Displaying publications 61 - 80 of 86 in total

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  1. 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.
  2. Developing a validated liquid chromatography-mass spectrometric method for the simultaneous analysis of five bioactive quassinoid markers for the standardization of manufactured batches of Eurycoma longifolia Jack extract as antimalarial medicaments
    Teh CH, Murugaiyah V, Chan KL
    J Chromatogr A, 2011 Apr 8;1218(14):1861-77.
    PMID: 21367427 DOI: 10.1016/j.chroma.2011.02.014
    An extensive comparative study on the electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) mass spectrometry using automated flow injection analysis (FIA), was performed on eurycomanone (1), 13α(21)-epoxyeurycomanone (2), eurycomanol (3), eurycomanol-2-O-β-d-glucopyranoside (4), and 13,21-dihydroeurycomanone (5), the bioactive markers isolated from Eurycoma longifolia. The effects of eluent mixture (methanol or acetonitrile in water) and acidic modifiers (acetic acid, formic acid and trifluoroacetic acid) on the ionization efficiency of the markers were also investigated. The ESI in the positive ion mode with methanol containing 0.1% (v/v) acetic acid was selected for the subsequent optimization of nebulizer pressure, dry gas flow, dry gas temperature and capillary voltage to improve the sensitivity of the total ion chromatogram (TIC). Fragmentation of the analytes was further investigated by varying the capillary exit offset voltage and fragmentation amplitude in positive mode of ESI. The detection limits (LODs) were determined in isolation mode (selected ion monitoring, SIM). Their limits of detection (LODs) ranged between 0.03 and 0.1μgmL(-1) while the intra-day and inter-day precisions were less than 5.72% and 4.82%, respectively. The method was next applied for the simultaneous analysis of the markers to standardize various batches of manufactured extracts of E. longifolia for potential use as antimalarial products. Multiple Reaction Monitoring (MRM) mode was used for the quantification of analytes which gave protonated molecular ion, [M+H](+). For those without pseudo-molecular ions, SIM mode was used to quantify the analytes. The batches contained 5.65-9.95% of eurycomanone (1), 5.21-19.75% of eurycomanol (3) and 7.59-19.95% of eurycomanol-2-O-β-d-glucopyranoside (4) as major quassinoids whereas, 13α(21)-epoxyeurycomanone (2), and 13,21-dihydroeurycomanone (5) were much lower in concentrations of 0.78-3.90% and 0.47-1.76%, respectively.
  3. Mechanisms of antihyperuricemic effect of Phyllanthus niruri and its lignan constituents
    Murugaiyah V, Chan KL
    J Ethnopharmacol, 2009 Jul 15;124(2):233-9.
    PMID: 19397979 DOI: 10.1016/j.jep.2009.04.026
    ETHNOPHARMACOLOGICAL RELEVANCE: Phyllanthus niruri Linn. (Euphorbiaceae) is used as folk medicine in South America to treat excess uric acid. Our initial study showed that the methanol extract of Phyllanthus niruri and its lignans were able to reverse the plasma uric acid of hyperuricemic animals.
    AIM OF THE STUDY: The study was undertaken to investigate the mechanisms of antihyperuricemic effect of Phyllanthus niruri and its lignan constituents.
    MATERIAL AND METHODS: The mechanisms were investigated using xanthine oxidase assay and uricosuric studies in potassium oxonate- and uric acid-induced hyperuricemic rats.
    RESULTS: Phyllanthus niruri methanol extract exhibited in vitro xanthine oxidase inhibition with an IC50 of 39.39 microg/mL and a moderate in vivo xanthine oxidase inhibitory activity. However, the lignans display poor xanthine oxidase inhibition in vitro and a relatively weak in vivo inhibitory activity at 10mg/kg. On the other hand, intraperitoneal treatment with Phyllanthus niruri methanol extract showed 1.69 folds increase in urinary uric acid excretion when compared to the hyperuricemic control animals. Likewise, the lignans, phyllanthin, hypophyllanthin and phyltetralin exhibited up to 2.51 and 11.0 folds higher in urinary uric acid excretion and clearance, respectively. The co-administration of pyrazinamide with phyllanthin exhibited a significant suppression of phyllanthin's uricosuric activity resembling that of pyrazinamide with benzbromarone.
