Whole genome sequencing of Streptococcus suis revealed potential drug resistance and zoonotic transmission in companion cat.

Streptococcus suis is a bacterium of clinical importance in diverse animal hosts including companion animals and humans. Companion animals are closely associated in the living environment of humans and are potential reservoirs for zoonotic pathogens. Given the zoonotic potential of S. suis, it is crucial to determine whether this bacterium is present among the companion animal population. This study aimed to detect Streptococcus suis in companion animals namely cats and dogs of the central west coast of Peninsular Malaysia and further characterize the positive isolates via molecular and genomic approach. The detection of S. suis was done via bacterial isolation and polymerase chain reaction assay of gdh and recN gene from oral swabs. Characterization was done by multiplex PCR serotyping, as well as muti-locus sequence typing, AMR gene prediction, MGE identification and phylogenomic analysis on whole genome sequence acquired from Illumina and Oxford Nanopore sequencing. Among the 115 samples, PCR assay detected 2/59 of the cats were positive for S. suis serotype 8 while all screened dog samples were negative. This study further described the first complete whole genome of S. suis strain SS/UPM/MY/F001 isolated from the oral cavity of a companion cat. Genomic analysis revealed a novel strain of S. suis having a unique MLST profile and antimicrobial resistance genes of mefA, msrD, patA, patB and vanY. Mobile genetic elements were described, and pathogenic determinants matched to human and swine strains were identified. Phylogenetic tree analysis on the core genome alignment revealed strain SS/UPM/MY/F001 was distinct from other S. suis strains. This study provided insight into the detection and genomic features of the S. suis isolate of a companion cat and highlighted its potential for antimicrobial resistance and pathogenicity.

Thyroid function status evaluation in patient post-radiotherapy for nasopharyngeal carcinoma: A retrospective study.

INTRODUCTION: Nasopharyngeal carcinoma (NPC) is among the most common malignancy in Malaysia. Radiationinduced hypothyroidism has been reported in other countries. However, in Malaysia, no studies were ever done to determine the effect of radiation on hypothyroidism. The objective of this study is to evaluate the practice of taking thyroid function test (TFT) and determine hypothyroidism post-radiation in patients with NPC. MATERIALS AND METHODS: A retrospective study on the symptoms and results of TFT according to the dosage of intensity-modulated radiotherapy (IMRT) given to patients with NPC. Data were traced and analysed. RESULTS: A total of 78 patients were identified. All patients received IMRT with 33-35 fractions of radiotherapy (RT) with total dosage of 66-70 Gray given. Not all patients had their thyroid function status measured routinely. Twelve patients did have symptoms of hypothyroidism. TFT were obtained in this group but the results were normal. No correlation was found between RT and hypothyroidism. CONCLUSION: There was no correlation between IMRT and the development of hypothyroidism. A prospective study with better control of inclusion and exclusion criteria, and longer follow-up period with TFT, is needed to demonstrate the consistency of these findings.

COVID-19 Pandemic: Two-year Experience and Response of a Teaching Hospital in Malaysia and the Effect on Postgraduate Orthopaedic Training.

As the number of COVID-19-related infections and deaths increased exponentially in the during 2020, few countries were equipped to manage and curb this novel coronavirus. Initially there was no proven cure or vaccine to this novel virus (SARS-Cov-2), leaving the authorities with no choice but to impose quarantines at the short-term expense of their economies. As we gain more knowledge on this novel virus, the tried-and-tested method of selective testing of the symptomatic patients, used successfully in almost all infectious respiratory diseases, has been replaced with trace-and-test method, as most of the infected patients remained asymptomatic. In early 2021, the availability of vaccines provided a shed of light out from this pandemic. Nevertheless, we faced an enormous task in juggling between vaccination of the population, managing patients with COVID-19 infection as well as non-COVID-19 patients. Here, we share our experience and response in managing this healthcare crisis across a two-year period during the pandemic and we hope other centres can learn from what we went through and help them derive a protocol to navigate through a future pandemic.

Detection of colistin-resistant Escherichia coli isolated from broiler chickens in Kelantan, Malaysia.

