Neophytadiene (NPT) is a diterpene found in the methanolic extracts of Crataeva nurvala and Blumea lacera, plants reported with anxiolytic-like activity, sedative properties, and antidepressant-like actions; however, the contribution of neophytadiene to these effects is unknown. This study determined the neuropharmacological (anxiolytic-like, antidepressant-like, anticonvulsant, and sedative) effects of neophytadiene (0.1–10 mg/kg p.o.) and determined the mechanisms of action involved in the neuropharmacological actions using inhibitors such as flumazenil and analyzing the possible interaction of neophytadiene with GABA receptors using a molecular docking study. The behavioral tests were evaluated using the light–dark box, elevated plus-maze, open field, hole-board, convulsion, tail suspension, pentobarbital-induced sleeping, and rotarod. The results showed that neophytadiene exhibited anxiolytic-like activity only to the high dose (10 mg/kg) in the elevated plus-maze and hole-board tests, and anticonvulsant actions in the 4-aminopyridine and pentylenetetrazole-induced seizures test. The anxiolytic-like and anticonvulsant effects of neophytadiene were abolished with the pre-treatment with 2 mg/kg flumazenil. In addition, neophytadiene showed low antidepressant effects (about 3-fold lower) compared to fluoxetine. On other hand, neophytadiene had no sedative or locomotor effects. In conclusion, neophytadiene exerts anxiolytic-like and anticonvulsant activities with the probable participation of the GABAergic system.

Background/Objectives: The antinociceptive and anti-inflammatory effects of a patent-pending ointment containing plant extracts from Eucalyptus globulus, Curcuma longa, Hamamelis virginiana, Echinacea purpurea, and Zingiber officinale were evaluated. Methods: Plant extracts were chemically characterized by gas chromatography–mass spectroscopy. The antinociceptive activity of the ointment was assessed using the hot plate, tail flick, and formalin tests, whereas the anti-inflammatory activity was measured using the acute and chronic TPA-induced ear edema tests. Mechanisms of action were evaluated using inhibitors from signaling pathways related to pain response and by using histological analysis and assessing the expression and activity of pro-inflammatory mediators. Results: The ointment showed antinociceptive and anti-inflammatory effects like those observed with diclofenac gel (1.16% v/v) and ketoprofen gel (2.5% v/v). The antinociceptive actions of the ointment are mediated by the possible participation of the opiodergic system and the nitric oxide pathway. The anti-inflammatory response was characterized by a decrease in myeloperoxidase (MPO) activity and by a reduction in ear swelling and monocyte infiltration in the acute inflammation model. In the chronic model, the mechanism of action relied on a decrease in pro-inflammatory mediators such as COX-2, IL-1β, TNF-α, and MPO. An in-silico study with myristic acid, one of the compounds identified in the ointment’s plant mixture, corroborated the in vivo results. Conclusions: The ointment showed antinociceptive activities mediated by the decrease in COX-2 and NO levels, and anti-inflammatory activity due to the reduction in IL-1β and TNFα levels, a reduction in MPO activity, and a decrease in NF-κB and COX-2 expression.

Ceiba aesculifolia (Kunth) Britten & Baker f (Malvaceae) is used for the folk treatment of mood disorders. C. aesculifolia bark was extracted in ethanol, and the extract (CAE) was chemically standardized using gas chromatography–mass spectrometry (GC-MS). This study evaluated the effects of CAE (10–100 mg/kg p.o.) on anxiolytic-like activity, sedation, locomotor activity, depression-like activity, and spatial working memory using in vivo rodent models. A possible mechanism for the anxiolytic-like and antidepressant-like actions induced by CAE was assessed using neurotransmission pathway inhibitors. Myristic acid was one of the compounds found in CAE using GC-MS. This study also evaluated the anxiolytic-like activity and the sedative actions of myristic acid and assessed a possible mechanism of action using neurotransmission pathway inhibitors and an in silico analysis. CAE elicited anxiolytic-like activity and antidepressant-like effects (ED₅₀ = 57 mg/kg). CAE (10–100 mg/kg) did not affect locomotor coordination or induce sedation. The anxiolytic-like and antidepressant-like actions of CAE were reverted by prazosin, suggesting a possible participation of the noradrenergic system. The anxiolytic-like activity of myristic acid was reverted by the co-administration of prazosin and partially reverted by ketanserin. The docking study revealed that myristic acid can form favorable interactions within 5-HT2A and α1A-adrenoreceptor binding pockets.

