Chemical Stability and Bioactivity of tanshinone I, tanshinone IIA, cryptotanshinone and dihydrotanshinone in in vitro test systems

Danshen Si Wu is a Traditional Chinese Medicine used for menopausal complains. Beside tanshinone IIA (Tan IIA), Danshen also contains tanshinone I (Tan I), cryptotanshinone (CT) and dihydrotanshinone (DT). The aim of this study was to compare the biological activity of these tanshinones and to determine their cytotoxicity and genotoxicity. Purities and stabilities of the substances were analyzed by LC-DAD and LC-MS analyses. DT and CT concentrations decreased rapidly in dimethylsulfoxide and were converted to Tan I and Tan IIA, respectively. In aqueous solution concentration of all tanshinones decreased after 24 h. Tan I and Tan IIA showed dose-dependent bioactivity mediated by ERα and ERβ. No cytotoxic and genotoxic effects for Tan I and Tan IIA were detected. In a yeast transactivation assay Tan I and Tan IIA showed antiandrogenic activity. A significant anabolic activity in C2C12 cells could be detected for Tan I and Tan IIA. In conclusion our data provide evidence that Tan I and Tan IIA are the most relevant bioactive tanshinones in Danshen. Our finding that all tanshinones display a certain instability in aqueous solutions is relevant when discussing their potential therapeutic benefits in humans.

Bioactive Phenolic Compounds from Lingonberry (Vaccinium vitis-idaea L.): Extraction, Chemical Characterization, Fractionation and Cellular Antioxidant Activity

Lingonberries contain high contents of bioactive compounds such as chlorogenic acids and anthocyanins. In addition to radical scavenging and antioxidant activities, these compounds can protect cells from DNA damage. For this reason, lingonberries might be well suited for nutraceuticals or natural biomedicines. To assess these applications, the present study characterized and identified the most effective extract, only consisting of anthocyanins, copigments or a mixture of both, obtained from a lingonberry juice concentrate. An extract was generated by using a XAD-7 column followed by fractionation into anthocyanins and copigments using adsorptive membrane chromatography. After identification of main polyphenols by HPLC–photodiode array–electrospray ionization–tandem mass spectrometry, free radical scavenging activity was analyzed by electron spin resonance spectroscopy using 2,2-diphenyl-1-picrylhydrazyl and galvinoxyl radicals. Furthermore, cyclic voltammetry analyses and the Trolox equivalent antioxidant capacity (TEAC) assay were applied. Finally, the reactive oxygen species (ROS) reducing effects of the lingonberry extract and its fractions were evaluated in HepG2 cells. While the combination of anthocyanins and copigments possessed the highest antioxidant activities, all samples (XAD-7 extract, anthocyanin and copigment fraction) protected cells from oxidative stress. Thus, synergistic effects between phenolic compounds may be responsible for the high antioxidant potential of lingonberries, enabling their use as nutraceuticals.

Synthesis and in vitro characterization of the genotoxic, mutagenic and cell-transforming potential of nitrosylated heme

Data from epidemiological studies suggest that consumption of red and processed meat is a factor contributing to colorectal carcinogenesis. Red meat contains high amounts of heme, which in turn can be converted to its nitrosylated form, NO-heme, when adding nitrite-containing curing salt to meat. NO-heme might contribute to colorectal cancer formation by causing gene mutations and could thereby be responsible for the association of (processed) red meat consumption with intestinal cancer. Up to now, neither in vitro nor in vivo studies characterizing the mutagenic and cell transforming potential of NO-heme have been published due to the fact that the pure compound is not readily available. Therefore, in the present study, an already existing synthesis protocol was modified to yield, for the first time, purified NO-heme. Thereafter, newly synthesized NO-heme was chemically characterized and used in various in vitro approaches at dietary concentrations to determine whether it can lead to DNA damage and malignant cell transformation. While NO-heme led to a significant dose-dependent increase in the number of DNA strand breaks in the comet assay and was mutagenic in the HPRT assay, this compound tested negative in the Ames test and failed to induce malignant cell transformation in the BALB/c 3T3 cell transformation assay. Interestingly, the non-nitrosylated heme control showed similar effects, but was additionally able to induce malignant transformation in BALB/c 3T3 murine fibroblasts. Taken together, these results suggest that it is the heme molecule rather than the NO moiety which is involved in driving red meat-associated carcinogenesis.

