Isolation, Structures, and Biological Activities of Triterpenoids from a Penares sp. Marine Sponge

Abstract

Six new triterpenoids (1-6) and the previously known penasterone, acetylpenasterol, and ergosta-4,24(28)-dien-3-one were isolated from a Penares sp. sponge collected from Vietnamese waters. Structures of the obtained compounds were established by extensive 1D and 2D NMR spectroscopy and mass spectrometry. Configurations of the triterpene epoxy lactones (1-4) were determined on the basis of NOESY and CD data and calculation of spin coupling constants and confirmed by X-ray crystallographic analysis of compound 2. The isolated triterpenoid 6 was cytotoxic against human leukemia HL-60 cells (IC₅₀ = 9.7 μM).

Further study on Penares sp. from Vietnamese waters: Minor lanostane and nor-lanostane triterpenes

“…From the subfraction A, a number of triterpenoids were isolated and described previously [8]. In the present study, we also isolated 24-ethylcholesta-4,24(28)-dien-3-one (10) ½a 27 D + 48.2 (c 0.28, CHCl 3 ) lit ½a 26 D + 52.0 (c 0.24, CHCl 3 ) [10] (analytical reversed phase HPLC, 100% EtOH) (2.8 mg; 0.002%) as a minor compound in addition to ergosta-4,24(28)-diene-3-one [11,12] (36.1 mg; 0.032%).…”

“…From the sponges belonging to the genus Penares, diverse indole and azetidine alkaloids [3] along with sphingolipids, [4] proline containing macrolides, [5] and triterpenes [6][7][8] were earlier isolated.…”

“…In continuation of our studies on the natural products of the Penares sp. from Vietnamese waters [8,9] and attempts to obtain the more detailed picture of biosynthetic transformations of lanostane triterpenoids in this animal, herein we describe the isolation and structure elucidation of new minor polar constituents from its ethanol extract.…”

Secondary Metabolites of the Marine Sponge Penares cf. schulzei, Fluorescence Properties of 24-Methylenecholesta-4,6,8(14)-Trien-3-One

“…We isolated compound 3 from a Penares sp. of sponge [7].The PMR spectrum of 5 exhibited a series of methyl resonances at 0.96 contained a peak for the molecular ion [M + H] + (m/z 393.3154) that corresponded to the formula C 28 H 40 O. A comparison of the experimental results and the literature on 5 identified it as 24-methylenecholesta-4,6,8(14)-trien-3-one.…”

“…In continuation of our research on natural compounds from sponges of this genus inhabiting the littoral waters of Vietnam [6,7], we communicate about slightly polar components of the EtOH extract of P. cf. schulzei (dry weight 22.1 g) collected during an expedition of the RV Akademik Oparin near the shores of Vietnam.…”