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Standardization of polar extracts of the aerial parts of Actinocephalus divaricatus (Körn.) Sano (Eriocaulaceae)

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Author(s):
Ana Caroline Zanatta Silva
Total Authors: 1
Document type: Master's Dissertation
Press: Araraquara. 2016-08-31.
Institution: Universidade Estadual Paulista (Unesp). Instituto de Química. Araraquara
Defense date:
Advisor: Lourdes Campaner dos Santos
Abstract

This work describes the chemical characterization of the methanolic extracts of the capitulae, scapes and leaves from Actinocephalus divaricatus, described the first time in the literature. First, the samples were analyzed by high-performance liquid chromatography (HLPC) coupled with a photodiode array detector (PAD) and mass spectrometry tandem coupled to an Orbitrap with electrospray ionization interface using an LC system for separating chromatographic metabolites (HPLC-ESI-HRMS). This strategy has allowed us to explore a differentiate the secondary metabolites present, identified as 31 compounds comprising 12 flavonoids, 5 naphthopyranones and 14 saponins. This differential analysis of the three parts of the plant contributes to the discussion of the Actinocephalus genus, since the studies reported in the literature are only of the Paepalanthus sect. Actinocephalus. The separation of the metabolites present in the methanolic extracts of the scapes and leaves was performed using chromatographic techniques, such as Sephadex, MPLC, HPLC-PAD and HPLC-IR. It was possible to obtain thirteen compounds: three phenolic acids, seven flavonoids, two naphthopyranones and one saponin. The structures of all the compounds were determined by data analysis by mono and bidimensional NMR. The standardization of the methanolic extracts was performed by the quantification of flavonoids and naphthopyranones by HPLC-PAD. The methodology was validated by evaluating the parameters of selectivity, linearity, detection and quantitation limits, accuracy and precision. The selectivity was confirmed by the retention time and UV absorption spectra of flavonoid and standard of naphthopyranone. Validated methods showed high selectivity and identified quercetin glycosides and paepalantine derivatives in extracts, with detection limits (2.56 μg.mL-1) and quantification (7.76 to 7.77 μg.mL-1) satisfactory to the analyzed conditions, and precision values (0.0028 to 3.90%) and accuracy (83-119%) within the limits recommended by ANVISA. The values found for the quercetin glycosides derivatives were 9.64, 39.96, 123.81 mg.g-1 of extract for the capitula scapes and leaves respectively. Paepalantine glycosylated derivatives were quantified only in the capitula and leaves and showed 39.51 and 5.99 mg.g-1 of extract for the capitula and leaves respectively. The phenols contents found were 126.41, 246.58 mg.g-1 and 512.24 mg.g-1 extract for the capitula scapes and leaves respectively. The antiradical activity using DPPH showed IC50 higher than the concentrations of the used extracts (250 μg.mL-1). At the same time, the antimicrobial activity was evaluated by using bacteria and yeast strains, and the methanolic extracts of the capitula, scapes and leaves showed poor sensitivity against the tested microorganisms. The values for the cytotoxicity of the extracts using the MTT assay were low, with the best results found in the methanolic extract of the capitula (IC50 = 66.98 μg.mL-1) against MCF7 (human breast cancer). Thus, the chemical study of the species A. divaricatus corroborates with the literature data has allowed us to state that Actinocephalus is a new genus, different from Paepalanthus with the presence of saponins in the scapes and leaves. (AU)