    CONCLUSIONS: The present study showed that the antihyperuricemic effect of Phyllanthus niruri methanol extract may be mainly due to its uricosuric action and partly through xanthine oxidase inhibition, whereas the antihyperuricemic effect of the lignans was attributed to their uricosuric action.
  4. Standardized quassinoid-rich Eurycoma longifolia extract improved spermatogenesis and fertility in male rats via the hypothalamic-pituitary-gonadal axis
    Low BS, Das PK, Chan KL
    J Ethnopharmacol, 2013 Feb 13;145(3):706-14.
    PMID: 23261482 DOI: 10.1016/j.jep.2012.11.013
    Eurycoma longifolia Jack, a small Simaroubaceae tree, known locally as 'Tongkat Ali' is popularly used as a sexual tonic in traditional medicine for aphrodisiac activity and improvement of fertility and male libido.
  5. Fulltext Decreased expression of alpha-2-HS glycoprotein in the sera of rats treated with Eurycoma longifolia extract
    Chen Y, Phang WM, Mu AK, Chan CK, Low BS, Sasidharan S, et al.
    Front Pharmacol, 2015;6:211.
    PMID: 26441666 DOI: 10.3389/fphar.2015.00211
    Eurycoma longifolia is a Malaysian native herb that has been widely used as an aphrodisiac and a remedy for andropause. Although the physiological effects of the plant extract were predicted as a result of the alterations in protein expression, the key protein(s) involved in these alterations are still unclear. In the present study, we have investigated the effect of standardized E. longifolia extract on serum protein expression up to 28 days following oral administration in rats. Serum protein profiles were analyzed by 2-dimensional electrophoresis, and altered proteins were identified via mass spectrometry. We observed that alpha-2-HS glycoprotein (AHS) was significantly decreased in the serum of experimentally treated rats compared to pre-treated animals. Moreover, reduction in AHS was confirmed using competitive enzyme-linked immunosorbent assay. AHS expression is known to be associated with insulin resistance and diabetes. Our data indicated that serum AHS was reduced in rats treated with standardized E. longifolia extract, and therefore form a prelude for further investigation into the effects of this natural extract in animal models involving infertility and diabetes.
  6. 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.
  7. 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.
  8. 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.
  9. Fulltext Depressant action of Averrhoa carambola
    Muir CK, Chan KL
    Med J Malaysia, 1980 Mar;34(3):279-80.
    PMID: 7191048
    The presence, in the fruit of Averrhoa carambola (star fruit), of a depressant agent with properties similar to those of tranquilizers was demonstrated.
  10. 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)
  11. The phytochemical and anti-inflammatory studies of Dillenia suffruticosa leaves
    Abubakar S, Al-Mansoub MA, Murugaiyah V, Chan KL
    Phytother Res, 2019 Mar;33(3):660-675.
    PMID: 30653753 DOI: 10.1002/ptr.6255
    The Dillenia suffruticosa leaves (Dilleniaceae), a folk medicine recommended in Southeast Asia for treating inflammation, were phytochemically studied for the first time and assessed for suppression of λ-carrageenan-induced paw oedema in rats. The crude methanolic extract orally administered at 5,000 mg/kg, displayed no toxicity and at 250 to 1,000 mg/kg significantly suppressed the paw oedema. Two-isolated triterpenoids, betulinic acid (1) and koetjapic acid (2) orally administered at 50 mg/kg, significantly reduced the paw oedema, (p 
  12. Fulltext Differentially expressed genes on the growth of mouse Leydig cells treated with standardised Eurycoma longifolia extract
    Khurshid Ahmed NA, Lim SK, Pandian GN, Sugiyama H, Lee CY, Khoo BY, et al.
    Mol Med Rep, 2020 Nov;22(5):3645-3658.