Prophage-mediated modulation of interaction of Streptococcus thermophilus J34 with human intestinal epithelial cells and its competition against human pathogens

The human intestinal microbiota plays an important role in human health. While adhesion to gastrointestinal mucosa is a prerequisite for colonisation, inhibition of adhesion is a property which may prevent or reduce infections by food borne pathogens. Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus represent the two lactic bacteria constituting the yoghurt culture. These starter cultures have been claimed to be probiotic. In our study we compared two S. thermophilus strains (i.e. lysogenic strain J34 and corresponding non-lysogenic [prophage-cured] strain J34-6), with respect to (1) their in vitro adhesion properties to HT29 cells and (2) their cell surface hydrophobicities. Effects of the two strains on inhibition of adhesion of the pathogens Listeria monocytogenes Scott A, Staphylococcus aureus 6732 and Salmonella enteritidis S489 were studied in vitro with HT29 cell cultures. Lysogenic strain J34 was shown to be considerably more effective than the non-lysogenic derivative strain J34-6.

Functional characteristics of Lactobacillus spp. from traditional Maasai fermented milk products in Kenya

In this study functional characteristics of 23 representative Lactobacillus strains isolated from the Maasai traditional fermented milk 'Kule naoto' were determined. The Lb. acidophilus group strains showed resistance to gastric juice and bile. In addition, some Lb. acidophilus strains expressed bile salt hydrolase activity, and had ability to assimilate cholesterol in vitro. In-vitro adhesion to HT29 MTX cells of up to 70% was recorded. Lb. fermentum strains showed almost 100% survival under simulated stomach acidic conditions and physiological salt concentrations of bile salts, hydrophobicity values were over 80%. Most strains of the Lb. casei and Lb. acidophilus groups showed aggregation abilities of above 50%. Many strains expressed a protective effect against N-methyl-N'-nitro-N-nitrosoguanidine induced DNA damage according to the 'comet assay' and none was virulent. The antibiotic minimum inhibitory concentration of selected strains was established. According to these results, the Lactobacillus spp associated with 'Kule naoto', contain potentially probiotic (functional) strains.

Functional properties of Lactobacillus plantarum strains isolated from Maasai traditional fermented milk products in Kenya

Lactobacillus plantarum was the major species among the lactic acid bacterial strains isolated from traditional fermented milk of the Maasai in Kenya. Selected strains were characterized for their functional properties using in vitro standard procedures. All strains expressed acid tolerance at pH 2.0 after 2-h exposure of values that ranged from 1% to 100%, while bile tolerance of acid-stressed cells at 0.3% oxgal varied from 30% to 80%. In vitro adhesion to the mucus-secreting cell line HT 29 MTX and binding capacity to extracellular protein matrices was demonstrated for several strains. The four strains tested in a simulated stomach duodenum passage survived with recovery rates ranging from 17% to 100%. Strains were intrinsically resistant to several antibiotics tested. From these in vitro studies, a number of Lb. plantarum strains isolated from the Maasai traditional fermented milk showed probiotic potential. The strains are good candidates for multifunctional starter culture development.

Boza, a natural source of probiotic lactic acid bacteria

AIMS

To evaluate the probiotic properties of strains isolated from boza, a traditional beverage produced from cereals.

