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Electrophoretic variations of enzyme, GDH (NADP-dependent glutamate dehydrogenase)(EC. 1.4.1.4) in characterizing clones and isolates of Malaysian Plasmodium falciparum

Ang HH, Chan KL, Mak JW

Korean J Parasitol, 1996 Sep;34(3):211-3.
PMID: 8843698

Malaysian, African and Thai Plasmodium falciparum isolates were cultured in vitro by the Trager and Jensen method (1976; 1977) and were later cloned by the limiting dilution method (Rosario, 1981). Forty-eight clones were obtained and were characterized by electrophoretic variations of GDH (NADP-dependent glutamate dehydrogenase)(EC. 1.4.1.4). It was found that they were pure clones because they possessed either GDH-1 or GDH-2 unlike their parent isolates which exhibited both GDH-1 and GDH-2.
Control of Mansonia mosquitos, vectors of brugian filariasis in Sarawak, Malaysia

Chang MS, Chan KL, Ho BC

Southeast Asian J. Trop. Med. Public Health, 1993;24 Suppl 2:93-104.
PMID: 7973956

Two field trials in the control of subperiodic brugian filariasis vectors, mainly Mansonia bonneae and Mansonia dives were carried out in Sarawak, East Malaysia. In the first trial, malathion ultra-low volume (ULV) spray was used to control the Mansonia mosquitos in two filariasis endemic villages. Six spray rounds were applied at biweekly intervals at Kampung Rasau and two spray rounds were applied at monthly intervals in Kampung Triboh. ULV malathion spray reduced biting Ma. bonneae population for 3 days after spraying. The biting density decreased to 50% of the pre-treatment level by the 12th - 13th day and reached the pre-treatment level by the 24th - 25th day. Contact bioassay tests on caged Mansonia mosquitos revealed considerable penetration of the malathion aerosol indoors and relatively adequate coverage outdoors. The estimated number of bites per case per day was 1.09 to 4 times less in the sprayed kampung than in an unsprayed control kampung. The parous and daily survival rates of Mansonia mosquitos were not significantly affected by the spraying. In a second trial, chemotherapy with diethylcarbamazine citrate (DEC) was combined with vector control through indoor residual spraying in Kampung Ampungan. The results were compared with the use of only DEC mass treatment in Kampung Sebangkoi and Kampung Sebamban. The combined control measures in Kampung Ampungan reduced the MfD-50 to 44% of the pre-treatment level over a period of 4 years. In the other two kampungs where only mass DEC therapy was applied, the microfilarial rate and MfD-50 declined significantly in the second blood survey but increased gradually in two subsequent follow-up blood surveys. The total insecticidal impact for Ma. bonneae was 3.9 to 1 indoors and 2.7 to 1 outdoors. These results indicated that quarterly pirimiphos-methyl indoor spraying used in integrated control could reduce indoor transmission by 3.9 times. The infective rate from the Ma. bonneae dissected in all three kampungs after the interventions, irrespective of DEC treatment alone or in combination with pirimiphos-methyl residual spraying were reduced by two fold. However the infection rate of brugian filarial larvae in Kampung Ampungan was significantly reduced after the use of DEC and insecticide. Annual Transmission Potential (ATP) showed a high significant reduction in Kampung Ampungan (p > 0.001) compared with Kampungs Sebangkoi and Schambam. In Ampungan, the ATP was reduced by 8.5 times indoors after the MDA and insecticidal application and 3 times outdoors. The reduction rate for Sebangkoi and Sebamban both indoors and outdoors were less than 2 fold.(ABSTRACT TRUNCATED AT 400 WORDS)
Susceptibility of Malaysian Plasmodium falciparum isolates to antimalarial drugs after cryopreservation and 12 months of continuous in vitro culture

