Alkaloids in Withania somnifera (L.) Dunal Root Extract Contribute to Its Anti-Inflammatory Activity.

The anti-inflammatory properties of the medicinal plant Withania somnifera (L.) Dunal (WS) are generally related to withanolides; consistently, several strategies are under investigation to increase the concentration of these compounds in WS extracts. However, a potential toxicity of withanolides has been highlighted, thus questioning the safety of such preparations. At variance, the relative contribution of alkaloids is underrated, in spite of preliminary evidence underlining a possible pharmacological relevance. Starting from these considerations, the efficacy/safety profile of WS root extract (WSE) was compared with those of WS extracts which are enriched in alkaloids (WSA) and withanolides (WSW), respectively. MTT assay was used to evaluate cell viability. The anti-inflammatory activities of the different extracts were estimated throughout the assessment of the inhibition of lipopolysaccharide (LPS)-activated release of nitric oxide (NO) and the upregulation of iNOS and COX-2 protein in RAW 264.7 cells. Both WSA and WSW were able to reduce LPS-mediated effects in RAW 264.7 cells, suggesting that alkaloids and withanolides may contribute to the anti-inflammatory activity of WSE. A significant higher anti-inflammatory activity and a lower toxicity were observed when WSA was compared to WSW. The present results highlighted that the contribution of alkaloids to WS pharmacological effects should not be neglected. Particularly, these compounds may concur to reach a more advantageous efficacy/safety profile when WS is used for anti-inflammatory purposes.

The standardized Withania somnifera Dunal root extract alters basal and morphine-induced opioid receptor gene expression changes in neuroblastoma cells.

BACKGROUND: Behavioral studies demonstrated that the administration of Withania somnifera Dunal roots extract (WSE), prolongs morphine-elicited analgesia and reduces the development of tolerance to the morphine's analgesic effect; however, little is known about the underpinning molecular mechanism(s). In order to shed light on this issue in the present paper we explored whether WSE promotes alterations of µ (MOP) and nociceptin (NOP) opioid receptors gene expression in neuroblastoma SH-SY5Y cells. METHODS: A range of WSE concentrations was preliminarily tested to evaluate their effects on cell viability. Subsequently, the effects of 5 h exposure to WSE (0.25, 0.50 and 1.00 mg/ml), applied alone and in combination with morphine or naloxone, on MOP and NOP mRNA levels were investigated. RESULTS: Data analysis revealed that morphine decreased MOP and NOP receptor gene expression, whereas naloxone elicited their up-regulation. In addition, pre-treatment with naloxone prevented the morphine-elicited gene expression alterations. Interestingly, WSE was able to: a) alter MOP but not NOP gene expression; b) counteract, at its highest concentration, morphine-induced MOP down-regulation, and c) hamper naloxone-induced MOP and NOP up-regulation. CONCLUSION: Present in-vitro data disclose novel evidence about the ability of WSE to influence MOP and NOP opioid receptors gene expression in SH-SY5Y cells. Moreover, our findings suggest that the in-vivo modulation of morphine-mediated analgesia by WSE could be related to the hindering of morphine-elicited opioid receptors down-regulation here observed following WSE pre-treatment at its highest concentration.

Withania somnifera (L.) Dunal root extract alleviates formalin-induced nociception in mice: involvement of the opioidergic system.

Withania somnifera (L.) Dunal extracts (WSEs) may possess therapeutic perspectives in the treatment of inflammation and pain. We aimed to evaluate the antinociceptive property of a WSE in the formalin test and to investigate the involvement of several neurotransmitter systems in this effect. The time spent licking the formalin-injected paw was recorded in CD1 mice after pretreatment with increasing doses of WSE. Also, c-Fos spinal cord expression and the effects of different compounds were investigated under these experimental conditions. Finally, the efficacy of WSE was analyzed following an injection of glutamate. WSE reduced the antinociceptive response during the tonic but not the acute phase of the formalin test and decreased formalin-induced c-Fos expression in spinal neurons. These effects were antagonized by the opioid antagonist naltrexone, whereas GABA, cannabinoid, δ-opioid, and nitric oxide compounds were ineffective. The administration of WSE also reduced nociception and c-Fos expression induced by glutamate injection. These results showed that WSE is effective in assays of chemical-induced nociception, indicating that this plant has potential valuable properties for the treatment of specific painful conditions. The antinocicetive effects of WSE in the formalin test appeared to be specifically mediated by the opioidergic system, although the involvement of the glutamatergic system cannot be excluded.

Withania somnifera root extract prolongs analgesia and suppresses hyperalgesia in mice treated with morphine.

