Kit Lam Chan - Academia.edu (original) (raw)
Papers by Kit Lam Chan
The Open Conference Proceedings Journal, 2013
The quassinoid-rich standardized extract of Eurycoma longifoia extract (TAF2) was found to posses... more The quassinoid-rich standardized extract of Eurycoma longifoia extract (TAF2) was found to possess various biological activities. However, the poor oral bioavailability of the bioactive quassinoids, 13α(21)-epoxyeurycomanone (EP) and eurycomanone (EN) in TAF2 necessitated a new formulation design to be developed. A lipid-based solid dispersion was formulated and the bioavailabilities of EP and EN were significant improved compared with the conventional powder-filled capsules. A double peak phenomenon was identified in the plasma concentration-time curve. The gastric emptying and variability of GIT absorption, the probable causes of the double peak phenomenon, were studied by administering TAF2 solid dispersion to Sprague Dawley rats. As marker compounds, theophylline and sulfasalazine were used to determine the gastric emptying and variability of GIT absorption. The percentage absorbed of the markers was calculated using Wagner-Nelson method. The results showed that 50 % of theophylline was absorbed at 3 h, indicating the transit time of TAF2 solid dispersion from the stomach to the small intestine. Whereas, the 50 % of sulfapyridine, the metabolite of sulfasalazine, was absorbed at 8 h, reflected time of TAF2 solid dispersion to reach the colon. The concentration of TAF2 in colon was 74.36 % for EP and 80.27 % for EN, respectively. The results indicated that the delayed gastric emptying and colon absorption were the causes of double peak phenomenon. Thus, the delayed onset of in vivo activity of the quassinoids in E. longifolia was probably due to the delay of gastric emptying and colon absorption.
International Journal of Pharmacy and Pharmaceutical Sciences
The present investigation addresses the inhibitory potential of five Andrographis paniculata (AP)... more The present investigation addresses the inhibitory potential of five Andrographis paniculata (AP) extracts of different polarity and its three active constituents on UGT1A1, UGT1A4 and UGT2B7. Bioluminescent assay with luciferin as a substrate was used to determine IC50 values for all extracts and constituents. The kinetic enzyme inhibition experiments were subsequently performed to determine Ki values and inhibition modes for extracts and constituents having IC50 values less than 10 μg/mL. Our results in general exhibit that AP extracts and constituents potently inhibited UGT1A1 and UGT2B7 with varying degrees of inhibition featuring Ki values from 1.0 up to 7.5 μg/mL. On the other hand, none of them showed significant inhibitory effect on UGT1A4. Of the extracts tested, AP ethanolic, AP aqueous (root) and AP aqueous (leaf) were found to inhibit UGT1A1, while the remaining, were devoid of any potent interaction. In contrast, AP ethanolic was found to exclusively and competitively i...
BMC Complementary and Alternative Medicine, 2012
Background Toxoplasma gondii infection causes toxoplasmosis, an infectious disease with worldwide... more Background 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. Methods In vitro toxoplasmacidal evaluation was performed using Vero cells as host for T. gondii. Light microscopy technique was used to study in situ antiparasitic activity. Results Significant anti-T. gondii activity was observed with clindamycin (EC50 = 0.016 μg/ml), follow by TAF 355 (EC50 = 0.369 μg/ml) and TAF 401 (EC50 = 0.882 μg/ml). Light microsc...
