Comparative study of the chemical composition of the species Mikania glomerata Sprengel and Mikania laevigata Schultz Bip. ex Baker

Comparative study of the chemical composition of the species Mikania glomerata Sprengel and Mikania laevigata Schultz Bip. ex Baker. Adulterations of plant raw materials often occur in the marketing of herbal medicine, usually in the form of substitutions and/or fakes. Many times, different plant species are commercialized in the place of the one recognized by the pharmacopoeia. This may occur due to the difficulties of obtaining the authentic plant material, or by an intentional use of a plant species that has less economic value but shows similar morphologic features. Therefore, it is necessary to carry out studies that can identify the chemical composition of those species of wide medicinal: use, which are the targets of adulterations. Mikania glomerata and Mikania laevigata, popularly known as guaco, are indistinctly commercialized in Brazil. A phytochemical screening by TLC was carried out to evaluate the chemical composition of both species. The RP-HPLC profiles were obtained and the quantification of coumarin was, determined by the same method. A phytochemical screening has shown that coumarin, triterpenes/steroids and flavonic heterosides are the constituents detected in both species. The RP-HPLC profiles were similar between the two species and levealed the predominance of polar compounds. In the quantification of coumarin, a content of 0.30% (w/w) was obtained for M glomerata and 0.43% (w/w) for M. laevigata. These values are in accord with the contents (min. 0.1%, w/w) described by the monograph of guaco-cheiroso in the Brazilian Pharmacopoeia. Therefore, the results indicated similar chemical profiles for M. glomerata and M. laevigata, as well as comparable coumarin contents, thus suggesting that the species might be used indistinctly.