Exploring the Nutritional and Antimicrobial Properties of Wild Fruit, <i>Castanopsis tribuloides</i> : In Vitro and In Silico Insights for Potential Antimicrobial Drug Development

A wild edible fruit<i>, Castanopsis tribuloides</i>, has been scientifically evaluated for its antibacterial capability and nutritional composition. In vitro analysis showed it possesses antimicrobial properties against <i>Bacillus subtilis</i>, <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, and <i>Staphylococcus aureus</i>. In silico analysis revealed that out of the identified 27 compounds isolated, 1-phenylbicyclo (3.2.2) nona-6,8-dien-2-one demonstrated a solid adherence to the Lipinski rule of drug design and exhibited a strong binding affinity to antibacterial enzymes tyrosyl-tRNA synthase (-8.13 kcal/mol) and dihydropteroate synthase (-8.84 kcal/mol). The protein-ligand complex revealed with MD simulation showed low RMSD (< 1 nm), higher SASA (170-180 nm²), and more consistent hydrogen bonding (∼1.2 bonds/frame). The binding energy evaluated using gmx_MMPBSA also yields a favorable total binding free energy for dihydropteroate synthase (Δ<i>G</i> _bind = -17.92 ± 0.84 kcal/mol) and tyrosyl-tRNA synthase (Δ<i>G</i> _bind = -12.75 ± 1.46 kcal/mol), indicating stable complex formation. In addition, the nuts are rich in various nutrients, such as carbohydrates (31.2 ± 0.08), proteins (20.51 ± 0.1 mg/g), dietary fiber (5.41 ± 0.01%), vitamin C (86.3 ± 0.26 mg/100 gm), and vitamin E (4.76 ± 0.02 mg/100 gm). The nuts also demonstrated significant antioxidant activity (52.25 ± 0.02 μg/mL), with a high amount of total phenolic (76.83 ± 0.02 mg QE/g) and flavonoid (70.4 ± 0.21 mg QE/g) content. These findings indicate the importance of <i>C. tribuloides</i> nuts as a valuable antibacterial and health-promoting resource.