![Research paper thumbnail of (E)-6-Bromo-3-{2-[2-(2-methoxybenzylidene)hydrazinyl]-1,3-thiazol-4-yl}-2H-chromen-2-one](https://attachments.academia-assets.com/99427189/thumbnails/1.jpg)
](Acta Crystallographica Section E Structure Reports Online, 2011
![Research paper thumbnail of 4,5,7,8,17-Pentahydroxy-14,18-dimethyl-6-methylene-3,10-dioxapentacyclo[9.8.0.01,7.04,19.013,18]nonadec-14-ene-9,16-dione methanol solvate dihydrate](https://attachments.academia-assets.com/99427150/thumbnails/1.jpg)
](Acta Crystallographica Section E Structure Reports Online, 2009
Teh et al. C 20 H 24 O 9 ÁCH 4 OÁ2H 2 O o899 supporting information sup-8
PLoS ONE, 2014
Eurycoma longifolia Jack has been widely used in traditional medicine for its antimalarial, aphro... more Eurycoma longifolia Jack has been widely used in traditional medicine for its antimalarial, aphrodisiac, anti-diabetic, antimicrobial and anti-pyretic activities. Its anticancer activity has also been recently reported on different solid tumors, however no anti-leukemic activity of this plant has been reported. Thus the present study assesses the in vitro and in vivo anti-proliferative and apoptotic potentials of E. longifolia on K-562 leukemic cell line. The K-562 cells (purchased from ATCC) were isolated from patients with chronic myelocytic leukemia (CML) were treated with the various fractions (TAF273, F3 and F4) of E. longifolia root methanolic extract at various concentrations and time intervals and the anti-proliferative activity assessed by MTS assay. Flow cytometry was used to assess the apoptosis and cell cycle arrest. Nude mice injected subcutaneously with 10 7 K-562 cells were used to study the anti-leukemic activity of TAF273 in vivo. TAF273, F3 and F4 showed various degrees of growth inhibition with IC50 values of 19, 55 and 62 mg/ml, respectively. TAF273 induced apoptosis in a dose and time dependent manner. TAF273 arrested cell cycle at G1and S phases. Intraperitoneal administration of TAF273 (50 mg/kg) resulted in a significant growth inhibition of subcutaneous tumor in TAF273-treated mice compared with the control mice (P = 0.024). TAF273 shows potent anti-proliferative activity in vitro and in vivo models of CML and therefore, justifies further efforts to define more clearly the potential benefits of using TAF273 as a novel therapeutic strategy for CML management.
Ethnopharmacological relevance: Phyllanthus niruri Linn. (Euphorbiaceae) is used as folk medicine... more 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 oxonateand uric acid-induced hyperuricemic rats. Results: Phyllanthus niruri methanol extract exhibited in vitro xanthine oxidase inhibition with an IC50 of 39.39 g/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 10 mg/kg. On the other hand, intraperitoneal treatment with Phyllanthus n...
Natural Product Communications, 2009
The present study investigated the effects of a standardized methanol extract of E. longifolia Ja... more The present study investigated the effects of a standardized methanol extract of E. longifolia Jack containing the major quassinoid constituents of 13α(21)-epoxyeurycomanone (1), eurycomanone (2), 13α,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 whe...
A strategy to circumvent the problem of multidrug resistant pathogen is consumption of functional... more A strategy to circumvent the problem of multidrug resistant pathogen is consumption of functional food rich in anti-infectives targeting bacterial virulence or host immunity. The black sea cucumber (Holothuria atra) is a tropical marine sea cucumer species traditionally consumed as remedy for many ailments. There is a paucity of knowledge the anti-infectives capacity of H. atra and the underlying mechanisms involved. The objectives of this study were to utilize the Caenorhabditis elegans-P. aeruginosa infection model to assess the anti-infective properties of H. atra. We first showed the capacity of a H. atra extract and fraction in promoting survival of C. elegans during a customarily lethal P. aeruginosa infection. The same chemical entities also attenuate the production of several P. aeruginosa virulence factors and biofilm. Treatment of infected transgenic lys-7::GFP worms with H. atra fraction restored the repressed expression of lys-7, a defense enzyme, indicating improved hos...
PloS one, 2015
Quassinoids are a group of diterpenoids found in plants from the Simaroubaceae family. They are a... more Quassinoids are a group of diterpenoids found in plants from the Simaroubaceae family. They are also the major bioactive compounds found in Eurycoma longifolia which is commonly used as traditional medicine in South East Asia to treat various ailments including sexual dysfunction and infertility. These uses are attributed to its ability to improve testosterone level in men. Chronic consumption of E. longifolia extracts has been reported to increase testosterone level in men and animal model but its effect on prostate growth remains unknown. Therefore, the present study investigates the effects of a standardized total quassinoids composition (SQ40) containing 40% of the total quassinoids found in E. longifolia on LNCaP human prostate cancer cell line. SQ40 inhibited LNCaP cell growth at IC50 value of 5.97 μg/mL while the IC50 on RWPE-1 human prostate normal cells was 59.26 μg/mL. SQ40 also inhibited 5α-dihydrotestosterone-stimulated growth in LNCaP cells dose-dependently. The inhibit...
