Antibacterial mouthwash alters gut microbiome, reducing nutrient absorption and fat accumulation in Western diet-fed mice

Abstract Prolonged use of antibacterial mouthwash is linked to an increased risk of systemic disease. We aimed to investigate if disturbing the oral microbiota would impact the lower gut microbiome with functional effects in diet-induced obesity. Mice were exposed to oral chlorhexidine and fed a Western diet (WD). Food intake and weight gain were monitored, and metabolic function, blood pressure, and microbiota were analyzed. Chlorhexidine reduced the number of viable bacteria in the mouth and lowered species richness in the gut but with proportional enrichment of some bacteria linked to metabolic pathways. In mice fed a Western diet, chlorhexidine reduced weight gain, body fat, steatosis, and plasma insulin without changing caloric intake, while increasing colon triglycerides and proteins, suggesting reduced absorption of these nutrients. The mechanisms behind these effects as well as the link between the oral microbiome and small intestinal function need to be pinpointed. While the short-term effects of chlorhexidine in this model appear beneficial, potential long-term disruptions in the oral and gut microbiota and possible malabsorption should be considered

Chemical characterization, antioxidant, cytotoxic and antibacterial activity of propolis extracts and isolated compounds from the Brazilian stingless bees <i>Melipona quadrifasciata</i> and <i>Tetragonisca angustula</i>

<p>Since chemical or pharmacological studies on the propolis of Brazilian native bees are scarce, the aim of this study was to evaluate the chemical profile, the antioxidant, cytotoxic and antibacterial activity of aqueous and hydro-alcoholic extracts and isolated compounds of propolis of the native bees, <i>Melipona quadrifasciata</i> and <i>Tetragonisca angustula</i>, against bacteria with (Gram-positive and Gram-negative) and without cell wall (mollicutes). The extracts presented a peculiar feature between green and yellow propolis. Despite the low content of flavonoid and phenolic compounds, a promising level of antioxidant activity without toxicity in the propolis extracts of <i>M. quadrifasciata</i> was observed. The best antimicrobial activity was that of the hydro-alcoholic extract against <i>Mycoplasma pneumoniae</i> and <i>Ureaplasma urealyticum</i> (MIC 125 μg/ml). We isolated two compounds and identified them from the aqueous and hydro-alcoholic extracts as the flavononol sakuranetin and gallic acid. Sakuranetin and gallic acid presented MICs of 50 and 25 μg/ml against <i>Mycoplasma hominis</i> and <i>Mycoplasma genitalium</i> respectively. Propolis from Brazilian native bees may constitute an alternative and undervalued source of compounds with biological activity. The mollicutes are the smallest self-replicating bacteria that constitute a model of cellular and molecular biology studies due to their small genome and restrict biochemical machinery. This is the first report investigating the potential of antibacterial molecules isolated from propolis of Brazilian native bees using this microorganism model. Our results contribute to a better understanding of the chemical and biological properties of these propolis types and provide evidence for its potential medicinal use.</p