Biotransformation of Silymarin Flavonolignans by Human Fecal Microbiota.

Flavonolignans occur typically in Silybum marianum (milk thistle) fruit extract, silymarin, which contains silybin, isosilybin, silychristin, silydianin, and their 2,3-dehydroderivatives, together with other minor flavonoids and a polymeric phenolic fraction. Biotransformation of individual silymarin components by human microbiota was studied ex vivo, using batch incubations inoculated by fecal slurry. Samples at selected time points were analyzed by ultrahigh-performance liquid chromatography equipped with mass spectrometry. The initial experiment using a concentration of 200 mg/L showed that flavonolignans are resistant to the metabolic action of intestinal microbiota. At the lower concentration of 10 mg/L, biotransformation of flavonolignans was much slower than that of taxifolin, which was completely degraded after 16 h. While silybin, isosilybin, and 2,3-dehydrosilybin underwent mostly demethylation, silychristin was predominantly reduced. Silydianin, 2,3-dehydrosilychristin and 2,3-dehydrosilydianin were reduced, as well, and decarbonylation and cysteine conjugation proceeded. No low-molecular-weight phenolic metabolites were detected for any of the compounds tested. Strong inter-individual differences in the biotransformation profile were observed among the four fecal-material donors. In conclusion, the flavonolignans, especially at higher (pharmacological) doses, are relatively resistant to biotransformation by gut microbiota, which, however, depends strongly on the individual structures of these isomeric compounds, but also on the stool donor.

Skin Protective Activity of Silymarin and its Flavonolignans.

Silybum marianum (L.) is a medicinal plant traditionally used in treatment of liver disorders. In last decades, silymarin (SM), a standardized extract from S. marianum seeds has been studied for its dermatological application, namely for UVB-protective properties. However, information on SM and its polyphenols effect on activity of enzymes participating in the (photo)aging process is limited. Therefore, evaluation of SM and its flavonolignans potential to inhibit collagenase, elastase, and hyaluronidase in tube tests was the goal of this study. The antioxidant and UV screening properties of SM and its flavonolignans silybin, isosilybin, silydianin, silychristin and 2,3-dehydrosilybin (DHSB) were also evaluated by a DPPH assay and spectrophotometrical measurement. DHSB showed the highest ability to scavenge DPPH radical and also revealed the highest UVA protection factor (PF-UVA) that corresponds with its absorption spectrum. SM and studied flavonolignans were found to exhibit anti-collagenase and anti-elastase activity. The most potent flavonolignan was DHSB. None of studied flavonolignans or SM showed anti-hyaluronidase activity. Our results suggest that SM and its flavonolignans may be useful agents for skin protection against the harmful effects of full-spectrum solar radiation including slowing down skin (photo)aging.

Dermal Delivery of Selected Polyphenols from Silybum marianum. Theoretical and Experimental Study.

Silymarin is a well-known standardized extract from the seeds of milk thistle (Silybum marianum L., Asteraceae) with a pleiotropic effect on human health, including skin anticancer potential. Detailed characterization of flavonolignans properties affecting interactions with human skin was of interest. The partition coefficients log Pow of main constitutive flavonolignans, taxifolin and their respective dehydro derivatives were determined by a High Performance Liquid Chromatography (HPLC) method and by mathematical (in silico) approaches in n-octanol/water and model lipid membranes. These parameters were compared with human skin intake ex vivo. The experimental log Pow values for individual diastereomers were estimated for the first time. The replacement of n-octanol with model lipid membranes in the theoretical lipophilicity estimation improved the prediction strength. During transdermal transport, all the studied compounds permeated the human skin ex vivo; none of them reached the acceptor liquid. Both experimental/theoretical tools allowed the studied polyphenols to be divided into two groups: low (taxifolin, silychristin, silydianin) vs. high (silybin, dehydrosilybin, isosilybin) lipophilicity and skin intake. In silico predictions can be usefully applied for estimating general lipophilicity trends, such as skin penetration or accumulation predictions. However, the theoretical models cannot yet provide the dermal delivery differences of compounds with very similar physico-chemical properties; e.g., between diastereomers.

In vivo evaluation of effect of anthocyanin-rich wheat on rat liver microsomal drug-metabolizing cytochromes P450 and on biochemical and antioxidant parameters in rats.

