26,27-Cyclosterols and Other Polyoxygenated Sterols from a Marine Sponge Topsentia sp.

Abstract

Thirty sterols (1-30) were isolated from bioactive fractions of a marine sponge Topsentia sp., of which 16 were new (1, 2, 8, 10-14, 16, 17, 19, 21, 24, 25, 27, and 30). They were characterized as sterols with 10 different side chains and as having various functionalities including 5alpha,8alpha-epidioxy (1-9), 5alpha,6alpha-epoxy-7-ol (10-15), 5,8-dien-7-one (24-28), 5-en-3beta-ol (29), and 1(10-->6)abeo-5,7,9-triene-3alpha,11alpha-diol (30) units and included polyoxygenated sterols (16-23). One of the key features of these new sterols is the presence of the (24R,25R,27R)-26,27-cyclo-24,27-dimethylcholestane side chain, whose absolute stereochemistry was defined by an acid-catalyzed ring-opening method and by comparison with the four synthetic isomers of known absolute stereochemistry. The occurrence of several known fungal sterols and relevant new sterols in this sponge suggested their possible origin from symbiotic fungi. Selected compounds were tested against a panel of five human solid tumor cell lines and displayed moderate to marginal cytotoxicity.

Peroxy natural products

“…379 A group of 5α,8α-epidioxysterols, topsentisterols A1-A3 604-606, were isolated from a marine sponge Topsentia sp. 380 The marine sponge Luffariella cf. variabilis was the source for a series of 5α,8α-epidioxy sterols 607-609.…”

Natural Bioactive Sterol 5α,8α-endoperoxides as Drug Lead Compounds

“…An ergostane-type sterol 9(11)-dehydroaxinysterol (27) Table 3, and also indicated significant growth inhibition in 21 human cancer cell lines at less than 0.60 μg/ mL [34] (Table 4).…”

“…Compounds 8-14 were evaluated for cytotoxicity against a panel of five human solid tumor cell lines (A549, SK-OV-3, SK-MEL-2, XF498 and HCT15), all compounds exhibited weak cytotoxicity. No clear correlations between structure and cytotoxicity could be delineated due to diverse variations of the side chain [27] (Figure 4).…”

Ganodermasides C and D, Two New Anti-Aging Ergosterols from Spores of the Medicinal MushroomGanoderma lucidum

“…9) Furthermore, the pyridine-induced deshielding effect was used to confirm the OH-9 configuration. 10) The proton signals at 2.54 (H-1) and 1.77 (H-11) (CDCl 3 ) were respectively shifted downfield to H 2.90 and H 2.00 (pyridine-d 5 ). The configuration of the chiral center at C-20 in the side chain was determined as 20R on the basis of the NOE correlations and a decoupling measurement, in which proton signal 1.14 (H-21) was irradiated.…”

“…10) The proton signals at H 2.50 (H-1) and H 1.70 (H-11) in CDCl 3 were respectively shifted downfield to H 2.91 and H 1.85 in pyridine-d 5 . The R-configuration at C-20 was determined from the NOE correlations and a decoupling measurement, in which H-21 ( H 1.08) was irradiated.…”