Effect of liver-protectingSempervivum tectorum extract on the immune reactivity of spleen cells in hyperlipidaemic rats

Wound healing activity and phytochemical screening of purified fractions of Sempervivum tectorum L. leaves on HCT 116

INTRODUCTION

Sempervivum tectorum L. (Crassulaceae), is a succulent perennial plant widespread in Mediterranean countries and commonly used in traditional medicine for ear inflammation, ulcers and skin rashes as a refrigerant and astringent.

OBJECTIVE

To demonstrate the therapeutic effects of the plant, various fractions were purified and characterised. The potential wound healing activity, proliferation rate and intracellular signalling cascades were investigated by using human epithelial colorectal carcinoma (HCT 116) cells.

METHODOLOGY

An extraction method without organic solvents was applied for the first time. The purification was carried out by droplet counter current chromatography (DCCC) coupled with high-performance liquid chromatography (HPLC) and electrospray ionisation mass spectrometry (ESI-MS) data. By nuclear magnetic resonance (NMR) [¹ H, ¹³ C and two-dimensional (2D) experiments] pure components were identified. Wound healing and cell proliferation assays were utilised to determine the role of the isolated S. tectorum (SVT) fraction on cellular migration and proliferation. The signalling pathways elicited from the SVT fractions, were analysed by Western blot analysis.

RESULTS

In this study two rare natural components were identified, namely monosaccharide sedoheptulose and polyalcohol 2-C-methyl-D-erythritol, along with known organic acids and flavonoids. The fractions with high level of sedoheptulose enhance the proliferation and the cellular migration of epithelial HCT 116 cells. The intracellular signalling cascades elicited from the purified fractions induce the c-Src-mediated transactivation of EGFR and the activation of the STAT3 pathway which, in turn, are crucially involved in the cellular proliferation and migration.

CONCLUSIONS

Our study demonstrates the efficacy of purified fractions of S. tectorum L. in enhancing cellular proliferation and migration, suggesting their potential role as topical therapeutic treatments for wound healing.

Sempervivum davisii: phytochemical composition, antioxidant and lipase-inhibitory activities

CONTEXT

Sempervivum davisii Muirhead (Crassulaceae) is a traditional medicinal herb from Eastern Anatolia. To date the composition of phytochemicals and physiological properties of this herb were not subjected to any research.

OBJECTIVE

This study identifies compounds in S. davisii hydrophilic extracts and evaluates their potential biological properties.

MATERIALS AND METHODS

Ethanol-based lyophilized extracts were obtained from aerial parts of plant (10 g of ground dry plant material in 200 mL of acidified aqueous ethanol, shaken for 2 h at 22 °C with supernatant collected and freeze-dried under vacuum). Phytochemical composition was investigated by liquid chromatography mass spectrometry (LC-MS/MS, phenolics) and gas chromatography mass spectrometry (GC-MS, volatiles). Phenolic compounds were quantified by high-performance liquid chromatography (HPLC) and the Folin-Ciocalteu assay. Subsequently, antioxidant capacity [ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) assays] and enzyme inhibitory properties (isolated porcine pancreatic lipase) of the extracts were determined.

RESULTS

Polyphenolic compounds were the main constituents of lyophilized extracts, among which kaempferol glycosides and quercetin hexoside dominated. The extracts exhibited potent antioxidant (FRAP values of 1925.2-5973.3 μM Fe²⁺/g DW; ORAC values of 1858.5-4208.7 μM Trolox Eq./g DW) and moderate lipase inhibitory (IC₅₀: 11.6-2.96 mg/mL) activities. Volatile compounds (nonanal, dehydroxylinalool oxide isomers, 2-decenal, 2-undecenal, 2,6-di-tetr-butylphenol) were also found.

CONCLUSIONS

Phenolic compounds with the dominating kaempferol and quercetin derivatives are the sources of potent antioxidant properties of S. davisii hydrophilic extracts. The extracts exhibit moderate inhibitory properties towards isolated pancreatic lipase.

[Importance of dietary hydroxycinnamic acids in the therapy of liver fibrosis]

Medicinal treatment of liver fibrosis is still unsolved. According to literature data, plant extracts containing hydroxycinnamic acids inhibit experimentally induced liver fibrosis.

AIM

The aim of this study was to provide data on the hydroxycinnamic acid content of medicinal plants, which can be applied in the adjuvant therapy of liver fibrosis.

METHODS

Content and composition of hydroxycinnamic acids from houseleek and seven known herbs were evaluated using spectrophotometry and high-performance liquid chromatography.

RESULTS

Hydroxycinnamic acid content was found to be high in Lamiaceae herbs, but it was lower in houseleek. Rosmarinic acid as the main compound was detected in all herb samples.

