Schisantherin D from Schisandra chinensis (Turcz.) Baill. exhibits anti-liver fibrosis capacity via modulating ETBR involved signaling, an in vitro and in vivo study

Excess levels of chemical hepatotoxicants (alcohol, aflatoxin B1), oxidative drugs (acetaminophen) and some cytokines (ET-1, TGF-β1) can induce chronic or acute liver injury. After these, the severe hepatic disease, especially the liver fibrosis (LF) occurs without taking measures, which brings threat to human health. The dibenzocyclooctadiene lignans of S. chinensis (SCDLs) were found to act as the hepatoprotective components via blocking endothelin B receptor (ETBR). While study on its anti-LF mechanisms especially for its refined compound of schisantherin D (SC-D) is still a lack. So this study aims to investigate the anti-fibrosis effect of SC-D with in vitro and in vivo assays. Bioinformatics analysis revealed the close relations of ETBR to Smad2, Smad3, Nrf2, etc. in LF-related signaling pathways (such as TGF-β/Smad and Nrf2/ARE). Histopathological staining on livers showed the recovery trend in SC-D treated LF mice. SC-D also modulated expressions of ETBR and fibrosis or anti-oxidative related proteins (such as TIMP1, p-Smad2/3, Nrf2, Smad7, etc.) in LF mice livers. Serum levels of TNF-α, COLI, ALT, AST and LDH in SC-D treated mice were also downregulated compared with LF mice, and upregulated expression of GSH. In vitro studies, SC-D also modulated expressions of LF-related proteins to the normal tendency in LX-2 cell, while weakened its anti- LX-2 proliferation effect by transfections of si-Smad7 or si-Nrf2. Accordingly the anti-LF approach of SC-D showed relations with modulating ETBR linked fibrosis and anti-oxidative related signaling. Also, Smad7 and Nrf2 might be the key factors for SC-D mediated anti-LF effect.

Lignans from Schisandra chinensis ameliorate alcohol and CCl4-induced long-term liver injury and reduce hepatocellular degeneration via blocking ETBR

ETHNOPHARMACOLOGICAL RELEVANCE

Chemical hepatotoxicity, especially alcoholic liver injury (ALI), commonly occurs in young and middle-aged people who drink heavily. ALI is extremely harmful and can induce severe disease states, such as hepatitis, liver fibrosis, cirrhosis, or liver cancer, which are similar to CCl₄-induced liver disease states in animals. In recent studies, the pathological changes of hepatocytes and the hepatic stellate cell have shown a significant connection between endoplasmic reticulum (ER) stress and the development of liver pathology in patients. However, the detailed pathological mechanism needs to be further studied. Schisandra chinensis, (S. chinensis), a fruit-bearing vine used in Traditional Chinese Medicine (TCM), has been used to treat chronic or acute diseases, including liver disease. S. chinensis-derived lignans (SCDLs) in particular have been shown to alleviate liver pathological changes.

AIM OF THE STUDY

This study sought to elucidate the mechanisms underlying SCDL-mediated hepatoprotection.

MATERIALS AND METHODS

We first used in silico target prediction and computational simulation methods to identify putative lignan-binding targets relative to the hepatoprotective effect. A gene microarray analysis was performed to identify differently expressed genes that might have significance in the disease pathological process. We then used histological analyses in a mice hepatotoxicity model to test the effectiveness of SCDLs in vivo, and a hepatocellular toxicity model to analyze the candidate-compound-mediated hepatoprotection and expression states of the key targets in vitro.