Ang HH, Chan KL, Mak JW

Chemotherapy, 1997 Sep-Oct;43(5):311-5.
PMID: 9309363 DOI: 10.1159/000239583

Eleven Malaysian Plasmodium falciparum isolates were cultured in vitro and later subjected to antimalarial evaluations in 96-well microtiter plates. After cryopreservation, the IC50 (nM) for ST 195, ST 196, ST 197, ST 244 and ST 245 isolates were, respectively: 180.9, 198.7, 482.0, 580.0 and 690.1 for chloroquine; 3.4, 3.4, 9.2, 4.0 and 5.8 for mefloquine; 21.9, 10.5, 40.7, 40.1 and 48.7 for quinine; 136.7, 58.8, 116.4, 29.4 and 95.4 for cycloguanil, and 48.3, 57.5, 47.4, 61.5 and 37.8 for pyrimethamine. Before cryopreservation they were 172.5, 141.5, 453.2, 636.0 and 651.6 nM for chloroquine; 4.8, 2.6, 9.0, 6.9 and 5.8 nM for mefloquine; 21.3, 8.3, 41.9, 49.6 and 40.1 nM for quinine, 129.9, 47.3, 109.3, 30.6 and 95.4 nM for cycloguanil, and 45.4, 47.4, 40.2, 66.3 and 36.0 nM for pyrimethamine. IC50 (nM) for Gombak A, Gombak C, ST 9, ST 12, ST 85 and ST 148 isolates after 12 months of continuous in vitro culture were, respectively: 477.0, 492.3, 367.1, 809.4, 566.5 and 341.8 for chloroquine; 2.9, 11.1, 8.5, 16.9, 5.3 and 4.2 for mefloquine; 6.2, 58.3, 52.7, 36.7, 31.8 and 26.2 for quinine; 154.5, 57.2, 130.3, 94.2, 81.4 and 102.9 for cycloguanil, 26.9, 24.9, 43.8, 31.0, 14.1 and 56.7 for pyrimethamine. Before the 12-month culture they were 472.3, 452.9, 352.7, 773.7, 702.7 and 322.7 nM for chloroquine; 2.6, 13.2, 8.5, 17.2, 5.0 and 4.0 nM for mefloquine; 6.2, 85.4, 53.9, 38.5, 35.8 and 38.5 nM for quinine; 106.8, 74.3, 112.4, 89.8, 91.8 and 103.3 nM for cycloguanil, and 26.9, 31.4, 47.0, 28.1, 14.9 and 56.7 nM for pyrimethamine. Thus none of these isolates differed in their original susceptibilities after either of these procedures.
Variability in schizonticidal drug susceptibility amongst clones and isolates of Plasmodium falciparum

Ang HH, Chan KL, Mak JW

Chemotherapy, 1997 Mar-Apr;43(2):142-7.
PMID: 9084924

Plasmodium falciparum isolates from Malaysia, Africa and Thailand were cultured in vitro following the method of Trager and Jensen and subsequently cloned using the limiting dilution method of Rosario. These clones were presently characterized against three schizonticidal drugs, chloroquine, mefloquine and quinine, using the modified in vitro microtechnique. Results showed that all the clones derived from Gombak A isolate were chloroquine-resistant with average IC50 values ranging at 0.1377-1.0420 microM (0.007-0.058 mefloquine activity), sensitive to mefloquine at 0.0032-0.0103 microM and quinine at 0.0025-0.0428 microM (0.075-3.080 mefloquine activity). Similarly, the TGR clone displayed resistance to chloroquine at 0.1715-0.5875 microM (0.002-0.029 mefloquine activity) but were also sensitive to mefloquine at 0.0008-0.0058 microM and quinine at 0.0055-0.0700 microM (0.055-0.202 mefloquine activity). In contrast, four out of six Gambian clones were sensitive to chloroquine at 0.0047-0.0172 microM (0.122-0.617 mefloquine activity) but all were sensitive to mefloquine at 0.0008-0.0029 and 0.0016-0.0102 microM (0.096-1.813 mefloquine activity). In general, most of the clones displayed susceptibility patterns similar to that of their parent isolates against the three schizonticidal drugs except Gm/B2 and Gm/H5 Gambian clones were chloroquine-resistant at 0.3427 microM (0.006 mefloquine activity) and 0.2260 microM (0.004 mefloquine activity), respectively. Further results indicated that they were pure clones compared to their parent isolates as their schizonticidal drug susceptibilities were statistically different (p < 0.05) except Gm/C6 and TGR/B7 clones against mefloquine (p < 0.05).
Fulltext Colonization of Mansonia dives Schiner in a field insectary

Chang MS, Ho BC, Chan KL

Southeast Asian J. Trop. Med. Public Health, 1991 Jun;22(2):229-34.
PMID: 1683011

