Eremoxylarins D-J, Antibacterial Eremophilane Sesquiterpenes Discovered from an Endolichenic Strain of Xylaria hypoxylon.

An endolichenic strain of the Ascomycetaceous Xylaria hypoxylon, cultivated alone or in coculture with another endolichenic fungus Dendrothyrium variisporum, produced seven new bioactive eremophilane sesquiterpenes eremoxylarins D-J (1-7). The isolated compounds disclosed a high similarity with the eremophilane core of the bioactive integric acid, and structures were elucidated by 1D and 2D NMR spectra and electronic circular dichroism (ECD) analyses. Eremoxylarins D, F, G, and I showed a selective activity against Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus with minimum inhibitory concentration (MIC) values between 0.39 and 12.5 µg/mL. Eremoxylarin I, the most antibacterial active sesquiterpene, was also active against HCoV-229E at a concentration nontoxic to the hepatoma Huh-7 cell line with an 50% inhibitory concentration (IC50) of 18.1 µM and a 50% cytotoxic concentration (CC50) of 46.6 µM.

SARS-CoV-2 and Prevotella spp.: friend or foe? A systematic literature review.

During this global pandemic of the COVID-19 disease, a lot of information has arisen in the media and online without scientific validation, and among these is the possibility that this disease could be aggravated by a secondary bacterial infection such as Prevotella, as well as the interest or not in using azithromycin, a potentially active antimicrobial agent. The aim of this study was to carry out a systematic literature review, to prove or disprove these allegations by scientific arguments. The search included Medline, PubMed, and Pubtator Central databases for English-language articles published 1999-2021. After removing duplicates, a total of final eligible studies (n=149) were selected. There were more articles showing an increase of Prevotella abundance in the presence of viral infection like that related to Human Immunodeficiency Virus (HIV), Papillomavirus (HPV), Herpesviridae and respiratory virus, highlighting differences according to methodologies and patient groups. The arguments for or against the use of azithromycin are stated in light of the results of the literature, showing the role of intercurrent factors, such as age, drug consumption, the presence of cancer or periodontal diseases. However, clinical trials are lacking to prove the direct link between the presence of Prevotella spp. and a worsening of COVID-19, mainly those using azithromycin alone in this indication.