RESULTS

The in silico analysis results indicated that endothelin receptor B (ETBR/EDNRB) is likely a significant node during the liver pathological change process and a promising key target for the SCDL compound schisantherin D on the hepatoprotective effect; experimental studies showed that schisantherin D alleviated the EtOH- and ET-1-induced HL-7702 cell (belongs to liver parenchymal cell lines) injury ratio, decreased the expression of ETBR, and inhibited ECMs and ET-1 secretion in LX-2 cells (one form of hepatic stellate cells). SCDLs ameliorated EtOH- and CCl₄-induced fibrosis formation in mice liver tissue. Liver tissue western blots of SCDL-treated mice showed downregulated α-SMA, ETBR, PLCβ, CHOP, Bax, and the apoptotic factors of cleaved-caspase 12, cleaved-caspase 9, and cleaved-caspase 3 hinted at an anti-apoptosis and hepatoprotective effect. The SCDL treatment also elevated serum glutathione (GSH) and reduced the serum-transforming growth factor-β1 (TGF-β1) level.

CONCLUSION

The findings indicated that SCDLs prevent hepatotoxicity via their anti-fibrotic, anti-oxidant, and anti-apoptosis properties. ETBR may be the key factor in promoting chemical hepatotoxicity.

Triterpenoid saponins from the stem bark of Catunaregam spinosa

Four new triterpenoid saponins, Catunaroside E (1; 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl}-siaresinolic acid), Catunaroside F (2; 3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl}-28-O-(β-D-glucopyranosyl)-oleanolic acid), Catunaroside G (3; 3-O-[α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl]- 28-O-(β-D-glucopyranosyl)-siaresinolic acid), and Catunaroside H (4; 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl}-28-O-(β-D-glucopyranosyl)-siaresinolic acid), and the known triterpenoid saponin Mussaendoside J (5), were isolated from the stem bark of Catunaregam spinosa . Their structures were elucidated on the basis of their spectral data and chemical evidence.

[Studies on the chemical constituents of Scyphiphora hydrophyllacea (II)]

OBJECTIVE

To study the chemical constituents of Scyphiphora hydrophyllacea.

METHODS

The compounds were isolated and purified by repeated column chromatography on silica and Sephadex LH-20 gel and their structures were identified by spectral analysis.

RESULTS

Six compounds were identified as friedelin (1), syringic acid (2), isoscopoletin (3), fraxetol (4), casuarinondiol (5) and guaiacylglycerol-beta-ferulic acid ether (6).

CONCLUSION

All of these six compounds are isolated from Scyphiphora hydrophyllacea for the first time.

Peripheral anti-inflammatory actions of corticotropin-releasing factor

Swelling, oedema, and loss of fluids and protein from the vascular compartment are immediate responses seen in living tissues after severe injury. Peptides of the corticotropin-releasing factor (CRF) superfamily have the unusual property of preventing the vascular leakage that occurs in tissues after damage. For example, CRF decreased protein extravasation, oedema and swelling in the anaesthetized rat's paw after exposure to heat or to extreme cold, in tracheal mucosa after exposure to formaldehyde, in skeletal muscle after a knife cut, and in brain cortex after freezing. The anti-inflammatory actions of CRF were independent of steroid release or hypotensive effects. CRF was a functional antagonist of inflammatory mediators such as histamine and substance P. It inhibited neurogenic inflammation, but interactions with unmyelinated sensory neurons did not account for the wide range of CRF's anti-inflammatory activities. Localized application of CRF prevented histamine-induced leaks in the hamster cheek pouch, and displaceable binding sites to iodinated CRF were found on blood vessels and on epithelial cells in close proximity to sites of vascular leakage. These results indicated peripheral sites of action. CRF may be the first example of a peptide hormone demonstrated to have potent anti-inflammatory agonist actions in vivo.

