Phytochemical screening, antioxidant and antibacterial activities of Guibourtia ehie and Syzygium rowlandii medicinal plants from gabon

Medicinal plants have been used for centuries as remedies for human diseases and continue to do important services at human being. These plants have served as a very important replacement for the resistant strains. Aqueous, chloroform and methanol extracts of Guibourtia ehie and Syzygium rowlandii were evaluated for phytochemical analyses, antimicrobial and antioxidant activities. The antimicrobial activity was evaluated by disc diffusion and microdilution assays. Antioxidant Activity Index (AAI) was determined for antioxidant activity evaluation. Phytochemical screening showed also high total phenol, saponins, flavonoids, alkaloids, sterols, triterpenes and proanthocyanidins. The extracts of Guibourtia ehie reduce the concentration of DPPH free radical, IC50 values are 34.0 ± 0.15 μg/mL and 49.0± 0.19 μg/mL for water and methanol extracts. Oxidation of β-carotene is inhibited by methanolic and aqueous extracts (55.64 ± 0.05% and 68.4 ± 0.05%). The IC50 of S. rowlandii is 91.5 ± 0.15 mg/mL. The relative antioxidant activity of methanol extracts was 95.4 %. However, water extract of Guibourtia ehie and methanol extract of Syzygium rowlandii had strong effects, AAI are 2.31 and 8.54, and can be compared to AAI of Vitamin C and BHT (AAI values of 11.32 and 7.85, respectively). The results of susceptibility testing with extracts of Guibourtia ehie and Syzygium rowlandii show that these plants exhibit the growth of nearly all microorganisms used in the essay. The study confirm the multiple uses of Guibourtia ehie and Syzygium rowlandii for the treatment of many infectious diseases and place them as candidate for further investigations for traditional drug utilizable as complementary and alternative medicines development and new active compounds.