Antinociceptive Effects of Aza-Bicyclic Isoxazoline-Acylhydrazone Derivatives in Different Models of Nociception in Mice

Background: In a study recently published by our research group, the compounds isoxazoline-acylhydrazone derivatives R-99 and R-123 presented promising antinociceptive activity. However, the mechanism of action of this compound is still unknown. Objective: This study aimed to assess the mechanisms involved in the antinociceptive activity of these compounds in chemical models of pain. Methods: Animals were orally pretreated and evaluated in the acetic acid-, formalin-, capsaicin-, carrageenan- and Complete Freund's Adjuvant (CFA)-induced pain models in mice. The effects of the compounds after pretreatment with naloxone, prazosin, yohimbine, atropine, L-arginine, or glibenclamide were studied, using the acetic acid-induced writhing test to verify the possible involvement of opioid, α1-adrenergic, α2-adrenergic or cholinergic receptors, and nitric oxide or potassium channels pathways, respectively. Results: R-99 and R-123 compounds showed significant antinociceptive activity on pain models induced by acetic acid, formalin, and capsaicin. Both compounds decreased the mechanical hyperalgesia induced by carrageenan or CFA in mice. The antinociceptive effects of R-99 and R-123 on the acetic acid-induced writhing test were significantly attenuated by pretreatment with naloxone, yohimbine or atropine. R-99 also showed an attenuated response after pretreatment with atropine and glibenclamide. However, on the pretreatment with prazosin, there was no change in the animals' response to both compounds. Conclusion: R-99 and R-123 showed antinociceptive effects related to mechanisms that involve, at least in part, interaction with the opioid and adrenergic systems and TRPV1 pathways. The compound R-99 also interacts with the cholinergic pathways and potassium channels.

Analgesic activity of Phong Thap Dan tablets in animal models

Phong thap dan tablets are intended to treat low back pain. This study was carried out to evaluate theanalgesic effects of Phong thap dan tablets in experimental animals. The analgesic effects were evaluated inthree animal models: hot plate, mechanical stimulation and acetic acid-induced writhing test. Mice were dividedinto 4 groups given oral water, control drug (codein phosphate in hot plate and mechanical stimulation tests oraspirin in writhing test), Phong thap dan at 2.88 tablets (1.44 g) or 8.64 tablets (4.32 g)/kg b.w/day, respectively.Our results showed that Phong thap dan tablets at both doses increased the reaction time to thermal stimulation,increased the paw withdrawal latency and the force required to elicit a paw withdrawal and decreased thenumber of acetic acid-induced writhing movements in mice. There was no statistically significant differencebetween 2 doses of Phong thap dan tablets in three animal models. We conclude that Phong thap dan tabletsat the doses of 2.88 tablets and 8.64 tablets/kg b.w/day showed significant analgesic effect in animal models.

Anti-Inflammatory and Analgesic Evaluation of Parinari curatellifolia Methanol Leaf Extract on Albino Rats

Aim: This research was designed to evaluate the anti-inflammatory and analgesic activities of Parinari curatellifolia methanol leaf extract in albino rats. Methodology: Phytochemical screening was carried out using standard methods. Anti-inflammatory activity of the extract was done using egg albumin and formalin induced hind paw edema model. Analgesic effect was evaluated using hot plate induced pain and acetic acid induced writhing test. For each model twenty (20) rats were used, divided into five (5) groups of four (4) rats each. Results: Parinari curatellifolia revealed the presence of alkaloids, flavonoids, tannins and phenols while steroids, anthraquinone, terpenoids and glycoside were not detected. For the egg albumin induced inflammation, the group treated with the standard drug (indomethacin) and the group that received the highest dose of the extract were significantly lower (P<0.05) than all the other groups with percentage inhibitions at 25.56% and 24.44% respectively there was no significant difference (P>0.05). For the formalin induced anti-inflammatory activity, at the 1st hour, the normal control group had its paw volume significantly different (P<0.05) from the treated groups. This trend was observed at the 2nd, 3rd and 4th hour. The hot plate method results revealed significant increased (P<0.05) in the analgesic activity of PCMLE at 400mg/kg body weight and the drug treated group when the control was compared with the treated groups with percentage inhibition of 34.32% and 52.94% respectively. The acetic acid induced writhing test revealed that the extract at the three doses of 100, 200 and 400 mg/kg body weight, showed a significant (P<0.05) percentage inhibition of 32.31%, 36.92% and 47.69%, respectively compared to negative control. Conclusion: This justifies the use of Parinari curatellifolia locally in the management of pain and inflammation.

