Displaying publications 1 - 20 of 36 in total

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  1. Ang HH
    Food Chem Toxicol, 2008 Jun;46(6):1969-75.
    PMID: 18328612 DOI: 10.1016/j.fct.2008.01.037
    The Drug Control Authority (DCA) of Malaysia implemented the phase three registration of traditional medicines on 1 January, 1992. A total of 100 products in various pharmaceutical dosage forms of a herbal preparation, containing Eugenia dyeriana, either single or combined preparations (more than one medicinal plant), were analyzed for the presence of lead contamination, using atomic absorption spectrophotometry. These samples were bought from different commercial sources in the Malaysian market, after performing a simple random sampling. Results showed that 22% of the above products failed to comply with the quality requirement for traditional medicines in Malaysia. Although this study showed that 78% of the products fully complied with the quality requirement for traditional medicines in Malaysia pertaining to lead, however, they cannot be assumed safe from lead contamination because of batch-to-batch inconsistency.
  2. Ang HH, Cheang HS
    Chemotherapy, 1999 Nov-Dec;45(6):446-51.
    PMID: 10567775
    Thirty clones were obtained from five Malaysian Plasmodium falciparum isolates using the limiting dilution method. These clones were then subjected to antimalarial testing using the modified in vitro microtechnique. The results showed that ST 85/B3, GC/C10 and ST 85/A2 clones decreased their susceptibilities to 19, 41 and 28% whilst ST 12/F8, ST 85/B3 and ST 85/B3 clones showed increases of 6, 43 and 21%, respectively, against chloroquine, mefloquine and quinine after cryopreservation. Further results also indicated that GC/B4, GC/B7, GC/C10, ST 85/A5, ST 85/D3, ST 148/F8 clones did not show any change (up to 2 decimal places) against chloroquine, ST 12/D5, ST 12/E8, ST 12/F8, ST 148/A5 clones against quinine after cryopreservation. They, however, maintained their original susceptibilities after cryopreservation.
  3. Ang HH, Cheang HS
    Jpn. J. Pharmacol., 1999 Apr;79(4):497-500.
    PMID: 10361892 DOI: 10.1254/jjp.79.497
    The anxiolytic effect of Eurycoma longifolia Jack in mice was examined. Fractions of E. longifolia Jack extract produced a significant increase in the number of squares crossed (controls= 118.2 +/- 10.2 squares), but significantly decreased both the immobility (controls = 39.4+/- 4.0 sec) and fecal pellets (controls= 12.3 +/-2.1 fecal pellets) when compared with control mice in the open-field test; they significantly increased the number of entries (controls=6.7+/-0.5 entries) and time spent (controls=42.9+/-0.1 sec) in the open arms, but decreased both the number of entries (controls= 13.2+/-0.7 entries) and time spent (controls= 193.4+/-0.7 sec) when compared with the control mice in the closed arms of the elevated plus-maze test. Furthermore, fractions of E. longifolia Jack extract decreased the fighting episodes significantly (controls= 18.0+/-0.4 fighting episodes) when compared with control mice. In addition, these results were found to be consistent with anxiolytic effect produced by diazepam. Hence, this study supports the medicinal use of this plant for anxiety therapy.
  4. Ang HH, Cheang HS
    Arch Pharm Res, 2001 Oct;24(5):437-40.
    PMID: 11693547 DOI: 10.1007/BF02975191
    It has been reported that Eurycoma longifolia Jack commonly known as Tongkat Ali has gained notoreity as a symbol of man's ego and strength by the Malaysian men because it increases male virility and sexual prowess during sexual activities. As such, the effects of 200, 400 and 800 mg/kg of butanol, methanol, water and chloroform fractions of E. longifolia Jack were studied on the laevator ani muscle in both uncastrated and testosterone-stimulated castrated intact male rats after dosing them for 12 consecutive weeks. Results showed that 800 mg/kg of butanol, methanol, water and chloroform fractions of E. longifolia Jack significantly increased (p<0.05) the leavator ani muscle to 58.56+/-1.22, 58.23+/-0.31, 60.21 +/-0.86 and 62.35 +/-0.98 mg/100 g body weight, respectively, when compared with the control (untreated) in the uncastrated intact male rats and 49.23+/-0.82, 52.23+/-0.36, 50.21+/-0.66 and 52.35+/-0.58 mg/100 g body weight, respectively, when compared to control (untreated) in the testosterone-stimulated castrated intact male rats. Hence, the pro-androgenic effect as shown by this study further supported the traditional use of this plant as an aphrodisiac.