    PMID: 32901880 DOI: 10.3892/mmr.2020.11485
    Eurycoma (E.) longifolia Jack (Tongkat Ali) is a widely applied medicine that has been reported to boost serum testosterone and increase muscle mass. However, its actual biological targets and effects on an in vitro level remain poorly understood. Therefore, the present study aimed to investigate the effects of a standardised E. longifolia extract (F2) on the growth and its associated gene expression profile in mouse Leydig cells. F2, even at lower doses, was found to induce a high level of testosterone by ELISA. The level was as high as the levels induced by eurycomanone and formestane in Leydig cells. However, Leydig cells treated with F2 demonstrated reduced viability, which was likely due to the diminished cell population at the G0/G1 phase and increased cell population arrested at the S phase in the cell cycle, as assessed by MTT assay and flow cytometry, respectively. Cell viability was revived when the treatment time‑point was prolonged to 96 h. Genome‑wide gene analysis by reverse transcription‑quantitative PCR of F2‑treated Leydig cells at 72 h, when the cell growth was not revived, and 96 h, when the cell growth had started to revive, revealed cyclin‑dependent kinase‑like 2 (CDKL2) to be a potential target in regulating the viability of F2‑treated Leydig cells. Functional analysis, as analysed using GeneMANIA Cytoscape program v.3.6.0 (https://genemania.org/), further suggested that CDKL2 could act in concert with Casitas B‑lineage lymphoma and sphingosine kinase 1 interactor‑A‑kinase anchoring protein domain‑containing genes to regulate the viability of F2‑treated Leydig cells. The findings of the present study provide new insights regarding the potential molecular targets associated with the biological effect of E. longifolia extract on cell growth, particularly on the cell cycle, which could aid in enhancing the bioefficacy and reducing the toxicity of this natural product in the future.
  13. NMR-based plasma metabolomic discrimination for male fertility assessment of rats treated with Eurycoma longifolia extracts
    Ebrahimi F, Ibrahim B, Teh CH, Murugaiyah V, Chan KL
    Syst Biol Reprod Med, 2017 Jun;63(3):179-191.
    PMID: 28306342 DOI: 10.1080/19396368.2017.1295332
    Male infertility is one of the leading causes of infertility which affects many couples worldwide. Semen analysis is a routine examination of male fertility status which is usually performed on semen samples obtained through masturbation that may be inconvenient to patients. Eurycoma longifolia (Tongkat Ali, TA), native to Malaysia, has been traditionally used as a remedy to boost male fertility. In our recent studies in rats, upon the administration of high-quassinoid content extracts of TA including TA water (TAW), quassinoid-rich TA (TAQR) extracts, and a low-quassinoid content extract including quassinoid-poor TA (TAQP) extract, sperm count (SC) increased in TAW- and TAQR-treated rats when compared to the TAQP-treated and control groups. Consequently, the rats were divided into normal- (control and TAQP-treated) and high- (TAW- and TAQR-treated) SC groups [Ebrahimi et al. 2016]. Post-treatment rat plasma was collected. An optimized plasma sample preparation method was developed with respect to the internal standards sodium 3- (trimethylsilyl) propionate- 2,2,3,3- d4 (TSP) and deuterated 4-dimethyl-4-silapentane-1-ammonium trifluoroacetate (DSA). Carr-Purcell-Meibum-Gill (CPMG) experiments combined with orthogonal partial least squares discriminant analysis (OPLS-DA) was employed to evaluate plasma metabolomic changes in normal- and high-SC rats. The potential biomarkers associated with SC increase were investigated to assess fertility by capturing the metabolomic profile of plasma. DSA was selected as the optimized internal standard for plasma analysis due to its significantly smaller half-height line width (W h/2) compared to that of TSP. The validated OPLS-DA model clearly discriminated the CPMG profiles in regard to the SC level. Plasma profiles of the high-SC group contained higher levels of alanine, lactate, and histidine, while ethanol concentration was significantly higher in the normal-SC group. This approach might be a new alternative applicable to the fertility assessment in humans through the quantitative metabolomic analysis of plasma without requiring semen.

