Phenolic Derivatives Isolated from Chamaecrista hildebrandtii (Vatke) Lock and Their Biological Activities

Chamaecrista hildebrandtii is used to prepare herbal medicines as laxative and purgative agents to treat diseases such as diarrhea, stomach ulcers, healing wounds and skin infections. Thus, this plant has shown great interest to researchers, but the chemical constituent of this plant has not been determined. The objective of the study was the extraction and purification of phytochemicals from C. hildebrandtii crude leaf extracts and to determine their antioxidant and antimicrobial ability. Extraction of the C. hildebrandtii leaves was done by macerating shade-dried and milled leaves in methanol that was further partitioned using water, hexane and ethyl acetate. Ethyl acetate fraction underwent further TLC analysis and repeated column chromatography with various solvent combinations to give a total of twelve fractions. Spectroscopic analysis was done using 1H NMR, 13C NMR, 1H-1H COSY, 2D-HSQC and 13C DEPT-135 and carefully compared with the literature available. Two phenolic compounds emodin (1,3,8-trihydroxy-6-methylanthraquinone) and chrysophanol (1,2-dihydroxy-6-methylanthrquinone) were isolated and identified. The antimicrobial activity was tested by disc diffusion method using Mueller Hinton agar growth medium. Emodin exhibited comparatively higher inhibitory activity against microbes in comparison with chrysophanol. Emodin showed a 55.1% DPPH inhibition while chrysophanol recorded a 58.2% inhibition. Emodin showed a desirable IC50 of 7.3 mg/mL compared to chrysophanol with an IC50 value of 12.3 mg/mL. The IC50 values of the two isolates were slightly higher than that of ascorbic acid (IC50 = 3.24 mg/mL). The outcome revealed that C. hildebrandtii leaf extracts may represent a promising natural source of polyphenols, which can be used as antimicrobial and antioxidant agents.