12-(S)-Hydroxyeicosatetraenoic Acid and GPR31 Signaling in Spinal Cord in Neuropathic Pain.

Neuropathic pain is a pressing unmet medical need requiring novel nonopioid-based therapeutic approaches. Using unbiased transcriptomic analysis, we found that the expression of Gpr31, a G protein-coupled receptor, increased in the dorsal horn of the spinal cord in rats with traumatic nerve injury-induced neuropathic pain. Daily intrathecal injections of siGpr31 reversed behavioral hypersensitivities in a time-dependent manner. GPR31, a Gα i protein-coupled receptor, has recently been cloned and is a receptor for 12-(S)-hydroxyeicosatetraenoic acid [12-(S)-HETE]. The lack of commercially available GPR31 antagonists has hampered the understanding of this receptor in pathophysiological states, including pain. To investigate this, our first approach was to identify novel GPR31 antagonists. Using a multidisciplinary approach, including in silico modeling, we identified the first highly potent and selective small-molecule GPR31 antagonist, SAH2. Here, we characterize the pharmacological activity in well-described models of neuropathic pain in rodents and provide evidence that 12-(S)-HETE/GPR31-dependent behavioral hypersensitivities are mediated through mitogen-activated protein kinase (MAPK) activation in the spinal cord. Our studies provide the pharmacological rationale for investigating contributions of GPR31 along the pain neuroaxis and the development of nonopioid GPR31-targeted strategies. SIGNIFICANCE STATEMENT: We have identified the first highly selective GPR31 antagonist. Using this antagonist, we have demonstrated that GPR31 signaling in the spinal cord is pronociceptive and MAPK pathways provided signaling mechanisms downstream of GPR31 activation in these processes.

Antioxidant activities of peptide hydrolysates obtained from the seeds of Treculia africana Decne (African breadfruit).

Protein hydrolysates usually possess higher nutritive value than an equivalent mixture of free amino acids. This study was aimed at determining the antioxidant activities of protein hydrolysates of Treculia africana seeds. Soluble protein was isolated from Treculia africana seed flour by alkaline solubilization and acid precipitation, and further hydrolyzed with three proteases (trypsin, pancreatin and pepsin) individually and in a sequential two- and three-protease systems. Antioxidant activities (DPPH, FRAP and lipid peroxidation) of the hydrolysates were investigated. Hydrolysates from Treculia africana seed protein showed varying degree of hydrolysis, pancreatin hydrolysates had the highest (94.92%) and pancreatin-pepsin hydrolysates had the least (6.59%). Pancreatin proved to be the most efficient protease for hydrolyzing Treculia africana protein with a high protein recovery of 156.06 mg/ml. Its hydrolysates exhibited the highest DPPH scavenging activity (71.02%) and had a high radical-mediated peroxidation of oleic acid. Likewise, pancreatin hydrolysates as well as trypsin-pancreatin hydrolysates showed the highest FRAP activity (37.17 and 38.52 µg/ml BHA, respectively). Pancreatin hydrolysates showed significant higher (p < 0.05) antioxidant potentials than other hydrolysates of T. africana seed protein. These findings showed the potential use of Treculia africana hydrolysates as antioxidants in reducing food spoilage and management of oxidative stress-related metabolic disorders.

Curcumin improves episodic memory in cadmium induced memory impairment through inhibition of acetylcholinesterase and adenosine deaminase activities in a rat model.

Curcumin, the main polyphenolic component of turmeric (Curcuma longa) rhizomes has been reported to exert cognitive enhancing potential with limited scientific basis. Hence, this study sought to evaluate the effect of curcumin on cerebral cortex acetylcholinesterase (AChE) and adenosine deaminase (ADA) activities in cadmium (Cd)-induced memory impairment in rats. Animals were divided into six groups (n = 6): saline/vehicle, saline/curcumin 12.5 mg/kg, saline/curcumin 25 mg/kg, Cd/vehicle, Cd/curcumin 12.5 mg/kg, and Cd/curcumin 25 mg/kg. Rats received Cd (2.5 mg/kg) and curcumin (12.5 and 25 mg/kg, respectively) by gavage for 7 days. The results of this study revealed that cerebral cortex AChE and ADA activities were increased in Cd-poisoned rats, and curcumin co-treatment reversed these activities to the control levels. Furthermore, Cd intoxication increased the level of lipid peroxidation in cerebral cortex with a concomitant decreased in functional sulfuhydryl (-SH) group and nitric oxide (NO), a potent neurotransmitter and neuromodulatory agent. However, the co-treatment with curcumin at 12.5 and 25 mg/kg, respectively increased the non-enzymatic antioxidant status and NO in cerebral cortex with a decreased in malondialdehyde (MDA) level. Therefore, inhibition of AChE and ADA activities as well as increased antioxidant status by curcumin in Cd-induced memory dysfunction could suggest some possible mechanism of action for their cognitive enhancing properties.

