Hepatoprotective effect of withanolide-rich fraction in acetaminophen-intoxicated rat: decisive role of TNF-α, IL-1ß, COX-II and iNOS.

CONTEXT: Overdose of acetaminophen (APAP) is common in humans and is often associated with hepatic damage. Withania somnifera (L.) Dunal (Solanaceae) shows multiple pharmacological activities including antioxidant and anti-inflammatory potential. OBJECTIVE: To evaluate the possible mechanism of hepatoprotective activity of withanolide-rich fraction (WRF) isolated from a methanolic extract of Withania somnifera roots. MATERIALS AND METHODS: Hepatotoxicity was induced by oral administration of APAP (750 mg/kg, p.o.) for 14 d. The control group received the vehicle. APAP-treated animals were given either silymarin (25 mg/kg) or graded doses of WRF (50, 100 and 200mg/kg) 2 h prior to APAP administration. Animals were killed on 15th day and blood and liver tissue samples were collected for the further analysis. RESULTS: In WRF-treated group, there was significant and dose-dependent (p < 0.01 and p < 0.001) decrease in serum bilirubin, ALP, AST and ALT levels with significant and dose-dependent (p < 0.01 and p < 0.001) increase in hepatic SOD, GSH and total antioxidant capacity. The level of MDA and NO decreased significantly (p < 0.01) by WRF treatment. Up-regulated mRNA expression of TNF-α, IL-1ß, COX-II and iNOS was significantly down-regulated (p < 0.001) by WRF. Histological alternations induced by APAP in liver were restored to near normality by WRF pretreatment. CONCLUSION: WRF may exert its hepatoprotective action by alleviating inflammatory and oxido-nitrosative stress via inhibition of TNF-α, IL-1ß, COX-II and iNOS.

Evaluation of the bioavailability of major withanolides of Withania somnifera using an in vitro absorption model system.

Withania somnifera (L.) Dunal, shows several pharmacological properties which are attributed mainly to the withanolides present in the root. The efficacy of medicinally active withanolides constituents depends on the absorption and transportation through the intestinal epithelium. We examined these characteristics by employing the Sino-Veda Madin-Darby canine kidney cells culture system, which under in vitro condition shows the absorption characteristics similar to the human intestinal epithelium. Thus, the aim of the present investigation was to assess the bioavailability of individual withanolides. Withanolides were diluted in Hank's buffered saline at a concentration of 2 µg/ml were tested for permeability studies carried out for 1 h duration. Permeability was measured in terms of efflux pump (P eff) in cm/s. P eff values of withanolide A (WN A), withanone (WNN), 1,2-deoxywithastramonolide (1,2 DWM), withanolide B (WN B), withanoside IV-V (WS IV-V), and withaferin A were 4.05 × 10(-5), 2.06 × 10(-5), 1.97 × 10(-5), 1.80 × 10(-5), 3.19 × 10(-6), 3.03 × 10(-6) and 3.30 × 10(-7) respectively. In conclusion, the nonpolar and low molecular weight compounds (WN A, WNN, 1,2 DWM, and WN B) were highly permeable. As against this, the glycosylated and polar WS IV and WS V showed low permeability. Surprisingly and paradoxically, the highly biologically active withaferin A was completely impermeable, suggesting that further studies possibly using human epithelial colorectal adenocarcinoma (Caco-2) cells may be needed to delineate the absorption characteristics of withanolides, especially withaferin A.

Effect of macronutrient deficiency on withanolides content in the roots of Withania somnifera and its correlationship with molybdenum content.

CONTEXT: The content of withanolides in the roots of Withania somnifera (L.) Dunal (Solanaceae) is important for therapeutic application. Earlier studies have shown that the deficiency of macro- and micronutrients affects the growth of W. somnifera. Therefore, we examined the effect of these deficiencies on the withanolides content of the roots. OBJECTIVE: To examine the effect of molybdenum accretion in nitrogen-, phosphorus-, calcium- and potassium-deficient soils on the accumulation of withanolides in the roots of W. somnifera. Different withanolides have different therapeutic applications hence major bioactive withanolides assume importance. MATERIALS AND METHODS: Methanol extracts of the roots were subjected to HPTLC and individual withanolides were identified by comparing their Rf values with those of the authentic samples. Molybdenum was quantified by atomic absorption spectroscopy. Free radical scavenging activity was monitored by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay. RESULTS: Molybdenum content in roots of nitrogen-, phosphorus-, calcium-, potassium-deficient, and control plants were 7.02 ± 2.1, 13.1 ± 1.6, 17.1 ± 0.9, 33.5 ± 3.3, and 33.9 ± 1.6 ppm, respectively. Levels of withaferine A increased with the increase in the Mo content in roots from 7.79 ± 2.2 mg/g to 12.57 ± 3.4 mg/g. Antioxidant activity of nitrogen-deficient plants was the lowest (24.7 ± 2.2%) compared to other groups. DISCUSSION AND CONCLUSION: It was observed that nitrogen metabolism-dependent molybdenum uptake influences the withanolides accumulation in the roots.