Antimicrobial, antioxidant, anti-inflammatory and cytotoxic study of extracts of Guibourtia tessmanii (harms) J. Léonard from Gabon

Abstract

Background: Gabonese flora abounds in a significant reserve of plants in medical matter. Thus, medicinal plants occupy a significant place in African pharmacopeia. Aim of this work was to evaluate the antimicrobial, antioxidant, anti-inflammatory and cytotoxic properties of extracts of Guibourtia tessmanii (Harms) J. Léonard. Methods: The test for sensitivity to microorganisms was performed by the diffusion method, while the MICs and MBCs were evaluated by the microdilution technique. Antioxidant tests were performed by scavenging the DPPH and ABTS radicals. Anti-inflammatory activity was determined by protein denaturing and membrane stabilization methods. The cytotoxicity was evaluated on the tadpoles of the green frog. Results: The antibacterial activity shows that the Gt F2 fraction and the water-acetone extract produced the greatest inhibitions. The water, water-ethanol and water-acetone extracts exhibited bactericidal effects on the majority of bacteria. In the case of trapping of the DPPH radical, the IC50 values varied from 6.92 ± 0.48 to 16.64 ± 0.20 μg/mL. For the decolouration of ABTS, oxidation was mainly inhibited by the water-acetetone, water-ethanol extracts and some fractions. The water and water-acetone extracts showed good inhibition of denaturation. The hemolysis test confirmed the good activities of the extracts. The lethal test showed that the LC50 drops from 171.37 ± 9.25 to 58.25 ± 7.21 μg/mL after 24 and 96 h of exposure. In tadpoles exposed to 7.81 μg / mL of extracts, the first mortalities (12.5%) were observed on the second day of exposure. From the ninth day, the mortality rate increased (25%) until the 16th day. Conclusion: Our results show that Guibourtia tessmanii may be a promising product for the isolations of molecules responsible for biological activities.