European Journal of Medicinal Chemistry, 2011
Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully cha... more Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully characterized by IR, 1 H NMR, 13 C NMR, elemental analysis and mass spectral data. The structures of some compounds were further confirmed by X-ray crystallography. All of these derivatives, 10aed and 15aeh, were screened in vitro for antimicrobial activity against various bacteria species including Mycobacterium tuberculosis and Candida albicans. The compounds 10c, 10d and 15e exhibited very good activities against all of the tested microbial strains.
![Research paper thumbnail of 6-Bromo-3-{2-[2-(diphenylmethylene)hydrazinyl]-1,3-thiazol-5-yl}-2 H -chromen-2-one chloroform monosolvate](https://attachments.academia-assets.com/92730080/thumbnails/1.jpg)
](Acta Crystallographica Section E Structure Reports Online, 2011
![Research paper thumbnail of ( Z )-3-(2-{2-[1-(4-Hydroxyphenyl)ethylidene]hydrazin-1-yl}-1,3-thiazol-4-yl)-2 H -chromen-2-one](https://attachments.academia-assets.com/92730109/thumbnails/1.jpg)
](Acta Crystallographica Section E Structure Reports Online, 2010
![Research paper thumbnail of 3-{2-[2-(Diphenylmethylene)hydrazinyl]thiazol-4-yl}-2 H -chromen-2-one](https://attachments.academia-assets.com/92730011/thumbnails/1.jpg)
](Acta Crystallographica Section E Structure Reports Online, 2010
In the title compound, C 25 H 17 N 3 O 2 S, the coumarin ring system is essentially planar with a... more In the title compound, C 25 H 17 N 3 O 2 S, the coumarin ring system is essentially planar with a maximum deviation of 0.019 (2) Å. A weak intramolecular C-HÁ Á ÁO hydrogen bond stabilizes the molecular structure, so that the coumarin plane is approximately coplanar with the thiazole ring, making a dihedral angle of 2.5 (10). The two phenyl rings are nearly perpendicular to each other, with a dihedral angle of 81.44 (12). In the crystal structure, the molecules are linked into an infinite chain along the b axis by intermolecular C-HÁ Á ÁO hydrogen bonds. Weak C-HÁ Á Á interactions are observed between the chains.
The Open Conference Proceedings Journal, 2013
The Nuclear Magnetic Resonance (NMR)-based plant metabolomic method was used for the analysis of ... more The Nuclear Magnetic Resonance (NMR)-based plant metabolomic method was used for the analysis of 29 Eurycoma longifolia Jack (Tongkat Ali) roots, harvested from the same source in Perak. The objective of study was to establish a standardised profile of the plant metabolites for comparison with those of E. longifolia root samples derived from other sources. The age of the plant, the climatic conditions, soil pH and geographical locations were considered as probable variables. The roots were extracted with distilled-diionized water. The 1 H-NMR profile of each extract and the major secondary quassinoid metabolites, eurycomanone, eurycomanol, and eurycomanol-2-O-β-D-glycopyranoside were obtained. The NMR spectra were binned to 0.04 ppm and the data were analysed using the AMIX-TOOLS and SIMCA-P. Preliminary identification of the secondary metabolites confirmed the presence of the quassinoids of study in all the extracts. The Principle Component Analysis (PCA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) were performed. The PCA results at 95 % confidence level showed that no outliers were observed among the samples, indicating that the plants were similar in NMR profile. However, from OPLS-DA, five groups were identified to be different in terms of age and were statistically significant at 95 % confidence level. The differences among the groups strongly reflected the changes in the type and level of the metabolites. The identification and quantification of the discriminating metabolites among the groups will be discussed. Further studies on the profiling of the root organic extract and the biomarker quantification are ongoing.