Evaluation of hyperalgesic effect of sitagliptin in albino mice

Various studies have showed the increased incidence of joint pain with the use of DPP-4 inhibitors. There is also some evidence of increase in inflammatory mediators like substance P, SDF-1 and other cytokines with the inhibition of DPP-4 from some experimental studies. But this association is still unclear and DPP-4 inhibitor continue to be prescribed in inflammatory disorders. So, this study was planned to assess the development of hyperalgesia in albino mice with the use of sitagliptin.Sitagliptin dissolved in saline was administered in the doses of 10, 20, 30 mg/kg to Albino mice of either sex weighing 25-30 gm. Hyperalgesia was assessed in the mice with hot plate method and acetic acid induced writhing test. We found that reaction time of the mice receiving higher dose of Sitagliptin in hot plate method was lower than that of mice receiving lower doses or distilled water (P-Value &#60;0.05). We also found that after injection of acetic acid, the number of writhing observed in the mice receiving higher dose of Sitagliptin was greater than that of mice receiving lower doses or distilled water (P-Value &#60;0.05). Our findings show that in a cohort of mice receiving Sitagliptin and distilled water at baseline, there was significant association between dose of Sitagliptin and hyperalgesia. However, P-Value was greater than 0.01, but with these finding we can’t rule out this association and need for further prospective studies to assess the relationship between DPP-4 inhibitors and hyperalgesia.

Analgesic and Anti-inflammatory Activities of Selenium and Alpha-tocopherol in Mouse Models of Pain Induced with Fluoride Exposure

Fluoride is an ineluctable environmental pollutant and its chronic exposure causes nociception and inflammation. Alpha-tocopherol and Selenium (Se) are widely available compounds that are safe if taken in moderation and exert a wide range of antioxidant, analgesic and anti-inflammatory activities. This study examined the protective activity of dietary supplements, alpha-tocopherol (2 mg/kg BW) and Selenium (05 µg/kg BW), by using thermal (Hot plate test, Tail-flick test), chemical (writhing test, formalin test) and neuropathic (allodynia test) tests in fluoride (20mg/kg BW) induced pain models. In addition, anti-inflammatory activity was also assessed with paw oedema assay. The obtained data suggest that hyperalgesia in fluoride exposure group was significantly (p<0.05) exhibited in hot plate, tail flick, writhing response, formalin and allodynia tests. Moreover, inflammation in fluoride exposure group was also significantly (p<0.05) increased in paw oedema tests in comparison with the control group. The combined administration of Se and alpha-tocopherol significantly (p<0.05) increased response latency in hot plate and tail flick tests, reduced writhing responses in the writhing test, increased withdrawal duration in allodynia test, inhibited formalin induced pain response in both phases but it was more pronounced in the second phase and attenuated formalin induced paw oedema in comparison with independent treatment of Se and alpha-tocopherol against NaF suggesting their analgesic and anti-inflammatory activities. These findings conclude the synergistic effects of selenium and alpha-tocopherol against fluoride induced nociception and inflammation.

