Drug resistance to Mycobacterium tuberculosis: from the traditional Chinese view to modern systems biology.

The pathogen, Mycobacterium tuberculosis (M. tuberculosis) is a well-evolved, organized pathogen that has developed drug resistance, specifically multidrug resistance (MDR) and extensive drug resistance (XDR). This review primarily summarizes the mechanisms of drug resistance by M. tuberculosis according to the traditional Chinese view. The traditional Chinese view of drug resistance includes: the physical barrier of the cell wall; mutations relating to current anti-TB agents; drug efflux pumps; and drug stress, including the SOS response systems, the mismatch repair systems and the toxin-antitoxin systems. In addition, this review addresses the integrated systems biology of genomics, transcriptomics, proteomics, metabolomics and interactomics. Development of the various levels of systems biology has enabled determination of the anatomy of bacteria. Finally, the current review proposes that further investigation regarding the population of individuals with a high drug metabolic speed is vital to further understand drug resistance in M. tuberculosis.

Genotoxicity investigation of araticum(Annona crassiflora Mart., 1841, Annonaceae) using SOS-Inductest and Ames test.

Although the use of medicinal plants or natural products has increased in recent decades all over the world, little information is available on their potential risk to health. Annona crassiflora Mart., a plant commonly known as araticum in Brazil, has been widely used in folk medicine for a long time since its seeds and leaves are often utilised in the treatment of cancer, snake bites, and venereal diseases, its fruits are consumed as tonic and astringent, and its bark powder has anti-fungal and anti-rheumatic properties. To evaluate the genotoxic and mutagenic properties induced by the ethanolic extract of araticum leaves, we performed the prophage λ induction (Inductest) and bacterial mutagenicity assays. We used Escherichia coli WP2s(λ) and RJF013 strains in the lysogenic induction test, whereas the mutagenic studies were carried out using Salmonella typhimurium histidine auxotroph strains TA97a, TA98, TA100, and TA102. Each experiment was performed three times in duplicate and included positive and negative controls. No statistically significant (p > 0.05) positive results were obtained for any of the strains tested, which suggests that the ethanolic extract of araticum leaves did not exhibit direct mechanisms of genotoxicity or mutagenicity that could be detected by the tests used in the present work.

Assessment of phenolic content, free-radical-scavenging capacity genotoxic and anti-genotoxic effect of aqueous extract prepared from Moricandia arvensis leaves.

The present study was undertaken to provide a set of data on the safety of an aqueous extract (AQE) from Moricandia arvensis. For this reason, Escherichia coli tested strains PQ35 and PQ37 were used to detect induction of DNA lesions by AQE. The SOS Chromotest showed that AQE induced a marginally genotoxic effect, as expressed by the induction factor (IF) value only with E. coli PQ37 tested strain (IF=1.77 at a dose of 250 microg/assay). The measurement of the anti-genotoxic activity of the AQE was also studied by inhibition of beta-galactosidase induction. A significant anti-genotoxic effect was observed with different tested doses of AQE, which suggests that M. arvensis extract has the potential to protect DNA from the action of nitrofurantoïn (NF) and free radicals generated by hydrogen peroxide (H2O2). In addition to anti-genotoxic activity, AQE showed a free-radical-scavenging capacity towards ABTS+* and DPPH*. Total phenolic content was also evaluated following Folin-Ciocalteu method and results indicated high correlation between total phenol content and anti-genotoxic and antioxidant activities for AQE, but the highest correlation was showed with its capacity to stabilize ABTS+* (R2=0.9944).

Assessment of the potential genotoxic risk of Phyllantus orbicularis HBK aqueous extract using in vitro and in vivo assays.

Phyllanthus orbicularis HBK is an endemic Cuban plant whose aqueous extract has been proposed as an effective drug for the treatment of viral diseases. In addition, antimutagenic properties of this extract have also been reported. In the present study, the genotoxicity of this plant extract was assessed using different in vitro and in vivo assays. Results from SOS gene induction, gene reversion and conversion, and SMART assays clearly show that P. orbicularis aqueous extract does not induce either primary DNA damage or mutation. Additionally, no statistically significant difference was found in the percentage of chromosomal aberrations in Chinese hamster ovarian (CHO) cells treated with the plant extract. On the contrary, micronuclei and abnormal anaphase were induced by this extract in CHO cells. This genotoxic effect was related to a high cytotoxicity. Single spots were detected in the SMART assay. These results point to a possible aneugenic effect of the P. orbicularis aqueous extract at cytotoxic doses which are much higher than those seen by their antiviral and antimutagenic activities.

Evaluation of transcriptional fusions with green fluorescent protein versus luciferase as reporters in bacterial mutagenicity tests.

A bacterial plasmid was constructed on which the regulatory region of the umuC gene of Escherichia coli was fused to the coding sequence of the green fluorescent protein gene (gfp) from the jellyfish Aequorea victoria. Escherichia coli AB1157 strains carrying the plasmid emitted fluorescence in the presence of mutagens that induce the SOS DNA repair system. Data on tests with nitrosoguanidine, methylmethane sulphonate and UV radiation (254 nm) are presented. Although fluorescent detection using this system was not as rapid or sensitive as a similar luminescent equivalent (umuC-luxAB), the gfp reporter system was more robust. Escherichia coli umu gene induction was also analysed in Salmonella typhimurium TA1537 cells following plasmid transfer and exposure to the same range of mutagens. There was no significant difference in sensitivity between the two species. These preliminary results will provide the basis for development of mutagenicity test systems useful in the testing of complex mixtures, such as environmental samples, and the investigation of physiological parameters influencing spontaneous mutagenesis in bacteria.