Previous studies demonstrated that Withania somnifera Dunal (WS), a safe medicinal plant, prevents the development of tolerance to the analgesic effect of morphine. In the present study, we investigated whether WS extract (WSE) (100 mg/kg, i.p.) may also modulate the analgesic effect induced by acute morphine administration (2.5, 5, 10 mg/kg, s.c.) in the tail-flick and in the hot plate tests, and if it may prevent the development of 2.5 mg/kg morphine-induced rebound hyperalgesia in the low intensity tail-flick test. Further, to characterize the receptor(s) involved in these effects, we studied, by receptor-binding assay, the affinity of WSE for opioid (µ, δ, k), cannabinoid (CB1, CB2), glutamatergic (NMDA), GABAergic (GABAA, GABAB), serotoninergic (5HT2A) and adrenergic (α2) receptors. The results demonstrated that (i) WSE alone failed to alter basal nociceptive threshold in both tests, (ii) WSE pre-treatment significantly protracted the antinociceptive effect induced by 5 and 10 mg/kg of morphine only in tail-flick test, (iii) WSE pre-treatment prevented morphine-induced hyperalgesia in the low intensity tail-flick test, and (iv) WSE exhibited a high affinity for the GABAA and moderate affinity for GABAB, NMDA and δ opioid receptors. WSE prolongs morphine-induced analgesia and suppresses the development of morphine-induced rebound hyperalgesia probably through involvement of GABAA, GABAB, NMDA and δ opioid receptors. This study suggests the therapeutic potential of WSE as a valuable adjuvant agent in opioid-sparing therapies.

Withania somnifera prevents acquisition and expression of morphine-elicited conditioned place preference.

Previous studies have reported that some of the central effects of morphine are counteracted by the administration of the methanolic extract of the root of Indian ginseng, Withania somnifera Dunal (WSE). The present study sought to determine whether WSE affects acquisition and expression of morphine-elicited conditioned place preference (CPP) in CD-1 mice. In CPP acquisition experiments, WSE (0, 25, 50, and 100 mg/kg) was administered, during conditioning, 30 min before morphine (10 mg/kg), whereas in expression experiments, WSE (0, 25, 50, and 100 mg/kg) was administered 30 min before the postconditioning test. The results demonstrate (i) that WSE was devoid of motivational properties; (ii) that WSE (100 mg/kg) was devoid of effects on spontaneous and morphine-stimulated motor activity and on spatial memory; and (iii) that WSE (50 and 100 mg/kg) significantly prevented the acquisition and expression of CPP. Further, to characterize the receptor(s) involved in these effects, we studied, by receptor-binding assay, the affinity of WSE for µ-opioid and γ-aminobutyric acid B receptors. These experiments revealed a higher affinity of WSE for γ-aminobutyric acid B than for µ-opioid receptors. Overall, these results point to WSE as an interesting alternative tool, worthy of further investigation, to study opiate addiction.

Synthesis and pharmacological evaluation of novel 4-alkyl-5-thien-2'-yl pyrazole carboxamides.

The synthesis of three series of novel 4-alkyl-5-(5'-chlorothiophen-2'-yl)-pyrazole-3-carbamoyl analogues of rimonabant with affinity for the CB1 cannabinoid receptor subtype is reported. Amongst the novel derivatives, compounds 21j, 22a, 22c, and 22f showed affinity values expressed as Ki ranging from 5.5 to 9.0 nM. Derivative 23e revealed a good CB1 affinity (K(i) = 11.7 nM) and the highest CB1 selectivity of the whole series (K(i)CB2/K(i)CB1 = 384.6). These new compounds appeared to be able to pass the blood brain barrier and to counteract the activity of cannabinoid agonist. According to the results of mice vas deferens assays, as in the case of rimonabant, derivatives 21a, 22a, and 22b showed inverse agonist activity. In contrast, as a preliminary result to be confirmed, compound 23a exhibited neutral antagonist profile. According to the data obtained through an acute animal model, selected compounds 21a, 22a, and 23a evidenced the capability to significantly reduce food intake. At specific conditions, the effect of the novel compounds were higher than that induced by rimonabant. Amongst the novel CB1 antagonist compounds, 23a may represent a useful candidate agent for the treatment of obesity and its metabolic complications, with reduced side effects relative to those instead observed with rimonabant.

Synthesis and biological evaluation of 1,8-naphthyridin-4(1H)-on-3-carboxamide derivatives as new ligands of cannabinoid receptors.

Cannabinoid receptors have been studied extensively in view of their potential functional role in several physiological and pathological processes. For this reason, the search for new potent, selective ligands for subtype CB receptors, CB(1) and CB(2), is still of great importance, in order to investigate their role in various physiological functions. The present study describes the synthesis and the biological properties of a series of 1,8-naphthyridine derivatives, characterised by the presence of some important structural requirements exhibited by other classes of cannabinoid ligands, such as an aliphatic or aromatic carboxamide group in position 3, and an alkyl or arylalkyl substituent in position 1. These compounds were assayed for binding both to the brain and to peripheral cannabinoid receptors (CB(1) and CB(2)). The results obtained indicate that the naphthyridine derivatives examined possess a greater affinity for the CB(2) receptor than for the CB(1) receptor. In particular, derivatives 6a and 7a possess an appreciable affinity for the CB(2) receptor, with K(i) values of 5.5 and 8.0 nM respectively; also compounds 4a, 5a and 8a exhibit a good CB(2) affinity, with K(i) values in the range of 10-44 nM. Furthermore, compounds 3g-i and 18 revealed a good CB(2) selectivity, with a CB(1)/CB(2) ratio >20.