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  1. Mohd Adnan LH, Abu Bakar NH, Simbak N, Mohamad N, Ismail R, Ahmad NZ, et al.
    Iran J Basic Med Sci, 2020 Jul;23(7):849-852.
    PMID: 32774804 DOI: 10.22038/ijbms.2020.41678.9841
    Opioids, amphetamines, and other types of substances have been widely abused around the world. Opioid dependence and tolerance are two distinct phenomena that have been associated with substance abuse issues. The management of its adverse consequences is becoming more challenging. More and more people are treated in Methadone Maintenance Therapy (MMT) program yet the issues are still unresolved. Researchers are continuing to study the best formulation in treating opioid dependent people starting with modern and alternative drug therapies. Since 2008 , thymoquinone (TQ) has been extensively studied by researchers around the world and has emerged to be a new potential drug candidate in managing substance abuse issues. Thus, the aim of this article is to review the effects that TQ may have on opioid dependent subjects and other abused substances such as amphetamine may have been studied. All of the articles from 2008 until 2019 involving the effects of TQ on substance abuse from Google Scholar®, Scopus®, and Pubmed® databases have been searched and reviewed. The keywords used were thymoquinone, opioid dependence, amphetamine, and Nigella sativa. The research results also have been discussed in this article. Based on the research conducted, TQ was effective in reducing the adverse health consequences associated with substance abuse such as withdrawal symptoms, tolerance, and cell damages. It is concluded that TQ could be a potential drug that can be complemented with the currently available drugs in substance abuse therapies.
  2. Ooi HS, Viswanathan S, Botross NP, Eow GB, Chin YT, Kanesalingam R, et al.
    Neurol India, 2020 8 30;68(4):850-855.
    PMID: 32859827 DOI: 10.4103/0028-3886.293469
    Background: The association between appendectomy and multiple sclerosis (MS) is unknown. In this study, we explored the association between appendectomy and MS and neuromyelitis optica spectrum disorder (NMOSD).

    Patients and Methods: MS and NMOSD patients older than 40 were identified from neurology records from hospitals in Malaysia. The diagnoses were based on the Revised McDonald (2010) and Wingerchuk (2015) criteria. Controls were sampled from Malaysia's normal population. Individuals were interviewed telephonically or face-to-face. The age inclusion criterion (over 40) differentiated high or low lifetime risk of appendicitis, as appendicitis incidence is rare after 40.

    Results: 49 MS, 71 NMOSD, and 880 controls met the inclusion criteria. Seventy-two individuals (9 MS, 4 NMOSD, 59 control) had undergone appendectomy. Appendectomy rates were 18.37% in the MS group (95% CI 7.5-29.2%), 5.6% in the NMOSD group (0.3%, 11%), and 6.7% among controls (5.1%, 8.4%), (MS vs NMOSD P = 0.036, MS vs controls P = 0.007). Binary regression analysis showed that MS was an independent risk factor for appendectomy (OR 2.938, 95% CI 1.302, 6.633, P = 0.009). NMOSD showed no association with appendectomy.

    Conclusion: MS is positively associated with appendectomy, unlike ulcerative colitis, which is negatively associated. We hypothesize that there is a commonality in the microflora in persons who have had these two illnesses.