Successful colonization of Mansonia dives, the principal vector of subperiodic Brugia malayi was established in a field insectary. Mean egg clusters laid on Eichhornia crassipes, Pistia stratiotes, Homalomena cordata and polystyrofoam strips were 12.0, 10.4, 9.5 and 13.7 respectively. However, the mean number of first instar larvae hatched from each egg cluster laid by females on the three plant substrates (range 51.1 to 58.6) was higher than that laid on the polystyrofoam strips (41.8). There were no significant differences in the success pupation and adult emergence rates among the three host plants used as attachment substrates. Adult emergence occurred at a mean of 10.8 days. The first adult emergence was observed at the 25th day after hatching and continued till the 50th day. The 50% mortality rates for the adults were estimated as 8 days for the males and 14 days for the females. The mean gonotrophic cycle ranged from 3.8 to 4.3 days with a mean of 4.04 days. 63.6% of Ma. dives females oviposited in a medium of rat dung and water. The mean incubation period of eggs ranged from 5.2 to 6.5 days with a mean of 5.7 days. The biology of Ma. dives and Ma. bonneae is briefly compared.
Efficacy of diethylcarbamazine and pirimiphos-methyl residual spraying in controlling brugian filariasis

Chang MS, Ho BC, Chan KL

Trop. Med. Parasitol., 1991 Jun;42(2):95-102.
PMID: 1680246

A control programme against subperiodic brugian filariasis was implemented in three villages, (Kg. Ampungan, Kg. Sebangkoi and Kg. Sebamban) in Sarawak, Malaysia. In Kampong Ampungan, the mass administration of diethylcarbamazine (DEC-citrate) combined with residual house spraying of pirimiphos-methyl reduced microfilarial rate to 8% of the pre-treatment level and microfilarial density (MfD50) to 44% of the pre-treatment level over a period of four years. In Kampong Sebangkoi and Kampong Sebamban, where only mass DEC therapy was applied, the microfilarial rate and MfD50 declined distinctly in the second blood survey but increased gradually in two subsequent follow-up blood surveys. In Kg, Ampungan, we observed a significant reduction of infective biting rate (88.3%), infection rate (62.5%) and transmission potential (88.1%) of Mansonia bonneae at the fourth spray round. The corresponding reduction rates in Kg. Sebangkoi and Kg. Sebamban were 35.3%, 26.7%, 42.2% and 24%, 30.8% and 15.4% respectively. The biting density of the vector was reduced by 79.8% indoors and 31.8% outdoors at the sprayed village, while only a slight decrease in densities (17.9% indoors and 12.4% outdoors) was observed at the unsprayed village. Bioassay tests revealed that pirimiphos-methyl had a substantial fumigant effect on the vector. The integrated control measure in controlling subperiodic brugian filariasis is discussed.
The effect of Bacillus thuringiensis israelensis [H-14] on emergence of Mansonia mosquitos from natural breeding habitat

Chang MS, Ho BC, Chan KL

Southeast Asian J. Trop. Med. Public Health, 1990 Sep;21(3):430-6.
PMID: 1981631

The measurement of the ultimate effects of the microbial insecticides on mosquito density is best obtained by assessment of adult populations. The main aims of this study are: (1) to assess the effect of Bacillus thuringiensis israelensis (Bti) FC Skeetal and Bactimos briquettes on the emergence rate of Mansonia bonneae developed from the introduced first-instar stage larvae and (2) to measure the effect of these two formulations of insecticides on Mansonia adult populations emerging from the natural breeding plots. Bti Skeetal and Bactimos briquettes at the lower applied dosages of 2.3 kg/ha and 1 briquette case/20 m2 respectively achieved 39-40% pupation rates and 31.5-34.2% adult emergence rates. At these low applied dosages, there was little or no direct effect on pupation from the surviving larvae and thereafter on the emergence of adults from the pupae. A two-fold increase in dosage, however, produced a drastic decline in the pupation rate and adult emergence rate. The rates dropped to 6.5% (pupation) and 4.3% (adult emergence) of the total larvae for Bactimos briquettes and to merely 1.5% (pupation) and 1.3% (adult emergence) of the total larvae for Skeetal. In studying the effect of Bti on the field populations of Mansonia mosquitos, two plots each were treated with Bactimos at 1 briquette case/10 m2 and Skeetal at 4.6 kg/ha. A wooden pyramid-shaped screened cage was placed on a cluster of host plants for a period of 2 weeks to trap the emerging adult mosquitoes. There were a total of 24 clusters of host plants in each plot.(ABSTRACT TRUNCATED AT 250 WORDS)
Protein variation and systematics of three subgenera of Malayan rats (Rodentia: Muridae, genus Rattus Fischer)

