Valerenic acid

Role of 5-HT5A and 5-HT1B/1D receptors in the antinociception produced by ergotamine and valerenic acid in the rat formalin test.[Pubmed:27068146]

Eur J Pharmacol. 2016 Jun 15;781:109-16.

Sumatriptan, dihydroergotamine and methysergide inhibit 1% formalin-induced nociception by activation of peripheral 5-HT1B/1D receptors. This study set out to investigate the pharmacological profile of the antinociception produced by intrathecal and intraplantar administration of ergotamine (a 5-HT1B/1D and 5-HT5A/5B receptor agonist) and Valerenic acid (a partial agonist at 5-HT5A receptors). Intraplantar injection of 1% formalin in the right hind paw resulted in spontaneous flinching behavior of the injected hindpaw of female Wistar rats. Intrathecal ergotamine (15nmol) or Valerenic acid (1 nmol) blocked in a dose dependent manner formalin-induced nociception. The antinociception by intrathecal ergotamine (15nmol) or Valerenic acid (1nmol) was partly or completely blocked by intrathecal administration of the antagonists: (i) methiothepin (non-selective 5-HT5A/5B; 0.01-0.1nmol); (ii) SB-699551 (selective 5-HT5A; up to 10nmol); (iii) anti-5-HT5A antibody; (iv) SB-224289 (selective 5-HT1B; 0.1-1nmol); or (v) BRL-15572 (selective 5-HT1D; 0.1-1nmol). Likewise, antinociception by intraplantar ergotamine (15nmol) and Valerenic acid (10nmol) was: (i) partially blocked by methiothepin (1nmol), SB-699551 (10nmol) or SB-224289 (1nmol); and (ii) abolished by BRL-15572 (1nmol). The above doses of antagonists (which did not affect per se the formalin-induced nociception) were high enough to completely block their respective receptors. Our results suggest that ergotamine and Valerenic acid produce antinociception via 5-HT5A and 5-HT1B/1D receptors located at both spinal and peripheral sites. This provides new evidence for understanding the modulation of nociceptive pathways in inflammatory pain.

Identification of the putative binding pocket of valerenic acid on GABAA receptors using docking studies and site-directed mutagenesis.[Pubmed:26375408]

Br J Pharmacol. 2015 Nov;172(22):5403-13.

BACKGROUND AND PURPOSE: beta2/3-subunit-selective modulation of GABAA receptors by Valerenic acid (VA) is determined by the presence of transmembrane residue beta2/3N265. Currently, it is not known whether beta2/3N265 is part of VA's binding pocket or is involved in the transduction pathway of VA's action. The aim of this study was to clarify the localization of VA's binding pocket on GABAA receptors. EXPERIMENTAL APPROACH: Docking and a structure-based three-dimensional pharmacophore were employed to identify candidate amino acid residues that are likely to interact with VA. Selected amino acid residues were mutated, and VA-induced modulation of the resulting GABAA receptors expressed in Xenopus oocytes was analysed. KEY RESULTS: A binding pocket for VA at the beta(+) /alpha(-) interface encompassing amino acid beta3N265 was predicted. Mutational analysis of suggested amino acid residues revealed a complete loss of VA's activity on beta3M286W channels as well as significantly decreased efficacy and potency of VA on beta3N265S and beta3F289S receptors. In addition, reduced efficacy of VA-induced IGABA enhancement was also observed for alpha1M235W, beta3R269A and beta3M286A constructs. CONCLUSIONS AND IMPLICATIONS: Our data suggest that amino acid residues beta3N265, beta3F289, beta3M286, beta3R269 in the beta3 subunit, at or near the etomidate/propofol binding site(s), form part of a VA binding pocket. The identification of the binding pocket for VA is essential for elucidating its pharmacological effects and might also help to develop new selective GABAA receptor ligands.

Analysis of beta-Subunit-dependent GABAA Receptor Modulation and Behavioral Effects of Valerenic Acid Derivatives.[Pubmed:27190170]

J Pharmacol Exp Ther. 2016 Jun;357(3):580-90.