  3. Lugova H, Andoy-Galvan JA, Patil SS, Wong YH, Baloch GM, Suleiman A, et al.
    Community Ment Health J, 2021 11;57(8):1489-1498.
    PMID: 33417170 DOI: 10.1007/s10597-020-00765-7
    Growing prevalence of mental illnesses and the role they play in the global disease burden is an emerging public health issue. The prevalence of depression and anxiety is on the rise in Malaysia. Low-income urban communities are among the key affected populations with regards to mental health problems. This cross-sectional study was aimed to determine the prevalence and severity of depression, anxiety and stress, and their associated factors among adults in the low-income community of Kuala Lumpur, Malaysia. A total of 248 participants aged 18-60 years old were recruited. Data were collected via face-to-face interviews using the Depression, Anxiety and Stress Scale-21 Items (DASS-21). Chi-squared test was used to examine the association between the variables. Multiple ordinal regression model was introduced to identify the predictors of depression, anxiety and stress. The proportions of participants with depression, anxiety and stress were 24.2% (95% CI: 19.6-30.4), 36.3% (95% CI: 29.9-43.0), and 20.6% (95% CI: 15.4-26.5), respectively. There was a statistically significant association of ethnicity (p = 0.002) and age (p = 0.014) with the severity of depression, ethnicity (p = 0.001) and age (p = 0.024) with the severity of anxiety, and ethnicity (p 
  4. Lu HT, Nordin R, Othman N, Choy CN, Kam JY, Leo BC, et al.
    J Med Case Rep, 2016 Aug 10;10(1):221.
    PMID: 27510438 DOI: 10.1186/s13256-016-1018-0
    BACKGROUND: Many cases of cardiac masses have been reported in the literature, but in this case report we described a rare case of biatrial cardiac mass that represented a challenge for diagnosis and therapy. The differentiation between cardiac masses such as thrombi, vegetations, myxomas and other tumors is not always straightforward and an exact diagnosis is important because of its distinct treatment strategy. Transthoracic/esophageal echocardiography and cardiac magnetic resonance play an important role in establishing the diagnosis of cardiac masses. However, no current noninvasive diagnostic tool has the ability to absolutely diagnose cardiac masses; obtaining a pathological specimen by surgical resection of cardiac masses is the only reliable method to diagnose cardiac masses accurately. Our case report is an exception in that the final diagnosis was affirmed by empirical anticoagulation therapy based on clinical judgment and noninvasive characterization of biatrial mass.

    CASE PRESENTATION: We described a 54-year-old Malay man with severe mitral stenosis and atrial fibrillation who presented with a biatrial mass. Transthoracic/esophageal echocardiography and cardiac magnetic resonance detected a large, homogeneous right atrial mass typical of a thrombus, and a left atrial mass adhering to interatrial septum that mimicked atrial myxoma. The risk factors, morphology, location, and characteristics of the biatrial cardiac mass indicated a diagnosis of thrombi. However, our patient declined surgery. As a result, the nature of his cardiac masses was not specified by histology. Of note, his left atrial mass was completely regressed by long-term warfarin, leaving a residual right atrial mass. Thus, we affirmed the most probable diagnosis of cardiac thrombi. During the course of treatment, he had an episode of non-fatal ischemic stroke most probably because of a thromboembolism.

    CONCLUSIONS: Noninvasive characterization of cardiac mass is essential in clarifying the diagnosis and directing treatment strategy. Anticoagulation is a feasible treatment when the clinical assessment, risk factors, and imaging findings indicate a diagnosis of thrombi. After prolonged anticoagulation therapy, complete resolution of biatrial thrombi was achievable in our case.

  5. Onuki M, Yokoyama K, Kimura K, Sato H, Nordin RB, Naing L, et al.
    J Occup Health, 2003 May;45(3):140-5.
    PMID: 14646288
    To assess dermal absorption of nicotine from tobacco leaves in relation to Green Tobacco Sickness (GTS), urinary cotinine concentrations were measured in 80 male tobacco-growing farmers and in 40 healthy males (controls) who did not handle wet tobacco leaves in Kelantan, Malaysia. Among non-smokers, urinary cotinine levels in farmers were significantly higher than those of controls; farmers with urinary cotinine of 50 ng/ml/m2 or above showed eye symptoms more frequently than those below this level (p<0.05). Farmers who did not wear protective equipment had subjective symptoms more frequently than those who used the equipment (p<0.05); some of these symptoms were seen more frequently in organophosphate (Tamaron) users than in non-users. As tobacco farmers evidence a risk of nicotine poisoning from tobacco leaves, assessment including GTS together with effects of pesticides will be necessary.
  6. Zahari Z, Lee CS, Ibrahim MA, Musa N, Mohd Yasin MA, Lee YY, et al.
    Pain Pract, 2017 09;17(7):930-940.
    PMID: 27996183 DOI: 10.1111/papr.12546
    BACKGROUND: Endogenous and exogenous opioids are substrates of the permeability glycoprotein (P-gp) efflux transporter, which is encoded by the ABCB1 (MDR1) gene. Genetic polymorphisms of ABCB1 may contribute to interindividual differences in pain modulation and analgesic responses. We investigated the relationship between ABCB1 polymorphisms and cold pain sensitivity among healthy males.

