Estudo fitoquímico de constituintes polares de resinas de Burseraceae

Abstract

The Amazon stands out for its vast plant biodiversity, which can be considered the source of the discovery of new natural substances. In this family, the study of acid triterpenes has been highlighted due to its biological application against harmful activity to human health. In this regard, the study aimed to isolate the polar chemical constituents of Burseraceae resins, as well as structurally modify the isolated substances in their respective methyl ester derivatives for the isolation of the most polar acid triterpenes. To achieve these goals, a broad reanalysis of hexane and ethyl acetate extracts by classical techniques (CCD) was first performed. Then, five species were selected: P. strumossum; P. paniculatum var modestum; P. cf. heptaphyllum; P. altsonii and P. hebetatum. The acid fractions of these species were compared by CCD, and the statistical treatment was performed by multivariate analysis (HCA and PCA). This analysis allowed the fractionation of P. hebetatum and P. altsonii extracts and the isolated substances were identified by MS (APCI) and NMR (1-D / 2D). The results showed that P. altsonii led to the isolation of 3α-hydroxytirucala-7,24-diene-21-oic acid. In addition, 3-oxo-tirucala-8,24-diene-21-oic acids, 3β-hydroxytirucala-8,24-diene-21-oic acids and 3α-hydroxyoleanan-12-eno-23-oxide were identified. oxo-28-oic in the other fractions of this species. The study of P. hebetatum led to the structural elucidation of the mixture of 3-oxo-tirucala-8,24-diene-21-oic acid (β-elemolic acid); 3α-hydroxytirucala-8,24-diene-21-oic (α-elemolic) and 3α-hydroxytirucala-7,24-diene-21-oic. The development of the strategy to formulate methyl derivatives from the acid fractions and the obtained standards was solved by the use of trimethylsilythiazomethane, followed by CCD reaction and 1H NMR spectroscopy. Subsequently, the study of the scaling up methodology consisted of transforming the acid triterpenes into P. strumossum methyl esters using acid catalysis employing hydrochloric acid in methanol which yielded good results, when the increase of the retention factor of the substances in CCD was observed. The P. strumossum methyl esters were separated by flash silica chromatography and subjected to MS identification (APCI). Mass spectrum analysis showed the presence of a mixture of 3-oxohydroxytirucala-8,24-dien-21-oic, 3-hydroxytirucala-8,24-dien-21-oic methyl derivatives (β-elemolic) and 3-hydroxytirucala-7,24-dien-21-oic (α-elemolic). The results were also suggestive for the presence of the elemolic acid 3-acetoxy derivative to the ursolic and oleanic acid methylated analogs