Chan KL, Dhaliwal SS, Yong HS

Comp. Biochem. Physiol., B, 1979;64(4):329-37.
PMID: 318313

1. Nine erythrocyte proteins coded by a separate locus each were analysed in and among seven Malayan species of Rattus belonging to three subgenera. 2. Electrophoretic data obtained confirm the specific status of the seven taxa and divide the seven species into three groups which correspond with Ellerman's (1949) subgenera Stenomys, Maxomys and Leopoldamys. 3. A comparative study together with 11 other species of Malayan Rattus previously analysed show that, with few exceptions, the overall relationships among the 18 species based on electrophoretic data correspond well with conclusions based on morphological evidence. 4. Malayan species of Rattus are relatively very diverse genetically (S = 0.27, range 0.01-0.94).
Protein variation and systematics in Malayan rats of the subgenus Lenothrix (Rodentia: Muridae, genus Rattus Fischer)

Chan KL, Dhaliwal SS, Yong HS

Comp. Biochem. Physiol., B, 1978;59(4):345-51.
PMID: 318285

1. Electrophoretic variations of 9 erythrocyte proteins, coded by a separate gene locus each, were analysed in and among the 5 Malayan species of Rattus belonging to the subgenus Lenothrix. 2. The average proportion of loci heterozygous per individual for the taxa analysed is 0.037. 3. The results obtained confirm the specific status of the 5 taxa studied. With respect to the relative affinities among the species studied, the present results could resolve the discrepancies between conclusions based on morphological evidence and those based on cytological evidence. 4. The 5 species of Rattus studied may be assigned to 4 groups and comparative data suggest that these groups are relatively distantly related to one another.
Susceptibility studies of Plasmodium falciparum isolates and clones against cycloguanil and pyrimethamine using the modified in vitro microtechnique

Ang HH, Chan KL, Mak JW

J Parasitol, 1996 Dec;82(6):1029-31.
PMID: 8973418

Six clones were derived from each Malaysian Plasmodium falciparum isolate and characterized for their susceptibilities against type II antifolate drugs, cycloguanil and pyrimethamine. Results showed that these isolates were of a heterogeneous population, with average IC50 values of Gombak C clones at 0.012-0.084 microM and 0.027-0.066 microM, ST 9 clones at 0.019-0.258 microM and 0.027-0.241 microM, ST 12 clones at 0.015-0.342 microM and 0.012-0.107 microM, ST 85 clones at 0.022-0.087 microM and 0.024-0.426 microM, and ST 148 clones at 0.027-0312 microM and 0.029-0.690 microM against cycloguanil and pyrimethamine, respectively. Generally, most of these clones displayed susceptibility patterns similar to their parent isolates except ST 9/A4, ST 9/A7, ST 9/B5, ST 9/D9, ST 9/D10, ST 148/A4, ST 148/A5, ST 148/A7, ST 148/F7, ST 148/F8 clones, which were sensitive at 0.027 microM, 0.019 microM, 0.022 microM, 0.063 microM, 0.037 microM, 0.031 microM, 0.042, microM, 0.042 microM, 0.062 microM, and 0.027 microM, whereas, ST 12/D7 clone was resistant at 0.342 microM, against cycloguanil respectively. However, ST 9/A4, ST 9/D8, ST 12/D5, ST 85/A5, ST 85/B3, ST 85/B4, ST 85/D3, ST 85/D7, ST 148/A6, and ST 148/A7 clones were resistant to pyrimethamine at 0.158 microM, 0.241 microM, 0.107 microM, 0.223 microM, 0.393 microM, 0.402 microM, 0.426 microM, 0.115 microM, 0.690 microM, and 0.520 microM, respectively.
Comparing the pharmacokinetics of 13α,21-dihydroeurycomanone and eurycomanone exclusively enriched in Eurycoma longifolia extracts and their spermatogenesis enhancement in andrographolide-induced oligospermia in rats

Chung WJ, Chan KL, Lee CY

J Pharm Pharmacol, 2021 Mar 04;73(2):161-168.
PMID: 33793798 DOI: 10.1093/jpp/rgaa026

