Antinociceptive and Anti-Inflammatory Activities of Acetonic Extract from Bougainvillea x buttiana (var. Rose).

Background:Bougainvillea x buttiana is an ornamental plant with antioxidant, anti-inflammatory, and cytotoxic activities, which has been traditionally used to treat respiratory diseases. This study aimed to investigate whether the acetonic extract of Bougainvillea x buttiana var. Rose (BxbRAE-100%) has analgesic and anti-inflammatory properties and its potential action mechanisms. Methods: Analgesic and anti-inflammatory activities were evaluated using three murine pain models and two acute inflammation models. In vitro, the ability of the extract to inhibit proteolytic activity and the activities of the enzymes phospholipase A2 (PLA2) and cyclooxygenase (COX) were evaluated. In silico analysis was performed to predict the physicochemical and Absorption, distribution, metabolism, and excretion (ADME) profiles of the compounds previously identified in BxbRAE-100%. Results: In vivo BxbRAE-100% decreased the nociceptive behaviors in the writhing model, the tail immersion, and the formalin test, suggesting that the extract has the potential to relieve pain at peripheral and central levels. Additionally, topical or oral BxbRAE-100% treatment reduced dose-dependent 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced ear inflammation and carrageenan-induced paw edema, respectively. In vitro, BxbRAE-100% significantly inhibited proteolytic activity and PLA2, COX-1 and COX-2 activities. In silico, the compounds previously identified in BxbRAE-100% met Lipinski's rule of five and showed adequate ADME properties. Conclusions: These results support the use of B. x buttiana in Traditional Mexican Medicine and highlight its potential for the development of new treatments for pain and inflammation.

Nociplastic pain mechanisms and toll-like receptors as promising targets for its management.

ABSTRACT: Nociplastic pain, characterized by abnormal pain processing without an identifiable organic cause, affects a significant portion of the global population. Unfortunately, current pharmacological treatments for this condition often prove ineffective, prompting the need to explore new potential targets for inducing analgesic effects in patients with nociplastic pain. In this context, toll-like receptors (TLRs), known for their role in the immune response to infections, represent promising opportunities for pharmacological intervention because they play a relevant role in both the development and maintenance of pain. Although TLRs have been extensively studied in neuropathic and inflammatory pain, their specific contributions to nociplastic pain remain less clear, demanding further investigation. This review consolidates current evidence on the connection between TLRs and nociplastic pain, with a specific focus on prevalent conditions like fibromyalgia, stress-induced pain, sleep deprivation-related pain, and irritable bowel syndrome. In addition, we explore the association between nociplastic pain and psychiatric comorbidities, proposing that modulating TLRs can potentially alleviate both pain syndromes and related psychiatric disorders. Finally, we discuss the potential sex differences in TLR signaling, considering the higher prevalence of nociplastic pain among women. Altogether, this review aims to shed light on nociplastic pain, its underlying mechanisms, and its intriguing relationship with TLR signaling pathways, ultimately framing the potential therapeutic role of TLRs in addressing this challenging condition.

Spinal alarmin HMGB1 and the activation of TLR4 lead to chronic stress-induced nociceptive hypersensitivity in rodents.