Antimicrobial resistant Escherichia coli have become an ever increasing problem in human, and animal health and production. The imprudent use of antibiotics and poor hygienic practices especially in poultry industries have been contributing to the emergence and spread of E. coli species resistant to broad spectrum antibiotics including Colistin. This study was conducted to detect colistin - resistance and antibiotic sensitivity patterns in E. coli isolated from broiler chickens in Kelantan. A total of 320 cloacal swabs were collected from apparently healthy broiler chickens in different districts of Kelantan and were analysed using routine microbiological methods, Kirby-Bauer method for antimicrobial susceptibility test and PCR amplification of species-specific and colistin - resistance encoding genes. Out of the 320 samples, 91 isolates were confirmed as E. coli and 21/91 (23.08%) were positive for colistin - resistant encoding gene, mcr-1. Most of the isolates were resistant to tetracycline (95.24%), chloramphenicol (85.71%), and sulphamethoxazole/ trimethoprim (85.71%). However, the isolates were less resistant towards piperacillin/ tazobactam (4.76%) and meropenem (9.52%). The findings from this study reveal the emerging threats of colistin - resistant in local food animal production, particularly in poultry production industry. However, more comprehensive, and large-scale studies focusing on more resistance patterns using determination of minimum inhibitory concentration (MIC), virulence and resistance characteristics and molecular epidemiology of colistin - resistant E. coli are recommended for better understanding of the epidemiology and to implement the appropriate control and prevention strategies.

COVID-19 Pandemic: Two-year Experience and Response of a Teaching Hospital in Malaysia and the Effect on Postgraduate Orthopaedic Training

@#As the number of COVID-19-related infections and deaths increased exponentially in the during 2020, few countries were equipped to manage and curb this novel coronavirus. Initially there was no proven cure or vaccine to this novel virus (SARS-Cov-2), leaving the authorities with no choice but to impose quarantines at the short-term expense of their economies. As we gain more knowledge on this novel virus, the tried-and-tested method of selective testing of the symptomatic patients, used successfully in almost all infectious respiratory diseases, has been replaced with traceand-test method, as most of the infected patients remained asymptomatic. In early 2021, the availability of vaccines provided a shed of light out from this pandemic. Nevertheless, we faced an enormous task in juggling between vaccination of the population, managing patients with COVID-19 infection as well as non-COVID-19 patients. Here, we share our experience and response in managing this healthcare crisis across a two-year period during the pandemic and we hope other centres can learn from what we went through and help them derive a protocol to navigate through a future pandemic.

Association of the polymorphism of the Toll-like receptor (TLR)-3 and TLR-9 genes with hepatitis C virus-specific cell-mediated immunity outcomes among Egyptian health-care workers.

Variations in the immune response could explain resistance to hepatitis C virus (HCV) infection. Toll-like receptor gene (TLR)-3 is an innate detector of dsRNA viruses, and the TLR-9 gene recognizes bacterial and viral unmethylated cytosine-phosphate-guanosine (CpG) motifs. We previously reported that the TLR-3.rs3775290 CC genotype was associated with HCV chronicity and that the TLR-9 gene played no major role in this infection. This study identified the role of TLR-3.rs3775290 (c.1377C/T), TLR-9.rs5743836 (-1237T→C) and TLR-9.rs352140 (G2848A) gene polymorphisms in predicting the outcome of HCV-specific cell-mediated immunity (CMI) among Egyptian health-care workers (HCWs). We enrolled 265 HCWs in this study and divided them into four groups. Group 1: 140 seronegative-aviraemic HCWs; group 2: 20 seronegative-viraemic HCWs; group 3: 35 subjects with spontaneously resolved HCV infection; and group 4: 70 chronic HCV HCWs (patients). All subjects were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis for the TLR-3.rs3775290, TLR-9.rs5743836 and TLR-9.rs352140 single nucleotide polymorphisms (SNPs). We also quantified HCV-specific CMI in the four groups using an interferon (IFN)-γ enzyme-linked immunospot (ELISPOT) assay in response to nine HCV genotype 4a, overlapping 15mer peptide pools covering the whole viral genome. No statistically significant difference was found between CMI-responding subjects with different HCV states and TLR-3.rs3775290 or TLR-9.rs352140 genotypes. However, there was a significant relationship between the outcome of the HCV-specific CMI and the TLR-9.rs5743836 genotype among the responding subjects (P = 0·005) and the chronic HCV patients (P = 0·044). In conclusion, TLR-9.rs5743836 SNP, but not TLR-3.rs3775290 or TLR-9.rs352140 genotypes, could predict the outcome of HCV-specific CMI responses among Egyptians infected with genotype-4.