    METHODS: Cold pain responses, including pain threshold and pain tolerance, were measured using the cold-pressor test (CPT). DNA was extracted from whole blood and genotyped for ABCB1 polymorphisms, including c.1236C>T (rs1128503), c.2677G>T/A (rs2032582), and c.3435C>T (rs1045642), using the allelic discrimination real-time polymerase chain reaction.

    RESULTS: A total of 152 participants were recruited in this observational study. Frequencies of mutated allele for c.1236C>T, c.2677G>T/A, and c.3435C>T polymorphisms were 56.6%, 49.7%, and 43.4%, respectively. Our results revealed an association of the CGC/CGC diplotype (c.1236C>T, c.2677G>T/A, and c.3435C>T) with cold pain sensitivity. Participants with the CGC/CGC diplotype had 90% and 72% higher cold pain thresholds (87.62 seconds vs. 46.19 seconds, P = 0.010) and cold pain tolerances (97.24 seconds vs. 56.54 seconds, P = 0.021), respectively, when compared with those without the diplotype.

    CONCLUSION: The CGC/CGC diplotype of ABCB1 polymorphisms was associated with variability in cold pain threshold and pain tolerance in healthy males.

  7. Zahari Z, Lee CS, Ibrahim MA, Musa N, Mohd Yasin MA, Lee YY, et al.
    Nurs Res, 2017 Mar-Apr;66(2):134-144.
    PMID: 28252574 DOI: 10.1097/NNR.0000000000000204
    BACKGROUND: Methadone is a substrate of the P-glycoprotein efflux transporter, which is encoded by ABCB1 (MDR1), and thus, ABCB1 polymorphisms may influence the transport of methadone at the blood-brain barrier, affecting its adverse effects.

    OBJECTIVES: This study investigated the association between ABCB1 polymorphisms and cold pressor pain responses among opioid-dependent patients on methadone maintenance therapy (MMT).

    METHODS: Malay male opioid-dependent patients receiving MMT (n = 148) were recruited. Cold pressor pain responses (pain threshold, pain tolerance, and pain intensity) were measured at 0, 2, 4, 8, 12, and 24 hours post-methadone dose. DNA was extracted from whole blood and genotyped for ABCB1 polymorphisms including 1236C>T (rs1128503), 2677G>T/A (rs2032582), and 3435C>T (rs1045642) using the allelic discrimination real-time polymerase chain reaction. Repeated-measure analysis of variance between-group analysis was used to compare the three cold pressor pain responses and ABCB1 polymorphisms (1236C>T, 2677G>T/A, and 3435C>T) according to genotypes and allelic additive models, genotype dominant and recessive models, haplotypes, and diplotypes.

    RESULTS: Patients with 2677 GG or 2677G allele had the lowest pain threshold compared with 2677G>T/A genotypes or alleles (p = .007 and .002, respectively). Haplotype analysis showed a significant association between ABCB1 haplotypes and pain threshold (p = .02). Patients with 2677G allele had the lowest pain tolerance compared to those with 2677T and 2677A alleles (2677G < 2677T < 2677A allele carriers; p = .05). In terms of pain intensity scores, patients with 2677 GG or 2677G allele had the highest scores compared to other 2677G>T/A genotypes or alleles (p = .04 and .008, respectively). Haplotype analysis revealed a significant difference between patients with CGC haplotype and those without this haplotype (p = .02).

