[Effect of thiamine, riboflavin and ascorbic acid on tetracycline, erythromycin and levomycetin activity]

The effect of antibiotics was estimated by inhibition of the protein increase in the broth culture of Staph, aureus during incubation at a temperature of 37 degrees for 18 hours. In some experiments preincubation of the antibiotic solutions with the vitamins for 2 hours at light and in dark was used. The antibiotic concentrations in gamma per 1 ml were equal to those of the vitamins. In the experiments with tetracycline and 2-hour preincubation at light the antibiotic in a concentration of 0.1gamma ml inhibited for certain the protein increase by 58.9%, in combination with thiamin it inhibited the protein by 60 per cent and in combination with ascorbic acid by 59%. Riboflavin lowered the activity of tetracycline to a value not differing for certain from the control one. In the experiments with preincubation in dark tetracycline inhibited the protein increase by 55.2%, in combination with thiamin it inhibited the protein increase by 50.5%, in combination with riboflavin by 53% and in combination with ascorbic acid by 57.2%. Erythromycin in a concentration of 0.03gamma/ml when preincubated at light inhibited the protein increase by 48.8% and in combinations with thiamin, riboflavin or ascorbic acid by 23, 27, 47.2% respectively. When preincubated in the darkness erythromycin alone inhibited the protein increase by 47.8% and in combinations with thiamin, riboflavin or ascorbic acid by 32.5, 51.1 or 49.8% respectively. The above vitamins has no effect on levomycetin activity.