OBJECTIVES: The quassinoids eurycomanone (EN) and 13α,21-dihydroeurycomanone (DHY) of Eurycoma longifolia Jack are reported to enhance spermatogenesis. This study aims to profile the pharmacokinetics of DHY, a minor and hitherto unstudied constituent, evaluate its spermatogenesis enhancement property and compare these attributes with that of the predominant EN.
METHODS: Crude Eurycoma longifolia extract was chromatographed into a DHY-enriched extract (DHY-F) and an EN-enriched extract (EN-F). Male Sprague-Dawley rats were administered intravenously and orally with both extracts and their plasma levels of both quassinoids were determined. The extracts were then tested for their spermatogenesis augmentation ability in normal rats and an andrographolide-induced oligospermia model.
KEY FINDINGS: Chromatographic enrichment resulted in a 28-fold increase of DHY in DHY-F and a 5-fold increase of EN in EN-F compared with non-chromatographed crude extracts. DHY showed better oral bioavailability (1.04 ± 0.58%) than EN (0.31 ± 0.19%). At 5 mg/kg, EN exhibited higher efficacy in spermatogenesis enhancement in normal rats and restoration of oligospermia to normal sperm profile versus DHY.
CONCLUSIONS: Despite the better pharmacokinetic profile of DHY, EN remains the main chemical contributor to plant bioactivity. DHY-F and EN-F represent improvements in developing Eurycoma longifolia as a potential phytomedicine for male infertility particularly oligospermia.
High performance liquid chromatography in phytochemical analysis of Eurycoma longifolia

Chan KL, Choo CY, Morita H, Itokawa H

Planta Med, 1998 Dec;64(8):741-5.
PMID: 17253320 DOI: 10.1055/s-2006-957570

An analytical method using HPLC with UV detection was developed to investigate the quassinoid content of Eurycoma longifolia Jack (Simaroubaceae) collected from various sources. Eurycomanone (1), longilactone (2), 14,15beta-dihydroxyklaineanone (3), 15beta-acetyl-14-hydroxyklaineanone (4), 6alpha-hydroxyeurycomalactone (5), and eurycomalactone (7) were isolated as reference standards and together with the synthesized 1beta,12alpha,15beta-triacetyleurycomanone (6, internal standard), were identified by NMR, MS, UV and IR spectroscopies. Their coefficient of variation values for 0.50-35 microg ml(-1) concentrations of quassinoids and their retention times measured within- and between-day were small. The recoveries of the spiked quassinoids in E. longifolia samples and their detection limits at 8.5 times signal to noise ratio were 99.75-109.13% and 0.01 microg ml(-1), respectively. From the root samples analysed, 1 had the highest concentration, being about 16.8-39.6 fold higher than the other quassinoids 2, 3, 5, 7 but 145.3 fold higher than 4 which showed the lowest concentration.
Semisynthetic 15-O-acyl- and 1,15-di-O-acyleurycomanones from Eurycoma longifolia as potential antimalarials

Chan KL, Choo CY, Abdullah NR

Planta Med, 2005 Oct;71(10):967-9.
PMID: 16254833 DOI: 10.1055/s-2005-864188

Among the quassinoids isolated from Eurycoma longifolia Jack, eurycomanone was identified as the most potent and toxic inhibitor of the chloroquine-resistant Gombak A isolate of Plasmodium falciparum. Several diacylated derivatives of eurycomanone, 1,15-di-O-isovaleryleurycomanone, 1,15-di-O-(3,3-dimethylacryloyl)- eurycomanone and 1,15-di-O-benzoyleurycomanone were synthesized by direct acylation with the respective acid chlorides. The monoacylated 15-O-isovaleryleurycomanone was synthesized by selective protection of the other hydroxy groups of eurycomanone with trimethylsilyl trifluoromethanesulphonate to enable the exclusive acylation of its C-15 hydroxy group. This was followed by the removal of the protecting groups with citric acid. The diacylated eurycomanones exhibited lower antiplasmodial activity against the Gombak A isolates and lower toxicity in the brine shrimp assay when compared to eurycomanone. In contrast, the monoacylated derivative displayed comparable antiplasmodial potency to eurycomanone, but its toxicity was reduced. Thus, preliminary studies of the synthesized acylated eurycomanones have shown that acylation only at the C-15 hydroxy group may be worthy of further antimalarial investigation.
HPLC analysis of plasma 9-methoxycanthin-6-one from Eurycoma longifolia and its application in a bioavailability/pharmacokinetic study

