Haloarchaea are extreme halophilic microorganisms belonging to the domain Archaea, phylum Euryarchaeota, and are producers of interesting antioxidant carotenoid compounds. In this study, four new strains of Haloarcula sp., isolated from saline lakes of the Atacama Desert, are reported and studied by high-resolution mass spectrometry (UHPLC-Q-Orbitrap-MS/MS) for the first time. In addition, determination of the carotenoid pigment profile from the new strains of Haloarcula sp., plus two strains of Halorubrum tebenquichense, and their antioxidant activity by means of several methods is reported. The effect of biomass on cellular viability in skin cell lines was also evaluated by MTT assay. The cholinesterase inhibition capacity of six haloarchaea (Haloarcula sp. ALT-23; Haloarcula sp. TeSe-41; Haloarcula sp. TeSe-51; Haloarcula sp. Te Se-89 and Halorubrum tebenquichense strains TeSe-85 and Te Se-86) is also reported for the first time. AChE inhibition IC₅₀ was 2.96 ± 0.08 μg/mL and BuChE inhibition IC₅₀ was 2.39 ± 0.09 μg/mL for the most active strain, Halorubrum tebenquichense Te Se-85, respectively, which is more active in BuCHe than that of the standard galantamine. Docking calculation showed that carotenoids can exert their inhibitory activity fitting into the enzyme pocket by their halves, in the presence of cholinesterase dimers.

Oral cancer, is part of several cancers that affect head and neck, and that according to numerous studies shows an increase of approximately 3-5 % of all cancers. In the last 10 years there has been an increased interest in saliva for its use as a diagnostic tool, due to its easy access, and non-invasive sample collection, unlike blood samples. Studies of metagenomics to the microbiota of oral cancer patients have shown the presence of some groups in greater proportion, it is postulated that they could be used as markers especially in the saliva of these patients. In Antofagasta the number of patients with this type of cancer increases each year. However, there are no studies on the changes that affect the oral microbiota in these patients. The objective of this study is to contribute to the knowledge of the microbiota present in the saliva of patients with oral cancer in the region of Antofagasta, limiting this study exclusively to the group of cultivable anaerobic bacteria. The strains identified are related to the group of Streptococcus mitis / oralis, S. anginosus and S. gordoni, only one strain is grouped near the cluster that includes S. australis and S. parasanguinis. 36.4 % of the molecularly identified isolates, are closely related to the S. anginosus species described in the literature in oropharyngeal tumors. The same percentage is obtained for the taxa related to the cluster that includes S. mitis, proposed in other studies as a diagnostic indicator in subjects with oral squamous cell carcinoma.