Barriers to implementing a national health screening program for men in Malaysia: An online survey of healthcare providers.

INTRODUCTION: This study aimed to determine the views and practices of healthcare providers and barriers they encountered when implementing the national health screening program for men in a public primary care setting in Malaysia. METHODS: An online survey was conducted among healthcare providers across public health clinics in Malaysia. All family medicine specialists, medical officers, nurses and assistant medical officers involved in the screening program for adult men were invited to answer a 51-item questionnaire via email or WhatsApp. The questionnaire comprised five sections: participants' socio-demographic information, current screening practices, barriers and facilitators to using the screening tool, and views on the content and format of the screening tool. RESULTS: A total of 231 healthcare providers from 129 health clinics participated in this survey. Among them, 37.44% perceived the implementation of the screening program as a "top-down decision." Although 37.44% found the screening tool for adult men "useful," some felt that it was "time consuming" to fill out (38.2%) and "lengthy" (28.3%). In addition, 'adult men refuse to answer' (24.1%) was cited as the most common patient-related barrier. CONCLUSIONS: This study provided useful insights into the challenges encountered by the public healthcare providers when implementing a national screening program for men. The screening tool for adult men should be revised to make it more user-friendly. Further studies should explore the reasons why men were reluctant to participate in health screenings, thus enhancing the implementation of screening programs in primary care.

Safety Assessment of Methanol Extract of Melastoma malabathricum L. Leaves following the Subacute and Subchronic Oral Consumptions in Rats and Its Cytotoxic Effect against the HT29 Cancer Cell Line.

Methanol extract of Melastoma malabathricum (MEMM) has been traditionally used by the Malay to treat various ailments. In an attempt to develop the plant as an herbal product, MEMM was subjected to the subacute and subchronic toxicity and cytotoxicity studies. On the one hand, the subacute study was performed on three groups of male and three groups of female rats (n = 6), which were orally administered with 8% Tween 80 (vehicle control group) or MEMM (500 and 1000 mg/kg) daily for 28 days, respectively. On the other hand, the subchronic study was performed on four groups of rats (n = 6), which were orally administered with 8% Tween 80 (vehicle control group) or MEMM (50, 250, and 500 mg/kg) daily for 90 days, respectively. In the in vitro study, the cytotoxic effect of MEMM against the HT29 colon cancer cell line was assessed using the MTT assay. MEMM was also subjected to the UHPLC-ESI-HRMS analysis. The results demonstrated that MEMM administration did not cause any mortality, irregularity of behaviour, modification in body weight, as well as food and water intake following the subacute and subchronic oral treatment. There were no significant differences observed in haematological parameters between treatment and control groups in both studies, respectively. The in vitro study demonstrated that MEMM exerts a cytotoxic effect against the HT29 colon cancer cell line when observed under the inverted and phase-contrast microscope and confirmed by the acridine orange/propidium iodide (AOPI) staining. The UHPLC-ESI-HRMS analysis of MEMM demonstrated the occurrence of several compounds including quercetin, p-coumaric acid, procyanidin A, and epigallocatechin. In conclusion, M. malabathricum leaves are safe for oral consumption either at the subacute or subchronic levels and possess cytotoxic action against the HT29 colon cancer cells possibly due to the synergistic action of several flavonoid-based compounds.

Real Time Microwave Biochemical Sensor Based on Circular SIW Approach for Aqueous Dielectric Detection.

