Antinociceptive activity of methanolic extract of Muntingia calabura leaves: further elucidation of the possible mechanisms

Background: Muntingia calabura (Elaecoparceae) is a medicinal plant traditionally used, particularly, by the Peruvian people to alleviate headache and cold, pain associated with gastric ulcers or to reduce the prostate gland swelling. Following the recent establishment of antinociceptive activity of M. calabura leaf, the present study was performed to further elucidate on the possible mechanisms of antinociception involved. Methods: The methanol extract of M. calabura (MEMC) was prepared in the doses of 100, 250 and 500 mg/kg. The role of bradykinin, protein kinase C, pottasium channels, and various opioid and non-opioid receptors in modulating the extract’s antinociceptive activity was determined using several antinociceptive assays. Results are presented as Mean ± standard error of mean (SEM). The one-way ANOVA test with Dunnett's multiple comparison was used to analyze and compare the data, with P < 0.05 as the limit of significance. Results: The MEMC, at all doses, demonstrated a significant (p < 0.05) dose-dependent antinociceptive activity in both the bradykinin- and phorbol 12-myristate 13-acetate (PMA)-induced nociception. Pretreatment of the 500 mg/kg MEMC with 10 mg/kg glibenclamide (an ATP-sensitive K+ channel inhibitor), the antagonist of μ-, δ- and κ-opioid receptors (namely 10 mg/kg β-funaltrexamine, 1 mg/kg naltrindole and 1 mg/kg nor-binaltorphimine), and the non-opioid receptor antagonists (namely 3 mg/kg caffeine (a non-selective adenosinergic receptor antagonist), 0.15 mg/kg yohimbine (an α2-noradrenergic antagonist), and 1 mg/kg pindolol (a β-adrenoceptor antagonist)) significantly (p < 0.05) reversed the MEMC antinociception. However, 10 mg/kg atropine (a non-selective cholinergic receptor antagonist), 0.15 mg/kg prazosin (an α1-noradrenergic antagonist) and 20 mg/kg haloperidol (a non-selective dopaminergic antagonist) did not affect the extract's antinociception. The phytochemicals screening revealed the presence of saponins, flavonoids, tannins and triterpenes while the HPLC analysis showed the presence of flavonoid-based compounds. Conclusions: The antinociceptive activity of MEMC involved activation of the non-selective opioid (particularly the μ-, δ- and κ-opioid) and non-opioid (particularly adenosinergic, α2-noradrenergic, and β-adrenergic) receptors, modulation of the ATP-sensitive K+ channel, and inhibition of bradikinin and protein kinase C actions. The discrepancies in MEMC antinociception could be due to the presence of various phytochemicals

Antiulcer activity of Muntingia calabura leaves involves the modulation of endogenous nitric oxide and nonprotein sulfhydryl compounds

Context: Muntingia calabura L. (Muntingiaceae) is a native plant species of the American continent and is widely cultivated in warm areas in Asia, including Malaysia. The plant is traditionally used to relieve pain from gastric ulcers. Objective: This study was designed to determine the antiulcer activity of a methanol extract of M. calabura leaves (MEMC) and the possible mechanisms of action involved. Materials and methods: An acute toxicity study was conducted using a single oral dose of 2000 mg/kg MEMC. The antiulcer activity of MEMC was evaluated in absolute ethanol- and indomethacin-induced gastric ulcer rat models. MEMC was administered orally (dose range 25–500 mg/kg) to rats fasted for 24 h. The animals were pretreated with NG-nitro-l-arginine methyl esters (l-NAME) or N-ethylmaleimide (NEM) prior to MEMC treatment to assess the possible involvement of endogenous nitric oxide (NO) and nonprotein sulfhydryl (NP-SH) compounds in the gastroprotective effect of MEMC. Results: As the administered dose did not cause toxicity in the rats, the oral median lethal dose (LD50) of MEMC was >2000 mg/kg in rats. MEMC exerted significant (p < 0.001) gastroprotective activity in the ethanol- and indomethacin-induced ulcer models dose-dependently. Histological evaluation supported the observed antiulcer activity of MEMC. l-NAME and NEM pretreatment significantly (p < 0.05) reversed and abolished the gastroprotective effect of MEMC, respectively. Discussion and conclusion: The results obtained indicate that MEMC has significant antiulcer activity that might involve the participation of endogenous NO and NP-SH compounds. These findings provide new pharmacological information regarding the potential use of M. calabura

