Effect of seasonality and growth conditions on the content of coumarin, chlorogenic acid and dicaffeoylquinic acids in Mikania laevigata Schultz and Mikania glomerata Sprengel (Asteraceae) by UHPLC–MS/MS

Abstract

Mikania glomerata and Mikania laevigata, both popularly called guaco, are used without distinction in Brazilian traditional medicine for respiratory diseases. Besides the genotype, seasonality and variations in cultivation conditions of medicinal plants may result in different concentrations of active components, affecting the safety, quality and efficiency expected of herbal medicines. Considering the lack of studies regarding the cultivation conditions of these two species and the importance of these studies for their safe use, we evaluated by ultra-high performance liquid chromatography-mass spectrometry how three bioactive secondary metabolites are influenced by seasonality and variations in the following cultivation conditions: temperature, luminosity and water availability. Hydro alcoholic extracts of the leaves were evaluated by UHPLC–MS and MS/MS, following the differences in the concentration of their chemical marker, coumarin, and other bioactive components: chlorogenic acid (3-O-caffeoylquinic acid) and dicaffeoylquinic acids. This is the first report on the presence of dicaffeoylquinic acid in these species. The results show significant influence of seasonality and the treatments on the contents of these compounds. The highest content of coumarin was found in extracts of M. laevigata collected from March–July, grown under 50% shade, at temperatures of 10°C and/or 22°C, and under conditions of lower water availability. M. glomerata showed high content of both caffeoylquinic acids, especially growing in full sunlight and temperatures of 10°C and/or 22°C, but lower concentrations were observed in the samples collected in July, which coincided with flowering. Although the present study showed influence of seasonality and environmental conditions on the chemical profile of the two species, the differences in composition between species were always greater than the variations due to seasonality or treatments within the same species, indicating that they should not be used without distinction. Coumarin is not a valid chemical marker for M. glomerata.