The aim of this study was to select and identify thermophilic bacteria from Caatinga biome (Brazil) able to produce thermoactive keratinases and characterize the keratinase produced by the selected isolate. After enrichment in keratin culture media, an Anoxybacillus caldiproteolyticus PC2 was isolated. This thermotolerant isolate presents a remarkable feature producing a thermostable keratinase at 60°C. The partially purified keratinase, identified as a thermolysin‐like peptidase, was active at a pH range of 5.0–10.0 with maximal activity at a temperature range of 50–80°C. The optimal activity was observed at pH 7.0 and 50–60°C. These characteristics are potentially useful for biotechnological purposes such as processing and bioconversion of keratin.
Staphylococcus aureus and Staphylococcus epidermidis are the main agents involved with implant-related infections. Their ability to adhere to medical devices with subsequent biofilm formation is crucial to the development of these infections. Herein, we described the antibacterial and antibiofilm activities of a quinazoline-based compound, N 4-benzyl-N 2-phenylquinazoline-2,4-diamine, against both biofilm-forming pathogens. The minimum inhibitory concentrations (MIC) were determined as 25 µM for S. aureus and 15 µM for S. epidermidis. At sub-MIC concentrations (20 µM for S. aureus and 10 µM for S. epidermidis), the compound was able to inhibit biofilm formation without interfere with bacterial growth, confirmed by scanning electron microscopy. Moreover, surfaces coated with the quinazoline-based compound were able to prevent bacterial adherence. In addition, this compound presented no toxicity to human red blood cells at highest MIC 25 µM and in vivo toxicity assay using Galleria mellonella larvae resulted in 82% survival with a high dose of 500 mg/kg body weight. These features evidence quinazoline-based compound as interesting entities to promising applications in biomedical fields, such as antimicrobial and in anti-infective approaches.
Iridoids are secondary metabolites with several biological activities. They are often found in species of the genus Tabebuia Gomes ex A.P. de Candolle. Tabebuia aurea (Silva Manso) Benth. & Hook. F. ex S. Moore, Bignoniaceae, is used to treat snake bites in traditional medicine. This study aimed to isolate the specioside -an the iridoid glycoside -from T. aurea, as well as investigate its potential biological properties, including anti-inflammatory, antibacterial, antibiofilm, cytotoxic, anti-Trichomonas vaginalis and antitrypanosomal activities. Specioside inhibited leucocyte recruitment into the peritoneal cavity in mice injected with carrageenan, data that demonstrated its anti-inflammatory potential. However, the additional evaluated biological properties were negligible.
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