Quality control and quantitation of catechin and epicatechin from leaves of Maytenus rigida Mart

Maytenus rigida Mart belongs to the family Celastraceae, formed by 106 genera and 1.300 species, that are widely distributed in tropical and subtropical regions. The species is distributed in Caatinga region of northeastern Brazil in the states of Sergipe, Paraíba and Pernambuco. Maytenus rigida is popularly known as bom nome or chapéu de couro. It is used in folk medicine for gastritis and gastric ulcer. The main secondary metabolites reported for this species are pentacyclic triterpenes, flavonoids and alkaloids. This work aimed to evaluate the quality control of raw material and the quantification of catechin and epicatechin by High Performance Liquid Chromatography (HPLC) in Maytenus rigida crude ethanolic extract (CEE) obtained from leaves. The plant material was collected in the municipal district of Boa Vista - PB in June of 2018. Physicochemical assays were developed with leaves: Determination of loss on drying, total ashes, limit assay for heavy metals, bulk density, following the recommendations of the 5^th Brazilian Pharmacopoeia. The content of total phenolic compounds was determined using the Folin-Ciocalteu method and total flavonoids was measured using the colorimetric method with AlCl₃ with CEE. The quantitation of (+)-Catechin and (-)-Epicatechin was performed with a validated method previously developed. M. rigida leaves presented 5.9% ± 0.143 of water content, 5.10% ± 0.136 of total ashes, < 10 ppm of heavy metals and 0.40 g/mL of bulk density. The total phenolic content was 187.52 ± 2.01 µg EAG/mg and the flavonoid content was 88.80 ± 1.47 µg EQ/mg. The evaluation of CEE showed the presence of 7.79 µg of (+)-Catechin/mg and 6.04 µg of (-)–Epicatechin/mg. The quality control analyzes performed with M. rigida established a better profile for the characterization of the drug. This study confirms the applicability of method for the quantification of phenolic compounds in extracts of Maytenus rigida.