N-Acetylglucosamine (GlcNAc)-decorated natural products represent a structurally unique class of metabolites that possess diverse biological activities. Through the genome mining of Coccidioides sp. CMB-TN39F, we identified a GlcNAc transferase-encoding terpene synthase gene cluster brc. Heterologous expression of this cluster in Aspergillus nidulans enabled the characterization of seven GlcNAc-adorned brasilane-type sesquiterpene glycosides, including six previously undocumented compounds, brasilane G−L (1−6), and one known compound, brasilane A (7). Functional characterization revealed that the cytochrome P450 BrcC functions as an epoxidase, catalyzing a stereoselective epoxidation of 7 to form 1. Compound 1 can undergo non-enzymatic conversions to generate compounds 2−5 under mildly acidic conditions. Pharmacological evaluation demonstrated that compounds 1−6 effectively downregulate the expression of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) in LPS/IFN-γ-stimulated THP-1-derived macrophages. Notably, 1, which features an epoxide moiety, exhibits superior anti-inflammatory activity compared to its biosynthetic precursor 7, with an IC50 value of 30.4 μM against IL-6. This study expands the chemical space of GlcNAc-conjugated terpenoids and showcases a biosynthetic logic in which enzymatic tailoring is coupled with nonenzymatic reactions to amplify both structural diversity and biological properties.
Ming-Min Wu, Yao-Hui Shi, Yu-Wei Lin et al.· Journal of Natural Products· 0 citations
Iron(II)/2-oxoglutarate-dependent (Fe/2OG) enzymes catalyze consecutive C-C bond formations to assemble complex heterobicyclic ring systems and generate three new stereocenters in piperazine alkaloids helvamide B and the arizonamides through C(sp3)-H activation─a transformation that remains challenging in synthetic chemistry. Here, we report a comprehensive mechanistic study of this unique transformation catalyzed by the Fe/2OG enzyme Hvm1, using a combination of deuterated substrates, substrate analogs bearing electron-withdrawing substituents, and multiple spectroscopic methods (LC-MS, X-ray crystallography, CD spectroscopy, and NMR). The reaction proceeds via consecutive radicaloid C-C (C3'-C2 and C3-C3″) couplings, involving sequential radical attack on the olefin and benzoyl group (Minisci variant), initiated by a C3' radical generated through C3' pro-S hydrogen atom transfer (HAT). The first C-C bond (C3'-C2) is formed on the Si-face of C2 with retention of C3' configuration. The second C-C bond (C3-C3″) formation can proceed with either of two stereochemical senses─antarafacial or suprafacial─relative to the first newly formed C3'-C2 bond: the antarafacial pathway leads to helvamide B, while the suprafacial pathway affords the previously unreported epimer, helvamide A. Crystal structure analysis identifies Y67 as a key residue governing the partitioning of stereochemical outcomes in the second C-C bond formation. Furthermore, the conclusive stereochemical assignment of helvamide B corrects the prior misassignment of the C3' configuration in the arizonamides.
Shengbin Zhou, Jia-Peng Zhang, Jia-Yu Zuo et al.· Journal of the American Chem...· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