Chronic stress affects millions of people around the world, and it can trigger different behavioral disorders like nociceptive hypersensitivity and anxiety, among others. However, the mechanisms underlaying these chronic stress-induced behavioral disorders have not been yet elucidated. This study was designed to understand the role of high-mobility group box-1 (HMGB1) and toll-like receptor 4 (TLR4) in chronic stress-induced nociceptive hypersensitivity. Chronic restraint stress induced bilateral tactile allodynia, anxiety-like behaviors, phosphorylation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38MAPK) and activation of spinal microglia. Moreover, chronic stress enhanced HMGB1 and TLR4 protein expression at the dorsal root ganglion, but not at the spinal cord. Intrathecal injection of HMGB1 or TLR4 antagonists reduced tactile allodynia and anxiety-like behaviors induced by chronic stress. Additionally, deletion of TLR4 diminished the establishment of chronic stress-induced tactile allodynia in male and female mice. Lastly, the antiallodynic effect of HMGB1 and TLR4 antagonists were similar in stressed male and female rats and mice. Our results suggest that chronic restraint stress induces nociceptive hypersensitivity, anxiety-like behaviors, and up-regulation of spinal HMGB1 and TLR4 expression. Blockade of HMGB1 and TLR4 reverses chronic restraint stress-induced nociceptive hypersensitivity and anxiety-like behaviors and restores altered HMGB1 and TLR4 expression. The antiallodynic effects of HMGB1 and TLR4 blockers in this model are sex independent. TLR4 could be a potential pharmacological target for the treatment of the nociceptive hypersensitivity associated with widespread chronic pain.

Effect of chronic lithium on mechanical sensitivity and trabecular bone loss induced by type-1 diabetes mellitus in mice.

Type-1 diabetes mellitus (T1DM) is a chronic condition characterized by long-term hyperglycemia that results in several complications such as painful peripheral neuropathy, bone deterioration, and increased risk of bone fractures. Lithium, a first-line therapy for bipolar disorder, has become an attractive agent for attenuating peripheral neuropathy and menopause-induced bone loss. Therefore, our aim was to determine the effect of chronic lithium treatment on mechanical hypersensitivity and trabecular bone loss induced by T1DM in mice. T1DM was induced in male C57BL/6J mice by intraperitoneal injection of streptozotocin (STZ, 50 mg/kg/day, for 5 consecutive days). 12 weeks after T1DM-induction, mice received a daily intraperitoneal injection of vehicle, 30 or 60 mg/kg lithium (as LiCl) for 6 weeks. Throughout the treatment period, blood glucose levels and mechanical sensitivity were evaluated every 2 weeks. After lithium treatment, the femur and L5 vertebra were harvested for microcomputed tomography (microCT) analysis. T1DM mice showed significant hyperglycemia, mechanical hypersensitivity, and significant trabecular bone loss as compared with the control group. Chronic lithium treatment did not revert the hindpaw mechanical hypersensitivity nor hyperglycemia associated to T1DM induced by STZ. In contrast, microCT analysis revealed that lithium reverted, in a dose-dependent manner, the loss of trabecular bone associated to T1DM induced by STZ at both the distal femur and L5 vertebra. Lithium treatment by itself did not affect any trabecular bone parameter in non-diabetic mice.

In Vivo Anti-Inflammatory Effect, Antioxidant Activity, and Polyphenolic Content of Extracts from Capsicum chinense By-Products.

By-products of Capsicum chinense Jacq., var Jaguar could be a source of bioactive compounds. Therefore, we evaluated the anti-inflammatory effect, antioxidant activity, and their relationship with the polyphenol content of extracts of habanero pepper by-products obtained from plants grown on black or red soils of Yucatán, Mexico. Moreover, the impact of the type of extraction on their activities was evaluated. The dry by-product extracts were obtained by maceration (ME), Soxhlet (SOX), and supercritical fluid extraction (SFE). Afterward, the in vivo anti-inflammatory effect (TPA-induced ear inflammation) and the in vitro antioxidant activity (ABTS) were evaluated. Finally, the polyphenolic content was quantified by Ultra-Performance Liquid Chromatography (UPLC), and its correlation with both bioactivities was analyzed. The results showed that the SFE extract of stems of plants grown on red soil yielded the highest anti-inflammatory effect (66.1 ± 3.1%), while the extracts obtained by ME and SOX had the highest antioxidant activity (2.80 ± 0.0052 mM Trolox equivalent) and polyphenol content (3280 ± 15.59 mg·100 g-1 dry basis), respectively. A negative correlation between the anti-inflammatory effect, the antioxidant activity, and the polyphenolic content was found. Overall, the present study proposed C. chinense by-products as a valuable source of compounds with anti-inflammatory effect and antioxidant activity.

