| Descripción |
This work describes the phytochemical studies of Dioclea violacea Mart. and the antioxidant and immunomodulatory activities evaluation of the isolates. Dioclea violacea is a climber plant belonging to Leguminosae (Fabaceae) family, sub-family Faboideae (Papilionoideae), tribe Phaseoleae, and it occurs in the coast from Guianes to São Paulo State (Brazil). The stems of one specimen was collected in Umburanas city, Bahia, in the characteristic ?caatinga? vegetation and tableland area. The material after drying and powdering was submitted to extraction with methanol. The methanolic extract was partitioned furnishing hexanic, chloroformic and ethyl acetate extracts. These extracts were submitted to purification separately and, their constituents were isolated and purified by CC and PTLC techniques in silica gel 60, 60H, 60PF, poliamide 6 and 11 and gel permeation on Sephadex LH20. In that way, the purified substances had its structures elucidated by 1H and 13C NMR including DEPT and nOe diff experiments, including two-dimensional techniques like HETCOR, HOMO/COSY, HMQC, HMBC, NOESY, and by EIMS, FAB, UV, IR, [a]D25 and DC data. From the hexanic extract were isolated and identified a-tocopherol, stigmast-4-en-3-one, b-sitosterol, stigmasterol, lupeol and b-amirin. From the chloroformic extract were isolated oleanolic acid, the new flavanone 7,4?-dihydroxy-6-methoxyflavanone, 7-hydroxy-6-methoxyflavanone, 5,7-dihydroxyflavanone, 5,7-dihydroxy-8-methoxy-flavanone, 7-hydroxyflavanone, 4?,7 dihydroxyflavanone, 7,3?,4?-trihydroxyflavanone all previously isolated from other sources. It was also isolated from this extract 7-hydroxy-6-methoxyflavanonol, 2?,4?-dihydroxychalcone, 2?,4,4?-trihydroxy-3-methoxychalcone, 2?,3,4,4?-tetrahydroxychalcone, besides the lactone lasiodiplodin and a new biflavonoid named a,b?-epoxy,-2,2?,4?-trihydroxychalcone-(b®4?)- 7,4?-dihydroxy-6-methoxy-flavanone. From the ethyl acetate extract were isolated epicatechin, a new A-type proanthocyanidin named 3?,4?,7-trihydroxyflavan-(2b®7,4b®8)-3-prenyl-fustin, besides epicatechin-(2b®7,4b®8)-epicatechin and epigallocatechin-(2b®7,4b®8)-epicatechin. The isolates were submitted to antioxidant evaluation employing the inhibition of b-carotene auto oxidation and DPPH scavenging methods, in which the more active substances were epicatechin, epicatechin-(2b®7,4b®8)-epicatechin and epigallocatechin-(2b®7,4b®8)-epicatechin. Some of the compounds were also submitted to immunomodulatory tests by the methods of inhibition of lymphocytes proliferation and inhibition of NO synthesis, where the most active compound was 7-hydroxyflavanone. Finally, the most active compound 7-hydroxyflavanone was synthesized from cinnamic acid and resorcinol by esterification reaction with polyphosphoric, followed by Fries rearrangement and cyclization, in lower yield (1,6%). The main products of reaction were 7-hydroxy-3,4-dihydro-4-phenylcumarin (68,7%) e a 5-hydroxy-3,4-dihydro-4-phenylcumarin (11,2%).
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