Title: Cytotoxic and antibacterial olean-12-ene glycosides and prenylated flavans from the aerial parts of Myrsine semiserrata Wall.: isolation, structure elucidation and glycone-dependent selectivity
Authors: Nguyen Thi Binh Yen
Nguyen Thuy Linh
Nguyen Hai Ngoc
Volume: 10
Issue: 8
Pages: 59-70
Publication Date: 2026/08/28
Abstract:
Two previously undescribed olean-12-ene glycosides, myrsineosides B (1) and C (2), were isolated from the ethyl acetate-soluble fraction of the aerial parts of Myrsine semiserrata Wall. (Primulaceae), alongside seven known compounds. Their structures were unambiguously established as 3-O-?-L-arabinopyranosyl castanopsol (1) and 3-O-?-D-xylopyranosyl castanopsol (2) using HR-ESI-MS, 1D/2D NMR analysis, and chemical hydrolysis. Chemotaxonomically, the isolation of prenylated flavans-such as kazinols A (6) and B (5)-represents a notable first record for a Primulaceae species. All isolates were evaluated against four human cancer cell lines and a microbial panel, revealing a distinct structure-activity relationship dependent solely on the C-3 pentose identity. The arabinoside 1 emerged as the most cytotoxic glycoside, exhibiting moderate activity against A549 (IC50 23.39 然) and KB (IC50 32.80 然) cell lines, rendering it two- to four-fold more potent than its xyloside isomer 2. Conversely, 2 displayed potent and selective antibacterial activity, inhibiting Gram-positive strains (E. faecalis, S. aureus, B. cereus) at a uniform MIC of 32 痢/mL. This potency is 4- to 8-fold below the corresponding MIC values of streptomycin. Notably, 2 remained inactive against Gram-negative strains (MIC > 256 痢/mL), a dichotomy consistent with a membrane-directed mode of action. Among the phenolics, kazinol B (5) was moderately cytotoxic (IC50 49.11-72.22 然) whereas kazinol A (6) was inactive, emphasising the critical contribution of the 2,2-dimethylpyran ring. These findings demonstrate that pentosyl castanopsol glycosides are structurally simple scaffolds tunable towards either mammalian cytotoxicity or Gram-positive-selective antibacterial activity.