Contribuição ao estudo fitoquímico da espécie Sambucus australis (Adoxaceae), obtenção de derivados do ácido ursólico, 3α-hidroxi-5β-colano-24-oato de metila, 3α-hidroxi-5β-colano-24-oato de etila e 3α-hidroxi-5β-colano-24-oato de isopropila e avaliação das suas atividades biológicas

Abstract

The species Sambucus australis, belonging to the family Adoxaceae, is known in Brazil by the popular names of "sabugueiro-do-rio-grande", "sabugueiro-do-Brasil" or simply "sabugueiro". The chemical investigation was carried out with extracts in hexane, in ethyl acetate and in ethanol of leaves and inflorescences. The fatty acids present in the hexane extract of the leaves and inflorescences of S. australis were identified by GC-MS, with palmitic acid (72.6%), linoleic (8.01%), vacenic (6.20 %) and arachidic (4.03%). The extracts were subjected to conventional chromatography, resulting in the isolation and structural characterization of the tetrameric damarenediol, the mixtures of α,β-amirin palmitate triterpenes, and α,β-amirine, of the mixture of β- sitosterol and stigmasterol and triterpene ursolic acid. Eleven derivatives were obtained from ursolic acid (SA-5), one of the constituents isolated from S. australis, were obtained through molecular modifications at the C-3 and C-24 positions of the triterpenic skeleton, four of which are unpublished in the literature. Thirteen methyl 3α-hydroxy-5β-cholane-24-oate derivatives (AL-1), thirteen derivatives of ethyl 3α-hydroxy-5β-cholane-24-oate (AL-2) and thirteen derivatives of isopropyl 3α-hydroxy-5β-cholane-24-oate (AL-3), with modification at the C-3 carbon of the steroidal skeleton. Of the derivatives obtained from methyl 3α-hydroxy-5β-cholane-24-oate (AL-1), five are unpublished in the literature; of the derivatives obtained from ethyl 3α-hydroxy-5β-cholane-24-oate (AL-2), twelve are unpublished in the literature; of 3α-hydroxy-5β-cholane-24-oate of isopropyl (AL-3), all are unpublished in the literature. In this work 50 derivatives were obtained, of which 34 are unpublished in the literature. The chemical constituents isolated from Sambucus australis and the derivatives obtained were characterized by IR spectroscopic methods, 1H NMR, 13C-BB NMR and 13C-DEPT 135° NMR. All the derivatives were tested for toxicity to Artemia salina and most of the samples showed high toxicity to the same; were also submitted to a qualitative test for inhibition of the acetylcholinesterase enzyme, in which the ursolic acid derivatives showed the best results for the inhibition of the acetylcholinesterase enzyme: four derivatives showed equal positive control inhibition halo (Eserin).