METHODS AND RESULTS

The strains survived low pH conditions (pH 3.0), grew well at pH 9.0 and were not inhibited by the presence of 0.3% (w/v) oxbile. Cytotoxicity levels of the bacteriocins, expressed as CC(50), ranged from 38 to 3776 microg ml(-1). Bacteriocin bacST284BZ revealed high activity (EC(50) = 735 microg ml(-1)) against herpes simplex virus type 1. Growth of Mycobacterium tuberculosis was 69% repressed after 5 days in the presence of bacST194BZ. Various levels of auto-cell aggregation and co-aggregation with Listeria innocua LMG 13568 were observed. Adhesion of the probiotic strains to HT-29 cells ranged from 18 to 22%.

CONCLUSIONS

Boza is a rich source of probiotic lactic acid bacteria. All strains survived conditions simulating the gastrointestinal tract and produced bacteriocins active against a number of pathogens. Adherence to HT-29 and Caco-2 cells was within the range reported for Lactobacillus rhamnosus GG, a well-known probiotic. In addition, the high hydrophobicity readings recorded define the strains as good probiotics.

SIGNIFICANCE AND IMPACT OF THE STUDY

Boza contains a number of different probiotic lactic acid bacteria and could be marketed as a functional food product.

[The combination effects of quercetin with the herbicides atrazine, cyanazine and gesamprim in mutagenicity tests]

The plant flavonol quercetin and the triazine herbicides atrazine, cyanazine, and gesamprim were examined individually and in combination for the induction of genotoxic effects. The sister chromatid exchange (SCE) assay and the gene mutation assay for 6-thioguanine resistance (HPRT) were carried out with Chinese hamster ovary (CHO) cells. Whereas no evidence of an increased SCE rate was found, the test substances caused a slightly increased mutation rate in the HPRT assay after metabolic activation with a subcellular liver enzyme preparation. Combination studies with two or three of the test substances did not result in higher mutation rates than those observed for the individual compounds tested singly.

Assessment of genotoxic effects by lindane

The well known and previously widespread insecticide lindane has been re-assessed for DNA-damaging activity. A first group of investigations using standard in vitro and in vivo mutagenicity assays did not indicate any genotoxic effects of lindane at all. The assay systems used were for the induction of HPRT mutations and sister chromatid exchanges in CHO cells cultured in vitro, and for micronuclei induction in vivo in bone marrow cells of rats, hamsters and mice. Also, lindane was assessed for its potential to induce sister chromatid exchanges in vivo in the bone marrow of Chinese hamsters. These specific assay systems had not been used previously for elucidating the genotoxic effects of this compound, but they are basically similar to other standard mutagenicity assays in which lindane has been shown to be devoid of genotoxic activity. The second part of the investigations was directed at re-evaluating a previously reported positive effect of the compound in primary rat hepatocytes in vitro. We performed in vitro and in vivo studies with hepatocytes from the rat liver and used alkaline elution to detect DNA damage. However, we could not demonstrate that lindane induced genotoxicity, unless considerable concomitant cytotoxicity was apparent as well. Finally, since lindane can be ingested and inhaled by humans, we also measured the induction of DNA damage in local target organs of absorption using single cell micro-gel-electrophoresis (the comet assay). In these cases lindane was genotoxic in cells of the gastric and nasal mucosa in vitro and also in vivo following appropriate routes of application (oral and inhalational exposure).

Re-examination of potassium sorbate and sodium sorbate for possible genotoxic potential

Potassium sorbate and sodium sorbate were investigated for possible genotoxic actions using the Salmonella/mammalian-microsome test, HGPRT and sister chromatid exchange (SCE) test with Chinese hamster ovary cells, the micronucleus test on bone marrow cells of mice and Chinese hamsters, and the chromosome aberration and SCE test on Chinese hamsters. In all the in vitro tests no signs of genotoxicity were detected. Whereas no in vivo mutagenicity of potassium sorbate and sodium sorbate with freshly prepared aqueous solutions and with stored potassium sorbate was found, investigations with stored sodium sorbate revealed weak clastogenic activity by increased chromosome aberrations and elevated numbers of micronuclei at doses of 200 mg/kg body weight, but no induction of SCEs.