Antimicrobial Plants Used by Fang Populations and Phytochemical Profiling of Erismadelphus exsul.

Gabon has a rich flora, many species of which are used in traditional medicine. However, little research has been carried out on this wealth. An ethnopharmacological survey in the Fang language was carried out among traditional practitioners to collect antimicrobial medicinal plants. Phytochemical profiling of ethanolic and methanolic extracts from Erismadelphus exsul Mildbr leaves was carried out using HPLC-ESI-Q/TOF and a molecular network approach. Antibacterial activity was assessed with disk diffusion and microdilution methods, antioxidant activity via DPPH and FRAP methods, and in vitro cell viability via Cell Counting Kit-8. A total of 21 medicinal plants were collected, grouped into 10 families, of which the Fabaceae is the most represented. Erismadelphus exsul was chosen for chemical and biological studies due to its citation frequency (RCF = 0.59) and the absence of previous phytochemical studies. These studies revealed 4 major families of natural compounds and annotated 19 compounds for the first time. The crude leaf extract showed significant antioxidant and antibacterial activity. Cytotoxicity studies showed that the leaves were not cytotoxic, unlike the bark. This study underlines the importance of preserving the ancestral knowledge of the Fang populations, while showing promising results for Erismadelphus exsul.

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.

Antibacterial and antioxidant activities of plants consumed by western lowland gorilla (Gorilla gorilla gorilla) in Gabon.

Zoopharmacognosy is the study of the self-medication behaviors of non-human animals that use plant, animal or soil items as remedies. Recent studies have shown that some of the plants employed by animals may also be used for the same therapeutic purposes in humans. The aim of this study was to determine the antioxidant and antibacterial activity of Ceiba pentandra, Myrianthus arboreus, Ficus subspecies (ssp.) and Milicia excelsa bark crude extracts (BCE), plants consumed by western lowland gorillas (Gorilla gorilla gorilla) in Moukalaba-Doudou National Park (MDNP) and used in traditional medicine, and then to characterize their phytochemical compounds. DPPH (2,2-Diphenyl-1-Picrylhydrazyl), phosphomolybdenum complex and ß-carotene bleaching methods were used to assess antioxidant activity. Antimicrobial susceptibility testing was performed using the diffusion method, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were assessed using the microdilution method. The highest level of total phenolics was found in Myrianthus arboreus aqueous extract [385.83 ± 3.99 mg [gallic acid equivalent (GAE)/g]. Total flavonoid (134.46 ± 3.39) mg quercetin equivalent (QE)/100 g of extract] were highest in Milicia excelsa, tannin [(272.44 ± 3.39) mg tannic acid equivalent (TAE)/100 g of extract] in Myrianthus arboreus and proanthocyanidin [(404.33 ± 3.39) mg apple procyanidins equivalent (APE)/100 g of extract] in Ceiba pentandra. Ficus ssp. (IC50 1.34 ±3.36 µg/mL; AAI 18.57 ± 0.203) ethanolic BCE and Milicia excelsa (IC50 2.07 ± 3.37 µg/mL; AAI 12.03 ± 0.711) showed the strongest antioxidant activity. Myrianthus arboreus ethanolic BCE (73.25 ± 5.29) and Milicia excelsa aqueous BCE (38.67 ± 0.27) showed the strongest percentage of total antioxidant capacity (TAC). Ceiba pentandra ethanolic BCE (152.06 ± 19.11 mg AAE/g) and Ficus ssp aqueous BCE (124.33 ± 39.05 mg AAE/g) showed strongest relative antioxidant activity (RAA). The plant BCE showed antimicrobial activity against multidrug resistant (MDR) E. coli (DECs) isolates, with MICs varying from 1.56 to 50 mg/mL and inhibition diameters ranging from 7.34 ± 0.57 to 13.67 ± 0.57mm. Several families of compounds were found, including total phenolic compounds, flavonoids, tannins and proanthocyanidins were found in the plant BCEs. The plant BCEs showed antioxidant activities with free radical scavenging and antimicrobial activities against 10 MDR E. coli (DECs) isolates, and could be a promising novel source for new drug discovery.

Cytotoxicity and Identification of Antibacterial Compounds from Baillonella toxisperma Bark Using a LC-MS/MS and Molecular Networking Approach.

