Exploring the capability of yeasts isolated from colombian fermented cocoa beans to form and degrade biogenic amines in a lab-scale model system for cocoa fermentation

Yeast starters for cocoa fermentation are usually tested according to their enzymatic activities in terms of mucilage degradation and flavor improvement, disregarding their influence on the production or elimination of toxic compounds as biogenic amines (BAs), important for human health. In this work, we tested 145 strains belonging to 12 different yeast species and isolated from the Colombian fermented cocoa beans (CB) for their capability of producing BAs in vitro. Sixtyfive strains were able to decarboxylate at least one of the amino acids tested. Pichia kudriavzevii ECA33 (Pk) and Saccharomyces cerevisiae 4 (Sc) were selected to evaluate their potential to modulate BAs, organic acids, and volatile organic compounds (VOCs) accumulation during a simulated cocoa fermentation. The growth of Sc or Pk in the presence of CB caused a significant reduction (p < 0.05) of 2-phenylethylamine (84% and 37%) and cadaverine (58% and 51%), and a significant increase of tryptamine and putrescine with a strong influence of temperature in BA formation and degradation. In addition, our findings pointed out that Pk induced a major production of fatty acidand amino acid-derived VOCs, while Sc induced more VOCs derived from fatty acids metabolism. Our results suggest the importance of considering BA production in the choice of yeast starters for cocoa fermentation

Carlina oxide from Carlina acaulis root essential oil acts as a potent mosquito larvicide

Developing effective larvicides for mosquito control is being challenging due to the quick development of resistance in targeted vectors. Botanical products can help, due to their multiple mechanisms of action coupled with eco-friendly features. Carlina acaulis (Asteraceae) is an Alpine perennial herb used as a traditional remedy and food. Its root essential oil (EO) has antimicrobial and antitrypanosomal properties, and is currently listed among botanicals employable in food supplements. Its insecticidal activity has not been explored so far. Here, after analysing the C. acaulis EO chemical composition by GC–MS and NMR, we detected extremely high larvicidal activity of this EO and its main constituent, carlina oxide, against Culex quinquefasciatus larvae by using the standard WHO protocol. LC50 were 1.31 and 1.39 μg mL-1, respectively. 24-h exposure to both products triggered significant mortality rates for five days post-treatment. Larvicidal tests on a wider scale confirmed >95% larvicidal effectiveness of the EO and carlina oxide tested at 1.25 μg L-1. Their non-target impact was evaluated through experiments on Daphnia magna adults. Both showed significantly lower toxicity if compared to cypermethrin. To shed light on the modes of action, carlina oxide was tested for anti-acetylcholinesterase activity by the Ellman method, with lower performances over galantamine. A moderate antioxidant potential was observed using DPPH and ABTS assays, since it has a role for preserving the shelf-life of herbal-based insecticides. Finally, cytotoxicity on vertebrate cells was noted, testing carlina oxide on human dermis, HCT116 and MDA-MB231 cell lines by MTT assay. Overall, the outstanding toxicity of the tested products make them excellent candidates to develop novel mosquito larvicides for real-world applications