Separation and Purification of Antimicrobial Substance from Rheum palmatum L. against Vaginitis-inducing Strains

Abstract

The present study aimed to explore natural substances as an alternative to antibiotics that result in adverse effects, such as reduced counts of essential lactic acid bacteria in the vagina and compromised vaginal function. For this purpose, Rheum palmatum L. methanol extracts were used to separate substances that do not inhibit lactic acid production in the vagina while inhibiting the pathogens causing vaginitis using different methods used in previous studies. Extraction was performed to separate the substance in the R. palmatum L. methanol extract with antibacterial activity against pathogens causing vaginitis. The maximum antibacterial substance was detected in the ethyl acetate layer extract on TLC (Thin Layer Chromatography). Fractionation by silica gel column chromatography to separate the antibacterial substance from the R. palmatum L. ethyl acetate layer extract revealed that fraction 4 had the maximum antibacterial substance. In addition, on analyzing fraction 4 using HPLC, two peaks were identified and separated at Rt 12.372 and Rt 13.44 min, with peak purities of 82.8% and 92.9%, respectively. After concentrating the fractions from both the peaks to 10 mg/mL, their antibacterial activity was tested against pathogens causing vaginitis and a beneficial strain found in the vagina. Inhibitory zones of 7 mm and 6.5 mm against Sphingomonas paucimobilis KCTC 2834 and Proteus mirabilis KCTC 2510, respectively, were identified. No antibacterial activity was found against the vaginal strain Lactobacillus coleohominis KCTC 21007.