Lifestyle, environmental pollution and lung cancer in cities of Liaoning in northeastern China

Several studies were conducted in cities of Liaoning Province, one of the areas of China with heavy concentrations of industry, to investigate the effects of life-style factors and environmental pollutants on lung cancer causation. A case-control study involving 1249 lung cancer patients and 1345 population-based controls was conducted in 1985-1988 in Shenyang, the capital of Liaoning. Cigarette smoking was found to be the principal cause of lung cancer in this population, accounting for 55% of the disease in males and 37% in females. There was also a significant increase in lung cancer risk associated with an overall index of indoor air pollution due to coal-burning emission. The population attributable risk (PAR) for indoor air pollution was 13% for males and 17% for females. Risks were significantly increased for workers in the non-ferrous smelter (odds ratio (OR) = 2.6, 95% CI, 1.3-5.1), chemical and drug manufacturing (OR = 3.0, 95% CI, 1.0-8.0), and the glass and pottery industry (OR = 1.6, 95% CI, 1.0-2.5). Studies in the Anshan Iron-Steel Complex showed a significant excess of lung cancer for workers exposed to a variety of dusts. A standardized proportional mortality ratio (SPMR) study of 8887 deaths during 1980-1989 among male workers of the complex indicated a 37% excess risk of lung cancer compared to residents of the city. A nested case-control study was then conducted in that complex. A total of 610 cases of lung cancer diagnosed during 1987-1993 and 959 randomly selected controls from 196 993 active and retired employees of the complex were interviewed. Historical monitoring records for dust and benzo(a)pyrene (B(a)P) were collected from 1956-1992 to calculate cumulative exposure for each person. Results suggested that risks were increased for all occupations in which there was exposure to dusts, with the highest risks seen among coke oven workers (OR = 3.5, 95% CI, 2.0-6.4) and fire-resistant brick makers (OR = 2.9, 95% CI, 1.9-4.4). Significant dose-response patterns between cumulative total dust, cumulative total B(a)P and lung cancer risk were observed. The findings suggest that smoking and environmental pollution combine to account for elevated rates of lung cancer in cities of northeastern China.

Inhibition of substance P-induced vascular leakage in rat by N-acetyl-neurotensin-(8-13)

Substance P (SP) administered 40 micrograms/kg s.c. to pentobarbital-anesthetized rats induced salivation and leakage of plasma constituents into the skin, muscle, trachea, esophagus and bladder, as measured by Monastral blue B labeling of small blood vessels or by extravasation of Evans blue dye into tissues. These SP effects were inhibited by N-acetyl-neurotensin-(8-13) (Ac-NT-(8-13)) and by CP-96,345, a nonpeptide SP receptor antagonist. Intralumenal injection of Ac-NT-(8-13) or CP-96,345 into the bladder reduced SP-induced leakage of Evans blue dye but not dye leakage into the pawskin, indicating a localised drug action. Ac-NT-(8-13) appears to act directly on discrete sites in skin and in mucous membranes to functionally antagonize the inflammatory effects of SP.

Potencies of various neurotensin-(8-13) analogs for inhibition of heat-induced edema in the anesthetized rat

Peptides of the neurotensin (NT) and xenopsin (XP) families inhibit vascular leakage in various models of tissue injury. In this study, we measured the potency of NT fragments, NT analogs and NT-(8-13) analogs for inhibition of thermal edema induced by immersion of the anesthetized rat's paw in 58 degrees C water for 1 min. The pattern of anti-edema potencies seen with sixteen NT-(8-13) analogs correlated well with the pattern of activities obtained in binding measurements to rat brain membrane preparations and to activities in isolated organ preparations. Replacement of Tyr11 with Trp in NT-(8-13) and Arg8 with D-Arg resulted in an analog [D-Arg8, Trp11]NT-(8-13) which was 5-times more potent than NT-(8-13). Substitution of D-Arg for Arg8 and Arg9 in NT-(8-13) produced analogs that retained anti-edema activity but with decreased effects on gut motility and hypotension.

