Displaying publications 1 - 20 of 23 in total

Abstract:
Sort:
  1. Er HM, Cheng EH, Radhakrishnan AK
    J Ethnopharmacol, 2007 Sep 25;113(3):448-56.
    PMID: 17698306
    The anti-proliferative effects of the aqueous and methanol extracts of leaves of Pereskia bleo (Kunth) DC (Cactaceae) against a mouse mammary cancer cell line (4T1) and a normal mouse fibroblast cell line (NIH/3T3) were evaluated under an optimal (in culture medium containing 10% foetal bovine serum (FBS)) and a sub-optimal (in culture medium containing 0.5% FBS) conditions. Under the optimal condition, the aqueous extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in 4T1 cells and 300 microg/mL in NIH/3T3 cells, whereas the methanol extract did not show any notable anti-proliferative effect in these cell lines, at any of the concentrations tested. Under the sub-optimal condition, the aqueous extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in NIH/3T3 cells, whilst the methanol extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in both cell lines. An upward trend of apoptosis was observed in both 4T1 and NIH/3T3 cells treated with increasing concentrations of the aqueous extract. The level of apoptosis observed at all the concentrations of the aqueous extract tested was consistently higher than necrosis. There was a significant (p<0.05) increase in the level of necrosis observed in the 4T1 cells treated with 300 microg/mL of the methanol extract. Generally, the level of necrosis was noted to be higher than that of apoptosis in the methanol extract-treated cells. The mutagenicity assay performed showed that in the absence of S-9 liver metabolic activation, the extract was not mutagenic up to the concentration of 165 microg/mL . However, in the presence of S-9 liver metabolic activation, the aqueous extract was mutagenic at all the concentrations tested. This study shows that both the aqueous and methanol extracts of the leaves from Pereskia bleo (Kunth) DC (Cactaceae) do not have appreciable anti-proliferative effect on the 4T1 and NIH/3T3 cells as the EC(50) values obtained are greater than 50 microg/mL when tested under optimal culture condition. Moreover, the aqueous extract may form mutagenic compound(s) upon the metabolisation by liver enzymes.
  2. Er HM, Wong PS, Nadarajah VD
    BMC Med Educ, 2023 Jun 02;23(1):397.
    PMID: 37268906 DOI: 10.1186/s12909-023-04368-0
    BACKGROUND: Open book examinations have been used to assess students' higher order cognitive skills. These examinations can be conducted online remotely with the advancement of technology. However, there are concerns regarding its validity and reliability particularly if the examinations are not proctored. The objective of this study was to explore the perceptions of faculty and students in health professions programmes about remote online open book examinations (ROOBE).

    METHODS: Semi-structured interviews were conducted among 22 faculty staff who were involved in ROOBE in health professions programmes. All interviews were audio recorded, transcribed verbatim and analysed using a thematic analysis approach. The perceptions of 249 medical students were obtained using an online questionnaire after they completed ROOBE.

    RESULTS: The faculty agreed that open book examinations could promote students' higher order cognitive skills and reduce students' stress. However, they were concerned about students' academic integrity during non-invigilated ROOBE which could affect recognition by accreditation and professional bodies. The shift from traditional practice of closed-book examinations to ROOBE required change management with the support of guidelines and faculty training.  Majority of the students claimed that the examinations were challenging as they assessed their ability to apply knowledge in real world problems. Nevertheless, they preferred ROOBE due to less anxiety and memorisation, and more emphasis on problem solving skills. The shortcomings were insufficient time for information searching during examinations and uncertainty in preparedness for future practice as they focused less on memorisation of factual knowledge during examination preparation. Cheating among peers and internet instability during non-invigilated ROOBE were the concerns highlighted by some students.

    CONCLUSIONS: Faculty and students expressed favourable views about ROOBE in promoting higher order cognitive skills. Adequate technological support was essential during ROOBE. While there was a need to address issues related to academic integrity, ROOBE could be included as an authentic assessment within the systems of assessment.

