Investigating a new Dillenia ovata endophytic bacteria to produce antioxidants and anti-diabetes activity in vitro and in vivo

A novel endophytic bacterium, <i>Bacillus</i> sp. DO-R5, with strong antioxidant and anti-diabetic properties, was isolated from <i>Dillenia ovata</i>, a traditional Vietnamese medicinal plant. <i>Bacillus</i> sp. DO-R5 was identified using morphological characteristics, SEM, and <i>16S rRNA</i> sequencing, demonstrated the highest bioactivity among the 19 isolates. Optimal fermentation conditions (8.9 g/L D-glucose, pH 7.5, 38 °C, and 70.5 h) were determined using the Box-Behnken design. Under these conditions, <i>Bacillus</i> sp. DO-R5 significantly enhanced the production of bioactive compounds including diosmin, rutin, and chlorogenic acid, and exhibited improved <i>in vitro</i> antioxidant, anti-inflammatory, and anti-diabetic activities. <i>In vivo</i>, the extract effectively reduced blood glucose, regulated lipid profiles, supported weight control, and protected organs. These findings emphasize the potential therapeutic use of <i>D. ovata</i> endophytic bacteria as a natural source of anti-diabetic drugs.