  5. Ang HH, Lee EL, Cheang HS
    Int J Toxicol, 2004 Jan-Feb;23(1):65-71.
    PMID: 15162849 DOI: 10.1080/10915810490269654
    The DCA (Drug Control Authority), Malaysia, has implemented the phase 3 registration of traditional medicines on 1 January 1992, with special emphasis on the quality, efficacy, and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicine preparations. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation, containing Tongkat Ali, were analyzed for mercury content using cold vapor atomic absorption spectrophotometer. Results showed that 36% of the above products possessed 0.52 to 5.30 ppm of mercury and, therefore, do not comply with the quality requirement for traditional medicines in Malaysia. Out of these 36 products, 5 products that possessed 1.05 to 4.41 ppm of mercury were in fact have already registered with the DCA, Malaysia. However, the rest of the products that contain 0.52 to 5.30 ppm of mercury still have not registered with the DCA, Malaysia. Although this study showed that only 64% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to mercury, they cannot be assumed safe from mercury contamination because of batch-to-batch inconsistency.
  6. Ang HH, Ikeda S, Gan EK
    Phytother Res, 2001 Aug;15(5):435-6.
    PMID: 11507738 DOI: 10.1002/ptr.968
    The butanol, methanol, water and chloroform extracts of the roots of Eurycoma longifolia Jack were studied using various tests of potency of treated male rats. The results showed that E. longifolia produced a dose-dependent, recurrent and significant increase in the episodes of penile reflexes as evidenced by increases in quick flips, long flips and erections of the treated male rats during the 30 min observation period. These results provide further evidence that E. longifolia increases the aphrodisiac potency activity in treated animals.
  7. Ang HH, Lee KL, Kiyoshi M
    Int J Environ Health Res, 2004 Aug;14(4):261-72.
    PMID: 15369991
    The DCA (Drug Control Authority), Malaysia implemented the phase 3 registration of traditional medicines on 1 January 1992 with special emphasis on the quality, efficacy and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicinal preparations. As such, a total of 100 traditional medicinal preparations, containing Smilax myosotiflora, in various pharmaceutical dosage forms, which were bought in the Malaysian market, were analysed for lead content using atomic absorption spectrophotometry. Results showed that 15% of the products analysed possessed 10.23-23.05 ppm of lead, and therefore, do not comply with the quality requirement for traditional medicines in Malaysia. The quality requirement for traditional medicines in Malaysia is that they should not exceed 10 ppm of lead. Out of these 15 products, five products exhibited 10.23-23.05 ppm of lead, in fact they have already been registered with the DCA Malaysia. However, the rest of the products, which possessed 12.24-20.72 ppm of lead, have still not been registered with the DCA Malaysia. Although this study successfully showed that only 85% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to lead, they cannot, however, be assumed to be safe from lead contamination because of batch-to-batch inconsistency.
  8. Ang HH, Lee KL, Kiyoshi M
    PMID: 14964739 DOI: 10.1515/jbcpp.2003.14.3.301
    Eurycoma longifolia Jack was investigated for sexual motivation activity in adult, middle-aged male mice and in retired breeders, using the modified open field and the modified runway choice methods. Each mouse received 500 mg/kg of one of 4 fractions of E. longifolia Jack, viz. chloroform, methanol, butanol, and water, whereas the mice in the control and yohimbine groups received 3 ml/kg of normal saline and 30 mg/kg of yohimbine daily respectively for 10 d. The results show a transient increase in the percentage of male mice responding to the right choice after chronic consumption of the fractions with 50 percent of the adult middle-aged male mice treated with E. longifolia Jack and yohimbine scoring the right choice after 8 and 5 days post-treatment respectively. In conclusion, this study has shown that E. longifolia Jack continues to enhance sexual motivation in adult, middle-aged male mice and in retired breeders.
  9. Ang HH, Lee KL, Kiyoshi M
    J Basic Clin Physiol Pharmacol, 2004;15(3-4):303-9.