In this study, a critical evaluation of analyte dielectric properties in a microvolume was undertaken, using a microwave biochemical sensor based on a circular substrate integrated waveguide (CSIW) topology. These dielectric properties were numerically investigated based on the resonant perturbation method, as this method provides the best sensing performance as a real-time biochemical detector. To validate these findings, shifts of the resonant frequency in the presence of aqueous solvents were compared with an ideal permittivity. The sensor prototype required a 2.5 µL volume of the liquid sample each time, which still offered an overall accuracy of better than 99.06%, with an average error measurement of ±0.44%, compared with the commercial and ideal permittivity values. The unloaded Qu factor of the circular substrate-integrated waveguide (CSIW) sensor achieved more than 400 to ensure a precise measurement. At 4.4 GHz, a good agreement was observed between simulated and measured results within a broad frequency range, from 1 to 6 GHz. The proposed sensor, therefore, offers high sensitivity detection, a simple structural design, a fast-sensing response, and cost-effectiveness. The proposed sensor in this study will facilitate real improvements in any material characterization applications such as pharmaceutical, bio-sensing, and food processing applications.

Influence of Graphene Oxide on the Ethanol Permeability and Ionic Conductivity of QPVA-Based Membrane in Passive Alkaline Direct Ethanol Fuel Cells.

Passive alkaline-direct ethanol fuel cells (alkaline-DEFCs) appear to be suitable for producing sustainable energy for portable devices. However, ethanol crossover is a major challenge for passive alkaline-DEFC systems. This study investigated the performance of a crosslinked quaternized poly (vinyl alcohol)/graphene oxide (QPVA/GO) composite membrane to reduce ethanol permeability, leading in enhancement of passive alkaline-DEFC performance. The chemical and physical structure, morphology, ethanol uptake and permeability, ion exchange capacity, water uptake, and ionic conductivity of the composite membranes were characterized and measured to evaluate their applicability in fuel cells. The transport properties of the membrane were affected by GO loading, with an optimal loading of 15 wt.% and doped with 1 M of KOH showing the lowest ethanol permeability (1.49 × 10-7 cm2 s-1 and 3.65 × 10-7 cm2 s-1 at 30 °C and 60 °C, respectively) and the highest ionic conductivity (1.74 × 10-2 S cm-1 and 6.24 × 10-2 S cm-1 at 30 °C and 60 °C, respectively). In the passive alkaline-DEFCs, the maximum power density was 9.1 mW cm-2, which is higher than commercial Nafion 117/KOH (7.68 mW cm-2) at 30 °C with a 2 M ethanol + 2 M KOH solution. For the 60 °C, the maximum power density of composite membrane achieved was 11.4 mW cm-2.

Periodic vicissitudes of different concentrations of a developed prototype killed S. aureus mastitis vaccine on immune modulators, mediators and immunoglobulins in cows.

Mastitis is the inflammation of the mammary gland due to microbial infiltration causing a reduced mammary function. This study aims at developing a vaccine using Malaysian local isolate of Staphylococcus aureus and evaluating serum amyloid A, Interleukin-10, IgM and IgG responses periodically. Four bacterin concentrations (106, 107, 108 and 109 cfu/ml of the local isolate of S. aureus) were adjuvanted with aluminium potassium sulphate. Thirty cows grouped into 4 treatment groups (G-) were vaccinated (2 ml) intramuscularly, with a fifth G-A as control. The mean concentration (MC) of serum amyloid A (SAA) was significantly different (sig-d) (p Ë‚ 0.05) in G-D at 0 h post vaccination (PV), 3 h PV, 24 h PV, weeks 1, 2, 3 and 4 PV (6-, 15-, 5-, 12-, 11-, 4- and 11-fold increased (FI) respectively). The MC of serum amyloid A was also sig-d in G-E at 0 h PV, weeks 1, 2 and 4 PV (3, 8, 5 and 8 FI respectively). The MC of IL-10 was sig-d in G-D and C at 3 h PV and week 2 PV (5 and 2 FI respectively). The IgM MC was sig-d in G-B and C at 3 h PV (5 and 6 FI respectively), at 24 h PV (5 and 9 FI respectively), at week 3 PV(2 and 2 FI respectively) and week 4 PV (3 and 4 FI respectively). The MC of IgG was sig-d in G-E at 0 h, 3 h and week 3 PV(5, 6 and 2 FI respectively) and in G-D at weeks 1-4 (3, 3, 3 and 5 FI respectively). In conclusion, elevated levels of SAA, IgG and IL-10 in G-D(108) informed our choice of best dosage which can be used to evoke immunity in cows.