Effect of Cadmium Stress on Non-enzymatic Antioxidant and Nitric Oxide Levels in Two Varieties of Maize (Zea mays).

Cadmium (Cd) is one of the most toxic heavy metals that inhibit physiological processes of plants. Hence, the present study sought to investigate the effect of cadmium-contaminated seeds from two varieties of maize (Zea mays) on non-enzymatic antioxidant and nitric oxide levels. Seeds of yellow and white maize were exposed to different concentrations of Cd (0, 1, 3 and 5 ppm) for two weeks. The results from this study revealed that both varieties of maize bio-accumulate Cd in leaves in a dose-dependent manner. In addition, Cd exposure caused a significant (p < 0.05) decrease in total phenolic, GSH and nitric oxide (NO) levels at the highest concentration tested when compared with control. Therefore, the observed decrease in NO and endogenous antioxidant status by Cd treatment in maize plants could suggest some possible mechanism of action for Cd-induced oxidative stress and counteracting effect of the plants against Cd toxicity.

In vitro antioxidant and enzyme inhibitory properties of the n-butanol fraction of Senna podocarpa (Guill. and Perr.) leaf.

Background This study evaluates the antioxidant activity and enzyme inhibitory properties of the n-butanol fraction of Senna podocarpa leaves on α-amylase, α-glucosidase, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, arginase, phosphodiesterase 5 (PDE-5), and angiotensin converting enzyme (ACE). Methods The total phenol and flavonoids, iron (Fe) chelation, and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radical scavenging were used to determine the antioxidant activity, and the inhibitory activities of α-glucosidase, α-amylase, AChE, BChE, tyrosinase, arginase, PDE-5 and ACE were also assessed. Results The n-butanol fraction of S. podocarpa shows high total phenol and total flavonoid contents. The n-butanol fraction of S. podocarpa leaves also chelates Fe2+ and ABTS radicals. The n-butanol fraction of S. podocarpa leaves also inhibited α-glucosidase, α-amylase, AChE, BChE, tyrosinase, arginase, PDE-5, and ACE at the concentration tested. Chromatographic analysis displayed the presence of ß-elemene, phytol and caryophyllene oxide chrysophanol, 3-oxo-methyl ester, α-humulene, ß-caryophyllene, rhein, emodin, and α-copaene. Conclusions Hence, the n-butanol fraction of S. podocarpa leaves demonstrates encouraging feat in controlling and/or managing cognitive dysfunction such as Alzheimer's disease and also hypertension, diabetes, erectile dysfunction, endothelial dysfunction, and hyperpigmentation.

Nephroprotective Effect of Essential Oils from Ginger (Zingiber officinale) and Turmeric (Curcuma longa) Rhizomes against Cadmium-induced Nephrotoxicity in Rats.

Several studies have shown that cadmium (Cd) induces nephrotoxicity and many plant foods phytochemicals have been found useful but their possible mechanism of action still remains unexplored. Hence, this study aimed to investigate the nephroprotective effect of essential oils from Nigeria ginger and turmeric rhizomes in cadmium-treated rats by examining their effect on renal function biomarkers (creatinine, urea and BUN), inflammatory cytokines (IL-6, IL-10 and TNF-Alpha) and renal adenosine deaminase (ADA) activity. The result revealed that essential oils from ginger and turmeric rhizomes exert anti-inflammatory effect by preventing alterations of renal function markers and cytokines (IL-6, IL-10 and TNF-Alpha) levels in Cd-treated rats. In addition, the essential oils inhibited renal ADA activity in Cdtreated rats. In conclusion, inhibition of ADA activity and modulation of inflammatory cytokines could be suggested as the possible mechanism of action by which essential oils from ginger and turmeric rhizomes exert their nephroprotective activities.

Aqueous extract of Carica papaya Linn. roots potentially attenuates arsenic induced biochemical and genotoxic effects in Wistar rats.

