Silymarin is an extract obtained from the seeds of milk thistle (Sylibum marianum L., Asteraceae) and contains several structurally related flavonolignans and a small family of flavonoids. Mouse spleen cells represent highly sensitive primary cells suitable for studying the pharmacological potential and biofunctional properties of natural substances. Cultivation of splenocytes for 24 h under standard culture conditions (humidity, 37 °C, 5% CO2, atmospheric oxygen) resulted in decreased viability of splenocytes compared to intact cells. A cytoprotective effect of silybin (SB), silychristin (SCH) and 2,3-dehydrosilybin (DHSB) was observed at concentrations as low as 5 µmol/ml. At 50 µmol/ml, these substances restored and/or stimulated viability and mitochondrial membrane potential and had anti-apoptotic effect in the order SB > DHSB > SCH. The substances demonstrated a concentration-dependent activity in restoring the redox balance based on the changes in the concentration of reactive oxygen species (ROS), hydrogen peroxide (H2O2) and nitric oxide. This was in the order DHSB > SCH > SB, which correlated with the suppressed expression of nuclear factor erythroid 2-related factor 2 (Nrf2), catalase and glutathione peroxidase. The strong stimulation of the superoxide dismutase 1 gene converting ROS to H2O2 points to its dominant role in the maintaining redox homeostasis in splenocytes, which was disrupted by oxidative stress due to non-physiological culture conditions. Our study showed significant differences in the cytoprotective, antioxidant and anti-apoptotic activities of SB, SCH, and DHSB on splenocytes exposed to mild and AAPH-induced oxidative stress.

• Keywords
• 2,3-dehydrosilybin, Apoptosis, Mouse splenocytes, Redox balance, Silybin, Silychristin, Viability,
• MeSH
• Antioxidants * pharmacology   MeSH
• Apoptosis * drug effects   MeSH
• Cytoprotection * drug effects   MeSH
• NF-E2-Related Factor 2 metabolism   MeSH
• Membrane Potential, Mitochondrial drug effects   MeSH
• Mice, Inbred BALB C MeSH
• Mice MeSH
• Nitric Oxide metabolism   MeSH
• Oxidative Stress drug effects   MeSH
• Hydrogen Peroxide metabolism   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Silybin MeSH
• Silymarin * pharmacology   analogs & derivatives   MeSH
• Spleen * cytology   drug effects   metabolism   MeSH
• Cell Survival drug effects   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antioxidants * MeSH
• dehydrosilybin MeSH Browser
• NF-E2-Related Factor 2 MeSH
• Nitric Oxide MeSH
• Hydrogen Peroxide MeSH
• Reactive Oxygen Species MeSH
• Silybin MeSH
• silychristin MeSH Browser
• Silymarin * MeSH

The chronic exposure of skin to ultraviolet (UV) radiation causes adverse dermal reactions, such as erythema, sunburn, photoaging, and cancer, by altering several signalling pathways associated with oxidative stress, inflammation, and DNA damage. One of the possible UV light protection strategies is the use of dermal photoprotective preparations. The plant hormone kinetin (N6-furfuryladenine; KIN) exhibits antioxidant and anti-senescent effects in human cells. Topically applied KIN also reduced some of the clinical signs of photodamaged skin. To improve the biological activities of KIN, several derivatives have been recently prepared and their beneficial effects on cell viability of skin cells exposed to UVA and UVB light were screened. Two potent candidates, 6-(tetrahydrofuran-2-yl)methylamino-9-(tetrahydrofuran-2-yl)purine (HEO) and 6-(thiophen-2-yl)methylamino-9-(tetrahydrofuran-2-yl)purine (HEO6), were identified. Here the effects of KIN, its N9-substituted derivatives the tetrahydropyran-2-yl derivative of KIN (THP), tetrahydrofuran-2-yl KIN (THF), HEO and HEO6 (both THF derivatives) on oxidative stress, apoptosis and inflammation in UVA- or UVB-exposed skin cell was investigated. Human primary dermal fibroblasts and human keratinocytes HaCaT pre-treated with the tested compounds were then exposed to UVA/UVB light using a solar simulator. All compounds effectively prevented UVA-induced ROS generation and glutathione depletion in both cells. HEO6 was found to be the most potent. All compounds also reduced UVB-induced caspase-3 activity and interleukin-6 release. THP and THF exhibited the best UVB protection. In conclusion, our results demonstrated the UVA- and UVB-photoprotective potential of KIN and its derivatives. From this point of view, they seem to be useful agents for full UV spectrum protective dermatological preparations.

• Keywords
• Keratinocyte cell line, Kinetin, Kinetin derivatives, Normal human skin fibroblasts, UVA, UVB,
• MeSH
• Antioxidants pharmacology   MeSH
• Keratinocytes * metabolism   MeSH
• Kinetin metabolism   pharmacology   MeSH
• Skin * radiation effects   MeSH
• Humans MeSH
• Ultraviolet Rays adverse effects   MeSH
• Inflammation metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antioxidants MeSH
• Kinetin MeSH

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.

• Keywords
• Silybum marianum, collagenase, elastase, sun protection factor,
• MeSH
• Antioxidants chemistry   isolation & purification   MeSH
• Flavonolignans chemistry   isolation & purification   MeSH
• Skin drug effects   pathology   radiation effects   MeSH
• Humans MeSH
• Silybum marianum chemistry   MeSH
• Plant Extracts chemistry   MeSH
• Seeds chemistry   MeSH
• Silymarin chemistry   isolation & purification   MeSH
• Ultraviolet Rays adverse effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antioxidants MeSH
• dehydrosilybin MeSH Browser
• Flavonolignans MeSH
• Plant Extracts MeSH
• Silymarin MeSH