Prevalence and risk factors of prehypertension in university students in Sabah, Borneo Island of East Malaysia

Unhealthy lifestyle contributes mainly to an increased prevalence of non-communicable diseases including hypertension and cardiovascular diseases tend to increase in Malaysia. These diseases lead to an increased risk of end organ damage and cardiovascular complications. In this study, the prevalence of prehypertension and its associated risk factors among a cohort of university students in Sabah was determined. This is a prospective, cross-sectional study conducted among 365 undergraduate students irrespective of faculties at Universiti Malaysia Sabah (UMS). Standardized and validated World Health Organization (WHO) STEPS questionnaires were used to collect sociodemographic data. Additionally, clinical and anthropometric data were measured and recorded by a trained staff, followed by descriptive and logistic regression analyses. A total of 365 UMS undergraduate students aged 18 years and above participated in the study. The prevalence of prehypertension among university students was high (31%) (95% CI [29.1%, 34.3%]). Well-known risk factors for hypertension including family history of hypertension, reduced sleep duration, reduced physical activity, smoking, being overweight or obese were significantly associated with the risk of developing prehypertension (P < .05) among UMS students. However, no association was observed between ethnicity, age, and gender with prehypertension. A worryingly high percentage of UMS students are prehypertensive, indicating the need of early preventive strategies aimed at increasing awareness, early screening, and lifestyle modification to reduce the rising burden of the disease and the associated complications in this age group

Modulation of POPDC1 expression by Phenothiazine and Trifluoperazine suppress colon cancer growth and migration

Objective: The aim of this study was to investigate the effects of CaM antagonist, PTZ, and TFP on cell proliferation and migration of colon cancer cells and its impact on POPDC protein expression. Methods: The 50% inhibitory concentration (IC50 ) of PTZ and TFP in SW1116, SW480, HCT-15, and COLO205 colon cancer cell lines are measured using MTT. Western blot and immunocytochemistry were used to determine the expression of PCNA, cyclin D1 (CD1), and POPDC proteins. Cell migration was observed using a scratch wound-healing assay. Results: Treatment with PTZ and TFP inhibited colon cancer cells growth in a dose-dependent manner. PTZ and TFP significantly inhibited the activation of proliferation markers, PCNA and CD1, and the migration of colon cancer cells. Furthermore, POPDC protein was significantly suppressed in all cell types of colon cancer, particularly in SW480. Finally, the CaM antagonist upregulates the POPDC1 expression in colon cancer cells. Conclusion: These findings suggest that CaM antagonists suppress colon cancer cells proliferation via downregulation of CD1 and PCNA. In addition, POPDC protein could be used as a biomarker in colon cancer, and CaM antagonist could be used to regulate POPDC1 expression. This study suggests that targeting POPDC1 with CaM inhibition could be a potential therapeutic strategy for colon cancer treatment

