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 Santalum yasi to be the most active. Resulting chemical workup enabled the isolation and structural characterization of a new acetylenic acid, methyl (E)-octadec-6-en-8-ynoate (1), and an atropisomeric stilbene glycoside (4) (Yasibeneoside) together with six known compounds: 11,13-octadecadien-9-ynoic acid (2), methyl octadeca-9,11-diynoate (3), gaylussacin (5) chrysin-7-beta-monoglucoside (6), neoschaftoside (7), and chrysin-6-C-glucoside-8-C-arabinoside (8). Compound 1 (18:2 (6t, 8a) is an example of a Δ6, Δ8 acetylenic system containing the trans 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 (E)-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.