CONCLUSIONS

Besides hydroxycinnamic acids, houseleek contains high amounts of antioxidant polyphenols, and its pharmacological effect is presumed to be attributed to synergism of all of these compounds. The hydroxycinnamic acid content of the herbs investigated was remarkable, therefore, the results support their dietary application in patients with chronic liver disease.

Comparative screening of the anti-oxidant and antimicrobial activities of Sempervivum marmoreum L. extracts obtained by various extraction techniques

This paper presents a comparative study of the anti-oxidant and anti-microbial activities, total phenolic compounds and total flavonoids in extracts obtained from houseleek (Sempervivum marmoreum L.) leaves by the classical (maceration), ultrasonic and Soxhlet extraction (CE, UE and SE, respectively). The extract obtained by the CE contained higher amounts of phenolic and flavonoid compounds and showed a better antioxidant activity than those obtained using other two techniques. All the extracts, independent of the extraction technique applied, showed antimicrobial activities against Aspergillus niger and Candida albicans only but not against the tested bacteria.

Antioxidant activity of Sempervivum tectorum and its components

The antioxidant properties of components of leaf extracts of the evergreen plant, Sempervivum tectorum (ST), have been evaluated using UV irradiated liposomal systems containing the spin trap 5-(diethoxyphosphoryl)-5-methyl-pyrroline-N-oxide. Decreases in free radical activity in the liposomal systems as measured by electron paramagnetic resonance (EPR) spectroscopy demonstrate that the lipophilic ST juice components, kaempferol (KA) and kaempferol-3-glucoside (KG) contribute significantly to the antioxidant properties of the juice. EPR spectral simulation established the presence of oxygen and carbon centered free radical adducts. The mixtures with low pH, citric and malic acid, and ST juice reveal increased EPR signals from oxygen centered radicals in comparison to the control, pointing to the important role of pH in oxygen radical formation. Parallel assays that measured thiobarbituric acid related substances confirm the antioxidant effects of KA and KG and explain the results of spin trapping experiments complicated by low pH's.

Antinociceptive activity ofSempervivum tectorum L. extract in rats

The extract of Sempervivum tectorum L. (Crassulaceae) containing several flavonoids is widely used as an antiinflammatory agent in folk medicine. Previous studies have demonstrated that various flavonoids or flavonoid-containing plant extracts produce significant antinociception, but no data are available concerning their antinociceptive effect especially at the spinal level. The purpose of the present study was to investigate the antinociceptive activity of Sempervivum tectorum L. extract on acute and inflammatory pain sensitivity in awake rats. The pain sensitivity was assessed by the acute tail- flick test in intact rats and by the paw withdrawal test after carrageenan-induced inflammation using heat stimulus. The plant extract was administered intraperitoneally and intrathecally in rats. The intraperitoneal injection of a high dose of the extract (1000 mg/kg) significantly (p < 0.05) increased the paw withdrawal latency of the inflamed paw. The intrathecal administration (30-300 micro g) caused a small, but significant increase (10%-15%) in tail- flick latency. In the carrageenan-induced inflammatory model, the intrathecally applied extract (30-1000 micro g) significantly decreased, but did not relieve the thermal hyperalgesia. The results suggest that the spinal cord does not seem to play an important role in the antinociceptive effects of this plant extract.

The effect of amiodarone and/or antioxidant treatment on splenocyte blast transformation

Previous studies have shown that free radical reactions may play an important role in the pathogenesis of the adverse effects of the antiarrhythmic agent amiodarone. The aim of this study was to investigate the role of free radical reactions in amiodarone-induced changes in the cell-mediated immune response. Therefore, we investigated the effects of amiodarone alone and in combination with either vitamin E or silymarin on (a) spontaneous blast transformation of splenocytes, (b) concanavalin A (con A)-induced proliferation of splenocytes at three different lectin concentrations, and (c) the content of conjugated dienes in liver homogenate. Forty-eight male Fischer 344 rats were randomized to one of the following groups: 1, control; 2, amiodarone; 3, vitamin E; 4, amiodarone+vitamin E; 5, silymarin; 6, amiodarone+silymarin. The con A-induced splenocyte proliferation was significantly decreased in amiodarone-treated rats at all three lectin concentrations. In the amiodarone-treated group, the change of spontaneous blast transformation was not significantly different from the control. In groups treated with amiodarone plus either antioxidant, both the spontaneous and con A-induced splenocyte proliferation were significantly increased compared with the amiodarone-treated group, and were similar to those in the control group. Amiodarone treatment significantly increased, and both silymarin and vitamin E combined with amiodarone significantly decreased, the conjugated diene content of liver homogenate compared with amiodarone treatment alone. In conclusion, free radicals generated by amiodarone may be implicated in the adverse effects of amiodarone on cell-mediated immune response, and antioxidants applied together with amiodarone may protect against or reduce both the unfavorable immunological effects of amiodarone and amiodarone toxicity.

