Evaluation of Cocoa Bean Shell Antimicrobial Activity: A Tentative Assay Using a Metabolomic Approach for Active Compound Identification.

Cocoa bean shell is one of the main by-products of chocolate manufacturing and possesses several compounds with biofunctionalities. It can function as an antibacterial agent, and its action is mostly reported against Streptococcus mutans. However, only a few studies have investigated the cocoa bean shell compounds responsible for this activity. This study aimed to evaluate several extracts of cocoa bean shells from different geographical origins and cocoa varieties and estimate their antimicrobial properties against different fungal and bacterial strains by determining their minimal inhibitory concentration. The results demonstrated antimicrobial activity of cocoa bean shell against one of the tested strains, S. mutans. Cocoa bean shell extracts were further analysed via LC-HRMS for untargeted metabolomic analysis. LC-HRMS data were analysed (preprocessing and statistical analyses) using the Workflow4Metabolomics platform. The latter enabled us to identify possible compounds responsible for the detected antimicrobial activity by comparing the more and less active extracts. Active extracts were not the most abundant in polyphenols but contained higher concentrations of two metabolites. After tentative annotation of these metabolites, one of them was identified and confirmed to be 7-methylxanthine. When tested alone, 7-methylxanthine did not display antibacterial activity. However, a possible cocktail effect due to the synergistic activity of this molecule along with other compounds in the cocoa bean shell extracts cannot be neglected. In conclusion, cocoa bean shell could be a functional ingredient with benefits for human health as it exhibited antibacterial activity against S. mutans. However, the antimicrobial mechanisms still need to be confirmed.

Proposals for Antimicrobial Testing Guidelines Applied on Ajowan and Spanish Lavender Essential Oils.

To fight the rising resistance of microorganisms to antibiotics, a strategy followed by several researchers is to focus on natural compounds, such as essential oils, as a source of potent antibacterial compounds. These last decades, hundreds of original papers have been written about microbiological assays that prove the antibacterial activity of essential oils and their use in the medical field. But can we really compare all the data available in the literature when the raw material, the microbiological assays, and/or the strains are different from one article to another? This review will point out the differences and the inadequate practices found in published articles that tested 2 lesser-studied essential oils-Spanish lavender and the ajowan-by the broth dilution method against Staphylococcus aureus, a human pathogenic bacterium. Many pitfalls were found in the literature, for example, a variable chemical composition rarely underlined by the authors, unidentified strains or clinical strains used without a related antibiogram, a lack of quality controls, and the assertion of questionable positive results. At last, some general guidelines that should be followed by every scientific researcher will be discussed.

An ethnobotanical survey and inhibitory effects on NLRP3 inflammasomes/Caspase-1 of herbal recipes' extracts traditionally used in Rwanda for asthma treatment.

ETHNOPHARMACOLOGICAL RELEVANCE: Respiratory diseases and asthma, in particular, are nowadays a global health problem. In Rwanda, some traditional healers claim to treat asthma with plant-based recipes, though there is no scientific proof so far. AIM OF THE STUDY: Our study aimed at evaluating the toxicity and the anti-inflammatory effect of plant recipes used in Rwanda against asthma in order to select potential candidates for further characterization of the active compounds. MATERIALS AND METHODS: Water (aqueous) and methanol-dichloromethane (organic) extracts from selected folkloric recipes were submitted for toxicity test on THP-1 derived macrophages using CellTiter-Glo Luminescent Cell Viability Assay. The evaluation of the anti-inflammatory effect of the plant extracts was carried out using the Caspase-Glo 1 Inflammasome assay on THP-1 -derived macrophages. RESULTS: Most of both organic and aqueous extract showed more than 95% of cell viability up to 200 µg/ml, except for R03Cn organic extract that inhibited 25% of the cell viability. Plant extracts inhibited caspase-1 activation in THP-1 derived macrophages in a dose-dependent manner. Four extracts (R03Cn and R07Kn aqueous extracts, R10MK and R19Sz organic extracts) strongly downregulated the activation of caspase-1 (more than 70% at 50 µg/ml). In general, organic extracts exhibited better caspase-1 inhibitory effects than their aqueous counterparts. CONCLUSIONS: The inhibition of inflammasome/caspase-1 is one of key mechanisms of action in asthma. Some traditional recipes are active on this mechanism and are thus strong candidates for the treatment of asthma and other inflammasome-mediated diseases. Further investigations are needed to characterize active molecules.

In vitro Study of Five Herbs Used Against Microbial Infections in Burundi.

The emergence of antimicrobial resistant infectious diseases remains a major threat to worldwide public health, in developed and in developing countries. Therefore, new antimicrobial agents acting by new mechanisms of action are urgently needed. As plants used in traditional medicine may help to overcome these problems, Justicia subsessilis, Platostoma rotundifolium, Pavetta ternifolia, Stomatanthes africanus, and Virectaria major (plants highly cited to be used against microbial infections in traditional Burundian medicine) were studied to assess their traditional use efficacy. We conducted a preliminary phytochemical screening of the extracts, as well as their direct and indirect (effect on antibiotic resistance) antibacterial activity on four bacterial strains (Staphylococcus sp. and Escherichia coli) by broth microdilution methods. All five medicinal plants investigated in this work were found to have direct antibacterial activity against all tested bacterial strains (minimum inhibitory concentration = 62.5-1000 µg/mL) that may support the use of these species in traditional Burundian medicine. Extracts (with no direct antibacterial activity), tested at 200 µg/mL, decreased the MIC values of ß-lactams and aminoglycoside antibiotics by a factor of 2 to 64-fold. These interactions between plant extracts and antibiotics could open an avenue of research against antibiotic resistance. Copyright © 2017 John Wiley & Sons, Ltd.

Terpenoids from Platostoma rotundifolium (Briq.) A. J. Paton Alter the Expression of Quorum Sensing-Related Virulence Factors and the Formation of Biofilm in Pseudomonas aeruginosa PAO1.

Platostoma rotundifolium (Briq.) A. J. Paton aerial parts are widely used in Burundi traditional medicine to treat infectious diseases. In order to investigate their probable antibacterial activities, crude extracts from P. rotundifolium were assessed for their bactericidal and anti-virulence properties against an opportunistic bacterial model, Pseudomonas aeruginosa PAO1. Whereas none of the tested extracts exert bacteriostatic and/or bactericidal proprieties, the ethyl acetate and dichloromethane extracts exhibit anti-virulence properties against Pseudomonas aeruginosa PAO1 characterized by an alteration in quorum sensing gene expression and biofilm formation without affecting bacterial viability. Bioguided fractionation of the ethyl acetate extract led to the isolation of major anti-virulence compounds that were identified from nuclear magnetic resonance and high-resolution molecular spectroscopy spectra as cassipourol, ß-sitosterol and α-amyrin. Globally, cassipourol and ß-sitosterol inhibit quorum sensing-regulated and -regulatory genes expression in las and rhl systems without affecting the global regulators gacA and vfr, whereas α-amyrin had no effect on the expression of these genes. These terpenoids disrupt the formation of biofilms at concentrations down to 12.5, 50 and 50 µM for cassipourol, ß-sitosterol and α-amyrin, respectively. Moreover, these terpenoids reduce the production of total exopolysaccharides and promote flagella-dependent motilities (swimming and swarming). The isolated terpenoids exert a wide range of inhibition processes, suggesting a complex mechanism of action targeting P. aeruginosa virulence mechanisms which support the wide anti-infectious use of this plant species in traditional Burundian medicine.