Protective effect of some amino acids synthesized derivatives and their chelates on Escherichia coli under X-ray irradiation.

The protective effects of novel synthesized derivatives of some amino acids — nicotinyl-L-tyrosinate and nicotinyl-L-tryptophanate schiff bases and their Cu(II) and Mn(II) chelates on growth, survival and membrane-associated ATPase activity of E. coli under X-ray irradiation were investigated. The specific growth rate and survival of E. coli were decreased at 10, 20 and 30 Gy doses. However, as 30 Gy was found to be the most effective irradiation dose, it was chosen for studying the radio-protective properties of different compounds. These compounds could increase the bacterial cell protection against X-ray irradiation in concentration-dependent manner. They had a role in stimulation of synthesis or regulation of activity of metal-dependent enzymes, required for reversing the X-ray irradiation damage. The study may prove useful for further estimation of the effectiveness of different compounds as radio-protectors on bacteria and other cells, especially mammalian cells under X-ray irradiation.

Effects of low intensity electromagnetic irradiation of 70.6 and 73 GHz frequencies and antibiotics on energy-dependent proton and potassium ion transport by E. coli.

The effects of low intensity (flux capacity 0.06 mW/cm2) coherent electromagnetic irradiation (EMI) of 70.6 and 73 GHz frequencies and their combined effects with antibiotics — ceftriaxone or kanamycin (0.4 or 15 µM, correspondingly) on E. coli K12 growth and survival have been reported previously. To further study the effects of EMI and antibiotics and mechanisms, decrease in overall energy (glucose)-dependent H+ and K+ fluxes across the cell membrane was investigated in E. coli. The depression of H+ and K+ fluxes rate was maximally achieved with the 73 GHz frequency. The EMI strengthened the effect of N,N’-dicyclohexycarbodiimide (DCCD, an inhibitor of the F0F1-ATPase). The 73 GHz EMI had more influence on H+ efflux inhibition, whereas 70.6 GHz on K+ influx. Also, EMI strengthened the depressive effects of ceftriaxone and kanamycin on the overall and DCCD-inhibited H+ and K+ fluxes. The 73 GHz EMI strengthened the effect of ceftriaxone on both ions fluxes. Kanamycin depressed H+ efflux more as compared to ceftriaxone, which was also strengthened with EMI. The results of E. coli H+ and K+ transport systems activities depression by irradiation and the irradiation effect on DCCD and antibiotics action indicated the EMI and antibiotics causing primary changes in the bacterial membrane.