Wiener klinische Wochenschrift, 2009
The habitats of Eurycoma longifolia Jack, a slender tree, are jungles in Malaysia and Indonesia. ... more The habitats of Eurycoma longifolia Jack, a slender tree, are jungles in Malaysia and Indonesia. It belongs to the family Simaroubaceae and is a source of quassinoids with anabolic, antimalarial and cytostatic activity. In this study, conducted during 2008 in Mae Sot, Thailand, a standardized extract of E. longifolia containing three major quassinoids, eurycomanone (1), 13,21-dihydroeurycomanone (2) and 13alpha(21)-epoxyeurycomanone (3) was evaluated for antiplasmodial activity against Plasmodium falciparum and its activity has been compared with that of artemisinin, using 38 fresh parasite isolates and assessment of inhibition of schizont maturation. The IC(50), IC(90) and IC(99) values for artemisinin were 4.30, 45.48 and 310.97 microg/l, and those for the root extract from E. longifolia 14.72, 139.65 and 874.15 microg/l respectively. The GMCOC for artemisinin was 337.81 mug/l, and for the plant extract it was 807.41 microg/l. The log-concentration probit regressions were parallel. The inhibitory activity of the E. longifolia extract was higher than that expected from the three quassinoids isolated from the plant, suggesting synergism between the quassinoids or the presence of other unidentified compounds.
Journal of Natural Products, 1987
Extracts of Brucea javanica fruit have been prepared and monitored for their in vitro and in vivo... more Extracts of Brucea javanica fruit have been prepared and monitored for their in vitro and in vivo antiplasmodial activities. The antimalarial activity of the fruit was found to be attributable to its quassinoid constituents. Nine of the quassinoids possessed in vitro IC50 values between 0.046-0.0008 microgram/ml against the chloroquine resistant Plasmodium falciparum strain (Kl) tested. The two quassinoid glycosides tested were considerably less active in vitro than the aglycones. Four quassinoids were found to possess activity in vivo against Plasmodium berghei infections in mice after oral dosing. All five quassinoids tested in vivo showed some toxicity.
Journal of Ethnopharmacology, 1995
... longifolia Jack, which is rich in quassinoids of mainly 13 ,18 dihydroeurycomanol (1), euryco... more ... longifolia Jack, which is rich in quassinoids of mainly 13 ,18 dihydroeurycomanol (1), eurycomanol2O D glucopyranoside (2), eurycomanol (3) and eury comanone (4 ... Chart, KL, Lee, SP, Sam, TW and Han, BH (1989) A quassinoid glycoside from the roots of Eurycoma longifolia. ...
The Open Conference Proceedings Journal, 2013
The quassinoid-rich standardized extract of Eurycoma longifoia extract (TAF2) was found to posses... more The quassinoid-rich standardized extract of Eurycoma longifoia extract (TAF2) was found to possess various biological activities. However, the poor oral bioavailability of the bioactive quassinoids, 13α(21)-epoxyeurycomanone (EP) and eurycomanone (EN) in TAF2 necessitated a new formulation design to be developed. A lipid-based solid dispersion was formulated and the bioavailabilities of EP and EN were significant improved compared with the conventional powder-filled capsules. A double peak phenomenon was identified in the plasma concentration-time curve. The gastric emptying and variability of GIT absorption, the probable causes of the double peak phenomenon, were studied by administering TAF2 solid dispersion to Sprague Dawley rats. As marker compounds, theophylline and sulfasalazine were used to determine the gastric emptying and variability of GIT absorption. The percentage absorbed of the markers was calculated using Wagner-Nelson method. The results showed that 50 % of theophylline was absorbed at 3 h, indicating the transit time of TAF2 solid dispersion from the stomach to the small intestine. Whereas, the 50 % of sulfapyridine, the metabolite of sulfasalazine, was absorbed at 8 h, reflected time of TAF2 solid dispersion to reach the colon. The concentration of TAF2 in colon was 74.36 % for EP and 80.27 % for EN, respectively. The results indicated that the delayed gastric emptying and colon absorption were the causes of double peak phenomenon. Thus, the delayed onset of in vivo activity of the quassinoids in E. longifolia was probably due to the delay of gastric emptying and colon absorption.
