin (1) by Alternaria alternata CGMCC 3.577 led to the production of seven new metabolites, 2–8. Their structures were determined by extensive spectroscopic (CD, IR, 1D- and 2D-NMR, and HR-ESI-MS) data analyses. The reactions in the bioprocess exhibited diversity, including specific oxidation, hydroxylation, reduction, epoxidation, and dehydration. In addition, a hypothetical biocatalytic pathway is proposed.

The catalytic promiscuity of the novel benzophenone C-glycosyltransferase, MiCGT, which is involved in the biosynthesis of mangiferin from Mangifera indica, was explored. MiCGT exhibited a robust capability to regio- and stereospecific C-glycosylation of 35 structurally diverse druglike scaffolds and simple phenolics with UDP-glucose, and also formed O- and N-glycosides. Moreover, MiCGT was able to generate C-xylosides with UDP-xylose. The OGT-reversibility of MiCGT was also exploited to generate C-glucosides with simple sugar donor. Three aryl-C-glycosides exhibited potent SGLT2 inhibitory activities with IC₅₀ values of 2.6×, 7.6×, and 7.6×10⁻⁷ M, respectively. These findings demonstrate for the first time the significant potential of an enzymatic approach to diversification through C-glycosidation of bioactive natural and unnatural products in drug discovery.

The catalytic promiscuity of the novel benzophenone C-glycosyltransferase, MiCGT, which is involved in the biosynthesis of mangiferin from Mangifera indica, was explored. MiCGT exhibited a robust capability to regio- and stereospecific C-glycosylation of 35 structurally diverse druglike scaffolds and simple phenolics with UDP-glucose, and also formed O- and N-glycosides. Moreover, MiCGT was able to generate C-xylosides with UDP-xylose. The OGT-reversibility of MiCGT was also exploited to generate C-glucosides with simple sugar donor. Three aryl-C-glycosides exhibited potent SGLT2 inhibitory activities with IC₅₀ values of 2.6×, 7.6×, and 7.6×10⁻⁷ M, respectively. These findings demonstrate for the first time the significant potential of an enzymatic approach to diversification through C-glycosidation of bioactive natural and unnatural products in drug discovery.

GuA6DT, a flavonoid prenyltransferase, was identified from Glycyrrhiza uralensis, and it was found that this enzyme regiospecifically transfers a dimethylallyl moiety to apigenin at the C-6 position. A further substrate specificity investigation indicated that the existence of hydroxyls at both the C-5 and C-7 positions of the flavone skeleton is critical for the prenylation. However, substitutions on the B-ring had negligible influence on the prenylation. A comparison of GuA6DT expression in different organs revealed that mRNA is mainly expressed in the aerial parts. Moreover, the GuA6DT mRNA was found to be regulated at the transcriptional level, because methyl jasmonate induced upregulation in cultured cells. GuA6DT is the first identified flavone prenyltransferase to exhibit strict substrate specificity and regiospecificity.

Prenylflavonoids are valuable natural products that are widely distributed in plants. They often possess divergent biological properties, including phytoestrogenic, anti-bacterial, anti-tumor, and anti-diabetic activities. The reaction catalyzed by prenyltransferases represents a Friedel–Crafts alkylation of the flavonoid skeleton in the biosynthesis of natural prenylflavonoids and often contributes to the structural diversity and biological activity of these compounds. However, only a few plant flavonoid prenyltransferases have been identified thus far, and these prenyltransferases exhibit strict substrate specificity and low catalytic efficiency. In this article, a flavonoid prenyltransferase from Sophora flavescens, SfFPT, has been identified that displays high catalytic efficiency with high regiospecificity acting on C-8 of structurally different types of flavonoid (i.e., flavanone, flavone, flavanonol, and dihydrochalcone, etc.). Furthermore, SfPFT exhibits strict stereospecificity for levorotatory flavanones to produce (2S)-prenylflavanones. This study is the first to demonstrate the substrate promiscuity and stereospecificity of a plant flavonoid prenyltransferase in vitro. Given its substrate promiscuity and high catalytic efficiency, SfFPT can be used as an environmentally friendly and efficient biological catalyst for the regio- and stereospecific prenylation of flavonoids to produce bioactive compounds for potential therapeutic applications.