Scientific Approaches in Screening the Analgesic property of Sida Cordata

Pain is likely the most common symptomatic complaint in medicine; an understanding of its mechanism is critical to interpret it. Nociception refers to the detection of noxious stimuli by nociceptors, followed by transduction and transmission of the sensory nervous information from the periphery to the brain. Plants have played a unique holistic role for the provision of food, drugs, clothing, shelter, etc. Natural compounds have been extensively explored for new drug discoveries. Indeed, plants have been used as medicines for more than 5000 years, as a source of antibiotics, antineoplastic, analgesics, cardioprotective, among others. About 70–90% of the population in developing countries continue to use ancient medicines based on plant extracts. Sida cordata popularly known as “bala” is regarded as a valuable drug in the Ayurvedic System of Indian Medicine. In order to validate the ethnomedical claim of Sida cordata as pain reliever, a study was conducted to evaluate the analgesic activity of ethanolic extract of Sida cordata whole plant in laboratory animals. For centrally mediated analgesic activity, eddy’s hot plate method was employed and Pentazocine was uses as reference control. For peripherally mediated analgesic activity, acetic acid induced writhing model was employed and Dicofenac was used as reference control. Sida cordata ethanolic extract was administered orally at the doses of 100 and 200 mg/kg. In eddy’s hot plate method, both the doses of Sida cordata significantly increased the reaction time compare to vehicle control. In acetic acid induced writhing test, both the doses of Sida cordata significantly reduced the number of writhing compare to vehicle control. In both the models, the effect produced by Sida cordata was comparable to that of respective reference control. The results obtained suggest that the ethanolic extract of Sida cordata has showed marked analgesic activity in experimental animal models and this strappingly supports the ethnopharmacological applications of the plant for the target activity.

Studies on Analgesic and Anti-Inflammatory Activities of Aerial Parts of Tephrosia Bracteolata GUILL. and PERR. (Fabaceae) in Rodents

Background: Tephrosia bracteolata is a widespread shrub belonging to the family (Fabaceae) and genus Tephrosia. It is traditionally used for treating rheumatic pains, dropsy and stomach ache.Objectives: In view of the ethnomedicinal claim and the continuous search for new medicinal agents, the phytochemical constituents, analgesic and anti-inflammatory activities of chloroform fraction (CF) of the methanol extract of Tephrosia bracteolata in mice and rats was evaluated.Methods: Preliminary phytochemical screening was conducted using standard method. Analgesic activity of CF (100, 200 and 400 mg/kg body weight orally) was investigated using acetic acid-induced writhing test and thermally induced pain model in mice. Additionally, anti-inflammatory activity was tested by carragenaan-induced paw edema in rats.Results: Phytochemical screening revealed the presence of alkaloids, triterpenes and flavonoids. The oral LD50 of CF was above 2000 mg/kg body weight. CF significantly (p<0.05) and dose dependently reduced the number of writhes with percentage inhibition of 47.76 48.41 and 72.6 % at dose of 100, 200 and 400mg/kg respectively. CF also significantly (p<0.05) and dose dependently increased the mean reaction time. At dose of 400 mg/kg, CF at 60 and 90 minutes exhibited greater activity when compared to the standard agent pentazocine. CF(200 and 400 mg/kg) at times 3, 4 and 5 hours significantly (p<0.05) decreased the paw edema in rats when compare with the ibuprofen treated group.Conclusions: The chloroform fraction of the methanol crude extract of Tephrosia bracteolata possesses analgesic and anti-inflammatory activities.

Synergistic Antinociceptive, Anti-inflammatory Interaction between Vitamin B12 and Ketorolac in Long Evans Rats

In certain painful disorders, B12 vitamins have been documented to be clinically useful alone or paired with non-steroidal anti-inflammatory drugs (NSAIDs). However, it has not been identified to equate these effects with related effects of ketorolac tromethamine (KT) and their combination. To test and compare the effects of vitamin B12 on pain with those of the combination of vitamin B12 with KT in rat models. This experimental research was performed at the Department of Physiology, BSMMU. The control (A, A1 with 5 ml/kg normal saline) and experimental (B1, B1a with 15 mg/kg B12; B2, B2a with 10 mg/kg KT; B3, B3a with B12+KT) groups of 5 rats in each group were divided into 40 (forty) long Evans rats (215±35 gm) of either sex. Both medications and vitamins were administered intraperitoneally in a single dose just one hour prior to the writhing and paw edema test caused by formalin. The statistical study was carried out by ANOVA, followed by the post-hoc Bonferroni test. In the interpretation of outcomes, p≤0.05 was regarded as significant. B12 lowered only the writhing count and KT lowered both writhing appearance latency time and writhing count significantly (p≤0.001) in the writhing test. However, the combination of B12 and KT significantly (p≤0.001) lowered both the study variables in the writhing test. In addition, KT lowered edema volume significantly (p≤0.01) in the paw edema test. The combination of B12 and KT, on the other hand, substantially (p≤0.001) decreased the amount of edema in the paw edema test. It can be concluded that vitamin B12 has analgesic and anti-inflammatory effects, and that the combination of B12 with KT is more effective than when administered individually.

