Acetylenic Fatty Acids and Stilbene Glycosides Isolated from Santalum yasi Collected from the Fiji Islands

In our continuing search for new anticancer and/or antimicrobial compounds from natural products, we screened for these activities in bark and leaf extracts of sandalwood plants collected from the Fiji Islands and found <i>Santalum yasi</i> to be the most active. Resulting chemical workup enabled the isolation and structural characterization of a new acetylenic acid, methyl (<i>E</i>)-octadec-6-en-8-ynoate (<b>1</b>), and an atropisomeric stilbene glycoside (<b>4</b>) (Yasibeneoside) together with six known compounds: 11,13-octadecadien-9-ynoic acid (<b>2</b>), methyl octadeca-9,11-diynoate (<b>3</b>), gaylussacin (<b>5</b>) chrysin-7-beta-monoglucoside (<b>6</b>), neoschaftoside (<b>7</b>), and chrysin-6-C-glucoside-8-C-arabinoside (<b>8</b>). Compound <b>1</b> (18:2 (6t, 8a) is an example of a Δ⁶, Δ⁸ acetylenic system containing the <i>trans</i> double bond at C-6 and the triple bond at C-8, which is reported here for the first time. All molecular structure elucidations and dereplications were performed using spectroscopic techniques, including 2D NMR and HRMS-MS/MS spectrometry. Methyl (<i>E</i>)-octadec-6-en-8-ynoate showed moderate activity activity with an IC₅₀ of 91.2 ug/mL against the human breast adenocarcinoma cell line MCF-7.