International Journal of Pharmacy and Pharmaceutical Sciences
The present investigation addresses the inhibitory potential of five Andrographis paniculata (AP)... more The present investigation addresses the inhibitory potential of five Andrographis paniculata (AP) extracts of different polarity and its three active constituents on UGT1A1, UGT1A4 and UGT2B7. Bioluminescent assay with luciferin as a substrate was used to determine IC50 values for all extracts and constituents. The kinetic enzyme inhibition experiments were subsequently performed to determine Ki values and inhibition modes for extracts and constituents having IC50 values less than 10 μg/mL. Our results in general exhibit that AP extracts and constituents potently inhibited UGT1A1 and UGT2B7 with varying degrees of inhibition featuring Ki values from 1.0 up to 7.5 μg/mL. On the other hand, none of them showed significant inhibitory effect on UGT1A4. Of the extracts tested, AP ethanolic, AP aqueous (root) and AP aqueous (leaf) were found to inhibit UGT1A1, while the remaining, were devoid of any potent interaction. In contrast, AP ethanolic was found to exclusively and competitively i...
BMC Complementary and Alternative Medicine, 2012
Background Toxoplasma gondii infection causes toxoplasmosis, an infectious disease with worldwide... more Background 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. Methods In vitro toxoplasmacidal evaluation was performed using Vero cells as host for T. gondii. Light microscopy technique was used to study in situ antiparasitic activity. Results Significant anti-T. gondii activity was observed with clindamycin (EC50 = 0.016 μg/ml), follow by TAF 355 (EC50 = 0.369 μg/ml) and TAF 401 (EC50 = 0.882 μg/ml). Light microsc...
Acta Crystallographica Section E Structure Reports Online, 2011
Acta Crystallographica Section E Structure Reports Online, 2009
Teh et al. C 20 H 24 O 9 ÁCH 4 OÁ2H 2 O o899 supporting information sup-8
PLoS ONE, 2014
Eurycoma longifolia Jack has been widely used in traditional medicine for its antimalarial, aphro... more Eurycoma longifolia Jack has been widely used in traditional medicine for its antimalarial, aphrodisiac, anti-diabetic, antimicrobial and anti-pyretic activities. Its anticancer activity has also been recently reported on different solid tumors, however no anti-leukemic activity of this plant has been reported. Thus the present study assesses the in vitro and in vivo anti-proliferative and apoptotic potentials of E. longifolia on K-562 leukemic cell line. The K-562 cells (purchased from ATCC) were isolated from patients with chronic myelocytic leukemia (CML) were treated with the various fractions (TAF273, F3 and F4) of E. longifolia root methanolic extract at various concentrations and time intervals and the anti-proliferative activity assessed by MTS assay. Flow cytometry was used to assess the apoptosis and cell cycle arrest. Nude mice injected subcutaneously with 10 7 K-562 cells were used to study the anti-leukemic activity of TAF273 in vivo. TAF273, F3 and F4 showed various degrees of growth inhibition with IC50 values of 19, 55 and 62 mg/ml, respectively. TAF273 induced apoptosis in a dose and time dependent manner. TAF273 arrested cell cycle at G1and S phases. Intraperitoneal administration of TAF273 (50 mg/kg) resulted in a significant growth inhibition of subcutaneous tumor in TAF273-treated mice compared with the control mice (P = 0.024). TAF273 shows potent anti-proliferative activity in vitro and in vivo models of CML and therefore, justifies further efforts to define more clearly the potential benefits of using TAF273 as a novel therapeutic strategy for CML management.