Clinical responses in cows vaccinated with a developed prototype killed Staphylococcus aureus mastitis vaccine.

Mastitis is an inflammatory condition of the udder that occurs as a result of the release of leucocytes into the udder in a response to bacterial invasion. The major causes of mastitis are an array of gram positive and negative bacteria, however, algae, virus, fungi, mechanical or thermal injury to the gland have also been identified as possible causes. Mastitis vaccines are yet to be developed using Malaysian local isolate of bacteria. The objective of the present experimental trial was to develop a monovalent vaccine against mastitis using S. aureus of Malaysian isolate and to evaluate the clinical responses such as temperature, respiratory rates and heart rates in vaccinated cows. S. aureus is a major causative bacteria in clinical and subclinical types of mastitis in cows. Four concentrations of the bacterin (106, 107, 108 and 109 cfu/ml of the local isolate of S. aureus) were prepared using Aluminium potassium sulfate adjuvant. Thirty cows were grouped into four treatment groups (B, C, D and E) with a fifth group as control (A). These groups were vaccinated intramuscularly(IM) with the prepared monovalent vaccine and its influence on the vital signs were intermittently measured. The mean of rectal temperature was significantly different (p˂ 0.05) at 0hr Post Vaccination [1]" in groups D and E (39.5 ±â€¯0.15 °C and 39.4 ±â€¯0.15 °C respectively) and at 3 h PV in groups C, D and E (39.8 ±â€¯0.14 °C, 39.9 ±â€¯0.14 °C and 40.3 ±â€¯0.14 °C respectively) compared to the control group. This indicated a sharp increased rectal temperatures between 0hr and 3 h PV in groups C, D and E which later declined at 24 h PV. The mean of rectal temperature of group E was significantly different (p˂ 0.05) at weeks 1 and 2 PV (39.87 ±â€¯0.19 °C and 39.80 ±â€¯0.18 °C respectively) compared to the control group. The mean of heart rate was significantly different (p˂ 0.05) at week 1 PV in groups D and E (83.0 ±â€¯3.8 beats/minute and 80.0 ±â€¯3.8 °C respectively) compared to control. A trending decrease was however observed in heart rates of group E from weeks through 4 PV and in group D from weeks 1 through 3 PV. The mean of respiratory rates was significantly different (p˂ 0.05) at week 3 PV in group B and D (31.0 ±â€¯1.2 breaths/minute and 28.0 ±â€¯1.2 breaths/minute) compared to control. In conclusion, this study highlights responses of these vital signs due to vaccination against S. aureus causing mastitis in cows. To the best of our knowledge the findings of this study adds value to the shallow literature on vital signs alterations in cows vaccinated against mastitis as elevated levels of temperature and heart rates of group D and E indicated obvious response.

Molecular analysis of fragile X syndrome (FXS) among Malaysian patients with developmental disability.

Fragile X syndrome (FXS) is a neurodevelopmental disorder commonly found worldwide, caused by the silencing of fragile X mental retardation 1 (FMR1) gene on the X-chromosome. Most of the patients lost FMR1 function due to an expansion of cytosine-guanine-guanine (CGG) repeat at the 5' untranslated region (5'UTR) of the gene. The purpose of this study is to identify the prevalence of FXS and characterize the FMR1 gene CGG repeats distribution among children with developmental disability in Malaysia. Genomic DNA of 2201 samples from different ethnicities (Malays, Chinese, Indian and others) of both genders were PCR-amplified from peripheral blood leukocytes based on specific primers at 5'UTR of FMR1 gene. Full mutations and mosaics were successfully identified by triple methylation specific PCR (ms-PCR) and subsequently verified with FragilEase kit. The findings revealed for the first time the prevalence of FXS full mutation in children with developmental disability in Malaysia was 3.5%, a slightly higher figure as compared to other countries. Molecular investigation also identified 0.2% and 0.4% probands have permutation and intermediate alleles, respectively. The CGG repeats length observation showed 95% of patients had normal alleles within 11 to 44 CGG repeats; with 29 repeats found most common among Malays and Indians while 28 repeats were most common among Chinese. In conclusion, this is the first report of prevalence and characterisation of CGG repeats that reflects genetic variability among Malaysian ethnic grouping.