    PMID: 15803965 DOI: 10.1515/jbcpp.2004.15.3-4.303
    Eurycoma longifolia Jack commonly known as Tongkat Ali in Malaysia, has been used in Malaysia to increase male virility and sexual prowess. The objective of this study is to evaluate sexual arousal in sexually sluggish old male rats, 24 months old and retired breeders, receiving 200, 400, or 800 mg/kg of various fractions of E. longifolia Jack, twice daily, for 10 days. Control rats received 3 ml/kg of normal saline. The aphrodisiac effect was monitored by the act of yawning and stretching because yawning, either alone or associated with stretching, is considered an ancestral vestige surviving throughout evolution that promotes sexual arousal. The results showed that 800 mg/kg of E. longifolia Jack increased yawning by 50% and stretching by 16.7% in sexually sluggish old male rats, by 676-719% and 31-336%, respectively, in sexually active male rats, and by 22-44% and 75-100%, respectively, in middle aged, 9 months old and retired breeders. We conclude that the results of this study support the folk use of this plant as an aphrodisiac.
  10. Ang HH, Lee KL, Kiyoshi M
    Int J Toxicol, 2005 May-Jun;24(3):165-71.
    PMID: 16040569 DOI: 10.1080/10915810590952942
    The DCA (Drug Control Authority) of Malaysia implemented the phase 3 registration of traditional medicines on 1 January 1992. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation containing Smilax luzonensis, either single or combined preparations, were analyzed for the presence of lead, using atomic absorption spectrophotometry. Results showed that 14% of the above products possessed 10.02 to 21.21 ppm of lead, and, therefore, they failed to comply with the quality requirement for traditional medicines in Malaysia ( <10 ppm). Although this study showed that 86% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to lead, they cannot be assumed safe from lead contamination because of batch-to-batch inconsistency.
  11. Ang HH, Lee KL
    Food Chem Toxicol, 2006 Aug;44(8):1245-50.
    PMID: 16567029 DOI: 10.1016/j.fct.2006.01.014
    The DCA (Drug Control Authority), Malaysia has implemented the phase three registration of traditional medicines on 1 January 1992. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation found in Malaysia, containing tongkat Ali hitam, either single or combined preparations, were analyzed for the presence of a heavy toxic metal, mercury, using atomic absorption spectrophotometer, after performing a simple random sampling to enable each sample an equal chance of being selected in an unbiased manner. Results showed that 26% of these products possessed 0.53-2.35 ppm of mercury, and therefore, do not comply with the quality requirement for traditional medicines in Malaysia. The quality requirement for traditional medicines in Malaysia is not exceeding 0.5 ppm for mercury. Out of these 26 products, four products have already registered with the DCA, Malaysia whilst the rest, however, have not registered with the DCA, Malaysia.
  12. Ang HH, Lee KL
    Fundam Clin Pharmacol, 2002 Dec;16(6):479-83.
    PMID: 12685506 DOI: 10.1046/j.1472-8206.2002.00106.x
    The effects of various fractions of Eurycoma longifolia Jack were studied on the orientation activities of the inbred, adult middle-aged Sprague-Dawley rats, 9 months old and retired breeders towards the receptive females (anogenital sniffing, licking, mounting), the environment (climbing, raring, exploration), themselves (nongenital grooming, genital grooming) and mobility (restricted, unrestricted) after treating these subjects twice daily for 10 days. Results showed that subjects treated with 800 mg/kg of E. longifolia Jack increased orientation activities towards the receptive females (anogenital sniffing, licking and mounting), increased genital grooming towards themselves and restricted movements to a particular area of the cage but decreased interest in the external environment (climbing, raring, exploration) as compared with the controls during the investigation period. In conclusion, this study gives further evidences that different fractions of E. longifolia Jack modified the orientation activities of the middle-aged male rats.
  13. Ang HH, Lee KL
    J Basic Clin Physiol Pharmacol, 2002;13(3):249-54.
    PMID: 12670032 DOI: 10.1515/jbcpp.2002.13.3.249
    The effect of increasing doses of various fractions of Eurycoma longifolia Jack extracts on libido was examined in middle-aged male rats. The results showed that a high dose (800 mg/kg) of all E. longifolia Jack extracts significantly increased mount frequency (MF) (P < 0.05) over that of untreated controls, but had no effect on the frequency of intromission or ejaculation. Methanol, chloroform, water, and butanol fractions exhibited MF of 2.5 +/- 0.1, 2.6 +/- 0.3, 2.5 +/- 0.1 and 2.6 +/- 0.2, respectively, in adult, middle-aged male rats, and retired breeders versus 2.3 +/- 0.1 in untreated controls. This translated to a minor increase in MF of 8.7%, 13.0%, 8.7%, and 13.0% for these fractions, respectively, during the 20-minute observation period. The results of this study show that E. longifolia Jack extracts can increase libido in middle-aged male rats.