    DISCUSSION: To the best of our knowledge, this study provides the first evidence that ABCB1 polymorphisms are associated with cold pressor pain responses among Malay male patients with opioid dependence on MMT. The results may provide an initial prediction on heightened pain sensitivity or hyperalgesia for individuals who are carriers of the ABCB1 polymorphisms.
  8. Zahari Z, Lee CS, Ibrahim MA, Musa N, Mohd Yasin MA, Lee YY, et al.
    J Pharm Bioallied Sci, 2020 Nov;12(Suppl 2):S787-S803.
    PMID: 33828379 DOI: 10.4103/jpbs.JPBS_248_19
    Introduction: Dopamine receptor D2 (DRD2) is one of the dopamine receptors that have been studied in relation to opioid dependence. It is possible, therefore, that DRD2 gene (DRD2) polymorphisms influence treatment outcomes of patients with opioid dependence. The objective of this study was to investigate the influence of DRD2 polymorphisms on the clinical outcomes of opioid-dependent patients on methadone maintenance therapy (MMT).

    Materials and Methods: Patients with opioid dependence (n = 148) were recruited from MMT clinics. Pain sensitivity, severity of the opiate withdrawal syndrome, and sleep quality were assessed using cold pressor test (CPT), Subjective Opiate Withdrawal Scale (SOWS-M), and Pittsburgh Sleep Quality Index (PSQI)-Malay, respectively. Deoxyribonucleic acid (DNA) was extracted from whole blood, and then was used for genotyping of Val96Ala, Leu141Leu, Val154Ile, Pro310Ser, Ser311Cys, TaqI A, -141C Ins/Del, and A-241G polymorphisms.

    Results: Among 148 patients, 8.1% (n = 12), 60.8% (n = 90), 27.7% (n = 41), and 29.1% (n = 43) had at least one risk allele for Ser311Cys, TaqI A, -141C Ins/Del, and A-241G polymorphisms, respectively. There were no significant differences in pain responses (pain threshold, tolerance, and intensity), SOWS, and PSQI scores between DRD2 polymorphisms.

    Conclusion: The common DRD2 polymorphisms are not associated with pain sensitivity, severity of the opiate withdrawal syndrome, and sleep quality in patients with opioid dependence on MMT. However, this may be unique for Malays. Additional research should focus on investigating these findings in larger samples and different ethnicity.

