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.

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.

HIV-exposed uninfected compared with unexposed infants show the presence of leucocytes, lower lactoferrin levels and antimicrobial-resistant micro-organisms in the stool

Background: HIV-exposed uninfected (HEU)-infants have been shown to be particularly vulnerable to infections. In this population, disturbance of the gut micro-environment might increase their susceptibility to enteric diseases and even favour the translocation of bacteria in the bloodstream. Methods: The gastro-intestinal micro-environment was explored in 22 HEU infants and 16 HIV-unexposed (HU) infants aged 6-24 weeks. Faecal leucocytes, firmicutes (gram-positive bacteria) and gracilicutes (gram-negative bacteria) were assessed by cytology. Faecal lactoferrin and sIgA were measured by ELISA. The spectrum of micro-organisms in infants' stool was analysed by culturing. Results: HEU infants were 14 times more likely to have leucocytes in their stool than HU infants (p < 0.005). The lactoferrin level was significantly lower in HEU infants than in HU infants (p = 0.02). Potentially pathogenic bacteria such as Escherichia coli were more prevalent in HEU than in HU infants (64% vs 23.5%). Also, E. coli strains resistant to key antibiotics including co-trimoxazole, β-lactam (cephalosporins included) and tetraclines were observed in some HEU infants. Conclusion: HEU infants are more likely to present an inflamed digestive tract as highlighted by the presence of leucocytes. In addition, there is a real risk of colonisation of HEU infants' microbiota by resistant micro-organisms.

Chemical composition, antioxidant and antimicrobial activities of stem barks of

<p>Aim of this work was to evaluate the phytochemical constituents, antioxidant and antimicrobial potential of water-acetone, water-ethanol and water extracts of <em>Englerina gabonensis</em> and <em>Sterculia tragacantha</em>.Presence of phenols was evaluated to estimate the effects of plants on microbial diseases. Water-acetone, water-ethanol and water extracts were examined for antioxidant activities. All plant extracts were tested against six reference strains, eleven clinical isolates and two fungal strains.</p><p>Phenolic content were highest in the water-acetone and water-ethanol extracts from <em>Englerinagabonensis</em> in comparison with <em>Sterculia tragacantha</em>.The AAI (Antioxidant Activity Index)of water-acetone and water-ethanol extracts of <em>Englerina gabunensis</em> are superiors with 2. Plant extracts of <em>Sterculia tragacantha</em> show weak antioxidant activity (AAI &lt; 0.5).The aqueous extract of <em>Englerina gabonensis </em>has a bactericidal effect on <em>Salmonella Spp</em>. Water-ethanol extract is bactericidal on <em>Bacillus cereus </em>LMG 13569 BHI, <em>Salmonella Spp</em>and <em>Neisseria meningitides. </em>Water-acetone extract presents a bactericidal activity on <em>Enterococcus faecalis</em>103907 CIP, <em>Escherichi coli</em>, <em>Staphylococcus aureus</em>, <em>Acinetobacter baumannii</em>and <em>Neisseria meningitides.</em></p><p>Our results suggest that <em>Englerina gabonensis</em> extracts contain greater antioxidant and antimicrobial properties than <em>Sterculia tragacantha </em>extracts.</p>

In vitro antiplasmodial activity and cytotoxicity of extracts and fractions of Vitex madiensis, medicinal plant of Gabon

Vitex madiensis Oliv. (Lamiaceae) is traditionally used to treat malaria symptoms in Haut-Ogooué, Gabon. Leaves and stem barks extracts were obtained using dichloromethane (CH(2)Cl(2)), ethyl acetate (EtOAc) and methanol (MeOH) as extraction solvents and fractionated on silica gel column. The in vitro antiplasmodial activity of CH(2)Cl(2), EtOAc and MeOH extracts and fractions was evaluated against the chloroquine-resistant FCB strain and field isolates of Plasmodium falciparum using the DELI test. The cytotoxicity of the extracts was tested on MRC-5 and THP1 cells using the tetrazolium salt MTT colorimetric assay, and the selectivity index (SI) of each extract was calculated. CH(2)Cl(2) extract, the EA1 fraction from EtOAc extract of stem barks and cyclohexane (L(cycl)), dichloromethane (L(DM)) and butanol (L(but)) fractions from MeOH/H(2)O extract of leaves exhibited the highest in vitro antiplasmodial activity on FCB strain and field isolates (IC(50) from 0.53 to 4.87 μg/ml) with high selectivity index (of 20.15-1800). These data support the use of V. madiensis in malaria treatment along with continued investigations within traditional medicines in the search of new antimalarial agents. The EA1, C(6)H(12) and CH(2)Cl(2) fractions could be selected for future investigation or/and for the treatment of malaria symptoms after standardization.