  3. Kok YY, Er HM, Nadarajah VD
    Med Sci Educ, 2021 Dec;31(6):1919-1929.
    PMID: 34518785 DOI: 10.1007/s40670-021-01364-1
    The achievement of learning goals via laboratory practical depends on both extrinsic and intrinsic factors. They could be limited by laboratory time, incurred cost, safety, self-efficacy, inadequate prior preparation by learners, and different learning styles. Hence, virtual laboratory simulation (vLAB) may be an appropriate e-learning tool to overcome these restrictions. In this study, student's perception of the usefulness of vLAB was determined by using deoxyribonucleic acid (DNA) gel electrophoresis and polymerase chain reaction (PCR) as case examples. The perception of Year 2 and 3 health science undergraduate students' (N = 87) was studied using a questionnaire consisting of 12 items, rated on a 5-point Likert-scale. The attainment of learning outcomes was assessed using pre-and post-tests containing multiple-choice questions (MCQs). In addition, student's experience and learning from the vLAB were further explored using qualitative analysis. Although there was no significant difference between the mean scores of the pre-and post-tests, results showed that all participants perceived vLAB well, with a median score of 4 (Agree) for all items in the questionnaire. It provides a meaningful learning experience and an authentic environment where students feel safe to practice what they have learnt in lectures. Moreover, vLAB facilitates individualised learning and enhances self-efficacy among students. In conclusion, vLAB prepares students for physical laboratory sessions by activating the prehension dimension of Kolb's learning cycle, therefore complementing and strengthening the attainments of health sciences laboratory learning goals and outcomes.
  4. Hussan F, Er HM, Nadarajah VD
    BMC Med Educ, 2024 Nov 22;24(1):1347.
    PMID: 39574101 DOI: 10.1186/s12909-024-06284-3
    BACKGROUND: Learning analytics (LA) is a tool for gathering, analysing, and interpreting data related to student's learning behaviour, engagement, and performance. As the student data collected by the institutions are used to construct LA, it is essential to understand the acceptance and readiness of the students regarding the implementation of LA.

    METHODS: A sequential mixed method research design was used in this study. A validated questionnaire was distributed to undergraduate students of Medicine, Dentistry and Pharmacy programmes to collect their general views on LA. Focus group interviews with a total of 18 students were conducted to explore their perceptions in depth, followed by thematic analysis of the transcribed data.

    RESULTS: Generally, the students were aware of their demographic data, utilisation of learning management system and academic performance data being collected by the university. They were agreeable for collection of those data which had direct association with their learning to be used for LA. However, they expressed concerns about the privacy, confidentiality, and security of the collected data. Three themes emerged from the interviews, i.e., self-regulated learning, evidence-based decision making and data management. The students perceived that LA could help them to monitor achievement of learning outcomes and provide support for individualised learning paths through recommendations of learning resources and learning motivation. They also opined that LA could help educators and institutions by providing feedback on teaching and learning methods, resource allocation and interventions to create conducive learning environment.

    CONCLUSIONS: LA is a useful tool to support self-regulated learning, however, precautions should be exercised during implementation to ensure data privacy and security.