  9. Wei AC, Ali MA, Yoon YK, Ismail R, Choon TS, Kumar RS, et al.
    Bioorg Med Chem Lett, 2012 Aug 1;22(15):4930-3.
    PMID: 22749825 DOI: 10.1016/j.bmcl.2012.06.047
    A series of twelve dispiropyrrolidines were synthesized using [3+2]-cycloaddition reactions. The synthesized compounds were screened for their antimycobacterial activity against M. tuberculosis H(37)Rv and INH resistant M. tuberculosis strains using agar dilution method, four of them showed good activity with MIC of less than 1 μM. Compound 4'-[5-(4-fluorophenyl)pyridin-3-yl]-1'-methyldispiro[indan-2,2' pyrrolidine-3',2″-indan]-1,3,1″-trione (4b) was found to be the most active with MIC of 0.1215 and 5.121 μM, respectively.
  10. Ashraf Ali M, Ismail R, Choon TS, Kumar RS, Osman H, Arumugam N, et al.
    Bioorg Med Chem Lett, 2012 Jan 1;22(1):508-11.
    PMID: 22142546 DOI: 10.1016/j.bmcl.2011.10.087
    Pyrrolothiazolyloxindole analogues share vital pharmacological properties, considered useful in Alzheimer's disease (AD). The aim of this study was synthesis and evaluate pyralothiazolyloxindole analogues if possess acetyl cholinesterase (AChE) inhibitory activity. The easily accessible one-pot synthesis of these compounds resulted to be significantly less difficult and expensive than that of donepezil. Several compounds possess anti-cholinesterase activity in the order of micro and sub-micromolar. Particularly, compound was the most potent inhibitors of the series against acetyl cholinesterase enzyme with IC(50) 0.11μmol/L.
  11. Pan Y, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, Pook PC, et al.
    J Ethnopharmacol, 2011 Jan 27;133(2):881-7.
    PMID: 21093571 DOI: 10.1016/j.jep.2010.11.026
    Andrographis paniculata (AP), Centella asiatica (CA) and Orthosiphon stamineus (OS) are three popular herbs traditionally used worldwide. AP is known for the treatment of infections and diabetes and CA is good for wound healing and healthy skin while OS is usually consumed as tea to treat kidney and urinary disorders. Interaction of these herbs with human cytochrome P450 2C19 (CYP2C19), a major hepatic CYP isoform involved in metabolism of many clinical drugs has not been investigated to date.
  12. Abdullah JM, Hussin AM, Tharakan J, Abdullah MR, Saad R, Kamari Z, et al.
    PMID: 17121309
    The number of cases of neurological disease is expected to rise in the next 10 years, making this the second leading cause of morbidity and mortality after heart disease in Malaysia. The lack of human resources in the neurological field currently serving the Malaysian population may cause a deficiency in specialized care, especially in rural areas where neurological and neurosurgical care may be lacking. Thus, a resolve was made to increase the numbers of specialists by the Universiti Sains Malaysia (USM) with the help of the Ministry of Health of Malaysia. A study was made to evaluate the number of referral centers needed in strategic parts of Malaysia. Our calculation was based on service demands and operative procedures following the guidelines of the Association of British Neurologists (ABN) where 15 minutes of service time was equivalent to 1 unit. Based on 2 million population covered in the state of Kelantan by this University Hospital, 4.27 neurologists are needed to meet service demands with a consultant to population ratio (CPR) of 1:468,384, compared to 7.46 neurosurgeons, with a CPR of 1:268,097. According to the current service demands, one neurologist has to work more than 407 hours per year and one neurosurgeon 1,219 hours per year in our hospital. Hospitals with a larger catchment area would need to have more neurologists and neurosurgeons for optimal care in their area. Thus, more neurologists and neurosurgeons are needed to be produced, since the existing numbers are too small for quality care in Malaysia.
  13. Pan Y, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, Pook PC, et al.
    J Nat Med, 2011 Jul;65(3-4):440-7.
    PMID: 21365364 DOI: 10.1007/s11418-011-0516-z
    We investigated the effects of Andrographis paniculata (AP) extracts and andrographolide on the catalytic activity of three human cDNA-expressed cytochrome P450 enzymes: CYP2C9, CYP2D6 and CYP3A4. In vitro probe-based high performance liquid chromatography assays were developed to determine CYP2C9-dependent tolbutamide methylhydroxylation, CYP2D6-dependent dextromethorphan O-demethylation and CYP3A4-dependent testosterone 6β-hydroxylation activities in the presence and absence of AP extracts and andrographolide. Our results indicate that AP ethanol and methanol extracts inhibited CYP activities more potently than aqueous and hexane extracts across the three isoforms. Potent inhibitory effects were observed on CYP3A4 and CYP2C9 activities (K (i) values below 20 μg/ml). Andrographolide was found to exclusively but weakly inhibit CYP3A4 activity. In conclusion, data presented in this study suggest that AP extracts have the potential to inhibit CYP isoforms in vitro. There was, however, variation in the potency of inhibition depending on the extracts and the isoforms investigated.
  14. Ali MA, Bastian S, Ismail R, Choon TS, Ali S, Aubry A, et al.
    J Enzyme Inhib Med Chem, 2011 Dec;26(6):890-4.
    PMID: 21395486 DOI: 10.3109/14756366.2011.559945