Wheat is one of the most important agricultural crops worldwide. Recently, anthocyanin-rich wheat genotypes were introduced to the market as a food with added value. In the experiment described here, two different genotypes with blue grain were studied (UC66049 and Skorpion). The aim of the investigation was to determine whether a 72-day-long intake of anthocyanin-rich wheat can influence the drug-metabolizing microsomal cytochromes P450 (using standard drug substrates of rat/human liver microsomal cytochromes P450) and antioxidant status, which indicated the ability of the rats' liver to metabolize drugs or xenobiotics. Consumption of an anthocyanin-rich diet moderately increased the activity and mRNA expression of the studied CYPs by 20-55% relative to the control (with the exception of CYP2B1/2). The health status of rats was good; the weight gain was lower in the group with anthocyanin-rich UC66049 grain compared to the other two groups (control and Skorpion-fed one). The antioxidant power of plasma was mildly but significantly higher in the test groups, other antioxidant parameters remained unaffected, except for an increased level of total SH groups. Based on our observations, there will most likely be no significant influence of the consumption of anthocyanin-rich wheat on the metabolism of xenobiotics and drugs.

UVA-photoprotective potential of silymarin and silybin.

Exposure to solar radiation is a major cause of environmental human skin damage. The main constituent of solar UV light is UVA radiation (320-400 nm); however, the need for protection against UVA has been marginalized for a long time. As a result, there is still a lack of useful agents for UVA protection. In this study, the effect of silymarin (SM) and its main constituent silybin (SB) pre-treatment on UVA-stimulated damage to primary human dermal fibroblasts were carried out. The cells were pre-treated for 1 h with SB or SM and then were exposed to UVA light, using a solar simulator. The effect of SB and SM on reactive oxygen species (ROS) and glutathione (GSH) level, caspase-3 activity, single-strand breaks (SSB) formation and protein level of matrix metalloproteinase-1 (MMP-1), heme oxygenase-1 (HO-1), and heat shock protein (HSP70) was evaluated. Treatment with both SM and SB resulted in a reduction in UVA-stimulated ROS generation and SSB production, as well as in the prevention of GSH depletion, a decrease in the activation of caspase-3 and protein level of MMP-1. They also moderately increased HO-1 level and reduced HSP70 level. Our data showed that both SM and SB are non-phototoxic and have UVA-photoprotective potential and could be useful agents for UV-protective dermatological preparations.

Schistosomiasis in European Travelers and Migrants: Analysis of 14 Years TropNet Surveillance Data.

Schistosomiasis remains one of the most prevalent parasitic diseases worldwide and the infection is frequently found in travelers and migrants. The European Network for Tropical Medicine and Travel Health conducted a sentinel surveillance study on imported schistosomiasis between 1997 and 2010. This report summarizes epidemiological and clinical data from 1,465 cases of imported schistosomiasis. Direct pathogen detection and serology were the main diagnostic tools applied. Of these, 486 (33%) cases were identified among European travelers, 231 (16%) among long-term expatriates, and 748 (51%) among non-European immigrants. Overall, only 18.6% of travelers had received pretravel advice; 95% of infections were acquired in the African region. On species level, Schistosoma mansoni was identified in 570 (39%) and Schistosoma haematobium in 318 (22%) cases; 57.5% of patients were symptomatic. Acute symptoms were reported in 27% of patients leading to earlier presentation within 3 months. Praziquantel was used in all patients to treat schistosomiasis. Many infections were detected in asymptomatic patients. In 47.4% of asymptomatic patients infection was detected by microscopy and in 39% by serology or antigen testing. Schistosomiasis remains a frequent infection in travelers and migrants to Europe. Travelers should be made aware of the risk of schistosomiasis infection when traveling to sub-Saharan Africa. Posttravel consultations particularly for returning expatriates are useful given the high potential for detecting asymptomatic infections.

The Phototoxic Potential of the Flavonoids, Taxifolin and Quercetin.

Quercetin, one of the most abundant polyphenols in the plant kingdom has been shown to be photodegraded on exposure to UV light. Despite the fact, it is a component of several dermatological preparations. Its phototoxic potential has not been evaluated to date. The aim of this study was to assess whether photo-induced degradation of quercetin is linked to phototoxic effects on living cells. Its dihydro derivative, taxifolin, was included in the study. For evaluation, the 3T3 Neutral Red Uptake Phototoxicity Test according to OECD TG 432 was used. To better approximate human skin, HaCaT keratinocytes, normal human epidermal keratinocytes and dermal fibroblasts were used, apart from the Balb/c 3T3 cell line. Quercetin showed a dose-dependent photodegradation in aqueous and organic environments and a phototoxic effect on all used cells. Quercetin pretreatment and following UVA exposure resulted in increased reactive oxygen species production and intracellular glutathione level depletion in human dermal fibroblasts. Taxifolin was found completely nonphototoxic and photostable. As only in vitro methodology was used, further studies using 3D skin models and/or human volunteers are needed to confirm whether exposure to sunlight, tanning sunbeds and/or phototherapy in people using cosmetics containing quercetin is a health risk.

Cranberry intervention in patients with prostate cancer prior to radical prostatectomy. Clinical, pathological and laboratory findings.