    ABBREVIATIONS: TA: Tongkat Ali; LOD: limit of detection; LOQ: limit of quantification; HPLC-UV: high performance liquid chromatography-ultrviolet; PDA: photodiode array; NMR: nuclear magnetic resonance; FID: free induction decay; LC-MS: liquid chromatography-mass spectrometry; GC-MS: gas chromatography-mass spectrometry; HSQC: heteronuclear single quantum coherence; CPMG: Carr-Purcell-Meibum-Gill; VLDL: very low density lipoprotein; HDL: high density lipoprotein; EDTA: ethylenediaminetetraacetic acid; ANOVA: analysis of variance; AMIX: analysis of mixtures; SIMCA: soft independent modeling of class analogy; PCA: principal components analysis; OPLS-DA: orthogonal partial least-squares discriminant analysis; VIP: variable importance plot; AUROC: area under the receiver operating characteristic; TSP: sodium 3-(trimethylsilyl) propionate- 2,2,3,3- d4; DSA: deuterated 4-dimethyl-4-silapentane-1-ammonium trifluoroacetate; ESI: electrospray ionization; TCA: trichloroacetic acid; ACN: acetonitrile; dd H2O: distilled deionized water; FSH: follicle-stimulating hormone; LH: luteinizing hormone; OECD: Organisation for Economic Co-operation and Development.

  14. Human red cell adenylate kinase polymorphism in West Malaysian populations
    Chan KL
    Hum. Hered., 1971;21(2):173-9.
    PMID: 5127408
  15. The ameliorative effects of Eurycoma longifolia Jack on testosterone-induced reproductive disorders in female rats
    Abdulghani M, Hussin AH, Sulaiman SA, Chan KL
    Reprod Biol, 2012 Jul;12(2):247-55.
    PMID: 22850474 DOI: 10.1016/s1642-431x(12)60089-8
    The objective of this research was to study the ameliorative effects of a standardized quassinoid-rich extract (TAF 273) of Eurycoma longifolia root on some reproductive disorders in female rats. An irregular estrous cycle and ovarian cystic follicles were induced in 21-day-old females by the daily administration of testosterone (10 mg/kg, sc) for three weeks. The hormone-treated rats exhibited persistent diestrous as well as ovaries containing cystic follicles. Upon treatment with TAF 273, fewer animals showed irregular estrous cycles and there was less follicular morphological damage. The reversal effect may be derived from the anti-estrogenic properties of the plant quassinoids.
  16. Determination of four lignans in Phyllanthus niruri L. by a simple high-performance liquid chromatography method with fluorescence detection
    Murugaiyah V, Chan KL
    J Chromatogr A, 2007 Jun 22;1154(1-2):198-204.
    PMID: 17418855 DOI: 10.1016/j.chroma.2007.03.079
    A new and simple analytical method using HPLC with fluorescence detection was developed for the simultaneous determination of four lignans (phyllanthin, hypophyllanthin, phyltetralin and niranthin) in Phyllanthus niruri L. plant samples. Optimal separation was achieved with an isocratic mobile phase consisting of acetonitrile-water (55:45 v/v). The method recorded limits of detection (S/N=5) for phyllanthin at 0.61 ng/mL, hypophyllanthin at 6.02 ng/mL, phyltetralin at 0.61 ng/mL and niranthin at 1.22 ng/mL, being 80, 8, 80 and 40 times, respectively, lower when compared with those derived using HPLC-UV detection. The limits of quantification (S/N=12) were 4.88 ng/mL for phyllanthin and phyltetralin, 9.76 ng/mL for niranthin and 24.4 ng/mL for hypophyllanthin showing 40, 8 and 20 times, respectively, lower than those from the UV detection method. The within-day and between-day accuracy for the four lignans were between 98.1% and 102.9% while their precision values were below 2.2%. The mean recovery was between 92.5% and 110.1%. The method was then successfully applied for the quantification of lignans in P. niruri plant samples. The highest amount of lignans was found in the leaves followed by fruits, branches and stem, whilst the roots have the least amount of lignans.