Microwave bio-sensor based on symmetrical split ring resonator with spurline filters for therapeutic goods detection.

A novel symmetrical split ring resonator (SSRR) based microwave sensor with spurline filters for detecting and characterizing the properties of solid materials has been developed. Due to the weak perturbation in the interaction of material under test (MUT) and planar microwave sensor, spurline filters were embedded to the SSRR microwave sensor which effectively enhanced Q-factor with suppressing the undesired harmonic frequency. The spurline filter structures force the presented sensor to resonate at a fundamental frequency of 2.2 GHz with the capabilities of suppressing rejected harmonic frequency and miniaturization in circuit size. A wide bandwidth rejection is achieved by using double spurlines filters with high Q-factor achievement (up to 652.94) compared to single spurline filter. The new SSRR sensor with spurline filters displayed desired properties such as high sensitivity, accuracy, and performance with a 1.3% typical percentage error in the measurement results. Furthermore, the sensor has been successfully applied for detecting and characterizing solid materials (such as Roger 5880, Roger 4350, and FR4) and evidently demonstrated that it can suppress the harmonic frequency effectively. This novel design with harmonic suppression is useful for various applications such as food industry (meat, fruit, vegetables), biological medicine (derived from proteins and other substances produced by the body), and Therapeutic goods (antiseptics, vitamins, anti-psychotics, and other medicines).

Duplication 17p11.2 (Potocki-Lupski Syndrome) in a child with developmental delay.

Potocki-Lupski syndrome (PTLS), also known as duplication 17p11.2 syndrome, trisomy 17p11.2 or dup(17)(p11.2p11.2) syndrome, is a developmental disorder and a rare contiguous gene syndrome affecting 1 in 20,000 live births. Among the key features of such patients are autism spectrum disorder, learning disabilities, developmental delay, attention-deficit disorder, infantile hypotonia and cardiovascular abnormalities. Previous studies using microarray identified variations in the size and extent of the duplicated region of chromosome 17p11.2. However, there are a few genes which are considered as candidates for PTLS which include RAI1, SREBF1, DRG2, LLGL1, SHMT1 and ZFP179. In this report, we investigated a case of a 3-year-old girl who has developmental delay. Her chromosome analysis showed a normal karyotype (46,XX). Analysis using array CGH (4X44 K, Agilent USA) identified an ~4.2 Mb de novo duplication in chromosome 17p11.2. The result was confirmed by fluorescence in situ hybridization (FISH) using probes in the critical PTLS region. This report demonstrates the importance of microarray and FISH in the diagnosis of PTLS.

Presence of methicillin resistance and heteroresistance among Coagulase Negative Staphylococci (CoNS) isolates obtained from Health Sciences students at a Public University.

This study was carried out to investigate the Coagulase Negative Staphylococci (CoNS) nasal carriage and the presence of methicillin resistant Coagulase Negative Staphylococci (MR-CoNS) among health sciences students at Faculty of Medicine and Health Sciences, Universiti Putra Malaysia. A total of 120 isolates of CoNS (62.5%) was isolated from 192 student volunteers. The mecA gene was detected in 15 isolates of CoNS (12.5%). Eight out of the 15 isolates of mecA positive CoNS were resistant to cefoxitin in disc diffusion test whereas the remaining seven isolates of mecA positive CoNS were susceptible to cefoxitin. Analysis of questionnaires showed no significant association between CoNS nasal carriage and the socio-demographic and risk factors except for the genders and history of cold (P < 0.050). Generally, this finding showed a relatively low level of methicillin resistance among CoNS nasal carriage from student volunteers.

