Molecular Docking and Anti-inflammatory Studies on Extracts of Prosopis africana (Guill. & Perr.) Taubert and Parkia biglobossa (Jacq.) Benth (Fabaceae)

Context: Prosopis africana and Parkia biglobossa have been used since ancient times in Sierra Leone, Mali, Uganda and Nigeria in the treatment of anti-inflammatory related diseases.

Aims: To evaluate the anti-inflammatory potentials of methanolic extracts and fractions of Prosopis africana, and Parkia biglobosa using in vivo and in silico methods.

Methods: Their pulverized stem barks were extracted with methanol using Soxlet extraction technique. The crude extracts, CMEPR and CMEPK were partitioned into n-hexane, ethylacetate and methanol fractions. The extracts and fractions were subjected to anti-inflammatory studies using egg albumin and Xylene inflammatory models. Molecular docking was carried out on compounds identified via GC-MS with the aid of Vina. Molecular interactions between outstanding compounds and target enzymes was viewed using Discovery Studio Visualizer, 2020. The phytochemical analysis was carried out using standard method.

Results: The results obtained from both egg albumin and Xylene inflammatory models revealed dose dependent inhibition of edema in both plants with the greatest inhibition observed at higher doses. CMEPR: 23.65%, 35.89%, 69.23% (egg albumin model); 48.65%, 64.86%, 78.38% (Xylene model), CMEPK: 33.33%, 46.15%, 73.08% (egg albumin model); 67.57%, 78.37%, 91.89% (Xylene model) for 100,200 and 400 mg/kg respectively. The ethylacetate fraction of Parkia biglobosa exhibited the highest edema inhibition (94.59%) comparable with the standard drug Piroxicam (89.18%). Molecular docking revealed l-(+)-ascorbic acid 2,6-dihexadecanote as a potent inhibitor of both cyclooxygenase-2 (Cox-2) and tumor necrosis factor alpha (TNF-α) with a binding affinity of -12.6 and -9.0 kcal/mol respectively compared to standard drugs.

Conclusions: This study revealed that methanolic extracts of Prosopis africana, and Parkia biglobosa possess promising anti-inflammatory properties with a mechanism of action that may involve the inhibition of Cox-2 and TNF-α. Further research is needed to identify the active compounds responsible for the activities observed.