Baillonella toxisperma is a medicinal plant used in northern Gabon to treat microbial diseases. It is a plant well-known by local populations, but very few studies have focused on the molecules responsible for the antibacterial activities of B. toxisperma. This study proposes a dereplication strategy based on molecular networking generated from HPLC-ESI-Q/TOF data, allowing investigation of the molecules responsible for the antibacterial activity of B. toxisperma. From this strategy, eighteen compounds were putatively identified. All of these compounds belonged mainly to five families of natural compounds, including phenylpropanolamines, stilbenes, flavonoids, lignans and phenolic glycosides. The chemical study carried out from the bark of B. toxisperma allowed us to identify, for the first time, compounds such as resveratrol and derivatives, epicatechin, epigallocatechin and epigallocatechin gallate. In addition, antibacterial activity (diffusion method and microdilution) and cytotoxicity (Cell Counting Kit-8 (CCK-8 Assay)) in vitro were evaluated. The crude ethanolic extract, as well as the fractions of B. toxisperma, showed significant antibacterial activity. However, the ethanolic fractions F2 and F4 presented high antibacterial activity compared to the crude extract. Cytotoxicity studies on colon-cancer cells (Caco-2) and human keratinocyte cells (HaCaT) showed moderate cytotoxicity in both cell types. This study clearly shows the therapeutic potential of the ethanolic extract of the bark of B. toxisperma and provides information on the phytochemical composition and bioactive compounds of the plant.

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.

Combined LC-MS/MS and Molecular Networking Approach Reveals Antioxidant and Antimicrobial Compounds from Erismadelphus exsul Bark.

Erismadelphus exsul Mildbr bark is widely used in Gabonese folk medicine. However, little is known about the active compounds associated with its biological activities. In the present study, phytochemical profiling of the ethanolic extract of Erismadelphus exsul was performed using a de-replication strategy by coupling HPLC-ESI-Q/TOF with a molecular network approach. Eight families of natural compounds were putatively identified, including cyclopeptide alkaloids, esterified amino acids, isoflavonoid- and flavonoid-type polyphenols, glycerophospholipids, steroids and their derivatives, and quinoline alkaloids. All these compounds were identified for the first time in this plant. The use of molecular networking obtained a detailed phytochemical overview of this species. Furthermore, antioxidant (2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) and ferric reducing capacity (FRAP)) and in vitro antimicrobial activities were assessed. The crude extract, as well as fractions obtained from Erismadelphus exsul, showed a better reactivity to FRAP than DPPH. The fractions were two to four times more antioxidant than ascorbic acid while reacting to FRAP, and there was two to nine times less antioxidant than this reference while reacting to DPPH. In addition, several fractions and the crude extract exhibited a significant anti-oomycete activity towards the Solanaceae phytopathogen Phytophthora infestans in vitro, and, at a lower extent, the antifungal activity against the wheat pathogen Zymoseptoria tritici had growth inhibition rates ranging from 0 to 100%, depending on the tested concentration. This study provides new insights into the phytochemical characterization and the bioactivities of ethanolic extract from Erismadelphus exsul bark.

Effect of aqueous extracts of Ficus vogeliana Miq and Tieghemella africana Pierre in 7,12-Dimethylbenz(a)anthracene -induced skin cancer in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Skin cancer is the most common form of cancer responsible for considerable morbidity and mortality. Tieghemella africana and Ficus vogeliana are used in traditional medicine to treat cancers. AIM OF THE STUDY: Therefore, the aim of this study was to investigate the antioxidant, antiangiogenic and anti-tumor activities of these plant extracts. MATERIALS AND METHODS: To achieve it, phytochemical screening, antioxidant activity and antiangiogenic activity were assessed. Thereafter, the anti-tumor activity was determined using skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene. RESULTS: The phytochemical result analysis showed that both plant extracts were rich in polyphenols, alkaloids and terpene compounds and possessed good antioxidant activity based on DPPH radical scavenging (IC50 = 9.70 µg/mL and 4.60 µg/mL and AAI values of 5.20 and 10.88) and strong total antioxidant capacity (115.44 VtCE (mg)/g of dry plant extract and 87.37 VtCE (mg)/g of dry plant extract, respectively). Additionally, both plant extracts possessed antiangiogenic activities (IC50 = 53.43 µg/mL and 92.68 µg/mL, respectively), which correlated with significant antitumor activities when using 35 mg/kg (65.02% and 77.54%) and 70 mg/kg of extracts (81.07% and 88.18%). CONCLUSIONS: In summary, this study illustrates the promising usage of Tieghemella africana and Ficus vogeliana plant extracts in treating skin cancer. However, further characterization of the extracts must be performed to isolate the most active anticancer compound.