Estudo químico e atividades biológicas de Talinum triangulare (Jacq.) Willd. (Portulacaceae) e Sphagneticola trilobata L. Pruski (Asteraceae)

Abstract

Chromatographic fractionation of extracts from the leaves and stem of Talinum triangulare (Portulacaceae) and extracts from Sphagneticola trilobata and the analysis of the fractions by chromatographic and spectroscopic techniques allowed to the isolation and identification of twenty eight constituents belongs to different classes of special metabolites. From the leaves of Talinum triangulare were identified β-carotene, lutein, and porphyrins such as 18-purpurin phytyl ester (3), phaeophytin a (4), 132-hydroxy phaeophytin a (5), 151-hydroxy,151-carbomethoxy-151-O-131-phaeophytin a lactone (6), 151-methylperoxide-151-carbomethoxy-151-O-131-phaeophytin a lactone (7), 151-carboxy-151-O-131-phaeophytin b lactone (ficuschlorinic D acid) (8), 151-hydroxy-151-acetyl-131-carboxy-phaeophytin b (taliclorin A) (9), 151-hydroxy-151-carbomethoxy-151-O-131-phaeophytin b lactone (10), 151-hydroperoxy-151-carbomethoxy-151-O-131-phaeophytin b lactone (11) and 151-acetyl-151-O-131-phaeophytin a lactone (12). Among them it can be highlight five news phaeophytins, 7, 9 (named taliclorin A), 10, 11 and 12, that are being described for the first in the literature. Other compounds such as allantoin and a mixture of 3β-O-βD-glicopiranosilestigmasterol and 3β-O-βD-glicopiranosilsitosterol were also identified in the extracts from the leaves of this plant. In the extracts from Talinum triangulare stem’s a mixtures of steroids, campesterol, escotenol, stigmasterol and silsitosterol, and the mixture of glycosides were isolated 3β-O-βD-glicopiranosilestigmasterol and 3β-O-βD-glicopiranosilsitosterol, besides allantoin, aspartic acid, asparagine and a new acrylamide, 3-N-acryloyl-N-pentadecanoil-propanoic acid (20). The study of circular dichroism made possible to define the absolute configuration of some porphyrins whose structures were defined as: 17R,18R-18-purpurin phytyl ester, 132R,17R,18R-132-hidroxyphaephytin (5), 17R,18R-151-hydroxy-151-carbomethoxy-151-O-131-lactone phaeophytin (6), 17R,18R-151metilperóxido-151-carbomethoxy-151-O-131-phaeophytin a lactone (7), 17R,18R-151-carboxy-151-O-131-phaeophytin b lactone (8), 17R,18R-151-hydroxy-151-acetyl-131-carboxy- phaeophytin b (9), 17R,18R-151-hydroxy-151-carbomethoxy-151-O-131-phaeophytin b lactone (10), 17R,18R-151-hydroperoxy-151-carbomethoxy-151-O-131-phaeophytin b lactone (11). Part of these results was published in Food Chemistry, 160, 204-208 (2014). Chromatographic fractionation of extracts from Sphagneticola trilobata and analysis of the fractions by chromatographic and spectroscopic techniques allowed to the isolation and identification of six substances, two carotenoids, β-carotene and lutein, a mixture of 3β-O-βD-glycopiranosylestigmasterol and 3β-O-βD-glycopiranosylsitosterol, a monoterpene identified as 8,9,10-trimethyl-1,4-dihydroxy-bicyclo[2.2.1]heptane and the triterpene known as fridelinol, which had not yet been isolated from this species. Tests with some gram positive and gram negative bacteria were performed with extracts of Talinum triangulare and Sphagneticola trilobata and presented results that confirmed the cited properties of these species. The cytotoxic activity of different tumor cell lines performed with the polar extract of Talinum triangulare showed significant inhibition against the tumor cell line HL60. On the other hand, the test with the larvae of Aedes aegypti using extracts of Talinum triangulare and Sphagneticola trilobata species were not significant.