Membrane stabilising effects of natural polyphenols and flavonoids from Sempervivum tectorum on hepatic microsomal mixed-function oxidase system in hyperlipidemic rats

The extensive role of the microsomal mixed-function oxidase (MFO) system in the oxidation of endo-and xenobiotics, in the detoxication, in the generation of reactive free radicals and in the decomposition of the end products of lipid peroxides is well documented in the literature. Steatotic liver is a very frequent damage with different etiology. Drug metabolising reactions are suppressed in fatty liver, in which pathologically increased production of reactive oxygen intermediates may lead to the peroxidation of microsomal membrane lipids and to the change of membrane bound enzyme activities because of overwhelmed protective mechanisms. The subnormal activity of the MFO system may diminish the non specific resistance of the organism. Therefore we have studied the effects of natural flavonoids and polyphenolic compounds on the mixed-function oxidases. Antioxidant, O(2)(-&z.rad;) and &z. rad;OH scavenger properties of Sempervivum tectorum extract (STF1) were proved by EPR spectroscopic and chemiluminometric techniques. Potential bioactive constituents were determined by chromatography (HPLC, TLC) and spectrometric (UV, UV-VIS) methods. In the present study we reflect on the membrane stabilising, antioxidant and lipid metabolism modifying effects of this extract. It was established that activities of NAD(P)H reductase and content of cytochrome P450 were normalised in liver microsomes of hyperlipidemic rats, if the animals were treated with STF1 (2 g/bwkg for 9 days in drinking water parallel with fat-rich diet feeding). Fatty acid composition, examined by HRGLC analysis, was changed beneficially. NADPH induced lipid peroxidation was also decreased in microsomes in in vivo and in vitro experiments. At the same time the STF1 had no significant influence on MFO system in normolipidemic animals and on cytochrome b5 concentration of microsome fractions of hyperlipidemic rats.

Tentative identification of polyphenols in Sempervivum tectorum and assessment of the antimicrobial activity of Sempervivum L

Polyphenols were isolated from sliced fresh leaves of Sempervivum tectorum. After 21 h of extraction by methanol and removal of chlorophyll, ethyl acetate was used to separate oligomeric and polymeric polyphenols: 0.07% of oligomeric and 0.13% of polymeric polyphenols were found. After acidic hydrolysis of the oligomeric polyphenols, it was established by TLC, HPLC, and FAB mass spectra that kaempferol was the unique aglycon of the three main oligomeric constituents of S. tectorum. Paper chromatography suggested delphinidol to be the only anthocyanidin detectable in the material obtained by acidic hydrolysis of the polymeric polyphenol fraction. After Haslam degradation of the same polymeric polyphenol fraction, only 4-thiobenzyl-(-)-epigallocatechin and 4-thiobenzyl-(-)-epigallocatechin-3-gallate were found and tentatively identified. We concluded that procyanidins of B2 type could be the major components of the polymeric polyphenol fraction of this plant. Antimicrobial activity of Sempervivum L. leaves against six of seven selected microorganisms was observed.

Oxidative stress in the liver and biliary tract diseases

Oxidative stress plays an important role in the pathogenesis of toxic liver diseases and of other hepatic alterations. We summarize the pathomechanism of free radical reactions in liver diseases and the results of experimental and clinical observations. Most of the hepatoprotective drugs belong in the group of free-radical scavengers, their mechanism of action involving membrane stabilization, neutralization of free radicals and immunomodulation. We demonstrate the effects of the different drugs used in the therapy of liver diseases in animal experiments and in human clinicopharmacological studies. The scavenger effect of these drugs has been demonstrated in the subcellular fractions of liver cells in animal experiments. In vitro incubation with some hepatoprotective drugs inhibit lectin-induced lymphocyte transformation while others decrease the antibody-dependent, spontaneous, and lectin-induced lymphocytotoxicity. Dihydroquinolin-type antioxidants and silymarin enhanced the superoxide dismutase activity of erythrocytes and lymphocytes. In addition, in a 6-month double-blind clinical trial of patients with chronic alcoholic liver disease, we studied the effects of silymarin therapy on liver function tests, on the parameters characterizing the oxidative stress and immune reaction, on serum procollagen III peptide level, and on liver histology. A wide range of methods was used. The silymarin preparate corrected the altered immune reaction and the decreased superoxide-dismutase activity of erythrocytes and lymphocytes in patients with alcoholic liver cirrhosis. The results indicate that these drugs exert hepatoprotective activity and can improve liver functions in alcoholic patients and in toxic liver diseases. We found a correlation between the bilirubin concentration and lipid peroxidation in cases with toxic liver and biliary tract diseases, and assume that there are two kinds of bilirubin, an antioxidant and a prooxidant form, on the basis of diene conjugates in the bile.