Ethnopharmacological relevance: Phyllanthus niruri Linn. (Euphorbiaceae) is used as folk medicine... more 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 oxonateand uric acid-induced hyperuricemic rats. Results: Phyllanthus niruri methanol extract exhibited in vitro xanthine oxidase inhibition with an IC50 of 39.39 g/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 10 mg/kg. On the other hand, intraperitoneal treatment with Phyllanthus n...
Natural Product Communications, 2009
The present study investigated the effects of a standardized methanol extract of E. longifolia Ja... more The present study investigated the effects of a standardized methanol extract of E. longifolia Jack containing the major quassinoid constituents of 13α(21)-epoxyeurycomanone (1), eurycomanone (2), 13α,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 whe...
A strategy to circumvent the problem of multidrug resistant pathogen is consumption of functional... more A strategy to circumvent the problem of multidrug resistant pathogen is consumption of functional food rich in anti-infectives targeting bacterial virulence or host immunity. The black sea cucumber (Holothuria atra) is a tropical marine sea cucumer species traditionally consumed as remedy for many ailments. There is a paucity of knowledge the anti-infectives capacity of H. atra and the underlying mechanisms involved. The objectives of this study were to utilize the Caenorhabditis elegans-P. aeruginosa infection model to assess the anti-infective properties of H. atra. We first showed the capacity of a H. atra extract and fraction in promoting survival of C. elegans during a customarily lethal P. aeruginosa infection. The same chemical entities also attenuate the production of several P. aeruginosa virulence factors and biofilm. Treatment of infected transgenic lys-7::GFP worms with H. atra fraction restored the repressed expression of lys-7, a defense enzyme, indicating improved hos...
PloS one, 2015
Quassinoids are a group of diterpenoids found in plants from the Simaroubaceae family. They are a... more Quassinoids are a group of diterpenoids found in plants from the Simaroubaceae family. They are also the major bioactive compounds found in Eurycoma longifolia which is commonly used as traditional medicine in South East Asia to treat various ailments including sexual dysfunction and infertility. These uses are attributed to its ability to improve testosterone level in men. Chronic consumption of E. longifolia extracts has been reported to increase testosterone level in men and animal model but its effect on prostate growth remains unknown. Therefore, the present study investigates the effects of a standardized total quassinoids composition (SQ40) containing 40% of the total quassinoids found in E. longifolia on LNCaP human prostate cancer cell line. SQ40 inhibited LNCaP cell growth at IC50 value of 5.97 μg/mL while the IC50 on RWPE-1 human prostate normal cells was 59.26 μg/mL. SQ40 also inhibited 5α-dihydrotestosterone-stimulated growth in LNCaP cells dose-dependently. The inhibit...
European Journal of Medicinal Chemistry, 2011
Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully cha... more Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully characterized by IR, 1 H NMR, 13 C NMR, elemental analysis and mass spectral data. The structures of some compounds were further confirmed by X-ray crystallography. All of these derivatives, 10aed and 15aeh, were screened in vitro for antimicrobial activity against various bacteria species including Mycobacterium tuberculosis and Candida albicans. The compounds 10c, 10d and 15e exhibited very good activities against all of the tested microbial strains.
Acta Crystallographica Section E Structure Reports Online, 2011
Acta Crystallographica Section E Structure Reports Online, 2010
Acta Crystallographica Section E Structure Reports Online, 2010
In the title compound, C 25 H 17 N 3 O 2 S, the coumarin ring system is essentially planar with a... more In the title compound, C 25 H 17 N 3 O 2 S, the coumarin ring system is essentially planar with a maximum deviation of 0.019 (2) Å. A weak intramolecular C-HÁ Á ÁO hydrogen bond stabilizes the molecular structure, so that the coumarin plane is approximately coplanar with the thiazole ring, making a dihedral angle of 2.5 (10). The two phenyl rings are nearly perpendicular to each other, with a dihedral angle of 81.44 (12). In the crystal structure, the molecules are linked into an infinite chain along the b axis by intermolecular C-HÁ Á ÁO hydrogen bonds. Weak C-HÁ Á Á interactions are observed between the chains.
