An investigation of the effect of seasonal variation on the phytochemical constituents in two nauclea species

Abstract

Nauclea diderrichii and Nauclea latifolia are two important African medicinal plants with several known bioactive phytochemicals. However, the presence of these phytochemicals can vary depending on the season of collection. Thus, this study investigates N. diderrichii and N. latifolia leaf samples collected in October (rainy season) and February (dry season) for any disparity in their phytochemical constituents. Pulverized samples were macerated for 24 hours in acetone. The dried extracts were subjected to phytochemical screening following standard procedures. Their Fourier transform infrared (FTIR) spectra were acquired and compared. Thin layer chromatographic analysis were carried out using the chloroform soluble fraction (CSF) and methanol soluble fraction (MSF)] of the extracts on pre-coated silica gel plates. The number of separated spots in each plate was noted after the developed plates were visualized under UV light and after spraying with vanillin-sulphuric acid reagent. Nauclea latifolia leaf extracts showed some variations in saponin and tannin contents as they were higher in rainy season, the number of fundamental IR vibrational peaks were more in rainy season, and the number of spots on TLC for the CSF and MSF varied. For N. diderrichii, in both seasons, no variation was observed. The study revealed some disparities in phytochemical constituents in N. latifolia leaf due to seasonal variation, while this was not so apparent with N. diderrichii leaf.