    A series of pyrazoline derivatives were synthesized and in vitro activity against Mycobacterium tuberculosis H37Rv was carried out. Among the synthesized compounds, compounds (4d) and (4f) 4-aminophenyl-3-(3,4-dimethoxyphenyl)-6,7-dimethoxy-2,3,3a,4-tetrahydroindeno[1,2-c]pyrazol-2-ylmethanone and 4-aminophenyl-6,7-dimethoxy-3-phenyl-2,3,3a,4-tetrahydroindeno[1,2-c]pyrazol-2-ylmethanone were found to be the most active agent against M. tuberculosis H37Rv with a minimum inhibitory concentration of 10 μg/mL.
  15. Ali MA, Ismail R, Choon TS, Yoon YK, Wei AC, Pandian S, et al.
    Acta Pol Pharm, 2011 May-Jun;68(3):343-8.
    PMID: 21648188
    A series of novel 3-(substituted phenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]isoxazole analogues were synthesized by the reaction of 5,6-dimethoxy-2-[(E)-1-phenylmethylidene]-1-indanone with hydroxylamine hydrochloride. The title compounds were tested for their in vitro anti-HIV activity. Among the compounds, (4g) showed a promising anti-HIV activity in the in vitro testing against IIIB and ROD strains. The IC50 of both IIIB and ROD were found to be 9.05 microM and > 125 microM, respectively.
  16. Suresh Kumar R, Ashraf Ali M, Osman H, Ismail R, Choon TS, Yoon YK, et al.
    Bioorg Med Chem Lett, 2011 Jul 1;21(13):3997-4000.
    PMID: 21621414 DOI: 10.1016/j.bmcl.2011.05.003
    Hexacyclic derivatives share vital pharmacological properties, considered useful in Alzheimer's disease. The aim of this study was synthesis and its evaluation for acetyl cholinesterase inhibitory activity of novel hexacyclic analogues. Compound 4f, showed potent inhibitory activity against acetyl cholinesterase enzyme with IC(50) 0.72 μmol/L.
  17. Pan Y, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, Pook PC, et al.
    Chem Biol Interact, 2011 Mar 15;190(1):1-8.
    PMID: 21276781 DOI: 10.1016/j.cbi.2011.01.022
    Orthosiphon stamineus (OS) has been traditionally used to treat diabetes, kidney and urinary disorders, high blood pressure and bone or muscular pain. To assess the possibility of drug-herb interaction via interference of metabolism, effects of four OS extracts of different polarity and three active constituents (sinensetin, eupatorin and rosmarinic acid) on major human cDNA-expressed cytochrome P450 (CYP) enzymes were investigated. Three substrate-probe based high-performance liquid chromatography (HPLC) assays were established to serve as activity markers for CYP2C9, CYP2D6 and CYP3A4. Our results indicate that OS extracts and constituents exhibited differential modulatory effects on different CYPs. While none of the OS components showed significant inhibition on CYP2C9, eupatorin strongly and uncompetitively inhibited CYP2D6 activity with a K(i) value of 10.2μM. CYP3A4 appeared to be the most susceptible enzyme to OS inhibitory effects. It was moderately inhibited by OS dichloromethane and petroleum ether extract with mixed-type and noncompetitive inhibitions (K(i)=93.7 and 44.9μg/mL), respectively. Correlation study indicated that the inhibition was accounted for by the presence of eupatorin in the extracts. When IC(50) values of these extracts were expressed in volume per dose unit to reflect inhibitory effect at recommended human doses from commercially available products, moderate inhibition was also observed. In addition, CYP3A4 was strongly and noncompetitively inhibited by eupatorin alone, with a K(i) value of 9.3μM. These findings suggest that co-administration of OS products, especially those with high eupatorin content, with conventional drugs may have the potential to cause drug-herb interactions involving inhibition of major CYP enzymes.
  18. Kimura K, Yokoyama K, Sato H, Nordin RB, Naing L, Kimura S, et al.
    Ind Health, 2005 Apr;43(2):285-94.
    PMID: 15895843
    We examined the effects of pesticides on the central and peripheral nervous system in the setting of a tobacco farm at a developing country. Maximal motor and sensory nerve conduction velocities (MCV and SCV, respectively) in the median, sural and tibial nerves, postural sway, and brain-evoked potentials (auditory event-related and visual-evoked potentials) were measured in 80 male tobacco farmers and age- and sex-matched 40 controls in Kelantan, Malaysia. Median SCV (finger-wrist) in farmers using Delsen (mancozeb, dithiocarbamate fungicide), who showed significant decrease of serum cholinesterase activities, were significantly lower compared with the controls. Sural SCV in farmers using Fastac (alpha-cypermethrin, pyrethroid insecticide) and median MCV (elbow-wrist) in farmers using Tamex (butralin, dinitroaniline herbicide) were significantly slowed compared with their respective controls. In Delsen (mancozeb, dithiocarbamate) users, the power of postural sway of 0-1 Hz was significantly larger than that in the controls both in the anterior-posterior direction with eyes open and in the right-left direction with eyes closed. The former type of sway was also significantly increased in Tamaron (methamidophos, organophosphorus insecticide) users. In conclusion, nerve conduction velocities and postural sway seem to be sensitive indicators of the effects of pesticides on the central and peripheral nervous system.
  19. Pan Y, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, Pook PC, et al.
    J Ethnopharmacol, 2010 Jul 20;130(2):275-83.
    PMID: 20457244 DOI: 10.1016/j.jep.2010.05.002
    ETHNOPHARMACOLOGICAL RELEVANCE: Centella asiatica (CA) has been widely cultivated as a vegetable or spice in China, Southeast Asia, India, Sri Lanka, Africa, and Oceanic countries and traditionally used for wound healing and maintaining normal blood pressure.

