Phytochemical Study, FTIR and GC-MS Characterization and Evaluation of the Antioxidant Activity of Letestua Durissima Extracts

The current study focused on extract content, phytochemical screening, GC-MS analysis, infrared analysis and antioxidant activity evaluation of bark, sapwood and heartwood of Letestua durissima, commonly called Kong Afane in Gabon, using DPPH and ABTS methods. The highest extract contents, reaching 37.3%, were observed in the bark. Phytochemical tests revealed the presence of alkaloids, polyphenols, sterols, terpenes, flavonoids and saponins in the extracts. The quantitative results highlighted high concentrations of polyphenols (95.56 mg GAE g−1 of dry extract in the acetone extract), condensed tannins (113.45 mg CE g−1 of dry extract in the extract toluene–ethanol) and flavonoids (20.26 mg CE g−1 of dry extract in the toluene–ethanol extract) in the bark. Regarding the evaluation of antioxidant activity, the results showed a significant capacity of the extracts to scavenge free radicals. This activity was more pronounced in the toluene–ethanol extracts, with an IC50 of 0.66 for the ABTS method and 2.39 for that of DPPH. The GC-MS identification of phenolic compounds such as hydroxybenzoic acid, protocatechuic acid, gallic acid, catechin and triterpenes could explain the high reactivity of our extracts as antioxidants.