Antinociceptive Activity of Methanolic Extract of Clinacanthus nutans

Methanolic extract of Clinacanthus nutans Lindau leaves (MECN) has been proven to possess antinociceptive activity that works via the opioid and NO-dependent/cGMP-independent pathways. In the present study, we aimed to further determine the possible mechanisms of antinociception of MECN using various nociceptive assays. The antinociceptive activity of MECN was (i) tested against capsaicin-, glutamate-, phorbol 12-myristate 13-acetate-, bradykinin-induced nociception model; (ii) prechallenged against selective antagonist of opioid receptor subtypes (β-funaltrexamine, naltrindole, and nor-binaltorphimine); (iii) prechallenged against antagonist of nonopioid systems, namely, α2-noradrenergic (yohimbine), β-adrenergic (pindolol), adenosinergic (caffeine), dopaminergic (haloperidol), and cholinergic (atropine) receptors; (iv) prechallenged with inhibitors of various potassium channels (glibenclamide, apamin, charybdotoxin, and tetraethylammonium chloride). The results demonstrated that the orally administered MECN (100, 250, and 500 mg/kg) significantly (p<0.05) reversed the nociceptive effect of all models in a dose-dependent manner. Moreover, the antinociceptive activity of 500 mg/kg MECN was significantly (p<0.05) inhibited by (i) antagonists of μ-, δ-, and κ-opioid receptors; (ii) antagonists of α2-noradrenergic, β-adrenergic, adenosinergic, dopaminergic, and cholinergic receptors; and (iii) blockers of different K+ channels (voltage-activated-, Ca2+-activated, and ATP-sensitive-K+ channels, resp.). In conclusion, MECN-induced antinociception involves modulation of protein kinase C-, bradykinin-, TRVP1 receptors-, and glutamatergic-signaling pathways; opioidergic, α2-noradrenergic, β-adrenergic, adenosinergic, dopaminergic, and cholinergic receptors; and nonopioidergic receptors as well as the opening of various K+ channels. The antinociceptive activity could be associated with the presence of several flavonoid-based bioactive compounds and their synergistic action with nonvolatile bioactive compounds

Antinociceptive activity of petroleum ether fraction obtained from methanolic extract of Clinacanthus nutans leaves involves the activation of opioid receptors and NO-mediated/cGMP-independent pathway

Background Methanol extract (MECN) of Clinacanthus nutans Lindau leaves (family Acanthaceae) demonstrated peripherally and centrally mediated antinociceptive activity via the modulation of opioid/NO-mediated, but cGMP-independent pathway. In the present study, MECN was sequentially partitioned to obtain petroleum ether extract of C. nutans (PECN), which was subjected to antinociceptive study with aims of establishing its antinociceptive potential and determining the role of opioid receptors and l–arginine/nitric oxide/cyclic-guanosine monophosphate (l–arg/NO/cGMP) pathway in the observed antinociceptive activity. Methods The antinociceptive potential of orally administered PECN (100, 250, 500 mg/kg) was studied using the abdominal constriction-, hot plate- and formalin-induced paw licking-test in mice (n = 6). The effect of PECN on locomotor activity was also evaluated using the rota rod assay. The role of opioid receptors was determined by pre-challenging 500 mg/kg PECN (p.o.) with antagonist of opioid receptor subtypes, namely β–funaltrexamine (β–FNA; 10 mg/kg; a μ-opioid antagonist), naltrindole (NALT; 1 mg/kg; a δ-opioid antagonist) or nor–binaltorphimine (nor–BNI; 1 mg/kg; a κ-opioid antagonist) followed by subjection to the abdominal constriction test. In addition, the role of l–arg/NO/cGMP pathway was determined by prechallenging 500 mg/kg PECN (p.o.) with l–arg (20 mg/kg; a NO precursor), 1H-[1, 2, 4] oxadiazolo [4,3-a]quinoxalin-1-one (ODQ; 2 mg/kg; a specific soluble guanylyl cyclase inhibitor), or the combinations thereof (l–arg + ODQ) for 5 mins before subjection to the abdominal constriction test. PECN was also subjected to phytoconstituents analyses. Results PECN significantly (p  0.05) affect the locomotor activity of treated mice. The antinociceptive activity of PECN was significantly (p  0.05) affected by ODQ. HPLC analysis revealed the presence of at least cinnamic acid in PECN. Conclusion PECN exerted antinocicpetive activity at peripheral and central levels possibly via the activation of non-selective opioid receptors and modulation of the NO-mediated/cGMP-independent pathway partly via the synergistic action of phenolic compounds

Antinociceptive activity of a synthetic oxopyrrolidine-based compound, ASH21374, and determination of its possible mechanisms