Presence of methicillin resistance and heteroresistance among Coagulase Negative Staphylococci (CoNS) isolates obtained from Health Sciences students at a Public University

This study was carried out to investigate the Coagulase Negative Staphylococci (CoNS) nasal carriage and the presence of methicillin resistant Coagulase Negative Staphylococci (MR-CoNS) among health sciences students at Faculty of Medicine and Health Sciences, Universiti Putra Malaysia. A total of 120 isolates of CoNS (62.5%) was isolated from 192 student volunteers. The mecA gene was detected in 15 isolates of CoNS (12.5%). Eight out of the 15 isolates of mecA positive CoNS were resistant to cefoxitin in disc diffusion test whereas the remaining seven isolates of mecA positive CoNS were susceptible to cefoxitin. Analysis of questionnaires showed no significant association between CoNS nasal carriage and the socio-demographic and risk factors except for the genders and history of cold (P < 0.050). Generally, this finding showed a relatively low level of methicillin resistance among CoNS nasal carriage from student volunteers.

Antinociception of petroleum ether fraction derived from crude methanol extract of Melastoma malabathricum leaves and its possible mechanisms of action in animal models.

BACKGROUND: Melastoma malabathricum L. (family Melastomaceae) has been traditionally used as remedies against various ailments including those related to pain. The methanol extract of M. malabathricum leaves has been proven to show antinociceptive activity. Thus, the present study aimed to determine the most effective fraction among the petroleum ether- (PEMM), ethyl acetate- (EAMM) and aqueous- (AQMM) fractions obtained through successive fractionation of crude, dried methanol extract of M. malabathricum (MEMM) and to elucidate the possible mechanisms of antinociception involved. METHODS: The effectiveness of fractions (100, 250 and 500 mg/kg; orally) were determine using the acetic acid-induced abdominal constriction test and the most effective extract was further subjected to the hot plate- or formalin-induced paw licking-test to establish its antinociceptive profile. Further elucidation of the role of opioid and vanilloid receptors, glutamatergic system, and nitric oxide/cyclic guanosine phosphate (NO/cGMP) pathway was also performed using the appropriate nociceptive models while the phytoconstituents analyses were performed using the phytochemical screening test and, HPLC-ESI and GCMS analyses. RESULTS: PEMM, EAMM and AQMM significantly (p < 0.05) attenuated acetic acid-induced nociception with the recorded EC50 of 119.5, 125.9 and 352.6 mg/kg. Based on the EC50 value, PEMM was further studied and also exerted significant (p < 0.05) antinociception against the hot plate- and formalin-induced paw licking-test. With regards to the mechanisms of antinociception,: i) PEMM significantly (p < 0.05) attenuated the nociceptive action in capsaicin- and glutamate-induced paw licking test.; ii) naloxone (5 mg/kg), a non-selective opioid antagonist, failed to significantly (p < 0.05) inhibit PEMM's antinociception iii) L-arginine (a nitric oxide precursor), but not NG-nitro-L-arginine methyl esters (L-NAME; an inhibitor of NO synthase), methylene blue (MB; an inhibitor of cGMP), or their respective combination, significantly (p < 0.05) reversed the antinociception of PEMM. Phytochemical analyses revealed the presence of several antinociceptive-bearing bioactive compounds, such as triterpenes and volatile compounds like oleoamide and palmitic acid. The presence of low flavonoids, such as gallocatechin and epigallocatechin, saponins and tannins in PEMM might synergistically contribute to enhance the major compounds antinociceptive effect. CONCLUSION: PEMM exerted a non-opioid-mediated antinociceptive activity at the central and peripheral levels via the inhibition of vanilloid receptors and glutamatergic system, and the activation of NO-mediated/cGMP-independent pathway. Triterpenes, as well as volatile oleoamide and palmitic acid, might be responsible for the observed antinociceptive activity of PEMM.