HPLC-DAD analysis of chemical markers in leaves of Mikania laevigata and Mikania glomerata submitted to long-term storage

Mikania laevigata Sch. Bip. ex Baker and Mikania glomerata Spreng., known in Brazil as guaco, are medicinal species widely used to treat respiratory affections. Stability analyses of vegetal drugs are crucial to assure the quality of derived products. The present study aimed at undertaking qualitative and quantitative analysis of cheminal markers [coumarin (CO), o-coumaric (OC), kaurenoic (KA), benzoylgrandifloric (BA) and cinnamoylgrandifloric (CA) acids] in dried leaves of M. laevigata and M. glomerata submitted to long-term storage. The plant materials were stored in a dark room with controlled temperature and humidity, and had their fingerprints analyzed three-monthly up to 18 months. Changes in chemical markers were evaluated by UV spectral purity of the peaks and by quantitative analysis of their contents (% w/w in dried leaves), employing an HPLC method previously reported by us [1]. The concentrations of the chemical markers did not vary significantly within the evaluated storage period (p>0.05) for both species. In contrast, changes in BA, CA and KA peaks were detected for three-months stored samples of both species and CO peak, found only in M. laevigata, was detected after six months of storage, suggesting compound degradation. The CO contents in M. laevigata samples ranged from 0.10±0.03% to 0.12±0.03% and therefore fulfill the Brazilian pharmacopoeical requirement established for the species (minimum of 0.1% w/w), except for the 12-month sample (0.09±0.03%) [2].Therefore, the quality control of Mikania species should be based both on the quantification of the selected compounds and fingerprint analysis.

Acknowledgement: FAPEMIG, CAPES and CNPq, for the financial support.

References: 1. Bertolucci SKV et al. (2009) Planta Med75:280–285.

2. Farmacopéia Brasileira IV (2005) Sexto fascículo:292.