Estudo fotoquímico e farmacológico de Apodanthera congestiflora Cogn.: Uma Cucurbitaceae da caatinga brasileira

Abstract

Apodanthera congestiflora Cogn. is a Cucurbitaceae endemic to the Brazilian Caatinga, used in folk medicine to treat back pain, skin blemishes and as a blood purifier. Until now, reports on this species are scarce, with a few scientific investigations and referring only to the roots. The objective of this work was to carry out a physical-chemical characterization of the plant drug (DV) of the species' stems, to evaluate its chemical composition, besides toxicological and anti-inflammatory profile. A quality profile of the DV was drawn in different particle sizes, using Pharmacopeial methods and thermal analysis (TG / DTA). DV was also subjected to extraction by different techniques that yielded aqueous extracts (EA’s), hydroalcoholic extract (EHC-Ac) and their respective organic phases: hexane (FHC-Ac) and dichloromethane (FDC-Ac). EA’s have undergone quantitative phytochemical screening presenting high saponin content. In the phytochemical study, FHC-Ac and FDC-Ac were subjected to chromatographic techniques, obtaining a mixture of phytosterols known as β-sitosterol (Ac-1), stigmasterol (Ac-2) and spinasterol (Ac-3), as well as three norcucurbitacins, also in mixture, called cayaponoside C5b (Ac-4), cabenoside C (Ac-5) and fevicordin C2 glycoside (Ac-6), the latter being unprecedented in the literature. Structural identification was performed by IV, 1H and 13C NMR. FDC-Ac has been tested for toxicity against human erythrocytes and in Swiss mice. In the in vitro test totoxicity was not evidenced, however in the in vivo test, FDC-Ac presented significant toxicity, with macroscopic and biochemical alterations. In addition, the in vivo anti-inflammatory activity of FDC-Ac was investigated, which was shown to be able to reduce inflammatory signs in the first 5 hours, with 7.5 mg kg-1 , being the most effective dose in reducing edema (66.6 %). The identification of three cucurbitacins in the phytochemical investigation, together with the biological tests performed in this study, demonstrate that A. congestiflora is a promising species in the search for therapeutic innovation, as it carries substances with high pharmacological potential in its composition. The quality control of the vegetable drug allowed to outline a physical-chemical profile of the powders obtained from the A. congestiflora stem that could serve as a basis for future studies of pre-formulation of an herbal product.