  5. Chen J, Er HM, Mohamed SM, Chen YS
    Biomed J, 2015 Jul-Aug;38(4):301-6.
    PMID: 25673170 DOI: 10.4103/2319-4170.151031
    BACKGROUND: Euphorbia hirta has been reported to possess anti-inflammatory activity. This study was carried out to determine the prostaglandin E 2 (PGE 2 ) inhibition activity of the fractions of the E. hirta aqueous extract on rabbit synovial fibroblast cells (HIG-82).
    METHODS: E. hirta aqueous extract was fractionated into five fractions (fractions A, B, C, D, and E) by reversed phase flash chromatography. Rabbit synovial fibroblast cells (HIG-82) were activated with phorbol myristate acetate and treated with the fractions. The amount of PGE 2 released into the medium was measured by enzyme-linked immunosorbent assay.
    RESULTS: Fraction A (0.1, 1, and 10 μg/ml) had the greatest PGE 2 inhibitory effect among the five fractions, and showed a greater extent of PGE 2 inhibition compared to the aqueous extract. In contrast, Fraction E had the greatest stimulatory effect on PGE 2 release.
    CONCLUSIONS: Fraction A of the aqueous extract inhibited the production of PGE 2 from activated HIG-82 cells to a greater extent than the crude aqueous extract. Bioactive compounds with anti-inflammatory activity are likely to be concentrated in Fraction A of E. hirta aqueous extract.
  6. Loh DS, Er HM, Chen YS
    J Ethnopharmacol, 2009 Dec 10;126(3):406-14.
    PMID: 19778596 DOI: 10.1016/j.jep.2009.09.025
    Euphorbia hirta (E. hirta) is a weed commonly found in tropical countries and has been used traditionally for asthma, bronchitis and conjunctivitis. However, one of the constituents in this plant, quercetin, was previously reported to be mutagenic. This work aimed to determine the level of quercetin in the aqueous and methanol plant extracts and to investigate the mutagenic effects of quercetin and the extracts in the Ames test utilising the mutant Salmonella typhimurium TA98 and TA100 strains. The antimutagenic activity of Euphorbia hirta aqueous and methanol extracts was also studied in Salmonella typhimurium TA98. HPLC analyses showed that quercetin and rutin, a glycosidic form of quercetin, were present in the acid-hydrolysed methanol extract and non-hydrolysed methanol extract respectively. The quercetin concentration was negligible in both non-hydrolysed and acid-hydrolysed aqueous extracts. The total phenolic contents in Euphorbia hirta were determined to be 268 and 93 mg gallic acid equivalent (GAE) per gram of aqueous and methanol extracts, respectively. Quercetin (25 microg/mL) was found to be strongly mutagenic in Salmonella typhimurium TA98 in the absence and presence of S-9 metabolic activation. However, both the aqueous and methanol extracts did not demonstrate any mutagenic properties when tested with Salmonella typhimurium TA98 and TA100 strains at concentrations up to 100 microg/mL in the absence and presence of S-9 metabolic activation. In the absence of S-9 metabolic activation, both the extracts were unable to inhibit the mutagenicity of the known mutagen, 2-nitrofluorene, in Salmonella typhimurium TA98. On the other hand, the aqueous extracts at 100 microg/mL and methanol extracts at 10 and 100 microg/mL exhibited strong antimutagenic activity against the mutagenicity of 2-aminoanthracene, a known mutagen, in the presence of S-9 metabolic activating enzymes. The results indicated that these extracts could modulate the xenobiotic metabolising enzymes in the liver at the higher concentrations.
  7. Er HM, Nadarajah VD, Ng SH, Wong AN
    Korean J Med Educ, 2020 Sep;32(3):185-195.
    PMID: 32723985 DOI: 10.3946/kjme.2020.166
    PURPOSE: Direct student involvement in quality processes in education has been suggested to encourage shared responsibilities among faculty and students. The objectives of this study were to explore undergraduate health professions students' understanding of quality assurance (QA) in education, and identify the challenges and enablers for student involvement in an Asian context.

    METHODS: Twenty semi-structured interviews were conducted among medical, dentistry, and pharmacy students in a Malaysian University. The interviews were audio-recorded, transcribed verbatim, and thematically analyzed to understand the students' perspectives of QA in education.

    RESULTS: The participants recognized the importance of QA towards ensuring the quality of their training, which will consequently impact their work readiness, employability, and quality of healthcare services. Academic governance, curriculum structure, content and delivery, faculty and student quality, teaching facilities, and learning resources were indicated as the QA areas. The challenges for students' involvement included students' attitude, maturity, and cultural barrier. To enhance their buy-in, clear objectives and impact, efficient QA mechanism, and recognition of students' contribution had been suggested.

    CONCLUSION: The findings of this study support student-faculty partnership in QA processes and decision making.

