Phytochemical study and evaluation of antioxidant and antimicrobial activities through in vitro and in silico studies of Citrus volkameriana Ten. & Pasq. seeds

Citrus seed waste is a significant byproduct of the Citrus processing industry. While Citrus fruit is a rich source of bioactive chemicals, little is known about the possible health benefits of the seeds. This study investigates the antioxidant and antibacterial properties of Citrus volkameriana Ten. & Pasq. (Family: Rutaceae) seeds' extracts as well as their constituents, to identify potential applications for this underutilised resource. The studied extracts are petroleum ether extract (CVPE) and 70 % aqueous methanolic extract (CVME). CVPE exhibited higher antioxidant activity than CVME using ABTS and ferric-reducing antioxidant power (FRAP) assays. The antimicrobial activity was evaluated using the disc diffusion method against different microbial strains, CVME inhibited the growth of Staphylococcus aureus, Staphylococcus epidermidis, and Helicobacter pylori at a minimal inhibitory concentration (MIC), ranging between 2.2 and 97 mg/mL. Whereas CVPE only inhibited the growth of methicillin-resistant Staphylococcus aureus (MRSA) at MIC 41.6 mg/mL. CVME showed potentially bactericidal activity against Staphylococcus aureus and Pseudomonas aeruginosa with a minimal bactericidal concentration (MBC) of 83.25 mg/mL for each. The MBC of CVME reached 20 mg/mL against Staphylococcus epidermidis. GC/MS analysis of the unsaponifiable and the saponifiable matters of CVPE revealed the identification of forty-three and fifteen compounds, respectively. Twenty compounds were identified in CVME using HPLC-ESI-MS/MS analysis where caffeic acid, quinic acid, caffeoyl quinic acid, citric acid, astringin, luteone 7-O-glucoside, and myricetin are the major peaks. Moreover, in silico molecular docking, drug-likeness, and ADMET features investigations were performed to identify the potential antimicrobial compounds from CVME. Astringin, luteone 7-O-glucoside, and myricetin showed the best docking score and good binding interactions with the active site of the bacterial target enzymes, DNA Gyrase B, topoisomerase and H. Pylori peptide deformylase. Finally, this study suggests that C. volkameriana seed extracts have the potential to be a natural source of antioxidants and antimicrobials. CVME, which is rich in phenolic compounds and has a wider spectrum of antimicrobial activity, could be a good candidate for further development. (c) 2024 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.