Traditional Medicinal Potential of Carob Seed Extract (<i>Ceratonia siliqua</i>): Antimicrobial, Antioxidant, and Antiproliferative Effects on MCF-7 Cancer Cells

Abstract

Background: The therapeutic use of medicinal plants has attracted growing global research interest. Objectives: The present study aimed to investigate the antibacterial and anticancer activities of carob seed extract. Methods: Functional groups present in the extract were identified using Fourier transform infrared spectroscopy (FTIR). Total phenolic and flavonoid content were quantified using the Folin-Ciocalteu method and aluminum chloride colorimetry, respectively. The cytotoxicity of various extract concentrations at different time points was evaluated on the MCF-7 breast cancer cell line using the MTT assay. Antibacterial properties were assessed by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) through disk diffusion and microdilution broth methods. Data analysis was performed using Excel 2016 software, ANOVA, and Duncan's post-hoc test. Results: The phenolic and flavonoid contents of the carob seed extract were 184.83 ± 0.5 mg gallic acid and 104.61 ± 0.3 mg quercetin per gram of dry extract, respectively. The FTIR spectrum analysis revealed the presence of hydroxyl groups and aromatic rings, indicative of antioxidant properties. The most significant inhibitory effect on cancer cells was observed at a concentration of 100 μg/mL after 48 hours. The extract demonstrated the strongest antimicrobial effect against Pseudomonas bacteria, with an inhibition zone diameter of 14.22 ± 0.22 mm and an MIC of 32.5 μg/mL. Conclusions: These results demonstrate that carob seed extract, with its high antioxidant activity, possesses antibacterial properties — particularly against gram-negative bacteria — and can inhibit cancer cell growth.