Enzymatic synthesis of amentoflavone glycoside using recombinant oleandomycin glycosyltransferase

Prenylation of flavonoids by DMATS1 and their anti-inflammatory activities

BACKGROUND

Prenylated flavonoids are widely distributed in plants, including fruits and vegetables in the Moraceae and Fabaceae families. These chemicals are potential functional food ingredients owing to their attractive biological activities. However, natural prenylated flavonoids are rare, which limits their application.

RESULTS

Here, we reported the prenylation of apigenin and genistein catalyzed by DMATS1, a dimethylallyl-l-tryptophan synthase from Fusarium fujikuroi. High-performance liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance identified their structure as 6-C-prenylapigenin (6-PA) and 6-C-prenylgenistein (6-PG), respectively. Cell-based assay suggested that both 6-PA and 6-PG induced the proliferation of THP-1 cells under low concentrations and were safe in doses less than 50 μmol L-1. 6-PA and 6-PG exhibited significant anti-inflammatory activity in lipopolysaccharide-stimulated THP-1 cells, and inhibited the production of nitric oxide as well as downregulating the transcriptional levels of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-8, and interleukin-1β.

CONCLUSION

The findings suggested that DMATS1 could catalyze the 6-C prenylation of apigenin and genistein, and the generated 6-PA and 6-PG exhibited anti-inflammatory activity, aiding in the recognition of 6-PA and 6-PG as nutraceuticals. © 2025 Society of Chemical Industry.

Enzymatic Synthesis of Biflavonoid Glycosides with Enhanced Antitumor Activity Using Glycosyltransferase and Sucrose Synthase

Biflavonoids, a distinctive subclass of plant flavonoids, have a unique dimerized structure and possess a range of biological activities. The clinical applications of biflavonoids in human health have been impeded by challenges related to bioavailability and hydrophilicity. In contrast, biflavonoid glycosides, which demonstrate enhanced pharmacodynamic and pharmacokinetic properties compared to their aglycones, are notably limited in availability. In this work, we developed a robust enzymatic system to biosynthesize biflavonoid glycosides using O-glycosyltransferase UGT74AN2 and sucrose synthase AtSuSy. This innovative system exhibited remarkable substrate promiscuity successfully, glycosylating 10 structurally diverse biflavonoids. Through purification and structural characterization, we identified four biflavonoid monoglycosides (1a, 2a, 4a, and 5a) as well as two diglycosides (1b and 3b). All synthesized products showed a significant increase in water solubility compared to their aglycones, with enhancements ranging from 20- to 980-fold. Furthermore, compound 1a demonstrated significantly enhanced antiproliferative activity against PC-3 cells compared to its corresponding aglycones. Metabolomic and transcriptomic analyses showed that the increased antitumor activity of 1a may be attributed to changes in the expression levels of various drug transporters, particularly within the ABC, PDE, and ATPase gene families. While compound 1 elevated the mRNA levels of several ABC transporters and ATPases, 1a did not induce these effects, highlighting a distinct mode of action. This study established an efficient enzymatic approach for the biosynthesis of biflavonoid glycosides and underscored their potential as valuable small molecules for drug discovery.

Recent Advances in the Inhibition of Membrane Lipid Peroxidation by Food-Borne Plant Polyphenols via the Nrf2/GPx4 Pathway

Lipid peroxidation (LP) leads to changes in the fluidity and permeability of cell membranes, affecting normal cellular function and potentially triggering apoptosis or necrosis. This process is closely correlated with the onset of many diseases. Evidence suggests that the phenolic hydroxyl groups in food-borne plant polyphenols (FPPs) make them effective antioxidants capable of preventing diseases triggered by cell membrane LP. Proper dietary intake of FPPs can attenuate cellular oxidative stress, especially damage to cell membrane phospholipids, by activating the Nrf2/GPx4 pathway. Nuclear factor E2-related factor 2 (Nrf2) is an oxidative stress antagonist. The signaling pathway regulated by Nrf2 is a defense transduction pathway of the organism against external stimuli such as reactive oxygen species and exogenous chemicals. Glutathione peroxidase 4 (GPx4), under the regulation of Nrf2, is the only enzyme that reduces cell membrane lipid peroxides with specificity, thus playing a pivotal role in regulating cellular ferroptosis and counteracting oxidative stress. This study explored the Nrf2/GPx4 pathway mechanism, antioxidant activity of FPPs, and mechanism of LP. It also highlighted the bioprotective properties of FPPs against LP and its associated mechanisms, including (i) activation of the Nrf2/GPx4 pathway, with GPx4 potentially serving as a central target protein, (ii) regulation of antioxidant enzyme activities, leading to a reduction in the production of ROS and other peroxides, and (iii) antioxidant effects on LP and downstream phospholipid structure. In conclusion, FPPs play a crucial role as natural antioxidants in preventing LP. However, further in-depth analysis of FPPs coregulation of multiple signaling pathways is required, and the combined effects of these mechanisms need further evaluation in experimental models. Human trials could provide valuable insights into new directions for research and application.

