Leaves, root bark, stems and fruits of some Katangan Vitex species (Lamiaceae), are widely used in traditional medicine to treat diabetes, diarrhea, and parasitic diseases, notably malaria. The observed morphological variability of Vitex species may imply a variability in their complex chemical compositions; their chemical profiles are then likely to vary according to morphology as well as to collection site. High performance thin-layer chromatography (HPTLC), thanks to the holistic fingerprints produced, is often recommended for the quality control of plant material.
This study aims to evaluate the chemical variability of five Vitex species and their morphotypes, by establishing chemical profiling methods. Leaves, root bark, stems and fruits samples were collected from various parts of Katanga and methanolic extracts were used to profile flavonoids, iridoids, diterpenes and triterpenes. Using Camag application, development and imaging instruments, HPTLC methods were developed and optimized, images being captured under UV (254 nm and 366 nm) and white light, before and after derivatization.
In methanolic extracts, organ-specific bands could be detected; we could identify some compounds, i.e. 20-hydroxyecdysone, aucubin, casticin and rotundifuran. Iridoids profiling yielded a very intense band common to all the samples investigated.
Although the chemical profiling of studied species showed strong similarities between them, there are certain specific bands that allow to differentiate them. The different morphotypes can be recognized by intensity differences in some major bands and by the presence or absence of certain bands.
Figure 1
Identification of 20-hydroxy-ecdysone in methanolic extracts of various Vitex samples.
Mobile phase : AcOEt-MeOH (80:20, v/v); detection : vanillin + sufuric acid, 105°C, 5 min
