RESUMEN
Three pregnene steroids, two of them new, were isolated from ethyl-acetate partition of liquid-cultivation of the extremophyle fungus Exophiala oligosperma, found in a pH 1.5 hydrochloric acid aqueous solution. Spectroscopic studies using NMR and HRMS, allowed the identification of the molecular structures of both Δ8,9-pregnenes, still not described in the literature.
Asunto(s)
Exophiala/química , Extremófilos , Pregnenos/química , Esteroides/química , Hongos , Pregnenos/aislamiento & purificación , Esteroides/aislamiento & purificaciónRESUMEN
A procedure is described for the preparation of A-homo-5-pregnenes via an acid catalyzed rearrangement of cyclopropylcarbinols assisted by microwave irradiation. 3alpha-Hydroxy and 4alpha-hydroxy-A-homo-5-pregnen-20-one, analogues of the neuroactive steroid allopregnanolone, were obtained by means of a regioselective epoxidation of a double bond in the expanded A-ring, using a fructose-derived chiral ketone as catalyst and oxone as oxidant. Although both these compounds were marginally active in inhibiting TBPS binding to GABA(A) receptors, 3beta-hydroxy-A-homo-5-pregnen-20-one was almost as active as allopregnanolone. Reduction of the double bond of the latter compound resulted in a ten fold loss of activity.
Asunto(s)
Pregnenos/síntesis química , Pregnenos/farmacología , Receptores de GABA-A/metabolismo , Animales , Compuestos Bicíclicos Heterocíclicos con Puentes/metabolismo , Hidróxidos/química , Masculino , Microondas , Modelos Moleculares , Conformación Molecular , Pregnenos/química , Unión Proteica/efectos de los fármacos , Ratas , Ratas WistarRESUMEN
Two new sulfated steroidal hexaglycosides, anasterosides A (2) and B (3), along with the known versicoside A (1) have been isolated from the Patagonian starfish Anasterias minuta. Their structures have been elucidated by spectroscopic analysis (NMR and FABMS) and chemical transformations. Compounds 1 and 2 and the synthetic pentaglycoside 1b derived from versicoside A showed antifungal activity against the plant pathogenic fungus Cladosporium cucumerinum. Desulfation of hexaglycoside 1 rendered a totally inactive saponin.
Asunto(s)
Antifúngicos/aislamiento & purificación , Colestenonas/aislamiento & purificación , Cladosporium/efectos de los fármacos , Glicósidos/aislamiento & purificación , Pregnenos/aislamiento & purificación , Estrellas de Mar/química , Animales , Antifúngicos/química , Antifúngicos/farmacología , Argentina , Colestenonas/química , Colestenonas/farmacología , Cromatografía Líquida de Alta Presión , Cromatografía en Capa Delgada , Relación Dosis-Respuesta a Droga , Glicósidos/química , Glicósidos/farmacología , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Pregnenos/química , Pregnenos/farmacología , Relación Estructura-ActividadRESUMEN
The utility of two locally isolated fungi, pathogenic to banana, for steroid biotransformation has been studied. The deuteromycetes Fusarium oxysporum var. cubense (IMI 326069, UAMH 9013) and Colletotrichum musae (IMI 374528, UAMH 8929) had not been examined previously for this potential. In general, F. oxysporum var. cubense effected 7alpha hydroxylation on 3beta-hydroxy-delta5-steroids, 6beta, 12beta, and 15alpha hydroxylation on steroidal-4-ene-3-ones, side-chain degradation on 17alpha,21-dihydroxypregnene-3,20-diones, and 15alpha hydroxylation on estrone. Both strains were shown to perform redox reactions on alcohols and ketones.
Asunto(s)
Androstenos/metabolismo , Colletotrichum/metabolismo , Fusarium/metabolismo , Pregnenos/metabolismo , Androstenos/química , Biotransformación , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Estructura Molecular , Pregnenos/química , Espectrofotometría InfrarrojaRESUMEN
The reaction of 16 alpha,17 alpha-epoxy-3 beta-hydroxy-5-pregnen-20-one with 6-methyl thiopurine activated with sodium hydride leads to the coupling of the purine base with the carbonyl group at C-20 to give a steroidal nucleoside analog, which is termed "nucleosteroid." In the presence of an excess of purine, a parallel reaction occurs in which the oxirane ring is opened, presumably by nucleophilic attack of an intermediate C-20 oxyanion, and yields as the main product of reaction an oligomeric mixture of nucleosteroid units linked together by ether linkages. Analogous reactions conducted with 3 beta-hydroxy-5-pregnen-20-one and with 3 beta,17 alpha-dihydroxy-5-pregnen-20-one gave minor amounts or only traces of the corresponding coupling adduct, and oligomerization did not occur. This behavior is interpreted in terms of the conformational differences showed by the different steroids to the attack by the purine.