  17. 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.
  18. Bioavailability and pharmacokinetic studies of eurycomanone from Eurycoma longifolia
    Low BS, Ng BH, Choy WP, Yuen KH, Chan KL
    Planta Med, 2005 Sep;71(9):803-7.
    PMID: 16206032
    A validated HPLC analysis of eurycomanone (1), a bioactive quassinoid, in rat plasma following oral and intravenous administration of Eurycoma longifolia Jack extract was developed for pharmacokinetic and bioavailability studies. Relatively high plasma eurycomanone concentrations were detected after an intravenous injection of 10 mg/kg extract F2 containing 1.96 mg/kg of the quassinoid. However, it declined rapidly to zero after 8 h. Its mean elimination rate constant (k(e)), biological half-life (t(1/2)), volume of distribution (V(d)) and clearance (CL) were 0.88 +/- 0.19 h (-1), 1.00 +/- 0.26 h, 0.68 +/- 0.30 L/kg and 0.39 +/- 0.08 L/h/kg, respectively. Following oral administration of eurycomanone, its Cmax and Tmax values were detected as 0.33 +/- 0.03 microg/mL and 4.40 +/- 0.98 h, respectively. The plasma concentration of the quassinoid after oral administration was much lower than after intravenous application in spite of the oral dose being 5 times higher. The results indicate that eurycomanone is poorly bioavailable when given orally. A comparison of the AUC (0-->infinity) obtained orally to that obtained after an intravenous administration (normalized for dose differences) revealed that the absolute bioavailability of the compound was low with 10.5 %. Furthermore, the compound appeared to be well distributed in the extravascular fluids because of its relatively high V(d) value. The poor oral bioavailability was not attributed to instability problems because eurycomanone has been shown to be stable under different pH conditions. Thus, its poor oral bioavailability may be due to poor membrane permeability in view of its low P value and/or high first-pass metabolism.
  19. Antihyperuricemic lignans from the leaves of Phyllanthus niruri
    Murugaiyah V, Chan KL
    Planta Med, 2006 Nov;72(14):1262-7.
    PMID: 16953466 DOI: 10.1055/s-2006-947224
    The methanol extract from the leaves of Phyllanthus niruri L. showed oral antihyperuricemic activity in potassium oxonate- and uric acid-induced hyperuricemic rats. Fractionation of the extract by resin chromatography led to the isolation of a less polar fraction which exhibited the highest reduction of plasma uric acid. Further antihyperuricemic-guided purification of the fraction afforded three lignans, phyllanthin (1), hypophyllanthin (2) and phyltetralin (3), of which 1 significantly reversed the plasma uric acid level of hyperuricemic animals to its normal level in a dose-dependent manner, comparable to that of allopurinol, benzbromarone and probenecid which are used clinically for the treatment of hyperuricemia and gout. Thus, the lignans of P. niruri are potential antihyperuricemic agents worthy of further investigation.
  20. Comparative X-ray and conformational analysis of a new crystal of 13α,21-dihydroeurycomanone with eurycomanone from Eurycoma longifolia and their anti-estrogenic activity using the uterotrophic assay
    Teh CH, Abdulghani M, Morita H, Shiro M, Hussin AH, Chan KL
    Planta Med, 2011 Jan;77(2):128-32.
    PMID: 20665368 DOI: 10.1055/s-0030-1250159
    13 α,21-Dihydroeurycomanone (1), a known quassinoid of Eurycoma longifolia Jack was recrystallized from chloroform into a novel crystal structure in space group P2 (1). Its X-ray data were compared with those of eurycomanone ( 2). Following intraperioneal injections at similar doses of 2.44 µmol/kg/day for 3 consecutive days, 2 displayed comparable potency with tamoxifen but was more potent than 1 in the anti-estrogenic effect against 17 α-ethynylestradiol (EE)-induced uterotrophy of immature rats.
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