Ethanolic Extracts of Adlay Testa and Hull and Their Active Biomolecules Exert Relaxing Effect on Uterine Muscle Contraction through Blocking Extracellular Calcium Influx in Ex Vivo and In Vivo Studies

Dysmenorrhea is one of the most prevalent disorders in gynecology. Historically, adlay (Coix lachryma-jobi L. var. Ma-yuen Stapf.) has been explored for its anti-tumor, pain relief, anti-inflammatory, and analgesic effects. The aim of this study was to evaluate the effects of adlay seeds on the inhibition of uterine contraction and thus dysmenorrhea relief, in vitro and in vivo. HPLC-MS and GC were used to elucidate the ethyl acetate fraction of adlay testa ethanolic extract (ATE-EA) and ethyl acetate fraction of adlay hull ethanolic extract (AHE-EA). Elucidation yielded flavonoids, phytosterols, and fatty acids. Uterine leiomyomas and normal adjacent myometrial tissue were evaluated by oxytocin- and PG-induced uterine contractility. ATE-EA and AHE-EA suppressed uterine contraction induced by prostaglandin F2 alpha (PGF2α), oxytocin, carbachol, and high-KCl solution ex vivo. In addition, the external calcium (Ca2+) influx induced contraction, and increased Ca2+ concentration was inhibited by ATE-EA and AHE-EA on the uterine smooth muscle of rats. Furthermore, ATE-EA and AHE-EA effectively attenuated the contraction of normal human myometrium tissues more than adjacent uterine leiomyoma in response to PGF2α. 3,5,6,7,8,3′,4′-Heptamethoxyflavone and chrysoeriol produced a remarkable inhibition with values of IC50 = 24.91 and 25.59 µM, respectively. The experimental results showed that treatment with ATE-EA at 30 mg/day effectively decreased the writhing frequency both on the oxytocin-induced writhing test and acetic acid writhing test of the ICR mouse.

Anti-allergic and anti-inflammatory activities of black cumin extracts in in vitro and in vivo model systems

Black cumin (Nigella sativa) is a widely used ingredient of traditional medicine for its broad-spectrum pharmacological actions, including anti-allergic, bronchial asthma, and anti-inflammatory properties. We sought to evaluate BC extracts' efficacy for their anti-allergic and anti-inflammatory properties using a comprehensive in vitro, in vivo, and silico experimental setup. To investigate whether BC extract has anti-inflammatory, anti-allergic, and analgesic therapeutic potentials in vitro and in vivo. The activity of BC was assessed through anti-allergic activity on rat basophilic leukemia-2H3 cell line, anti-inflammatory activity on J774.1A cell line, anti-inflammatory activity by carrageenan-induced rat paw edema, analgesic activity by acetic acid-induced writhing test, and ingenuity analysis of the BC extracts in inflammation control. BC exerted potent anti-allergic activity by inhibiting antigen-induced degranulation. An anti-inflammatory effect is shown by inhibiting TNF-α pro-duction. The acetic acid-induced writhing test shown a dose-dependent reduction of writhing number following BC administration. Rat paw edema test shown the dose-dependent reduction of paw edema volume following BC administration. Ingenuity Pathway Analysis (IPA) suggested BC extracts containing ferulic acid, p-coumaric acid, kaempferol, and quercetin can inhibit inflammation. This study suggests that bioactive compounds in BC extract act as an anti-allergic and anti-inflammatory agent by regulating several downstream and upstream inflammation pathways.