Contribuição ao estudo farmacognóstico das raízes da batata de purga (Operculina macrocarpa (Linn.) Urb.)

Abstract

The plant species Operculina macrocarpa (Linn.) Urb. is a medicinal plant belonging to the Convolvulaceae family very common in the Northeast of Brazil, being popularly known as "batatas-de-purga", "jalapa" or "jalapa do Brasil". The tuberous, large, starchy and resinous roots are the part of the plant used for medicinal purposes, which have purgative properties of drastic action, or only laxative, as the best established activities. The present study aimed to perform pharmacognostic study of the roots of Operculina macrocarpa (Linn.) Urb. regarding phytochemistry and quality control of the plant drug. The plant material was collected, through transversal cuts, in the Horto de Plantas Medicinais Professor Francisco José de Abreu Matos, which was characterized macroscopically under naked eye. To obtain the plant drug, the roots were dried and triturated, which was submitted to quality control tests, such as determination of yield, humidity, total ash, foam index, as well as granulometric analysis, followed by phytochemical prospection of the fresh roots. A factorial design 23 with triplicate in central point was carried out, in which eleven hydroalcoholic extracts were produced at 10% (w/v) by maceration, having as independent variables the solvent concentration, the particle size and the extraction time, while the dependent variables corresponded to the dry residue obtained from the extracts and the content of total polysaccharides. The chromatographic profile of the extracts was also performed, using silica gel as stationary phase, ethyl acetate: methanol: chloroform: acetic acid (5:2:2:1, v/v/v/v) as mobile phase and sulfur vanillin as developer. The plant drug from the roots of Operculina macrocarpa presented adequate regarding the quality assays, with a high foaming index, indicating high concentrations of saponins in the roots. The phytochemical approach of the fresh roots revealed the presence of alkaloids, condensed tannins, saponins, steroids, triterpenoids, starch and reducing sugars. The determination of the dry residue of the extracts was positively influenced by the variable granulometry and, by the chromatographic profile, it was observed two bands of purple coloration, which can represent the presence of terpenoids, being present in all the analyzed extracts. The pharmacognostic data obtained are useful for future chemical-pharmacological studies, which prove the medicinal and traditional use of the species studied.