silychristin and isosilybin

The exposure of naked unprotected skin to solar radiation may result in numerous acute and chronic undesirable effects. Evidence suggests that silymarin, a standardized extract from Silybum marianum (L.) Gaertn. seeds, and its major component silybin suppress UVB-induced skin damage. Here, we aimed to investigate the UVA-protective effects of silymarin's less abundant flavonolignans, specifically isosilybin (ISB), silychristin (SC), silydianin (SD), and 2,3-dehydrosilybin (DHSB). Normal human dermal fibroblasts (NHDF) pre-treated for 1 h with flavonolignans were then exposed to UVA light using a solar simulator. Their effects on reactive oxygen species (ROS), carbonylated proteins and glutathione (GSH) level, caspase-3 activity, single-strand breaks' (SSBs) formation and protein level of matrix metalloproteinase-1 (MMP-1), heme oxygenase-1 (HO-1), and heat shock protein (HSP70) were evaluated. The most pronounced preventative potential was found for DHSB, a minor component of silymarin, and SC, the second most abundant flavonolignan in silymarin. They had significant effects on most of the studied parameters. Meanwhile, a photoprotective effect of SC was mostly found at double the concentration of DHSB. ISB and SD protected against GSH depletion, the generation of ROS, carbonylated proteins and SSBs, and caspase-3 activation, but had no significant effect on MMP-1, HO-1, or HSP70. In summary, DHSB and to a lesser extent other silymarin flavonolignans are potent UVA-protective compounds. However, due to the in vitro phototoxic potential of DHSB published elsewhere, further studies are needed to exclude phototoxicity for humans as well as to confirm our results on human skin ex vivo and in vivo.

Topics: Caspase 3; Cells, Cultured; Cytoprotection; DNA Breaks, Single-Stranded; Fibroblasts; Glutathione; Heme Oxygenase-1; HSP70 Heat-Shock Proteins; Humans; Matrix Metalloproteinase 1; Protein Carbonylation; Reactive Oxygen Species; Silymarin; Skin; Sunscreening Agents; Ultraviolet Rays

According to the results obtained in this study, drought stress can enhance the accumulation of silymarin in milk thistle seeds. Moreover, under drought stress, the share of silybin increased which possess the greatest degree of biological activity among the silymarin components. Silymarin, an isomeric mixture of flavonolignans found in milk thistle (Silybum marianum (L.) Gaertn) seeds, has been used for its hepatoprotective effects for more than 2,000 years. Biosynthesis and accumulation of active substances like silymarin in plant tissues highly interacts with the environmental conditions. Effects of moderate and severe drought stress (based on soil moisture depletion) on silymarin content and composition in milk thistle seeds were evaluated in a field study. Averaged across treatments, milk thistle seeds contained 19.3 g kg(-1) silymarin. Drought stress enhanced silymarin accumulation in milk thistle seeds. Plants grown under moderate and severe drought stress treatments contained 4 and 17 % greater silymarin than those grown in well-watered condition, respectively. Greater content of sylimarin in stressed plants was attributed to more contents of silybin, isosilybin and silychristin, while silydianin content was lower under drought condition. According to the results obtained in this study, drought stress enhanced accumulation of silymarin in milk thistle seeds and improved its quality by increasing the share of silybin, which possess the greatest degree of biological activity among the silymarin components.

Topics: Antioxidants; Droughts; Seeds; Silybin; Silybum marianum; Silymarin

Silymarin is one of the most potent antioxidant so far developed from plant sources used as hepatoprotectants. Influence of different concentrations (0, 1, 2, 4, 6 and 8mg/50ml culture) and exposure time (24, 48, 72, 96 and 120h) of salicylic acid on lipoxygenase activity, linoleic acid content, growth and production of silymarin in hairy root cultures of S. marianum were investigated. Detection and identification of flavonolignans was carried out by high performance liquid chromatograph method. Salicylic acid enhanced silymarin production (1.89mgg(-1) DW). The optimal feeding condition was the addition of salicylic acid (6 mg/50 ml culture) after 24h in which the silymarin content was 2.42 times higher than the control (0.78mgg(-1) DW). The content of silybin, isosilybin, silychristin, silydianin and taxifolin were 0.703, 0.017, 0.289, 0.02 and 0.863mgg(-1) DW respectively in these samples, while in non-treated hairy roots were 0.027, 0.046, 0.23, 0.022 and 0.453 respectively. Lipoxygenase activity also affected by elicitation. lipoxygenase activity increased 24h after treatment by approximately 1.57- fold (0.21 Delta OD(234)/mgproteinmin(-1)). Upon elicitation with salicylic acid, linoleic acid content of hairy roots (38.26mgg(-1) DW) were also elevated after 24h, in which the linoleic acid content was 2.37 times higher than the control (16.1mgg(-1) DW). It is feasible that elicitation with salicylic acid regulates the jasmonate pathway, which in turn mediates the elicitor-induced accumulation of silymarin.