Xenopsin, neurotensin, neurotensin(8-13) and N-acetyl-neurotensin(8-13) inhibit vascular leakage in rats after tissue injury

Swelling, edema and leakage of proteins from the vascular compartment are immediate inflammatory responses of living tissues to local injury. Xenopsin, neurotensin (NT), NT(8-13) and NAcNT(8-13) administered to male rats anesthetized with sodium pentobarbital 60 mg/kg i.p. inhibited swelling and edema in the paw induced by immersion in 58 degrees water for 1 min. The ED50 values for xenopsin. NT, NAcNT(8-13) and NT(8-13) for reducing heat-induced edema were 0.9, 1.5, 1.9 and 2.1 nmol/kg i.v., respectively. NAcNT(8-13) was chosen as a prototype for further studies because, compared to NT, it had minimal hypotensive effects. NAcNT(8-13), 4 nmol/kg i.v., injected 10 min before mechanical injury to muscle, produced by a 4 cm midline surgical incision in the rectus abdominis, or before freeze injury to the cortex, produced by applying a cold probe (-50 degrees C) to the skull for 4 min, reduced vascular leakage, measured as area of Monastral blue staining of the injured tissues. NAcNT(8-13), 4 nmol/kg i.v., also attenuated pulmonary edema induced by epinephrine bitartrate 10 micrograms/kg i.v. The ability of NAcNT(8-13) to inhibit vascular leakage was not linked to its transient hypotensive effects and it was not blocked by alpha-helical-CRF(9-41), a putative CRF receptor antagonist, or by chlorpheniramine, a H1-histamine receptor antagonist.

Corticotropin-releasing factor inhibition of substance P-induced vascular leakage in rats: possible sites of action

Substance P (SP), 40 micrograms/kg SC, induced protein leakage in the skin, muscle, trachea and esophagus of the anesthetized rat as measured by Monastral blue B labeling of small blood vessels. CRF, 30 micrograms/kg SC, injected 30 min before SP, decreased the SP-induced dye leakage. To locate where CRF might act, autoradiographic studies of [125I]-CRF binding to esophageal segments were conducted and displaceable binding of [125I]-CRF to submucosal elements in the esophageal epithelium were revealed, suggesting that CRF acts on selective sites to reduce vascular leakage.

Corticotropin-releasing factor: an inhibitor of vascular leakage in rat skeletal muscle and brain cortex after injury

Corticotropin-releasing factor (CRF) and other peptides of the corticoliberin superfamily inhibit development of edema in skin and mucosa after noxious stimuli. Here, the breadth of CRFs protective activity on small blood vessels was examined after injury to skeletal muscle or to brain cortex. Male rats (243 +/- 15 g) were anesthetized with sodium pentobarbital 60 mg/kg i.p. and Monastral blue 60 mg/kg i.v. was injected 3 min before mechanical injury to muscle produced by a 4 cm midline surgical incision in the rectus abdominis or before freeze injury to the cortex produced by applying a cold probe (-50 degrees C) to the skull for 4 min. Vascular leakage, measured as area of dye staining multiplied by its light intensity, was quantified with an image-analysis system. CRF, having the human/rat sequence, 30 micrograms/kg s.c., injected once (30 min) or twice (30 min and 10 min) before injury to muscle or to brain, inhibited the lesion size by 58% and 55%, respectively (tissues taken at 0.5 and 1 h). Microscopy showed that CRF inhibited Monastral blue labeling of small blood vessels. The ED50 (95% C.L.) of CRF for reducing vascular leakage in muscle after celiotomy was 24 (9 to 64) micrograms/kg s.c. h/rCRF injected 30 micrograms/kg s.c. 2 h before celiotomy inhibited vascular leakage after celiotomy in adrenalectomized rats and this effect was not obtained with dexamethasone phosphate, 1 mg/kg s.c. alpha-Helical CRF (9-41), a CRF receptor antagonist, attenuated the actions of CRF on celiotomy. Laser-Doppler flowmeter measurements of skeletal muscle showed that the anti-inflammatory effects of CRF occurred when there were no significant concurrent changes in blood flow. From these results, we surmise that CRF has a versatile protective effect on small blood vessels when it inhibits leakage within different vascular beds.