  8. Ramamurthy S, Er HM, Devi Nadarajah V, Radhakrishnan AK
    Med Teach, 2021 Jul;43(sup1):S6-S11.
    PMID: 31408404 DOI: 10.1080/0142159X.2019.1646894
    BACKGROUND: Lifelong learning (LL) is an important outcome of medical training. The objective of this study is to measure the orientation of medical students toward LL and to determine the types of self-directed learning (SDL) activities that contribute toward LL skills.

    METHODS: The Jefferson Scale of Physician Lifelong Learning for medical student (JeffSPLL-MS) questionnaire was used. Factor analysis was performed, Cronbach's alpha and effect size were calculated. The types of learning activities that contribute to LL skills were identified.

    RESULTS: Three-factor structure emerged from the factor analysis and were identified as learning beliefs and motivation, skills in seeking information and attention to learning opportunities. A significant increase (p 

  9. Er HM, Jia Ming MK, Keng PS, Nadarajah VD
    Am J Pharm Educ, 2019 Aug;83(6):6851.
    PMID: 31507283 DOI: 10.5688/ajpe6851
    Objective. To evaluate pharmacy students' perceptions of the educational value of reflective portfolio and to gain an understanding of the factors that might influence these perceptions. Methods. Bachelor of Pharmacy (BPharm) students' perceptions of using reflective portfolios were evaluated by administering the same questionnaire at the beginning of years 2, 3 and 4 of the curriculum. Statistical analysis was carried out to determine the differences among the perception scores of different academic years. Semi-structured interviews were completed with fourth-year students to further explore their experiences with the reflective portfolio. Students' deep information processing (DIP) skills were compared with those of students from another pharmacy cohort whose curriculum did not include a reflective portfolio. Results. The students' perceptions of the reflective portfolio improved significantly as they progressed from year 2 to year 4 of the curriculum. The factors that contributed to a positive experience were a clear understanding of objectives and guidelines for the reflective portfolio, useful mentor feedback, a positive learning attitude and motivation, and having a user-friendly technology platform for submission of the portfolio. The students' DIP skills after completing the reflective portfolio were higher than those of students who did not have a reflective portfolio assignment in their curriculum. Conclusion. Pharmacy students' appreciation of the educational value of a reflective portfolio increased as they progressed to their final year, and their DIP skills improved. These findings support the use of a reflective portfolio as a learning tool for BPharm students' personal and professional development.
  10. Er HM, Nadarajah VD, Raben R, Kamarudin NH
    Med Educ, 2024 Aug 30.
    PMID: 39212298 DOI: 10.1111/medu.15499
  11. Lee KH, Chen YS, Judson JP, Chakravarthi S, Sim YM, Er HM
    Malays J Pathol, 2008 Dec;30(2):95-102.
    PMID: 19291918 MyJurnal
    The effect of water extracts of Euphorbia hirta on the histological features and expressions of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in the rat articular cartilage was investigated. Arthritis was induced in rats using Freund's Complete Adjuvant containing heat-killed M. tuberculosis, and treated with water extracts of E. hirta. Paraffin tissue sections of the arthritic joints were evaluated. The extent of cartilage degeneration was found to be greatest in rats treated with the highest dosage of E. hirta, followed by rats in the untreated group. Rats treated with the intermediary and low dosages of Euphorbia hirta showed improved histology. MMP-13 levels were found to be decreased with decreasing dosages of E. hirta. TIMP-1 levels were found to increase with decreasing dosages of E. hirta. MMP-3 levels fluctuated without any appreciable pattern. Low dosages of E. hirta seem to be beneficial in reducing cartilage degeneration in cases of arthritis.
  12. Nadarajah VD, Sow CF, Syed Aznal SS, Montagu A, Boursicot K, Er HM
    J Med Educ Curric Dev, 2020 11 19;7:2382120520970894.
    PMID: 33283046 DOI: 10.1177/2382120520970894
    A preparatory framework called EASI (Evaluate, Align, Student-centred, Implement and Improve) was developed with the aim of creating awareness about interim options and implementation opportunities for online Clinical and Communication Skills (CCS) learning. The framework, when applied requires faculty to evaluate current resources, align sessions to learning outcomes with student-centred approaches and to continuously improve based on implementation experiences. Using the framework, we were able to generate various types of online CCS learning sessions for implementation in a short period of time due to the recent Covid-19 pandemic. Importantly we learnt a few lessons post-implementation from both students and faculty perspective that will be used for planning and delivery of future sessions. In summary, the framework was useful for creating or redesigning CCS sessions which were disrupted during the pandemic, however post-implementation experience suggests the framework can also be used for future solutions in online CCS learning as healthcare systems and delivery are increasingly decentralised and widely distributed.
  13. Mamat NH, Nadarajah VD, Er HM, Ramamurthy S, Pook PCK
    Med Teach, 2021 Jul;43(sup1):S25-S32.
    PMID: 31491355 DOI: 10.1080/0142159X.2019.1654089
    BACKGROUND: Student evaluation of the learning environment is important to enhance learning experiences. Programs such as Pharmacy use feedback from the evaluation to identify teaching-learning issues and use it to improve the quality of the learning experiences. The article aims to explore the general observations from the evaluation; to identify how the feedback is used to improve the learning environment and to identify lessons for educators in managing and using the feedback.

