Marine natural products. Novel C₂₁Δ²⁰pregnanes from the sea raspberry (Gersemia rubiformis)

Muricenones A and B: New Degraded Pregnanes From a Gorgonian of the Genus Muricea

“…From a biosynthetic point of view, compounds 1 and 2 could be biosynthesized from a pregnane such as that shown in Scheme 1 by oxidation of the hydroxyl group at C-3 and double bond isomerization to give an α,β-unsaturated ketone, followed by oxidative cleavage of ring A and decarboxylation of the resulting α-ketoacid. Although the starting pregnane of Scheme 1 was not found in the extracts of Muricea sp., it is a known metabolite found in the octocoral Gersemia rubiformis [9] and as the aglycon of the muricins isolated from Muricea fruticosa. [13] The carbon skeleton of muricenones A (1) and B (2) has not been found among natural products.…”

Electron impact induced fragmentations of the 1,4-diene analogues of steroid hormones and related steroids

“…1 l p , 17a, 21-Trihydroxypregna-1,4-diene-3,20-dione (8) was purchased from Makor Chemicals (Israel). Compounds 1-7 and 9 were prepared as previously de~cribed.…”

An improved route to pregna-5,20-dien-3β-ol (muricin aglycone): Carbon and proton nuclear magnetic resonance assignments for the aglycone and a number of related pregnene derivatives

“…The secondary alcohol (13,5.40 g, 15.0 mmol) was dissolved in dichloromethane (100 mL) and pyridine (15 mL) and treated with methanesulphonyl chloride (10 mL). When the reaction was complete (1 8 h), saturated aqueous sodium bicarbonate (100 mL) was added, the mixture was extracted with dichloromethane (200 mL), washed with water and brine, dried, and evaporated to yield a yellow solid (5.7 g).…”

“…The pregnene derivative 1 was identified as aglycone from a complex saponin mixture from 3 species of starfish (1)(2)(3). The free pregnene derivatives 2-4 were isolated from the sponge Haliclona rubens (4), two others (5 and 6), were extracted from the soft coral Gersemia rubiformis (5), and steroid 6 together with 7 and 8 were isolated from an unidentified Pacific soft coral (6). More recently the vinyl steroid 5 was identified as the aglycone of muricin (9) as well as several other galactosamine saponins, from the Pacific gorgonian Muricea fruticosa (7), which displayed antifungal activity.…”