Metabólitos secundários e avaliação de atividades biológicas de Siolmatra brasiliensis (Cogn.) Baill. (Cucurbitaceae) e espécie do gênero Ziziphus Mill. (Rhamnaceae)

Abstract

Twenty compounds were isolated from the crude hydroethanolic stem extract of Siolmatra brasiliensis, the structures were assigned by extensive NMR and HR-ESI-MS analyses. Five flavonoids, two lignans, one glycosylated phytosterol and seven nor-cucurbitacins already described in the literature were identified, along with a previously undescribed phenolic derivative and four dammarane-type saponins (siolmatrin and siolmatrosides II-V). The antinociceptive and in vitro antiglycation activities of the crude extract and fractions from the species were evaluated. It is suggested that the presence of dammarane-type saponins and nor-cucurbitacins are responsible for the observed antinociceptive activity of the extract and especially the ethyl acetate fraction, on the other hand, the identified phenolic compounds may be responsible for the anti-glycation activity observed specially in the chloroform fraction. Four species of Ziziphus were included in this project to evaluate biological activities, in which, Z. joazeiro and Z. glaziovii presented promising results of bacterial inhibition of Aliivibrio fischeri and Bacillus subtilis, and all extracts showed significant cytotoxic activities against PC- 3 and HT-29. Seventeen compounds were isolated from the chloroform fraction of Z. glaziovii stem extract, one xanthone, one lignan, two lupane-type triterpenes, four ceanothane-type triterpenes and one glycosylated phytosterol, besides seven previously undescribed dammarane-type saponins (ziziglaziovigenin, ziziglaziovigenin 3-O-α-L-arabinopyranoside, ziziglaziovigenin-3-O-α-L-arabinofuranosyl-(1-2)-α-L-arabinopyranoside, ziziglaziovigenin 3-O-β-D-glucopyranosyl-(1-3)-α-L-arabinopyranoside, 16,22:16,30-diepoxy-20-hydroxydammar-24-methylidene 3-O-β-D-apiofuranosyl-(1-3)-O-[6-(3-methoxy-4-hydroxybenzoate)-β-D-glucopyranosyl-(1-2)]-β-D-glucopyranosyl-(1-2)-β-D-glucopyranoside, 16,22-epoxy-15,16,20-trihydroxydammar-24-methylidene 3-O-β-D-apiofuranosyl-(1-3)-O-[6-(3-methoxy-4-hidroxybenzoate)-β-D-glucopyranosyl-(1-2)]-β-D-glucopyranosyl-(1-2)-β-D-glucopyranoside e 16,22:16,30-diepoxy-20-hydroxydammar-24-methylidene 3-O-α-L-arabinofuranosyl-(1-2)-O-[4-O-sodium-sulphate-β-D-glucopyranosyl-(1-3)]-α-L-arabinopyranoside. The compounds evaluated for antibacterial activity, where epigouanic acid and alphitolic acid showed good inhibition of B. subtilis (IC50 of 20 and 12 μM, respectively). The isolated compounds presented up to a 10 µM concentration, none or weak cytotoxic activity. UHPLC-MS-MS analysis of the alkaloidal fraction from the crude stem extract of Z. joazeiro stem allowed the identification of eight Ib-type cyclopeptide alkaloids, the structures were suggested by mass fragmentation proposals.