Midecamycin Is Inactivated by Several Different Sugar Moieties at Its Inactivation Site

Glycosylation inactivation is one of the important macrolide resistance mechanisms. The accumulated evidences attributed glycosylation inactivation to a glucosylation modification at the inactivation sites of macrolides. Whether other glycosylation modifications lead to macrolides inactivation is unclear. Herein, we demonstrated that varied glycosylation modifications could cause inactivation of midecamycin, a 16-membered macrolide antibiotic used clinically and agriculturally. Specifically, an actinomycetic glycosyltransferase (GT) OleD was selected for its glycodiversification capacity towards midecamycin. OleD was demonstrated to recognize UDP-D-glucose, UDP-D-xylose, UDP-galactose, UDP-rhamnose and UDP-N-acetylglucosamine to yield corresponding midecamycin 2'-O-glycosides, most of which displayed low yields. Protein engineering of OleD was thus performed to improve its conversions towards sugar donors. Q327F was the most favorable variant with seven times the conversion enhancement towards UDP-N-acetylglucosamine. Likewise, Q327A exhibited 30% conversion enhancement towards UDP-D-xylose. Potent biocatalysts for midecamycin glycosylation were thus obtained through protein engineering. Wild OleD, Q327F and Q327A were used as biocatalysts for scale-up preparation of midecamycin 2'-O-glucopyranoside, midecamycin 2'-O-GlcNAc and midecamycin 2'-O-xylopyranoside. In contrast to midecamycin, these midecamycin 2'-O-glycosides displayed no antimicrobial activities. These evidences suggested that besides glucosylation, other glycosylation patterns also could inactivate midecamycin, providing a new inactivation mechanism for midecamycin resistance. Cumulatively, glycosylation inactivation of midecamycin was independent of the type of attached sugar moieties at its inactivation site.

Flavonoids, terpenoids, and polyketide antibiotics: Role of glycosylation and biocatalytic tactics in engineering glycosylation

Flavonoids, terpenoids, and polyketides are structurally diverse secondary metabolites used widely as pharmaceuticals and nutraceuticals. Most of these molecules exist in nature as glycosides, in which sugar residues act as a decisive factor in their architectural complexity and bioactivity. Engineering glycosylation through selective trimming or extension of the sugar residues in these molecules is a prerequisite to their commercial production as well to creating novel derivatives with specialized functions. Traditional chemical glycosylation methods are tedious and can offer only limited end-product diversity. New in vitro and in vivo biocatalytic tools have emerged as outstanding platforms for engineering glycosylation in these three classes of secondary metabolites to create a large repertoire of versatile glycoprofiles. As knowledge has increased about secondary metabolite-associated promiscuous glycosyltransferases and sugar biosynthetic machinery, along with phenomenal progress in combinatorial biosynthesis, reliable industrial production of unnatural secondary metabolites has gained momentum in recent years. This review highlights the significant role of sugar residues in naturally occurring flavonoids, terpenoids, and polyketide antibiotics. General biocatalytic tools used to alter the identity and pattern of sugar molecules are described, followed by a detailed illustration of diverse strategies used in the past decade to engineer glycosylation of these valuable metabolites, exemplified with commercialized products and patents. By addressing the challenges involved in current bio catalytic methods and considering the perspectives portrayed in this review, exceptional drugs, flavors, and aromas from these small molecules could come to dominate the natural-product industry.