Abstract
Background: Cowpea (Vigna unguiculata) is a nutritionally important legume rich in storage proteins, mainly 7S and 11S globulins. These proteins have gained recent attention due to their potential bioactive properties, including antimicrobial effects. Chemical modification such as methylation may enhance their functional and biological activities.
Objectives: This study aimed to extract and characterize cowpea protein isolate (CPI) and its globulin fractions (7S and 11S), evaluate their antibacterial activities, and investigate the effect of methylation on enhancing their potency.
Materials and Methods: CPI was extracted from cowpea seeds, and 7S and 11S globulins were purified and designated as P7S and P11S. Their methylated derivatives (M7S and M11S) were prepared to enhance charge and solubility properties. Urea-PAGE was conducted to assess electrophoretic mobility and protein charge, while pH-solubility curves were used to determine isoelectric points (IEPs). Antibacterial activities were tested against Listeria monocytogenes LMG 10470 and Salmonella enterica serovar Typhimurium ATCC 14028 by determining minimum inhibitory concentrations (MICs) and evaluating their synergistic effects with penicillin G (1 U). Structural alterations in treated bacteria were examined using transmission electron microscopy (TEM).
Results: Methylated proteins (M7S and M11S) exhibited faster electrophoretic migration toward the cathode compared with their native forms, indicating increased positive charge. IEPs were estimated at pH 4, 5, 7, 8, and 9 for CPI, P7S, M7S, P11S, and M11S, respectively. P11S and M11S showed considerable antibacterial activity with MICs of 12.5 and 5 μg/mL against L. monocytogenes and 50 and 12.5 μg/mL against S. Typhimurium, respectively. Combination treatments with penicillin G enhanced bacterial growth inhibition in a dose-dependent manner. TEM imaging revealed membrane damage, swelling, vacuole formation, and cell lysis in treated bacterial cells.
Conclusions: Cowpea 11S globulin (P11S) exhibited stronger antibacterial effects than 7S globulin (P7S). Methylation significantly enhanced antibacterial potency, particularly for M11S. These findings highlight methylated cowpea globulins as promising natural antimicrobial agents with potential for future nutraceutical or therapeutic applications.
Recommended Citation
Abdel-Shafi, Seham; Osman, Ali; Tartour, Eman; Sitohy, Mahmoud; and Enan, Gamal
(2026)
"Antibacterial Activities of Methylating Cowpea Globulins,"
Al-Farahidi Biomedical Journal: Vol. 2:
Iss.
1, Article 1.
Available at:
https://fbmj.uoalfarahidi.edu.iq/journal/vol2/iss1/1