  14. Ang HH, Lee KL
    Int J Toxicol, 2007 Sep-Oct;26(5):433-9.
    PMID: 17963130 DOI: 10.1080/10915810701583036
    The DCA (Drug Control Authority) of Malaysia implemented phase 3 registration of traditional medicines in January 1992 with special emphasis on the quality, efficacy, and safety of all dosage forms of these medicines. For this reason, a total of 100 herbal products containing Smilax myosotiflora were purchased in the Malaysian market and analyzed for mercury content, as mercury is a recognized reproductive toxicant. The products were analyzed using cold vapor atomic absorption spectrophotometry. It was found that 89% of the above products do not exceed 0.5 ppm of mercury. Heavy metal poisoning such as mercury has been associated with traditional medicines. Therefore, it is important that doctors and health care practitioners are aware of these risks and finding ways to minimize them, including questions pertaining to the use of these remedies during the routine taking of a patient's history.
  15. Saw JT, Bahari MB, Ang HH, Lim YH
    Med J Malaysia, 2006 Oct;61(4):422-32.
    PMID: 17243519
    A cross sectional survey on pattern and perception of herbal use among medical patients in Penang Hospital was conducted. Among 250 patients surveyed, 67.9% were using herbal medicine and conventional medicine concomitantly. A majority of the patients used herbs for health maintenance (51.3%) purpose. More than 90% of herbal users did not disclose herbal use to their physician and "Doctor never asked" was the major reason given (54.2%). The Chinese reported the highest rate of herbal use but was least likely to disclose. These findings are important for health professionals to ensure medication safety and recognise potential drug herb interaction.
  16. Saw JT, Bahari MB, Ang HH, Lim YH
    Complement Ther Clin Pract, 2006 Nov;12(4):236-41.
    PMID: 17030294
    This is a cross-sectional survey evaluating the use of herbal medicines in medical wards patients that may interfere with the effect of antiplatelet or anticoagulant therapy. Among the 250 patients participated, 42.4% (n=106) were taking herbs with 76 patients (71.7%) using herbs for the past 12 months. Overall, almost 31% (n=23, N=76) of patients were taking one or more of the specified herbal medicines [ginseng (Panax ginseng), garlic (Allium sativum), ginkgo (Gingko biloba) thought to interact with antiplatelet or anticoagulant therapy. The study showed that 21% (n=16, N=76) of patients co-ingested specified herbs with antiplatelet or anticoagulant therapy, of which half of them were at risk of potential drug-herb interactions. A large proportion of respondents involved in potential drug-herb interaction were elderly people (62.5%, n=5). However, more than 90% of herbal users did not disclose the use of herbal medicine to their health professionals. It is thus prudent for all care givers to be aware of the possibility of drug-herb interaction and inquire about herbal use from patients.
  17. Ang HH, Cheang HS, Mak JW
    Chemotherapy, 2005 Oct;51(6):377-80.
    PMID: 16227695
    Exposure of Plasmodium falciparum to increasing sublethal drug concentrations followed by drug treatment led to the development of many resistant parasites. Therefore, the susceptibility of these clones to the type II antifolate drugs, cycloguanil and pyrimethamine, before and after subculturing them in vitro for a period of 3 years, was studied.
  18. Ang HH, Chan KL, Mak JW
    Folia Parasitol., 1998;45(3):196-8.
    PMID: 9805783
    Five Malaysian isolates of the protozoan Plasmodium falciparum Welch were cultured in vitro following the method of Trager and Jensen (1976, 1977) and subsequently cloned using the limiting dilution method of Rosario (1981). Thirty clones were obtained and were later characterized against schizontocidal drugs, chloroquine, mefloquine and quinine, using the modified in vitro microtechnique. Results showed that these local isolates were heterogeneous and most of the clones exhibited similar pattern of susceptibility as their parent isolate except for ST 168 clone and two ST 195 clones that were sensitive but two ST 165 clones, two ST 168 clones and five ST 195 clones were resistant against quinine, respectively. Results also indicated that they were pure clones compared to their parent isolate because their drug susceptibility studies were significantly different (p < 0.05).
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