Inhibitory effects of gynostemma pentaphyllum on the UV induction of bacteriophage lambda in lysogenic Escherichia coli

The Effect of Gynostemma pentaphyllum Extract on Mouse Dermal Fibroblasts

Background. The objective of this paper is to demonstrate the effect of Gynostemma pentaphyllum extract on mouse dermal fibroblasts. Recent studies have shown that this plant may possess great antioxidant properties, which can be very beneficial in combating oxidative stress. Methods. Gynostemma pentaphyllum extract was prepared and mouse dermal fibroblasts were obtained and cultured as per our laboratory protocols. Twelve samples of cells were cultured under the same conditions and both negative and positive controls were established. Induction of oxidative stress was carried out using ultraviolet C (UVC) light. Viable cell count was carried out, using microscopy. The analysis of the overall results was processed using SPSS version 16.0. Results. Statistical analysis showed strong positive correlation between the concentration of Gynostemma pentaphyllum and the mean duration of cell viability (rs = 1), with a high level of statistical significance (P < 0.01). Likewise, strong positive correlation existed between trials of cell viability (rs = 0.988–1), with statistical significance (P < 0.01). Conclusion. Gynostemma pentaphyllum extract prolongs viability of mouse dermal fibroblasts damaged by UVC light-induced oxidative stress. The results show the potential benefits of this extract on dermal cell aging.

Inhibitory Effects of Anti-SARS Traditional Chinese Medicines on the UV Irradiation of λ-Lysogen

By using λ-lysogen as a model, the inhibitory effects of anti-severe acute respiratory syndrome (SARS) traditional Chinese medicines (TCMs) prescription I on the UV irradiation were investigated in this present study. It was found that the prescription I possessed obvious inhibitory effects on the UV induction of λ-lysogen, the inhibitory rate reaching 83.87%. Among five medicinal herbs prescribed in that formula, Herba Patriniae, Radix Astragali and Radix Glycyrrhizae played important roles. When these three herbs were eliminated from the recipe separately, the inhibitory effects were prominently decreased. If only one of these five medicinal herbs was added into the medium of λ-lysogen, the inhibitory rates ranged from 27.0% ~ 45.0%. By electron spin resonance (ESR) detection, we found that the prescription I , Herba Patriniae and other main herbs in that recipe, could quench effectively the free radicals generated in the process of λ-lysogenic cells by UV. These results provide a novel idea for further studying the pharmacology of TCM and exploring the mechanism of SARS virus infection.

A novel method for evaluating free radical scavenging abilities of antioxidants using ultraviolet induction of bacteriophage lambda

A novel biological method used to evaluate free radical scavenging abilities of antioxidants using ultraviolet (UV) induction of bacteriophage lambda in lysogenic Escherichia coli kappa12 (lambda+) has been developed. This method is based on the induction of bacteriophage lambda from lysogenic cycle to lytic cycle by ultraviolet irradiation, and formation of free radicals during the course of induction. In the experiments, 10(8)cells/ml and 30s (39J/m2) were determined as the cell density of the lysogenic bacterium and UV irradiation time, respectively. The reliability of this method was demonstrated by electron paramagnetic resonance (EPR) spectroscopy and spin trapping with DMPO. This method had good reproducibility with intra-day variations (RSD, %) of less than 4% and inter-day variations (RSD, %) of less than 5%, respectively. By this method, the free radical scavenging abilities (ID50) of well-known antioxidants such as glutathione, superoxide dismutase (SOD), catalase (CAT) and carotenoids were determined quantitatively. The results were consistent with the ones obtained by conventional methods for evaluating free radical scavenging abilities. This developed method is reliable and uses common instruments and inexpensive, stable reagents, thus it could be utilized as a routine laboratory quantitative assay to screen a large number of substances that have potential to scavenge the free radical.

Effect of glutathione on UV induction of prophage lambda

The effect of glutathione (GSH) on the ultraviolet (UV) induction of lambda prophage was investigated in lysogenic Escherichia coli. The data showed that extracellular GSH could inhibit the UV induction of lambda prophage. The inhibitory rates were concentration dependent, and the maximal rate obtained was 94% with 3.0 M GSH. The effect was also measured in three different lambda lysogens: a wild-type strain (wt), an isogenic GSH-deficient strain, and an isogenic strain producing increased amounts of GSH. The result showed that when subjected to UV irradiation (254 nm, 60 J m(-2)), GSH-deficient strain was approximately fivefold more sensitive to be lysed than wt, whereas the strain with higher intracellular GSH levels was only 28% susceptible to be lysed. With electron spin resonance and spin trapping techniques, we observed that free radical signals occurred in the suspensions of UV irradiated lysogenic cells and the intensity of signals was influenced by GSH levels. These results indicate that GSH can significantly inhibit the UV induction of lambda prophage, and that this effect is correlated to its capacity to scavenge free radicals generated after UV irradiation.