This study was carried out to determine the antinociceptive activity of a novel synthetic oxopyrrolidine-based compound, (2R,3R,4S)-ethyl 4-hydroxy-1,2-dimethyl-5-oxopyrrolidine-3-carboxylate (ASH21374), and to elucidate the involvement of the opioid, vanilloid, glutamate, and nitric oxide – cyclic guanosine monophosphate (NO/cGMP) systems in modulating the observed antinociception. ASH21374, in the doses of 2, 10, and 100 mg/kg body mass, was administered orally to mice 60 mins prior to exposure to various antinociceptive assays. From the results obtained, ASH21374 exhibited significant (P< 0.05) antinociceptive activity in the abdominal constriction, hot-plate, and formalin tests that was comparable with 100 mg/kg acetylsalicylic acid or 5 mg/kg morphine, respectively. ASH21374 also attenuated capsaicin- and glutamate-induced paw licking. Pre-treatment with 5 mg/kg naloxone significantly (P< 0.05) inhibited the activity in all assays, while pretreatment with 10 mg/k-funaltraxamine, 1 mg/kg naltrindole, or 1 mg/kg nor-binaltorphimine significantly (P< 0.05) reversed the activity in the abdominal constriction test. L-Arginine,NG-nitro-L-arginine methyl esters (L-NAME), methylene blue, and their combinations, failed to inhibit the ASH21374 antinociceptive activity. In conclusion, ASH21374 demonstrated antinociceptive activities on the peripheral and central nervous systems, mediated through the activation of opioid receptors, inhibition of the glutamatergic system, and attenuation of vanilloid-mediated nociceptive transmission. Further studies have been planned to determine the pharmacological potential of ASH21374

Antinoceptive activity of methanolic extract of Clinacanthus nutans leaves : possible mechanisms of action involved

Methanolic extract of Clinacanthus nutans Lindau leaves (MECN) has been proven to possess antinociceptive activity that works via the opioid and NO-dependent/cGMP-independent pathways. In the present study, we aimed to further determine the possible mechanisms of antinociception of MECN using various nociceptive assays. The antinociceptive activity of MECN was (i) tested against capsaicin-, glutamate-, phorbol 12-myristate 13-acetate-, bradykinin-induced nociception model; (ii) prechallenged against selective antagonist of opioid receptor subtypes (β-funaltrexamine, naltrindole, and nor-binaltorphimine); (iii) prechallenged against antagonist of nonopioid systems, namely, α2-noradrenergic (yohimbine), β-adrenergic (pindolol), adenosinergic (caffeine), dopaminergic (haloperidol), and cholinergic (atropine) receptors; (iv) prechallenged with inhibitors of various potassium channels (glibenclamide, apamin, charybdotoxin, and tetraethylammonium chloride). The results demonstrated that the orally administered MECN (100, 250, and 500 mg/kg) significantly () reversed the nociceptive effect of all models in a dose-dependent manner. Moreover, the antinociceptive activity of 500 mg/kg MECN was significantly () inhibited by (i) antagonists of μ-, δ-, and κ-opioid receptors; (ii) antagonists of α2-noradrenergic, β-adrenergic, adenosinergic, dopaminergic, and cholinergic receptors; and (iii) blockers of different K+ channels (voltage-activated-, Ca2+-activated, and ATP-sensitive-K+ channels, resp.). In conclusion, MECN-induced antinociception involves modulation of protein kinase C-, bradykinin-, TRVP1 receptors-, and glutamatergic-signaling pathways; opioidergic, α2-noradrenergic, β-adrenergic, adenosinergic, dopaminergic, and cholinergic receptors; and nonopioidergic receptors as well as the opening of various K+ channels. The antinociceptive activity could be associated with the presence of several flavonoid-based bioactive compounds and their synergistic action with nonvolatile bioactive compounds

Antinociceptive activity, elucidation of mechanism of action and identification of bioactive components of muntingia calabura L. Leaf extracts

