ISOLATION AND CHARACTERIZATION OF CHEMICAL CONSTITUENTS FROM CHRYSOPHYLLUM ALBIDUM G. DON-HOLL. STEM-BARK EXTRACTS AND THEIR ANTIOXIDANT AND ANTIBACTERIAL PROPERTIES

Abstract
Chrysophyllum albidum, native to Nigeria, has a long history of use in traditional medicine, particularly for treating infections and diseases related to oxidative stress. This study aimed to isolate the chemical compounds responsible for its antioxidant and antibacterial properties to support its ethnomedicinal applications.Crude extracts of the stem-bark of Chrysophyllum albidum were obtained using 80% ethanol and subsequently partitioned with ethyl acetate (EtOAc) and n-butanol. The solvent fractions and isolated compounds were evaluated for antioxidant activity using the DPPH assay. Antibacterial properties were assessed through agar diffusion and broth microdilution methods. The EtOAc fraction underwent further chromatographic separation, yielding four compounds, whose structures were elucidated using NMR (1D and 2D) and MS techniques.

Results
Fractionation of the EtOAc extract, which exhibited the strongest antioxidant and antimicrobial activities, resulted in the isolation of stigmasterol (1), epicatechin (2), epigallocatechin (3), and procyanidin B5 (4). Notably, procyanidin B5, isolated for the first time from the genus Chrysophyllum, demonstrated the highest antioxidant activity with IC50 values of 8.8 μM and 11.20 μM in the DPPH and nitric oxide assays, respectively. It also exhibited significant inhibitory effects against Escherichia coli (MIC 156.25 μg/mL), Staphylococcus aureus (MIC 156.25 μg/mL), Pseudomonas aeruginosa (MIC 625 μg/mL), and Bacillus subtilis (MIC 156.25 μg/mL).

Conclusion
The antibacterial and antioxidant activities of epicatechin, epigallocatechin, and procyanidin B5 isolated from the stem-bark of Chrysophyllum albidum lend scientific support to its traditional AZ 628 medicinal uses.