In Africa, the fruit, leaf, seed and roots of Carica papaya Linn. are generally used to treat a variety of diseases such as malaria, cancer, and cardiovascular diseases. In this study, we evaluated the protective potentials of aqueous extract of C. papaya roots on arsenic-induced biochemical and genotoxic effects in Wistar rats. Rats were induced intraperitoneal with sodium arsenate (dissolved in distilled water at 3 mg/kg body weight) for 21 days and the animals were administered simultaneously with 200 mg/kg body weight vitamin C, 100 and 150 mg/kg body weight of the C. papaya Linn. root aqueous extract once daily for three weeks. Results obtained reveals that activities of plasma 8-OHdG, serum lipids concentration, atherogenic index (AI), coronary artery index (CRI), aspartate transaminase, alanine transaminase, alkaline phosphatase, total bilirubin levels were elevated significantly (p < 0.05) and catalase, glutathione peroxidase, superoxide dismutase, plasma hematological profile were progressively reduced (p < 0.05) in arsenic-alone exposed rats. Significant increase in the quantity of chromosomal aberrations (CA), micronuclei (MN) frequency, oxidative damages in the bone marrow cells from arsenic alone rats was observed. Though, mitotic index scores in these cells were progressively reduced (p < 0.05). In animals administered with aqueous extract of C. papaya roots and vitamin C, the altered parameters were significantly recovered towards the levels observed in normal control rats. These results suggest that aqueous C. papaya roots preparations might have therapeutic potential as a supplement that can be applied in arsenic poisoning.

Curcumin inhibits adenosine deaminase and arginase activities in cadmium-induced renal toxicity in rat kidney.

In this study, the effect of enzymes involved in degradation of renal adenosine and l-arginine was investigated in rats exposed to cadmium (Cd) and treated with curcumin, the principal active phytochemical in turmeric rhizome. Animals were divided into six groups (n = 6): saline/vehicle, saline/curcumin 12.5 mg/kg, saline/curcumin 25 mg/kg, Cd/vehicle, Cd/curcumin 12.5 mg/kg, and Cd/curcumin 25 mg/kg. The results of this study revealed that the activities of renal adenosine deaminase and arginase were significantly increased in Cd-treated rats when compared with the control (p < 0.05). However, co-treatment with curcumin inhibits the activities of these enzymes compared with Cd-treated rats. Furthermore, Cd intoxication increased the levels of some renal biomarkers (serum urea, creatinine, and electrolytes) and malondialdehyde level with a concomitant decrease in functional sulfhydryl group and nitric oxide (NO). However, co-treatment with curcumin at 12.5 mg/kg and 25 mg/kg, respectively, increases the nonenzymatic antioxidant status and NO in the kidney, with a concomitant decrease in the levels of malondialdehyde and renal biomarkers. Therefore, our results reinforce the importance of adenosine deaminase and arginase activities in Cd poisoning conditions and suggest some possible mechanisms of action by which curcumin prevent Cd-induced renal toxicity in rats.

Evaluation of acute and subacute toxicity of aqueous extract of Crassocephalum rubens leaves in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Crassocephalum rubens is found throughout tropical Africa including the Indian Ocean islands. The leaves are commonly eaten in form of soups and sauces in South-Western Nigeria, also in other humid zones of Africa. Traditionally, it is used as an antidote against any form of poisoning; used to treat stomach and liver complaints; and externally to treat burns, sore eyes, earache, leprosy and breast cancer. In this study, acute and subacute toxicity of aqueous extract of C. rubens leaves was evaluated in rats in order to assess its safety profile. MATERIALS AND METHODS: In acute toxicity study, rats were given a single oral administration of aqueous extract of C. rubens leaves at graded doses (250-5000mg/kg). The animals were monitored for behavioural changes and possible mortality over a period of 24h and thereafter, for 14 days. In the subacute toxicity study, rats of both sexes were administered C. rubens orally at doses of 250mg/kg, 500mg/kg, 750mg/kg and 1000mg/kg body weight daily, for 28 days. Rats were observed weekly for any changes in general behaviour and body weights. In addition, other relevant parameters were assayed at the end of the main and reversibility study periods. RESULTS: There was no observed adverse effect; including mortality in the animals. The extract caused no significant difference in the body weights as well as organs weights of treated groups when compared with the control groups. Haematological and biochemical parameters also revealed no toxic effects of the extract on rats. Histological assessments were normal in liver and kidney. CONCLUSIONS: It can therefore be suggested based on the results from this study that aqueous extract of C. rubens leaves, at dosage levels up to 1000mg/kg, is non-toxic and could also offer protection on some body tissues. Aqueous extract of C. rubens could therefore, be considered safe. This study supports the application of Crassocephalum rubens in traditional medicine.