Characterization of pain-related behaviors, changes in bone microarchitecture and sensory innervation induced by chronic cadmium exposure in adult mice.

Because of the relative lack of understanding of the neurobiological mechanisms that drive toxic effects of cadmium in bone, the purpose of this study was to characterize a preclinical model of chronic cadmium exposure. Adult male C57BL/6 J mice were exposed to cadmium 25 mg/L (as CdCl2) in drinking water for 16 weeks. During this time, pain-related behaviors including hindpaw mechanical sensitivity and vertical rears were evaluated every four weeks. We assessed changes in bone microarchitecture at the femoral neck and L5 vertebra by microcomputed tomography and quantified the density of nerve fibers expressing PGP 9.5 (a pan-neuronal marker) and CGRP (a marker of sensory nerve fibers subfamily) at the femoral neck and glabrous skin of the hindpaw using immunohistochemistry. Cadmium exposure produced mechanical hypersensitivity in both hindpaws along with decreased rearing activity (surrogate for musculoskeletal-related pain) without affecting the horizontal activity (a measure of locomotor behavior) in comparison to the control group. Intraperitoneal acute treatment with morphine and gabapentin reversed pain-related behaviors in cadmium-exposed mice. Furthermore, exposure to cadmium resulted in significant trabecular bone deterioration at the femoral neck and L5 vertebra. We also observed a significant reduction in the density of both CGRP+ and PGP 9.5+ nerve fibers in the femoral neck, but not in the hindpaw glabrous skin, suggesting tissue-dependent neurotoxicity. This model may help in developing a mechanism-based understanding of the factors that generate and maintain musculoskeletal pain and bone loss caused by chronic cadmium exposure and in translating these findings into new therapies for treating cadmium-induced bone toxicity.

Characterization of Mechanical Allodynia and Skin Innervation in a Mouse Model of Type-2 Diabetes Induced by Cafeteria-Style Diet and Low-Doses of Streptozotocin.

Background: Painful distal symmetrical polyneuropathy (DPN) is a frequent complication of type-2 diabetes mellitus (T2DM) that commonly presents as neuropathic pain and loss of skin nerve fibers. However, there are limited therapies to effectively treat DPN and many of the current animal models of T2DM-induced DPN do not appear to mirror the human disease. Thus, we validated a DPN mouse model induced by a cafeteria-style diet plus low-doses of streptozotocin (STZ). Methods: Female C57BL/6J mice were fed either standard (STD) diet or obesogenic cafeteria (CAF) diet for 32 weeks, starting at 8 weeks old. Eight weeks after starting diets, CAF or STD mice received either four low-doses of STZ or vehicle. Changes in body weight, blood glucose and insulin levels, as well as oral glucose- and insulin-tolerance tests (OGTT and ITT) were determined. The development of mechanical hypersensitivity of the hindpaws was determined using von Frey filaments. Moreover, the effect of the most common neuropathic pain drugs was evaluated on T2DM-induced mechanical allodynia. Finally, the density of PGP -9.5+ (a pan-neuronal marker) axons in the epidermis from the hindpaw glabrous skin was quantified. Results: At 22-24 weeks after STZ injections, CAF + STZ mice had significantly higher glucose and insulin levels compared to CAF + VEH, STD + STZ, and STD + VEH mice, and developed glucose tolerance and insulin resistance. Skin mechanical sensitivity was detected as early as 12 weeks post-STZ injections and it was significantly attenuated by intraperitoneal acute treatment with amitriptyline, gabapentin, tramadol, duloxetine, or carbamazepine but not by diclofenac. The density of PGP-9.5+ nerve fibers was reduced in CAF + STZ mice compared to other groups. Conclusion: This reverse translational study provides a painful DPN mouse model which may help in developing a better understanding of the factors that generate and maintain neuropathic pain and denervation of skin under T2DM and to identify mechanism-based new treatments.

000Synthesis of new α-aminophosphonates: Evaluation as anti-inflammatory agents and QSAR studies.

