Bioactive anthraquinone dimers from the leafhopper pathogenic fungus Torrubiella sp. BCC 28517

Abstract

Torrubiellins A (1) and B (2), two new dimeric anthraquinones were isolated from the leafhopper pathogenic fungus Torrubiella sp. BCC 28517. The structures of the new compounds were elucidated by analyses of the NMR spectroscopic and mass spectrometry data. Torrubiellin B (2) exhibited broad range of biological activities.

Absolute configuration and anti-tumor activity of torrubiellin B

“…Comparison of the MS and NMR data of 1 with those previously reported for torrubiellin B suggested that they are identical. 17 The structure of 1 was finally confirmed as torrubiellin B by careful analysis of COSY, HMBC, and ROESY correlations. Interpretation of the COSY and HMBC correlations shown in Figure 2 revealed two anthracene moieties being fused via a cyclopentene ring.…”

“…H-10 0 showed ROE correlations to H-5 0 and H-11 eq and furthermore H-11 eq had a correlation to H-2, thus indicating the (5 0 S ⁄ ,10 0 R ⁄ ,10a 0 S ⁄ ) relative configuration of 1 as shown in Figure 4, which is in agreement with that previously reported. 17 Torrubiellin B may be viewed as a 4,5 0 -linked heterodimeric biaryl of 7-hydroxyemodin and 1,8,10-trihydroxy-6-methyl4a,10-dihydroanthracen-9(4H)-one, in which the rotation along the biaryl axis is blocked by the methylene linker between C-3 and C-10a. In contrast to axially chiral biaryls of anthracene-9,10-dione monomers, 18 torrubiellin B has only central chirality elements due to the C-5 0 , C-10, 0 and C-10a 0 chirality centers and the projection angle between the planes of the two monomers is governed by the central chirality.…”

“…17 After thorough UV and LCMS analysis of the crude ethyl acetate extract of Acremonium sp. analyzed in this study typical UV absorption maxima at 223, 250, 273, 293, and 442 nm, as well as a prominent pseudomolecular ion peak at 269.5 [MÀH] À were detected that account for emodin, but no signals were found for aloe-emodin or for chrysophanol.…”

“…BCC 28517 and the relative configuration of the compound had been determined through NOE experiments. 17 However, the absolute configuration of the compound was unknown so far. The determination of the absolute configuration of torrubiellin B (1) especially in light of its prominent activity against cancer cells is an important issue during structure determination.…”

Symbionts, a promising source of bioactive natural products

“…Compound 162 are antimalarial, antifungal and antibacterial [53]. Another insect pathogen Aschersonia paraphysata BCC 11964 produces aschernaphthopyrones A (164, Scheme 10) and B (165, Scheme 10), two new biarylic dihydronaphthopyrones [54].…”