Research into plant as an alternative treatment for pain has been widely explored due to its potentially low adverse effect with great therapeutic activity. Muntingia calabura L. (Tiliaceae) has recently gained a medicinal status as well as attention from throughout the world. The present study examined the potential antinociceptive activity of methanol extract of Muntingia calabura (MEMC) leaves using the acetic acid-induced abdominal constriction, formalin and hot plate test following the determination of its safety using acute toxicity test. Then the possible involvement of MEMC-induced antinociception through capsaicin, glutamate, bradykinin, opioidergic, dopaminergic serotonergic, noradrenergic, adenosisnergic, protein kinase C (PKC), nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) and potassium channel pathway was evaluated. Experimental animals (n=6) were pretreated orally with 10% dimethyl sulfoxide (DMSO; negative control), 5 mg/kg morphine or 100 mg/kg aspirin (positive control) or 100, 250, and 500 mg/kg of MEMC, followed by the administration of receptor antagonists and/or induction of nociception. The crude MEMC extract was further partitioned into three fractions: petroleum ether extract (PEMC), ethyl acetate extract (EAMC) and aqueous extract (AEMC). The antinociceptive profiling demonstrates PEMC produced a significantly better activity than EAMC and AEMC. Possible mechanism of PEMC action was studied using the same assays. Result on the acute toxicity study shows no mortality and significant behavioural and physiological changes detected. Oral administration of MEMC and PEMC shows a dose-dependent inhibition in acetic acid-induced abdominal constriction test, formalin-, capsaicin-. glutamate-, bradykinin- and PMA-induced paw licking test, while only the highest dose produced significant pain inhibition in hot plate test. Furthermore, the antinociception caused by MEMC and PEMC in acetic acid-induced abdominal constriction test was significantly attenuated by intraperitoneal treatment of naloxone (non-specific opioid receptor antagonist; 5 mg/kg), naltrindole (δ opioid receptor antagonist; 1 mg/kg) norbinaltorphimine (κ opioid receptor antagonist; 1 mg/kg), β-funaltraxamine (μ opioid antagonist; 10 mg/kg), pindolol (5-HT1A receptor antagonist; 1 mg/kg), caffeine (nonselective adenosine receptor antagonist; 3 mg/kg) and yohimbine (α2 adrenoceptor antagonist; 0.15 mg/kg). While both extracts did not act on dopaminergic receptor system, PEMC, but not MEMC, was significantly reversed by i.p. injection of atropine (non-selective cholinergic antagonist; 10 mg/kg). At the same time, MEMC and PEMC were found to inhibit pain through NO/cGMP/PKC as well as potassium channel pathways. The potential antinociceptive activity seen was probably due to synergistic effect of flavonoids, tannins, polyphenolic compounds, triterpene and steroid present in the extracts based on their phytochemical screening. High performance liquid chromatography analysis shows several peaks, detected at different wavelengths of the chromatogram, which were suggested to be flavonoid-based compounds. In conclusion, the synergistic effects of various bioactive components suggested to be responsible in the antinociceptive activity of MEMC as well as the semi-purified PEMC extract which involved in central and peripheral pain pathways. The activation of potassium pathway as well as opioid, adenosinergic, noradrenergic and serotonergic receptors while inhibits NO/cGMP/PKC pathways, TRPV1, glutamate and bradykinin receptors might be the possible mode of action of both the extracts in exerting their analgesic effect

Psychological effects on self-medication during the pandemic COVID-19 in WP Labuan: A development of questionnaire and pilot-testing

Self-Medication, which is a practice to self-treat using medicine without consulting a medical practitioner or a doctor, is a common practice and the Pandemic Covid-19 may have caused people to resort to self-medication in order to reduce the infectivity of the Covid-19. Objective: To validate and develop an instrument in Bahasa Melayu to assess the psychological distress and self-medication during pandemic Covid-19 in WP Labuan. Methods: A pilot study was conducted among 160 participants in WP Labuan. Reliability testing on internal consistency and content validity was performed on the adapted Covid-19 Peritraumatic Distress Index (CPDI) as well as domain on knowledge, practice and attitude of self-medication. Result: A panel of seven experts evaluated the research instrument for content validity and it was found to have good content item validity. The CPDI domain showed good internal consistency of Cronbach’s Alpha of 0.919. The mean (SD) CPDI score of the respondents in WP Labuan was 32.55 (15.98). 64.2% of the respondents experienced psychological distress. The variable for Area (town/countryside) was found to be statistically significant (p<0.05) to be associated with selfmedication during the pandemic. Conclusion: The instrument established sound reliability and validity and therefore, can be an effective tool for assessing psychological distress and self-medication in the Malaysian population