5.1. Plant Extraction and Compounds Purification

Barks and roots of C. abbreviata were collected from mature shrubs in Makueni County, Kenya. Its identity was confirmed by DNA barcoding approach in the lab. All materials were pulverized before extraction. The crude extract (CE) was obtained through a first extraction of barks and roots from C. abbreviata that were pulverized with 95% ethanol, and a second extraction with ethyl acetate, and dried. The extracts were combined and concentrated to a small volume to provide a crude extract. The concentrate of the ethanol phase was suspended in deionized water, successively partitioned with CHCl₃, EtOAc, and n-BuOH and subjected to column chromatography over silica gel. The CHCl₃ and EtOAc extracts were combined and subjected to column chromatography over silica gel eluting with a gradient CHCl₃-MeOH (0- > 100%), followed by column chromatography over octadecyl silane and sephadex LH-20. Preparative thin layer chromatography was used to purify the compounds, and purity over 95% was verified by HPLC-UV. To characterize the compounds, UV and NMR data were collected from UV-2550 spectrometer and Bruker Avance 500 or 600 NMR spectrometers.