Two new terpenoid derivatives from a new soft coral species of the <i>Nephthea</i> genus of the Indian Ocean

Abstract

Chemical examination of a new soft coral species of the <i>Nephthea</i> genus of the Indian Ocean furnishes a new sesquiterpenoid and a new diterpenoid along with some sesquiterpenes and steroids. The structure of the new sesquiterpenoid has been established as 1<i>S</i>, 3<i>R</i>, 4<i>S</i>, 5<i>S</i>, 7<i>S</i>-3,4-epoxy guaia-Δ¹⁰⁽¹²⁾-ene <b>3</b> and that of a new monohydroxy diterpenoid as <b>4</b> by a study of their physical and spectral (¹H, ¹³C, 2D NMR, IR, UV and mass) data. Other known

compounds isolated are Δ⁹⁽¹⁵⁾ -africanene <b>1</b>, 9-aristolene <b>2</b>, the ubiquitous batyl alcohol 7, two 4α-methylsteroids, 4α-methylcholest-24(28)-en-3β-yl acetate <b>5</b> and 4α, 23, 24-trimethylcholest-22-ene-3β-yl acetate <b>6</b> two polyhydroxy steroids, 3β, 7β, 19-trihydroxyergosta-5, 24 (28)-diene <b>11</b> and 24-methylenecholestane-3β, 5α, 6β-triol <b>12</b> in addition to three monohydroxysteroids, 24-methylcholesta-7, 25-diene-3β-ol <b>8</b>, 24-ethylidenecholest-5-en-3β-ol (Δ⁵-avenasterol, <b>9</b>) and 24-ethylcholest-5-en - 3β-ol <b>10</b>. Besides the report of two new terpenoids, this is the first report on the presence of 4α-methyl

steroids in a <i>Nephthea </i>species.