    METHODS: A cross-sectional data analysis of Pharmacy students' learning environment from 2011-2015 based on data from module, faculty, IMU-REEM and Student Barometer Survey was applied. Feedback obtained from the data was triangulated to establish commonalities/differences of the issues.

    RESULTS: Based on the analysis, issues affecting Pharmacy student learning experiences were identified. The identified issues included teaching by subject matter experts, pedagogical delivery and physical learning environment. Seven lessons were presented for educators to assess the practicality of the feedback.

    CONCLUSIONS: The feedback serves as a means to improve the Pharmacy program. Nonetheless, the challenges lie between the ideal and realistic expectations of students in optimizing the learning experiences. Lessons acquired from the evaluation of the learning environment are essential for educators in managing and using the information.

  14. Er HM, Nadarajah VD, Chen YS, Misra S, Perera J, Ravindranath S, et al.
    Med Teach, 2021 Jul;43(sup1):S12-S17.
    PMID: 31522577 DOI: 10.1080/0142159X.2019.1659942
    Outcome-based education (OBE) has brought along a significant development in health professions education in the past decade. The shift from a process-driven to product-driven model of education is valuable for ensuring graduate quality and facilitating global movement of healthcare workers. Such a model can align the expectations of key stakeholders in an era of rapid knowledge expansion and technological advancement. Nevertheless, the experienced benefits of OBE depend on the effectiveness of its implementation. This article therefore provides practical tips and strategies for implementing OBE in order to maximize its potential.
  15. Er HM, Nadarajah VD, Hays RB, Yusoff N, Loh KLY
    Med Sci Educ, 2019 Dec;29(4):1103-1108.
    PMID: 34457589 DOI: 10.1007/s40670-019-00802-5
    Challenges in assessment implementation include assessment blueprinting, accuracy and timeliness of result processing, item analysis and personalised feedback. These challenges were addressed by an online assessment system (OAS) that translates the educational framework of outcome-based education (OBE) into an integrated platform applicable across academic programmes. OBE principles of transparency, measurability, relevance, and individualisation was feasibly addressed using technology. The system development required continuous stakeholder engagement and feedback. Its implementation involved change management at institutional level with shifts in procedures, responsibilities, staff competencies and resource allocation. This article describes approaches taken and the lessons learned in developing and implementing OAS to enhance assessment practice for medical science programmes.
  16. Tan DM, Fu JY, Wong FS, Er HM, Chen YS, Nesaretnam K
    Nanomedicine (Lond), 2017 Oct;12(20):2487-2502.
    PMID: 28972460 DOI: 10.2217/nnm-2017-0182
    AIM: To develop 6-O-palmitoyl-ascorbic acid-based niosomes targeted to transferrin receptor for intravenous administration of tocotrienols (T3) in breast cancer.

