Bacteriostatic and fungistatic activities of Oreganum vulgare extract and volatile oil and interaction studies in combination with antibiotics and antifungal agents against food poisoning pathogens

The use of food preservatives to prevent spoilage of the product during transportation and shelf life by food manufacturers is common. Artificial preservatives added may prevent the food but they may be carcinogenic and may harm the consumer’s health. In food producing animals also, due to misuse of antimicrobials, antibiotic resistance have been developed which is affecting food industry. The present study was done to find out Oreganum vulgare, the most common food herb’s antimicrobial potential against food poisoning organisms. The volatile oil was analysed by GC-MS and chloroform extract was fractionated into phenolic and non-phenolic part. The fractions and volatile oil were used alone and in combination with standard antimicrobials to evaluate the interaction effect. Volatile oil consisted of mainly Carvacrol (86.5%), Þ-cymene (7.2%) followed by bornyl acetate. The Minimum Inhibitory Concentration (MIC) was found to be lowest for volatile oil followed by phenolic fraction when used alone and both in combination against Shigella flexneri, Aspergillus flavus and Salmonella enterica ser. Typhi. Synergism was shown by volatile oil with a FICI of 0.265, 0.187, 0.280 when combined with ciprofloxacin and fluconazole respectively against Shigella flexneri, Salmonella enterica ser. Typhi and Aspergillus flavus. Obtained data suggest the potential use of volatile oil and phenolic fraction of chloroform extract as along with standard antimicrobials as more effective combination with lesser side effects. The demonstrated antimicrobial activity of phenolic fraction and volatile oil when used alone suggests their use in food industry as preservatives without any toxicity. The interaction studies data with standard antimicrobials indicates the use of these combinations to infected food producing animals and humans; hence may solve the problem of antibiotic resistance in future.