Comparative Antibacterial Activities of Extracts from Two Varieties of Bitter Gourd (Momordica charantia).

<b>Background and Objective:</b> <i>Momordica charantia</i> (Bitter gourd) is renowned for its significant pharmacological benefits, including anti-inflammatory and antioxidant properties. Its antibacterial activity is crucial for treating infections, particularly those caused by antibiotic-resistant bacteria. This study aims to compare the antibacterial activities of extracts from two varieties of <i>M. charantia</i> (Okinawa and Morya) against 10 human pathogenic bacteria. <b>Materials and Methods:</b> Okinawa and Morya powders were sourced from Roi Et and Nakhon Ratchasima, Thailand. Both powders were extracted using ethanol, dichloromethane and hexane. The agar disc diffusion method served as the primary antibacterial activity screening, while the broth microdilution assay determined the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The zone of inhibition (ZOI) diameter (mm) was measured and analyzed using Duncan's Multiple Range Test (DMRT) with SAS software. A p<0.05 was considered statistically significant. <b>Results:</b> Okinawa extracted with dichloromethane exhibited the largest ZOI at 11 mm against <i>Escherichia coli</i> pk. The lowest MIC value at 0.049 mg/mL was observed in both Okinawa and Morya extracts across all three solvents against <i>Pseudomonas aeruginosa</i> TISTR 902, <i>Pseudomonas aeruginosa</i> TISTR 2370, <i>Staphylococcus aureus</i> TISTR 1466 and <i>Klebsiella pneumoniae</i> TISTR 1383. The lowest MBC value at 0.78 mg/mL was found in Okinawa extracted with hexane against <i>Staphylococcus aureus</i> TISTR 1466. <b>Conclusion:</b> This study presents the first evidence of the antibacterial activity of Okinawa and Morya extracts against human pathogenic bacteria, including MDR-<i>Klebsiella pneumoniae</i>. These findings offer potential benefits for developing natural antibiotic drugs to combat infections caused by the tested pathogenic bacteria.