    MATERIALS & METHODS: Niosomes were prepared using film hydration and ultrasonication methods. Transferrin was coupled to the surface of niosomes via chemical linker. Nanovesicles were characterized for size, zeta potential, morphology, stability and biological efficacy.

    RESULTS: When evaluated in MDA-MB-231 cells, entrapment of T3 in niosomes caused 1.5-fold reduction in IC50 value compared with nonformulated T3. In vivo, the average tumor volume of mice treated with tumor-targeted niosomes was 12-fold lower than that of untreated group, accompanied by marked downregulation of three genes involved in metastasis.

    CONCLUSION: Findings suggested that tumor-targeted niosomes served as promising delivery system for T3 in cancer therapy.

  17. Shankar PR, Azhar T, Nadarajah VD, Er HM, Arooj M, Wilson IG
    Korean J Med Educ, 2023 Sep;35(3):235-247.
    PMID: 37670520 DOI: 10.3946/kjme.2023.262
    PURPOSE: The perception of faculty members about an individually tailored, flexible-length, outcomes-based curriculum for undergraduate medical students was studied. Their opinion about the advantages, disadvantages, and challenges was also noted. This study was done to help educational institutions identify academic and social support and resources required to ensure that graduate competencies are not compromised by a flexible education pathway.

    METHODS: The study was done at the International Medical University, Malaysia, and the University of Lahore, Pakistan. Semi-structured interviews were conducted from 1st August 2021 to 17th March 2022. Demographic information was noted. Themes were identified, and a summary of the information under each theme was created.

    RESULTS: A total of 24 (14 from Malaysia and 10 from Pakistan) faculty participated. Most agreed that undergraduate medical students can progress (at a differential rate) if they attain the required competencies. Among the major advantages mentioned were that students may graduate faster, learn at a pace comfortable to them, and develop an individualized learning pathway. Several logistical challenges must be overcome. Providing assessments on demand will be difficult. Significant regulatory hurdles were anticipated. Artificial intelligence (AI) can play an important role in creating an individualized learning pathway and supporting time-independent progression. The course may be (slightly) cheaper than a traditional one.

    CONCLUSION: This study provides a foundation to further develop and strengthen flexible-length competency-based medical education modules. Further studies are required among educators at other medical schools and in other countries. Online learning and AI will play an important role.

  18. Wong JY, Chen YS, Chakravarthi S, Judson JP, L SR, Er HM
    Exp Ther Med, 2013 Nov;6(5):1247-1250.
    PMID: 24223653
    Euphorbia hirta is widely used in traditional remedies and has been used cross-culturally for generations against maladies such as asthma, skin ailments and hypertension. Previous studies have demonstrated that Euphorbia hirta has antibacterial activity, and have also indicated certain antimolluscidal, antimalarial and anti-inflammatory properties, the latter of which have been suggested to be more pronounced than those of the rheumatological drug, etanercept. To date, no studies have identified the anatomical effects of this herb on the organs of test animals. This study aimed to identify the effects of Euphorbia hirta on the ultrastructure of the murine liver, kidney and aorta. A total of 32 adult male Sprague-Dawley rats were divided into four groups; three groups were fed with aqueous extracts of Euphorbia hirta at doses of 1, 10 and 50 mg/kg, respectively, every alternate day for 50 days, while one group served as a control. The animals were later sacrificed and the liver, kidney and aorta harvested for examination by electron microscopy. The aorta showed no ultrastructural changes across the groups. Renal and hepatic tissue from the treated groups demonstrated dose-dependent injuries, which showed architectural damage beginning in the nuclei and spreading outwards. Taking into consideration the properties of Euphorbia hirta that have been described in previous studies, in addition to the results from the present study, it appears that the herb may exhibit similar effects to those of the quinolone group of antibiotics. Further in-depth investigations are required into the potential effects of Euphorbia hirta, deleterious and otherwise.
  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.

Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links