Tan S, Yuen KH, Chan KL

Planta Med, 2002 Apr;68(4):355-8.
PMID: 11988862 DOI: 10.1055/s-2002-26751

A new and simple HPLC method using fluorescence detection was developed to determine 9-methoxycanthin-6-one, an active compound of Eurycoma longifolia Jack in rat and human plasma. The method entailed direct injection of plasma sample after deproteinization using acetonitrile. The mobile phase comprised acetonitrile and distilled water (55 : 45, v/v). Analysis was run at a flow rate of 1.0 ml/min with the detector operating at an excitation wavelength of 371 nm and emission wavelength of 504 nm. The method was specific and sensitive with a detection limit of 0.6 ng/ml and a quantification limit of approximately 1.6 ng/ml. The method was applied in a pilot pharmacokinetic/bioavailability study of the compound in rats. Less than 1 % of the compound was found to be absorbed orally.
Effect of 7-day daily replacement of culture medium containing Eurycoma longifolia Jack constituents on the Malaysian Plasmodium falciparum isolates

Ang HH, Chan KL, Mak JW

J Ethnopharmacol, 1995 Dec 15;49(3):171-5.
PMID: 8824743 DOI: 0.1016/0378-8741(95)01321-0

Six Malaysian chloroquine-resistant Plasmodium falciparum isolates were cultured in vitro following the candle-jar method. Antimalarial evaluations of daily replacement of culture medium containing chloroquine and a semi-purified extract of Eurycoma longifolia Jack (containing 13 beta, 18-dihydroeurycomanol (1), eurycomanol-2-O-beta-D-glucopyranoside (2), eurycomanol (3) and eurycomanone (4)) were performed on 6-well plates at 37 degrees C for a week. Presence or absence of the parasites was determined microscopically on thin-film Giemsa-stained preparations. Results showed that the antimalarial activity of Eurycoma longifolia Jack was dose-dependent and reached a maximum of < 50% at 0.07-5.00 micrograms ml-1 after 1 day post-treatment. However, complete inhibitions were observed at 1.25-5.00 micrograms ml-1 extract after 3 days post-treatment and 0.62 and 0.31 micrograms ml-1 after 4 and 6 days post-treatment, respectively. Further results indicated that chloroquine exhibited total inhibition at concentrations > 2.50 and 0.62 micrograms ml-1 after 1 and 2 days post-treatment, respectively and at all concentrations after 3 days post-treatment.
Fulltext In vitro anti-Toxoplasma gondii activity of root extract/fractions of Eurycoma longifolia Jack

Kavitha N, Noordin R, Chan KL, Sasidharan S

BMC Complement Altern Med, 2012;12:91.
PMID: 22781137 DOI: 10.1186/1472-6882-12-91

Toxoplasma gondii infection causes toxoplasmosis, an infectious disease with worldwide prevalence. The limited efficiency of drugs against this infection, their side effects and the potential appearance of resistant strains make the search of novel drugs an essential need. We examined Eurycoma longifolia root extract and fractions as potential sources of new compounds with high activity and low toxicity. The main goal of this study was to investigate the anti-T. gondii activity of crude extract (TACME) and four fractions (TAF 273, TAF 355, TAF 191 and TAF 401) from E. longifolia, with clindamycin as the positive control.
Physico-chemical effects of the major quassinoids in a standardized Eurycoma longifolia extract (Fr 2) on the bioavailability and pharmacokinetic properties, and their implications for oral antimalarial activity

Low BS, Teh CH, Yuen KH, Chan KL

Nat Prod Commun, 2011 Mar;6(3):337-41.
PMID: 21485270

A simple validated LC-UV method for the phytochemical analysis of four bioactive quassinoids, 13alpha(21)-epoxyeurycomanone (EP), eurycomanone (EN), 13alpha,21-dihydroeurycomanone (ED) and eurycomanol (EL) in rat plasma following oral (200 mg/kg) and intravenous administration (10 mg/kg) of a standardized extract Fr 2 of Eurycoma longifolia Jack was developed for pharmacokinetic and bioavailability studies. The extract Fr 2 contained 4.0%, 18.5%, 0.7% and 9.5% of EP, EN, ED and EL, respectively. Following intravenous administration, EP displayed a relatively longer biological half-life (t1/2 = 0.75 +/- 0.25 h) due primarily to its lower elimination rate constant (k(e)) of 0.84 +/- 0.26 h(-1)) when compared with the t1/2 of 0.35 +/- 0.04 h and k(e) of 2.14 +/- 0.27 h(-1), respectively of EN. Following oral administration, EP showed a higher C(max) of 1.61 +/- 0.41 microg/mL over that of EN (C(max) = 0.53 +/- 0.10 microg/mL). The absolute bioavailability of EP was 9.5-fold higher than that of EN, not because of chemical degradation since both quassinoids were stable at the simulated gastric pH of 1. Instead, the higher log K(ow) value of EP (-0.43) contributed to greater membrane permeability over that of EN (log K(ow) = -1.46) at pH 1. In contrast, EL, being in higher concentration in the extract than EP, was not detected in the plasma after oral administration because of substantial degradation by the gastric juices after 2 h. Similarly, ED, being unstable at the acidic pH and together with its low concentration in Fr 2, was not detectable in the rat plasma. In conclusion, upon oral administration of the bioactive standardized extract Fr 2, EP and EN may be the only quassinoids contributing to the overall antimalarial activity; this is worthy of further investigation.
The effect of Eurycoma longifolia on sperm quality of male rats