BACKGROUND AND OBJECTIVES: Recently, we described an inverse association between cranberry supplementation and serum prostate specific antigen (PSA) in patients with negative biopsy for prostate cancer (PCa) and chronic nonbacterial prostatitis. This double blind placebo controlled study evaluates the effects of cranberry consumption on PSA values and other markers in men with PCa before radical prostatectomy. METHODS: Prior to surgery, 64 patients with prostate cancer were randomized to a cranberry or placebo group. The cranberry group (n=32) received a mean 30 days of 1500 mg cranberry fruit powder. The control group (n=32) took a similar amount of placebo. Selected blood/urine markers as well as free and total phenolics in urine were measured at baseline and on the day of surgery in both groups. Prostate tissue markers were evaluated after surgery. RESULTS: The serum PSA significantly decreased by 22.5% in the cranberry arm (n=31, P<0.05). A trend to down-regulation of urinary beta-microseminoprotein (MSMB) and serum gamma-glutamyltranspeptidase, as well as upregulation of IGF-1 was found after cranberry supplementation. There were no changes in prostate tissue markers or, composition and concentration of phenolics in urine. CONCLUSIONS: Daily consumption of a powdered cranberry fruit lowered serum PSA in patients with prostate cancer. The whole fruit contains constituents that may regulate the expression of androgen-responsive genes.

Cytotoxicity evaluation of large cyanobacterial strain set using selected human and murine in vitro cell models.

The production of cytotoxic molecules interfering with mammalian cells is extensively reported in cyanobacteria. These compounds may have a use in pharmacological applications; however, their potential toxicity needs to be considered. We performed cytotoxicity tests of crude cyanobacterial extracts in six cell models in order to address the frequency of cyanobacterial cytotoxicity to human cells and the level of specificity to a particular cell line. A set of more than 100 cyanobacterial crude extracts isolated from soil habitats (mainly genera Nostoc and Tolypothrix) was tested by MTT test for in vitro toxicity on the hepatic and non-hepatic human cell lines HepG2 and HeLa, and three cell systems of rodent origin: Yac-1, Sp-2 and Balb/c 3T3 fibroblasts. Furthermore, a subset of the extracts was assessed for cytotoxicity against primary cultures of human hepatocytes as a model for evaluating potential hepatotoxicity. Roughly one third of cyanobacterial extracts caused cytotoxic effects (i.e. viability<75%) on human cell lines. Despite the sensitivity differences, high correlation coefficients among the inhibition values were obtained for particular cell systems. This suggests a prevailing general cytotoxic effect of extracts and their constituents. The non-transformed immortalized fibroblasts (Balb/c 3T3) and hepatic cancer line HepG2 exhibited good correlations with primary cultures of human hepatocytes. The presence of cytotoxic fractions in strongly cytotoxic extracts was confirmed by an activity-guided HPLC fractionation, and it was demonstrated that cyanobacterial cytotoxicity is caused by a mixture of components with similar hydrophobic/hydrophilic properties. The data presented here could be used in further research into in vitro testing based on human models for the toxicological monitoring of complex cyanobacterial samples.

Involvement of cytochrome P450 1A in sanguinarine detoxication.

Sanguinarine (SA), a member of the benzo[c]phenanthridine alkaloids, is a potent anti-microbial agent with anti-inflammatory and anti-neoplastic properties. However, toxicity of the alkaloid severely limits its medical applications. Recent report by Williams et al. implicated rat hepatic cytochrome P450 (CYP) 1A2 as a likely modulator of SA toxicity. Indeed, the in vitro toxicity of SA in primary culture of rat hepatocytes and human hepatic cell line HepG2, demonstrated as lactate dehydrogenase leakage and metabolic capability (MTT assay), was diminished following induction of CYP1A by 2,3,7,8-tetrachlorodibenzo-p-dioxin, 3-methylcholanthrene, and beta-naphtoflavone. Using microsomes containing recombinant CYP1A1 or CYP1A2 we show that SA causes non-competitive inhibition of the former and competitive inhibition of the latter as assessed by ethoxyresorufin de-ethylation (EROD). In human hepatic microsomes SA exhibits competitive inhibition of EROD activity with apparent K(i) of 2 microM, a value identical to that observed for CYP1A2 inhibition in recombinant system. Pre-incubation of SA with human liver microsomes resulted in time-dependent, but not dose-dependent decline in EROD activity suggesting CYP1A2 inhibition is not mechanism based. SA also inhibits activity of NADPH:CYP reductase, an enzyme required for CYP activity, with IC(50) very similar to that observed for EROD inhibition. Tentative mechanism for CYP1A involvement in decreased in vitro SA toxicity is discussed.