| Summary: | The chemical investigation of <i>Homotrigona apicalis</i> propolis collected in Binh Dinh province, Vietnam, led to the isolation of nine compounds, including four sesquiterpenes: spathulenol (<b>1</b>), 1<i>α</i>H,5<i>β</i>H-aromandendrane-4<i>β</i>,10<i>α</i>-diol (<b>2</b>), 1<i>β</i>,6<i>α</i>-dihydroxy-4(15)-eudesmene (<b>3</b>), and 1<i>β</i>H,5<i>β</i>H-aromandendrane-4<i>α</i>,10<i>β</i>-diol (<b>4</b>); three triterpenes: acetyl oleanolic acid (<b>5</b>), 3<i>α</i>-hydroxytirucalla-8,24-dien-21-oic acid (<b>6</b>), and ursolic acid (<b>7</b>); and two xanthones: cochinchinone A (<b>8</b>) and <i>α</i>-mangostin (<b>9</b>). Sesquiterpens <b>1</b>–<b>4</b> and triterpene <b>6</b> were isolated for the first time from stingless bee propolis. Plants in the <i>Cratoxylum</i> and <i>Aglaia</i> genus were suggested as resin sources of the propolis sample. In the antibacterial activity evaluation, the EtOH extract only showed moderate activity on <i>S. aureus</i>, while the isolated compounds <b>7</b>–<b>9</b> showed good antibacterial activity, with IC<sub>50</sub> values of 0.56 to 17.33 µg/mL. The EtOH extract displayed selective cytotoxicity against the A-549 cancer cell line, with IC<sub>50</sub> values of 22.82 ± 0.86 µg/mL, and the xanthones <b>8</b> and <b>9</b> exhibited good activity against the KB, HepG-2, and A-549 cancer cell lines, with IC<sub>50</sub> values ranging from 7.55 ± 0.25 µg/mL to 29.27 ± 2.07 µg/mL. The cytotoxic effects of xanthones <b>8</b> and <b>9</b> were determined by the inhibition of the EGFR and HER2 pathways using a molecular docking study. Compounds <b>8</b> and <b>9</b> displayed strong binding affinity with EFGR and HER2, with values of −9.3 to −9.9 kcal/mol. Compounds <b>5</b>, <b>8,</b> and <b>9</b> showed potential <i>α</i>-glucosidase inhibitory activities, which were further confirmed by computational studies. The binding energies of compounds <b>5</b>, <b>8,</b> and <b>9</b> were lower than that of arcabose.
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