Purification, stability and antifungal activity of verbascoside from Lippia javanica and Lantana camara leaf extracts

The biological properties of verbascoside are numerous and include antimicrobial activities. As part of a drive to identify alternatives to synthetic fungicides for crop protection, this study was aimed at investigating methods of preparing verbascoside-rich plant extracts from viable sources of the compound and monitoring its stability under various conditions. Leaf extracts of Lippia javanica Spreng. and Lantana camara Linne (Verbenaceae) were partially purified using column chromatography and high speed centrifugal countercurrent chromatography, the latter yielding fractions with higher purity (71%) than those from a single column chromatographic separation (38-44% pure). Verbascoside remained stable upon heating, but was completely decomposed after four hours exposure of the extract to sunlight. Compared to the other storage conditions, the compound was best preserved in a dry form in the dark. Analysis by high performance liquid chromatography revealed that the verbascoside content of plant parts of L camara from natural populations was highly variable, both within and between populations. However, several specimens produced high levels of the compound (Hazyview: Plant 3 (83.0 mg/g dry weight), Magoebaskloof 2: Plant 5 (64.8 mg/g) and White River: Plant 2 (64.0 mg/g)), suggesting that L camara is an excellent source of verbascoside. Extracts of the plant displayed effective in vivo inhibition of Penicillium digitatum on oranges. (c) 2012 Elsevier B.V. All rights reserved.