Certain members of the Coronaviridae family have emerged as zoonotic agents and have recently caused severe respiratory diseases in humans and animals, such as SARS, MERS, and, more recently, COVID-19. Antivirals (drugs and antiseptics) capable of controlling viruses at the site of infection are scarce. Microalgae from the Chlorellaceae family are sources of bioactive compounds with antioxidant, antiviral, and antitumor activity. In the present study, we aimed to evaluate various extracts from Planktochlorella nurekis in vitro against murine coronavirus-3 (MHV-3), which is an essential human coronavirus surrogate for laboratory assays. Methanol, hexane, and dichloromethane extracts of P. nurekis were tested in cells infected with MHV-3, and characterized by UV-vis spectrophotometry, nuclear magnetic resonance (NMR) spectroscopy, ultraperformance liquid chromatography-mass spectrometry (UPLC-MS), and the application of chemometrics through principal component analysis (PCA). All the extracts were highly efficient against MHV-3 (more than a 6 Log unit reduction), regardless of the solvent used or the concentration of the extract, but the dichloromethane extract was the most effective. Chemical characterization by spectrophotometry and NMR, with the aid of statistical analysis, showed that polyphenols, carbohydrates, and isoprene derivatives, such as terpenes and carotenoids have a more significant impact on the virucidal potential. Compounds identified by UPLC-MS were mainly lipids and only found in the dichloromethane extract. These results open new biotechnological possibilities to explore the biomass of P. nurekis; it is a natural extract and shows low cytotoxicity and an excellent antiviral effect, with low production costs, highlighting a promising potential for development and implementation of therapies against coronaviruses, such as SARS-CoV-2.

Bioactive compounds of natural matrices are of interest because of their application in the food and pharmaceutical industries. One important source of bioactives is propolis, a resinous biomass that bees make from the plants surrounding the hive. Regarding Colombian propolis, studies have mostly been directed towards identifying flavonoids and their biological activity in vitro. There are no works on the oil extract of propolis and its chemical composition and bioactivity through metabolomic analysis. In this sense, this work studied the volatile composition of propolis oil extract samples from Colombia, following a metabolomic approach; in this work, the oily Colombian propolis extracts (OECP) obtained by an ultrasound assisted extraction (UAE) with different solvents were studied using spectroscopy and physicochemical analysis. A strong correlation was observed between the antioxidant activity and their concentrations of polyphenols, terpenoids, and carotenoids. Simultaneously, it was possible to expand the number of compounds identified by applying FTIR spectroscopy to the sample analysis, relating infrared bands to specific compounds. Besides, it was also possible to discriminate the samples according to their geographical origin. Colombian propolis oil extracts have characteristics as bioactive compounds such as the sesquiterpenes bisabolol, α-zingiberene, β-bisabolene, and α-trans-bergamotene and the monoterpenes α-pinene, linalool, and p-cymene.

The essential oil from leaves of Arracacia xanthorrhiza Bancr. grown in Colombia was analyzed by GC-FID and GC-MS. A total of 94 volatile compounds were identified, representing the total composition of the essential oil. The distribution of the families was: monoterpene hydrocarbons (82.4%), oxygenated monoterpenes (1.6%), sesquiterpene hydrocarbons (7.3%), oxygenated sesquiterpenes (1.1%), aliphatic compounds (1.9%), aromatic compounds (0.1%), and others (5.1%). The major constituents were limonene (54.4%) and myrcene (21.4%).