In this paper, we report the synthesis of a new series of α-aminophosphonates derivatives based in an efficient three-component reaction. All compounds prepared showed significant anti-inflammatory activity, being the compounds 1a, 1c, 1d, 1f, 2b and 2c the most promising ones, in terms of maximal efficacy (over 95%), potency (ED50 range between 0.7 and 10.1 mg/ear) and relative potency (range from 0.04 to 0.67). Compounds 1a, 1c, 1d and 1f significantly decrease the number of neutrophils (range from 46.7 to 63.0%) and monocytes (18.9-34.1%) in blood samples from the orbital sinus. Additionally, QSAR model revealed that the spherical molecular shape and the location of the HOMO on the phenyl ring improves the anti-inflammatory activity of the compounds. The values of R2, Q2, s and F statistical parameters and the QUIK, asymptotic Q2 and Overfitting rules validate the descriptive and predictive ability of the QSAR model. Altogether these results suggest that these new α-aminophosphonates are potential agents for the treatment of inflammation.

Protein hydrolysates and ultrafiltered < 1 KDa fractions from Phaseolus lunatus, Phaseolus vulgaris and Mucuna pruriens exhibit antihyperglycemic activity, intestinal glucose absorption and α-glucosidase inhibition with no acute toxicity in rodents.

BACKGROUND: Protein hydrolysates from food plants, such as legumes, have emerged as a new alternative to treat hyperglycemia, an important risk factor contributing to the development of type 2 diabetes mellitus (T2DM) and its complications. The aim of this work was to assess the antihyperglycemic activity and inhibition of α-glucosidase, and intestinal glucose absorption, and acute toxicity of total hydrolysates and < 1 kDa fractions from Phaseolus lunatus L., Phaseolus vulgaris L., and Mucuna pruriens (L.) DC., obtained by hydrolysis with Alcalase®-Flavourzyme® or pepsine-pancreatin enzymatic systems. RESULTS: In vivo results showed that three of six total hydrolysates and four of six < 1 kDa fractions suppressed starch-induced postprandial hyperglycemia (ED50 range between 1.4 and 93 mg kg-1 ). In vitro, total hydrolysates and fractions, particularly from M. pruriens, inhibited carbohydrate intestinal absorption (from 19.2 to 40%), and α-glucosidase activity (IC50 from 0.86 to 75 mg mL-1 ). Finally, none of the hydrolysates and fractions tested did not show any signs of toxicity (LD50 > 5000 mg kg-1 ). CONCLUSION: These results suggest that hydrolysates and < 1 kDa fractions from P. lunatus, P. vulgaris and M. pruriens are suitable candidates to treat or prevent T2DM. © 2018 Society of Chemical Industry.

Acute Hypoglycemic and Antidiabetic Effect of Teuhetenone A Isolated from Turnera diffusa.

Diabetes mellitus is a chronic degenerative disease that causes long-term complications and represents a serious public health problem. Turnera diffusa (damiana) is a shrub that grows throughout Mexico and is traditionally used for many illnesses including diabetes. Although a large number of plant metabolites are known, there are no reports indicating which of these are responsible for this activity, and this identification was the objective of the present work. Through bioassay-guided fractionation of a methanolic extract obtained from the aerial part of T. diffusa, teuhetenone A was isolated and identified as the main metabolite responsible for the plant's hypoglycemic activity. Alpha-glucosidase inhibitory activity and cytotoxicity of this metabolite were determined. Hypoglycemic and antidiabetic activities were evaluated in a murine model of diabetes in vivo, by monitoring glucose levels for six hours and comparing them with levels after administering various controls. Teuhetenone A was not cytotoxic at the tested concentrations, and did not show inhibitory activity in the glucosidase test, and the in vivo assays showed a gradual reduction in glucose levels in normoglycemic and diabetic mice. Considering these results, we suggest that teuhetenone A has potential as an antidiabetic compound, which could be further submitted to preclinical assays.