The Open Conference Proceedings Journal, 2013
The Nuclear Magnetic Resonance (NMR)-based plant metabolomic method was used for the analysis of ... more The Nuclear Magnetic Resonance (NMR)-based plant metabolomic method was used for the analysis of 29 Eurycoma longifolia Jack (Tongkat Ali) roots, harvested from the same source in Perak. The objective of study was to establish a standardised profile of the plant metabolites for comparison with those of E. longifolia root samples derived from other sources. The age of the plant, the climatic conditions, soil pH and geographical locations were considered as probable variables. The roots were extracted with distilled-diionized water. The 1 H-NMR profile of each extract and the major secondary quassinoid metabolites, eurycomanone, eurycomanol, and eurycomanol-2-O-β-D-glycopyranoside were obtained. The NMR spectra were binned to 0.04 ppm and the data were analysed using the AMIX-TOOLS and SIMCA-P. Preliminary identification of the secondary metabolites confirmed the presence of the quassinoids of study in all the extracts. The Principle Component Analysis (PCA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) were performed. The PCA results at 95 % confidence level showed that no outliers were observed among the samples, indicating that the plants were similar in NMR profile. However, from OPLS-DA, five groups were identified to be different in terms of age and were statistically significant at 95 % confidence level. The differences among the groups strongly reflected the changes in the type and level of the metabolites. The identification and quantification of the discriminating metabolites among the groups will be discussed. Further studies on the profiling of the root organic extract and the biomarker quantification are ongoing.
Wiener klinische Wochenschrift, 2009
The habitats of Eurycoma longifolia Jack, a slender tree, are jungles in Malaysia and Indonesia. ... more The habitats of Eurycoma longifolia Jack, a slender tree, are jungles in Malaysia and Indonesia. It belongs to the family Simaroubaceae and is a source of quassinoids with anabolic, antimalarial and cytostatic activity. In this study, conducted during 2008 in Mae Sot, Thailand, a standardized extract of E. longifolia containing three major quassinoids, eurycomanone (1), 13,21-dihydroeurycomanone (2) and 13alpha(21)-epoxyeurycomanone (3) was evaluated for antiplasmodial activity against Plasmodium falciparum and its activity has been compared with that of artemisinin, using 38 fresh parasite isolates and assessment of inhibition of schizont maturation. The IC(50), IC(90) and IC(99) values for artemisinin were 4.30, 45.48 and 310.97 microg/l, and those for the root extract from E. longifolia 14.72, 139.65 and 874.15 microg/l respectively. The GMCOC for artemisinin was 337.81 mug/l, and for the plant extract it was 807.41 microg/l. The log-concentration probit regressions were parallel. The inhibitory activity of the E. longifolia extract was higher than that expected from the three quassinoids isolated from the plant, suggesting synergism between the quassinoids or the presence of other unidentified compounds.
Journal of Natural Products, 1987
Extracts of Brucea javanica fruit have been prepared and monitored for their in vitro and in vivo... more Extracts of Brucea javanica fruit have been prepared and monitored for their in vitro and in vivo antiplasmodial activities. The antimalarial activity of the fruit was found to be attributable to its quassinoid constituents. Nine of the quassinoids possessed in vitro IC50 values between 0.046-0.0008 microgram/ml against the chloroquine resistant Plasmodium falciparum strain (Kl) tested. The two quassinoid glycosides tested were considerably less active in vitro than the aglycones. Four quassinoids were found to possess activity in vivo against Plasmodium berghei infections in mice after oral dosing. All five quassinoids tested in vivo showed some toxicity.
Journal of Ethnopharmacology, 1995
... longifolia Jack, which is rich in quassinoids of mainly 13 ,18 dihydroeurycomanol (1), euryco... more ... longifolia Jack, which is rich in quassinoids of mainly 13 ,18 dihydroeurycomanol (1), eurycomanol2O D glucopyranoside (2), eurycomanol (3) and eury comanone (4 ... Chart, KL, Lee, SP, Sam, TW and Han, BH (1989) A quassinoid glycoside from the roots of Eurycoma longifolia. ...