Argemone ochroleuca Sweet (Papaveraceae) is used in folk medicine as a sedative and hypnotic agent. This study aimed to evaluate the anxiolytic-like, sedative, antidepressant-like, and anticonvulsant activities of a dichloromethane extract of A. ochroleuca stems (AOE), chemically standardized using gas chromatography–mass spectrometry (GC–MS), and its active compound dihydrosanguinarine (DHS). The anxiolytic-like, sedative, antidepressant-like, and anticonvulsant activities of the AOE (0.1–50 mg/kg p.o.) and DHS (0.1–10 mg/kg p.o.) were evaluated using murine models. A possible mechanism for the neurological actions induced by the AOE or DHS was assessed using inhibitors of neurotransmission pathways and molecular docking. Effective dose 50 (ED₅₀) values were calculated by a linear regression analysis. The AOE showed anxiolytic-like activity in the cylinder exploratory test (ED₅₀ = 33 mg/kg), and antidepressant-like effects in the forced swimming test (ED₅₀ = 3 mg/kg) and the tail suspension test (ED₅₀ = 23 mg/kg), whereas DHS showed anxiolytic-like activity (ED₅₀ = 2 mg/kg) in the hole board test. The AOE (1–50 mg/kg) showed no locomotive affectations or sedation in mice. A docking study revealed the affinity of DHS for α2-adrenoreceptors and GABA_A receptors. The anxiolytic-like and anticonvulsant effects of the AOE are due to GABAergic participation, whereas the antidepressant-like effects of the AOE are due to the noradrenergic system. The noradrenergic and GABAergic systems are involved in the anxiolytic-like actions of DHS.

Background: Combining antinociceptive drugs with different mechanisms of action can reduce the doses and the adverse effects, with a possible increase in the antinociceptive effect. This work evaluated the antinociceptive effect of the combination of an ethanol extract of Justicia spicigera (JSE) with naproxen (NPX) or tramadol (TML) using the formalin test in rats. Methods: Rats received JSE (30–200 mg/kg p.o.), NPX (50–300 mg/kg p.o.), or TML (5–50 mg/kg p.o.) 60 min before paw administration with formalin (5%). Different proportions of the combination between NPX and JSE, as well as TML and JSE, were used in the formalin test to obtain the dose–response curve of each drug and the experimental effective dose 50 (ED₅₀). The levels of IL-1β and COX2 were assessed using a Western blot analysis as a possible mechanism of action for the combination of JSE and analgesics. A pharmacokinetic study was conducted to evaluate the effect of JSE on the pharmacokinetic parameters of NPX. Results: The ED₅₀ values for the proportions NPX:JSE were 107.09 mg/kg (1:1), 102.44 mg/kg (3:1), and 73.82 mg/kg (1:3). The ED₅₀ values for the proportions TML:JSE were 66 mg/kg (1:1), 29.5 mg/kg (1:3), and 78 mg/kg (3:1). The combination NPX:JSE (1:3) showed the best synergistic interaction index (0.501). The pharmacokinetic study revealed that there were no significant changes in the pharmacokinetic parameters of NPX administered individually and the combination NPX:JSE. Conclusions: In this preclinical study, the combination NPX:JSE showed antinociceptive effects by decreasing the levels of COX2 and IL-1β without affecting NPX’s pharmacokinetics.

Stanhopea tigrina Bateman ex Lindl. (Orchidaceae) is an orchid endemic to Mexico, known as “Calavera” or “calaverita”, in the Huasteca Potosina (central region of Mexico). This plant species is used for the folk treatment of mental disorders and urological kidney disorders, according to the ethnomedicinal information obtained in this study. Ethanolic extracts of leaves (HE) and pseudobulb (PE) were obtained by microwave-assisted extraction (MAE). Gas Chromatography coupled with Mass Spectrometry (GC-MS) was used to carry out the chemical characterization of HE and PE. The pharmacological effects (antioxidant, diuretic, anxiolytic, locomotor, hypnotic, and sedative) of HE and PE were evaluated. The possible mechanism of action of the anxiolytic-like activity induced by HE was assessed using inhibitors of the GABAergic, adrenergic, and serotonergic systems. The possible mechanism of the diuretic action of HE was assessed using prostaglandin inhibitory antagonists and nitric oxide synthase (NOS) blockers. HE at 50 and 100 mg/kg exerted anxiolytic-like activity without inducing hypnosis or sedation. Flumazenil, prazosin, and ketanserin inhibited the anxiolytic-like activity shown by HE, which suggests the participation of GABA, α₁-adrenergic receptors, and 5-HT₂ receptors, respectively. The diuretic effect was reversed by the non-selective NOS inhibitor L-NAME, which caused the reduction in nitric oxide (NO). These results demonstrate that the ethanolic extract of S. tigrina leaves exhibited anxiolytic-like activity and diuretic effects without inducing hypnosis or sedation. This work validates the medicinal uses of this orchid species.