Chan KL, Low BS, Teh CH, Das PK

Nat Prod Commun, 2009 Oct;4(10):1331-6.
PMID: 19911566

The present study investigated the effects of a standardized methanol extract of E. longifolia Jack containing the major quassinoid constituents of 13alpha(21)-epoxyeurycomanone (1), eurycomanone (2), 13alpha,21-dihydroeurycomanone (3) and eurycomanol (4) on the epididymal spermatozoa profile of normal and Andrographis paniculata induced infertile rats. The standardized MeOH extract at doses of 50, 100 and 200 mg/kg, the EtOAc fraction (70 mg/kg), and standardized MeOH extract at 200 mg/kg co-administered with the EtOAc fraction of A. paniculata at 70 mg/kg were each given orally to male Sprague-Dawley albino rats for 48 consecutive days. The spermatozoa count, morphology, motility, plasma testosterone level and Leydig cell count of the animals were statistically analyzed by ANOVA with a post-hoc Tukey HSD test. The results showed that the sperm count of rats given the standardized MeOH extract alone at doses of 50, 100 and 200 mg/kg were increased by 78.9, 94.3 and 99.2%, respectively when compared with that of control (p < 0.01). The low count, poor motility and abnormal morphology of the spermatozoa induced by the A. paniculata fraction were significantly reversed by the standardized MeOH extract of E. longifolia (p < 0.001). The plasma testosterone level of the rats treated with the standardized MeOH extract at 200 mg/kg was significantly increased (p < 0.01) when compared with that of the control and infertile animals. The spermatocytes in the seminiferous tubules and the Leydig cells appeared normal. Testosterone level was significantly higher in the testes (p < 0.01) than in the plasma after 30 days of oral treatment with the standardized MeOH extract. Interestingly, eurycomanone (2) alone was detected in the rat testis homogenates by HPLC-UV and confirmed by LC/MS, and may have contributed towards the improvement of sperm quality. Thus, the plant may potentially be suitable for the management of male infertility.
Urinary NMR-based metabolomic analysis of rats possessing variable sperm count following orally administered Eurycoma longifolia extracts of different quassinoid levels

Ebrahimi F, Ibrahim B, Teh CH, Murugaiyah V, Chan KL

J Ethnopharmacol, 2016 Apr 22;182:80-9.
PMID: 26899442 DOI: 10.1016/j.jep.2016.02.015

Eurycoma longifolia (Tongkat Ali, TA) roots have been ethnically used as a remedy to boost male sexual desire, libido, energy and fertility.
The cytotoxicity and chemical constituents of the hexane fraction of Typhonium flagelliforme (Araceace)

Choo CY, Chan KL, Sam TW, Hitotsuyanagi Y, Takeya K

J Ethnopharmacol, 2001 Sep;77(1):129-31.
PMID: 11483390

The plant, Typhonium flagelliforme (Araceae), commonly known as the "rodent tuber" in Malaysia, is often used as an essential ingredient of herbal remedies for alternative cancer therapies. The hexane extract of this plant was evaluated for cytotoxic activity against in vitro culture on P388 murine leukaemia cells and showed weak IC(50) of 15 microg/ml. The partial chemical constituents were identified as methyl esters of hexadecanoic acid, octadecanoic acid, 9-octadecenoic acid and 9,12-octadecadienoic acid. In addition, several common aliphatics were identified as dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane and eicosane. The unique methyl ester of 13-phenyltridecanoic acid was isolated and positively identified using spectroscopic methods. None of the identified compounds showed or are known to have cytotoxic behaviour.

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