Bioactive 6<i>S</i>‑Styryllactone Constituents of <i>Polyalthia parviflora</i>

Parvistones A–E (<b>1</b>–<b>5</b>), five new styryllactones possessing a rare α,β-lactone moiety and a 6<i>S</i> configuration, were isolated from a methanolic extract of <i>Polyalthia parviflora</i> leaves. The structures and the absolute configuration of the isolates were elucidated using NMR spectroscopy, specific rotation, circular dichroism, and X-ray single-crystal analysis. Compounds <b>8</b>, <b>9</b>, <b>11</b>, and <b>12</b> were isolated for the first time. The results were supported by comparing the data measured to those of 6<i>R</i>-styryllactones. Moreover, a plausible biogenetic pathway of the isolated compounds was proposed. The structure–activity relationship of the compounds in an in vitro anti-inflammatory assay revealed the 6<i>S</i>-styryllactones to be more potent than the 6<i>R</i> derivatives. However, the effect was opposite regarding their cytotoxic activity. In addition, 6<i>S</i>-styrylpyrones isolated showed more potent anti-inflammatory and cytotoxic activity when compared to the 1<i>S</i>-phenylpyranopyrones obtained

Bioactive 6<i>S</i>‑Styryllactone Constituents of <i>Polyalthia parviflora</i>

Parvistones A–E (<b>1</b>–<b>5</b>), five new styryllactones possessing a rare α,β-lactone moiety and a 6<i>S</i> configuration, were isolated from a methanolic extract of <i>Polyalthia parviflora</i> leaves. The structures and the absolute configuration of the isolates were elucidated using NMR spectroscopy, specific rotation, circular dichroism, and X-ray single-crystal analysis. Compounds <b>8</b>, <b>9</b>, <b>11</b>, and <b>12</b> were isolated for the first time. The results were supported by comparing the data measured to those of 6<i>R</i>-styryllactones. Moreover, a plausible biogenetic pathway of the isolated compounds was proposed. The structure–activity relationship of the compounds in an in vitro anti-inflammatory assay revealed the 6<i>S</i>-styryllactones to be more potent than the 6<i>R</i> derivatives. However, the effect was opposite regarding their cytotoxic activity. In addition, 6<i>S</i>-styrylpyrones isolated showed more potent anti-inflammatory and cytotoxic activity when compared to the 1<i>S</i>-phenylpyranopyrones obtained