Toxicity, Antibacterial, and Phytochemical Analyses of Antrocaryon klaineanum Pierre Extracts

Medicinal plants are traditionally used in Gabon to treat several types of illnesses. The study's purpose was to determine the toxic, antibacterial, and anti-inflammatory effects of Antrocaryon klaineanum Pierre extracts and to characterize their phytochemical compounds. Toxicity was evaluated on frog tadpoles (Phrynobatrachus africanus Hallowell). The microorganism susceptibility test was performed by the diffusion method, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were evaluated using the microdilution technique. Anti-inflammatory activity was tested through protein denaturation and membrane stabilization methods. Chromatography and molecular network techniques were used to characterize chemical compounds. The lethality test showed that the lethal concentration (LC₅₀) increased from 110.03 ± 1.25 to 15.86 ± 2.21 μg/mL after 24 and 96 hours of exposure. In tadpoles exposed to 7.81 μg/mL extract, the first mortalities (12.5%) were observed on the fifth day of exposure. A relative decrease in mature erythrocytes exposed to plant extracts was observed. The antibacterial activity shows that the Ak F₂, Ak F₃, and Ak F₄ fractions (from the water-ethanol crude extract) gave the greatest antibacterial activities compared to the other extracts. The water, water-acetone, and water-ethanol extracts showed good inhibition of denaturation. The haemolysis test shows that the extracts exhibited good anti-inflammatory activities. Phytochemical characterisation revealed four major compounds, including monogallate epicatechin and hydroxy-ergostadian. The molecular network revealed five main clusters. Our study shows that A. klaineanum Pierre could be a promising natural product for the isolation of molecules with potential biological activities.

Ethnopharmacological Study and Antibacterial Activities of Some Plants Used in Traditional Medicine for the Treatment of Diarrheal Diseases in Gabon

The purpose of this work was to develop ethnopharmacological and biological studies of plants used in traditional medicine for the treatment of diarrheal diseases. This study results in scientific data that validates the uses of these plants in traditional medicine. Firstly, ethnopharmacological surveys were conducted with a few traditional healers from the provinces of Estuaire, Haut Ogooué and Woleu-Ntem in Gabon. Next, ethnobotanical data such as percentage of families, species, routes of administration, methods of preparation, parts used and number of plant names were analyzed and summarized. Finally, the antibacterial activities of some plants have been evaluated by diffusion and microdilution methods. Thirty-four (34) traditional healers were interviewed. A total of 90 plant species were identified during this study. They belong to 44 families, the most represented were Leguminoseae (13.33%), Apocynaceae (7.78%), Annonaceae (5.55%), Euphorbiaceae (4.44%) and Anacardiaceae (4.44%). Trees were used more (44.44%) than shrubs (32.22%), herbaceous plants (16.67%) and lianas (6.67%). The drug administration was mainly oral (84.62%) and by the anal route. Decoction and maceration were the two most used methods of preparation. Among identified plants, twenty-seven (27) plant extracts were subjected to microbiological analyzes. Plant extracts tested were active on Gram-negative and Gram-positive bacteria. Cola nitida extracts gave the best antibacterial activity against Enterococcus faecalis 103907 CIP. This study identified 90 antidiarrheal plant species and clearly shows the antimicrobial potential of several medicinal species.

Structure elucidation of a new lanostane triterpene from Gabonese Ganoderma orbiforme fruiting bodies

The structure and complete nuclear magnetic resonance (NMR) assignments of orbifomitellic acid, a novel lanostane triterpene isolated from the fruiting bodies of a Gabonese Ganoderma orbiforme (Polyporaceae), are reported. Within the vast catalogue of lanostanes documented from Ganoderma spp., orbifomitellic acid is the first disclosing a -COOH group at C-4.

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

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.

A Study of the Therapeutic Potential of Lentinus squarrosulus (Agaricomycetes) from Gabon

Lentinus squarrosulus is a mushroom widely used in Gabon for its culinary and medicinal properties. The bioactive potential of mushrooms might be attributable to the presence of several pharmaceutically important mycocompounds that need to be ascertained scientifically. A study of the therapeutic potential of L. squarrosulus, the species of lignicolous fungus exploited in Gabon, was carried out on the basis of a chemical screening performed on three extracts in order to highlight different important chemical groups. This chemical screening was followed by a study of the fungus's antioxidant activity and prediction of its additional pharmacological activities. Chemical screening revealed that three extracts (aqueous, hydroethanolic, and ethanolic) of L. squarrosulus were almost free of tannins and were poor in total flavonoids and moderately rich in reducing sugars. Aqueous and ethanolic extracts were rich in total polyphenols, whereas aqueous and hydroethanolic extracts were rich in alkaloids. The aqueous extract was rich in saponosides and the hydroethanolic extract was rich in coumarins. The dosage of phenolic compounds confirmed the fungus's richness in total polyphenols, especially for aqueous and ethanolic extracts, its poverty in flavonoids and absence of tannins in ethanolic and hydroethanolic extracts. Regarding antioxidant activities, the results obtained for diphenyl picryl hydrazyl trapping tests showed that the different extracts tested had antioxidant activity ranging from low to moderate (0.12 ≤ antioxidant activity index [IAA] ≤ 0.6); the greatest activity was obtained with ethanolic extract (IAA = 0.6). Hence, we conclude that L. squarrosulus extracts can be used as easily accessible sources of natural antioxidants for potential preventative therapies.