Research for bioactive molecules and not resistant to infectious agents remains topical for science. The total polyphenols (TPP) and total flavonoids (TFv) of the hydroethanolic extracts and fractions obtained were quantified according to the spectrophotometric method described in the literature using the Folin-Ciocalteu reagent and the colorless solutions of sodium nitrite 2.5% and aluminum chloride 10% respectively. The characterization of chemical compounds was made by coupling liquid chromatography (LC) and mass spectroscopy (MS). Thus, 15 chemical compounds were characterized, seven from Gnetum africanum (EBa) and eight from Gnetum buchholzianum (EBb). The majority of which were stilbens, such as Gnetupendin D, Dimethoxygnetulin, Methoxyparvifolol D, Isorhaponcitin from Eba and Gnetuhaidin P, Gnetupendin D, Gnetuhainin C, phenols (Alcohol Homovanillyl, Alcohol Erythro guaiacylglycerol-β-O-4'-coniferyl, and Alcohol Homovanillyl from EBb. The minority were flavonoids such as Dimethoxydihydropyraneriodictyol,

This study was aimed at evaluating gastroprotective activity and the acute oral toxicity of the aqueous extract of the stem bark of Cylicodiscus gabunensis. Gastritis was induced with 96% (v/v) ethanol after pre-treatment with different doses of the aqueous extract of C. gabunensis. The gastroprotective effect was determined with the help of macroscopic and microscopic analysis of injured stomachs and the percentages of ulcer inhibition were calculated. Subsequently, using colorimetric methods, a phytochemical screening was carried out on the dry extract of C. gabunensis in order to determine the families of compounds present therein. After the screening, the dry extract was fixed on silica gel and mounted on a chromatographic column in order to isolate the bioactive compounds. Finally, the structures of the isolated compounds were obtained using spectral methods (MS, 1H NMR, 13C NMR, HSQC, and HMBC). The result of this study shows that C. gabunensis does not present any acute toxicity at the doses tested. However, the gastroprotective effect was observed for all doses, with a maximum inhibition of the ulcer at 63.94% at the dose of 400 mg/kg of extract; against 56.73% inhibition for aluminium and magnesium hydroxide at a dose of 50 mg/kg. The phytochemical screening of the crude extract of C. gabunensis showed the presence of several secondary metabolites including sterols, triterpenes and saponins. Five compounds were isolated and characterized by spectroscopic methods as being: \(\beta\)-sitosterol (1), lupeol (2), betulinic acid (3), betulin (4) and 3-O-\(\beta\)-D- sitosterol glucopyranoside (5). LD50 has been found over 5000 mg/kg, indicating that C. gabunensis was not toxic.