Browsing by Autor "Pamela Canaviri-Paz"

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Microwave-Assisted Semisynthesis and Leishmanicidal Activity of Some Phenolic Constituents from Lichens
(Multidisciplinary Digital Publishing Institute, 2023) Grover Castañeta; Rodrigo Villagomez; Efraín Salamanca; Pamela Canaviri-Paz; José A. Bravo; José L. Vila; Daniela Bárcenas-Pérez; José Cheel; Beatriz Sepúlveda; Alberto Giménez
Leishmaniasis is considered one of the most untreated tropical diseases in the world. In this study, we investigated the in vitro leishmanicidal activity and cytotoxicity of various isolated lichen substances, including atranorin (1), usnic acid (2), gyrophoric acid (3), salazinic acid (4), galbinic acid (5), and parietin (6), and some semi-synthetic imine derivatives of usnic acid (7, 8, 9) and atranorin (10, 11, 12, 13). Imine condensation reactions with hydrazine and several amines were assisted by microwave heating, an efficient and eco-friendly energy source. The most interesting result was obtained for compound 2, which has high leishmanicidal activity but also high cytotoxicity. This cytotoxicity was mitigated in its derivative, 9, with better selectivity and high antileishmanic activity. This result may indicate that the usnic acid derivative (9) obtained using condensation with two cyclohexylamine groups is a promising lead compound for the discovery of new semisynthetic antiparasitic drugs.
Safeguarding of quinoa beverage production by fermentation with Lactobacillus plantarum DSM 9843
(Elsevier BV, 2020) Pamela Canaviri-Paz; Rownoke Jannat Janny; Åsa Håkansson
Plant-based beverages are increasing in popularity and quinoa is an attractive option. A hygienic implication linked to the production of beverages from raw material originating from plants is the high microbial contamination. The safety of the product can be guaranteed by lactic acid fermentation, and by using a probiotic strain as starter culture for the fermentation, the final product will benefit from a high number of live probiotics. In this study, a commercial probiotic strain was used for fermentation of a quinoa-based beverage. White quinoa grains were boiled, mixed with water and pasteurized before the beverage was fermented by Lactobacillus plantarum DSM 9843 at 30 °C for 2 days and then stored at 4 °C for 28 days. pH and production of D- and L-lactic acid were monitored, and viable counts were performed for total aerobes, Lactobacillus and Enterobacteriaceae. Colonies from countable plates were randomly picked and in total 335 isolates were identified by 16S rRNA gene sequencing. After heat treatment isolates of Enterobacter, Salmonella, Escherichia, Pantoea, Enterococcus, Klebsiella, and Leclercia were found in the heat-treated but unfermented quinoa beverage. After fermentation pH has decreased below 4, Enterobacteriaceae count was below detection limit and the Lactobacillus count was high 10.6 log CFU/ml (10.3-10.8) (p = 0.002 compared to inoculated counts). During storage pH and the concentration of lactic acid remained stable but after 28 days the lactobacilli count had decreased to 6.9 (6.6-7.2) (p = 0.065 compared to inoculated counts). The majority of isolates picked from Rogosa and Tryptic Soy Agar was identified as Lactobacillus plantarum but 19% and 6% were identified as Enterococcus mudtii and Pediococcus pentosaceous, respectively. The fermentation process applied improved the safety and stability of the product and fortified it with a high content of live probiotics. A safety problem is the spontaneous growth of enterococci (Enterococcus mudtii) during fermentation, enterococci originating from the native quinoa. A solution to this problem can be to increase the rate of the lactic acid fermentation, e.g. by using a higher inoculum of a more active starter culture, and/or to use a starter culture more antagonistic toward enterococci.