Valerenic acid (VA)-a beta2/3-selective GABA type A (GABAA) receptor modulator-displays anxiolytic and anticonvulsive effects in mice devoid of sedation, making VA an interesting drug candidate. Here we analyzed beta-subunit-dependent enhancement of GABA-induced chloride currents (IGABA) by a library of VA derivatives and studied their effects on pentylenetetrazole (PTZ)-induced seizure threshold and locomotion. Compound-induced IGABA enhancement was determined in oocytes expressing alpha1beta1gamma2S, alpha1beta2gamma2S, or alpha1beta3gamma2S receptors. Effects on seizure threshold and locomotion were studied using C57BL/6N mice and compared with saline-treated controls. beta2/3-selective VA derivatives such as VA-amide (VA-A) modulating alpha1beta3gamma2S (VA-A: Emax = 972 +/- 69%, n = 6, P < 0.05) and alpha1beta2gamma2S receptors (Emax = 1119 +/- 72%, n = 6, P < 0.05) more efficaciously than VA (alpha1beta3gamma2S: VA: Emax = 632 +/- 88%, n = 9 versus alpha1beta2gamma2S: VA: Emax = 721 +/- 68%, n = 6) displayed significantly more pronounced seizure threshold elevation than VA (saline control: 40.4 +/- 1.4 mg/kg PTZ versus VA 10 mg/kg: 49.0 +/- 1.8 mg/kg PTZ versus VA-A 3 mg/kg: 57.9 +/- 1.9 mg/kg PTZ, P < 0.05). Similarly, VA's methylamide (VA-MA) enhancing IGABA through beta3-containing receptors more efficaciously than VA (Emax = 1043 +/- 57%, P < 0.01, n = 6) displayed stronger anticonvulsive effects. Increased potency of IGABA enhancement and anticonvulsive effects at lower doses compared with VA were observed for VA-tetrazole (alpha1beta3gamma2S: VA-TET: EC50 = 6.0 +/- 1.0 muM, P < 0.05; VA-TET: 0.3 mg/kg: 47.3 +/- 0.5 mg/kg PTZ versus VA: 10 mg/kg: 49.0 +/- 1.8 mg/kg PTZ, P < 0.05). At higher doses (>/=10 mg/kg), VA-A, VA-MA, and VA-TET reduced locomotion. In contrast, unselective VA derivatives induced anticonvulsive effects only at high doses (30 mg/kg) or did not display any behavioral effects. Our data indicate that the beta2/3-selective compounds VA-A, VA-MA, and VA-TET induce anticonvulsive effects at low doses (/=10 mg/kg.

Impact of Altitudes and Habitats on Valerenic Acid, Total Phenolics, Flavonoids, Tannins, and Antioxidant Activity of Valeriana jatamansi.[Pubmed:26971960]

Appl Biochem Biotechnol. 2016 Jul;179(6):911-26.

The changes in total phenolics, flavonoids, tannins, Valerenic acid, and antioxidant activity were assessed in 25 populations of Valeriana jatamansi sampled from 1200 to 2775 m asl and four habitat types of Uttarakhand, West Himalaya. Significant (p < 0.05) variations in total phenolics, flavonoids, Valerenic acid, and antioxidant activity in aerial and root portions and across the populations were observed. Antioxidant activity measured by three in vitro antioxidant assays, i.e., 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic) (ABTS) radical scavenging, 2,2'-diphenyl-1-picryylhydrazyl (DPPH) free radical scavenging, and ferric-reducing antioxidant power (FRAP) assays, showed significant (p < 0.05) differences across the populations. However, no clear pattern was found in phytochemicals across the altitudinal range. Among habitat types, (pine, oak, mixed forest, and grassy land), variation in phytochemical content and antioxidant activity were observed. Equal class ranking, neighbor-joining cluster analysis, and principal component analysis (PCA) identified Talwari, Jaberkhet, Manjkhali, and Khirshu populations as promising sources with higher phytochemicals and antioxidant activity. The results recommended that the identified populations with higher value of phytochemicals and antioxidants can be utilized for mass multiplication and breeding program to meet the domestic as well as commercial demand.