Topics: Antioxidants; Cell Culture Techniques; Flavonolignans; Linoleic Acid; Lipoxygenase; Plant Roots; Quercetin; Salicylic Acid; Silybin; Silybum marianum; Silymarin

A sensitive method for the simultaneous quantitation of six active constituents in commercial silymarin standardized extracts was developed based on liquid chromatography (LC) in combination with mass spectrometry (MS). The six main active constituents, namely, silydianin, silychristin, diastereoisomers of silybin (silybin A and B), and diastereoisomers of isosilybin (isosilybin A and B) were completely separated and quantified by LC/MS. Silymarin obtained from Sigma-Aldrich Co. was evaluated and used as standard reference material for the six individual constituents in comparing the relative content of silymarin and the relative ratio of each constituent in commercial standardized silymarin extracts, respectively. Significant variation was found between different commercial silymarin sources. As a result, this method has proven useful in evaluating and quantifying the six active constituents in commercial milk thistle extracts. The calibration curves were over the range from 0.25 to 100 microg/mL for silychristin and silydianin, and from 0.10 to 100 microg/mL for silybin A, silybin B, isosilybin A and isosilybin B, respectively (r(2)> or =0.9958). For all six active constituents, the overall intra-day precision values, based on the relative standard deviation replicate for four QC levels, ranged from 1.18% to 12.4% and accuracy ranged from 89.4% to 112%. This methodology could easily be incorporated into standardized testing to assess content uniformity including lot-to-lot variation as part of routine process controls as well as a means to describe cross-product variation among the exiting marketed formulations.

Topics: Chromatography, Liquid; Plant Extracts; Reproducibility of Results; Sensitivity and Specificity; Silybin; Silymarin; Spectrometry, Mass, Electrospray Ionization; Stereoisomerism; Tandem Mass Spectrometry

Development of sustained delivery systems for herbal medicines was very difficult because of their complexity in composition. The concept of synchronized release from sustained release systems, which is characterized by release of multiple components in their original ratio that defines a herbal medicine, served as the basis for keeping the original pharmacological activity. In this study, erodible matrix systems based on glyceryl monostearate and polyethylene glycol 6000 or poloxamer 188 were prepared to perform strict control on synchronized release of the five active components of silymarin, i.e. taxifolin, silychrystin, silydianin, isosilybin and silybin. The matrix system was prepared by a melt fusion method. Synchronized release was achieved with high similarity factor f(2) values between each two of the five components. Erosion profiles of the matrix were in good correlation with release profiles of the five components, showing erosion-controlled release mechanisms. Through tuning some of the formulation variables, the system can be adjusted for synchronized and sustained release of silymarin for oral administration. In vitro hemolysis study indicated that the synchronized release samples showed a much better stabilizing effect on erythrocyte membrane.

Topics: Animals; Chemistry, Pharmaceutical; Delayed-Action Preparations; Drug Carriers; Drug Compounding; Flavonols; Glycerides; Hemolysis; In Vitro Techniques; Molecular Structure; Poloxamer; Polyethylene Glycols; Protective Agents; Quercetin; Rabbits; Silybin; Silymarin; Solubility; Technology, Pharmaceutical; Time Factors

A selective and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed for the characterization of silymarin in commercially available milk thistle extract. In this study, six main active constituents, including silydianin, silychristin, diastereomers of silybin (silybin A and B) and diastereomers of isosilybin (isosilybin A and B) in silymarin, were completely separated on a YMC ODS-AQ HPLC column using a gradient mobile phase system comprised of ammonium acetate and methanol/water/formic acid. Identification and characterization of the major constituents were based not only on the product ion scan, which provided unique fragmentation information of a selected molecular ion, but also on the specific fragmentation of multiple reaction monitoring (MRM) data, which confirmed the retention times of LC chromatographic peaks. The method was applied in the analysis of human plasma samples in the presence of silymarin and appeared to be suitable for the pharmacokinetic studies in which the discrimination of silymarin constituents is essential.

Topics: Chromatography, High Pressure Liquid; Plant Extracts; Silybin; Silybum marianum; Silymarin; Spectrometry, Mass, Electrospray Ionization; Spectrophotometry, Ultraviolet

The mixture of flavonolignans [Legalon: silybin (2a), isosilybin (3), silydianin (4) and silychristin (5)] and derivatives of silybin (2b-d) were assessed for their inhibitory activity on the oxidative burst of PMA-stimulated human PMNLs. The inhibitory effect of flavonolignans on O(2)(-) release were compared with that of vitamin E (1). The flavonolignans tested exhibited the following order in inhibition of O(2)(-) release by PMA-stimulated PMNLs: 5,7,4"- trimethylsilybin (2c) approximately vitamin E (1) > Legalon >or= peracetylsilybin (2b) > silybin (2a) > peracetyl-5,7,4"-trimethylsilybin (2d). The flavonolignans inhibited not only the O(2)(-) release, but also the H(2)O(2) formation in PMA-stimulated PMNLs. The inhibitory capacity of flavonolignans on H(2)O(2) formation was similar to their inhibitory capacity on O(2)(-) release. These data suggest that the flavonolignans have antioxidant properties on the PMNL oxidative burst. The fact that the trimethyl derivative of silybin (2c) has a greater inhibitory effect than silybin itself suggests that the efficacy of the antioxidant properties is dependent on the lipophilicity of the molecules. This is underlined by the fact that peracetylation of all of the hydroxyl groups in silybin resulted in a total loss of the antioxidant activity of the molecule. In summary, flavonolignans inhibit the oxidative burst of PMNLs, and this inhibitory effect depends on the chemical structure of the flavonolignans.

Topics: Flavonoids; Humans; Hydrogen Peroxide; Neutrophils; Phytotherapy; Respiratory Burst; Silybum marianum; Silymarin; Structure-Activity Relationship; Superoxides; Vitamin E