    AIM OF THE STUDY: The present study was carried out to examine the potential modulatory effects of three commercially available active components (asiaticoside, asiatic acid and madecassic acid) and four extracts (aqueous, ethanol, dichloromethane and hexane) of CA on three major cDNA-expressed human cytochrome P450 (CYP) isoforms.

    MATERIALS AND METHODS: High-performance liquid chromatography (HPLC)-based enzyme assays, namely tolbutamide 4-methyhydroxylase, dextromethorphan O-demethylase and testosterone 6beta-hydroxylase assays were developed to probe activities of CYP2C9, CYP2D6 and CYP3A4, respectively. Probe substrates were incubated with or without each active component and extract for each isoform, followed by examination of the kinetics parameters, IC(50) and K(i), to characterize modulatory effects.

    RESULTS: CYP2C9 was more susceptible to inhibitory effects by CA extracts compared to CYP2D6 and CYP3A4. Moderate degree of inhibition was observed in ethanol (K(i)=39.1 microg/ml) and dichloromethane (K(i)=26.6 microg/ml) extracts implying potential risk of interaction when CYP2C9 substrates are consumed with CA products. The two extracts however showed negligible inhibition towards CYP2D6 and CYP3A4 (IC(50)'s of 123.3 microg/ml and above). Similarly CA aqueous and hexane extracts did not significantly inhibit all three isoforms investigated (IC(50)'s of 117.9 microg/ml and above). Among the active constituents investigated, asiatic acid and madecassic acid appeared to selectively inhibit CYP2C9 and CYP2D6 more than CYP3A4. Of particular interest is the potent inhibitory effect of asiatic acid on CYP2C9 (K(i)=9.1 microg/ml). This signifies potential risk of interaction when substrates for this isoform are taken together with CA products with high asiatic acid content. Inhibitions of asiatic acid with the other isoforms and that of madecassic acid with all isoforms were only moderate (K(i)'s ranged from 17.2 to 84.4 microg/ml). On the other hand, the IC(50) values for asiaticoside were high (1070.2 microg/ml or above) for all three isoforms, indicating negligible or low potential of this compound to modulate CYP enzymatic activity.

    CONCLUSION: Centella asiatica extracts and active constituents inhibited CYP2C9, CYP2D6 and CYP3A4 activities with varying potency with CYP2C9 being the most susceptible isoform to inhibition. Significant inhibition was observed for asiatic acid and CA ethanol and dichloromethane extracts, implying involvement of semipolar constituents from CA in the effect. This study suggested that CA could cause drug-herb interactions through CYP2C9 inhibition.

  20. Ali MA, Ismail R, Choon TS, Yoon YK, Wei AC, Pandian S, et al.
    Bioorg Med Chem Lett, 2010 Dec 1;20(23):7064-6.
    PMID: 20951037 DOI: 10.1016/j.bmcl.2010.09.108
    Series of pyrolidine analogues were synthesized and examined as acetylcholinesterase (AChE) inhibitors. Among the compounds, compounds 4k and 6k were the most potent inhibitors of the series. Compound 4k, showed potent inhibitory activity against acetyl cholinesterase enzyme with IC(50) 0.10 μmol/L. Pyrolidine analogues might be potential acetyl cholinesterase agents for AD.
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