Displaying publications 141 - 160 of 338 in total

Abstract:
Sort:
  1. Sim KM, Mak CN, Ho LP
    J Asian Nat Prod Res, 2009 Aug;11(8):757-60.
    PMID: 20183320 DOI: 10.1080/10286020903058933
    A new amide alkaloid, N-(3',4',5'-trimethoxy-cis-cinnamoyl)pyrrolidine (1), named sarmentomicine was isolated from the ethanol extract of the leaves of Malayan Piper sarmentosum, together with two known phenylpropanoids. Their structures were elucidated on the basis of spectroscopic analysis.
    Matched MeSH terms: Alkaloids/isolation & purification*; Alkaloids/chemistry
  2. Nge CE, Gan CY, Lim KH, Ting KN, Low YY, Kam TS
    Org. Lett., 2014 Dec 19;16(24):6330-3.
    PMID: 25454201 DOI: 10.1021/ol503072g
    Two new indole alkaloids characterized by previously unencountered natural product skeletons, viz., criofolinine (1), incorporating a pyrroloazepine motif within a pentacyclic ring system, and vernavosine (2, isolated as its ethyl ether derivative 3, which on hydrolysis regenerated the putative precursor alkaloid 2), incorporating a pyridopyrimidine moiety embedded within a pentacyclic carbon framework, were isolated from a Malayan Tabernaemontana species. The structures and absolute configuration of these alkaloids were determined on the basis of NMR and MS analysis and confirmed by X-ray diffraction analysis.
    Matched MeSH terms: Indole Alkaloids/isolation & purification; Indole Alkaloids/chemistry*
  3. Tan KK, Khoo TJ, Rajagopal M, Wiart C
    Nat Prod Res, 2015;29(24):2346-9.
    PMID: 25738993 DOI: 10.1080/14786419.2015.1013954
    Chloroform extract of bark of Artabotrys crassifolius Hook.f. & Thomson exhibited antibacterial activities against both American Type Culture Collection and clinical bacterial strains in vitro with zones of inhibition ranging from 7 to 14 mm. Further analysis of this extract yielded artabotrine, liridine, lysicamine and atherospermidine. Artabotrine displayed a broad array of antibacterial activity mostly against Gram-positive bacteria with minimum inhibitory concentration (MIC) values ranging from 1.25 μg/mL to 5 μg/mL. Of note, artabotrine, liridine and lysicamine are bactericidal against Gram-negative extended-spectrum beta-lactamase-producing Klebsiella with MIC values equal 2.5, 2.5 and 10 μg/mL, respectively, and minimum bactericidal concentrations values equal to 2.5, 5 and 20 μg/mL.
    Matched MeSH terms: Alkaloids/isolation & purification; Alkaloids/chemistry*
  4. Ramanathan S, Parthasarathy S, Murugaiyah V, Magosso E, Tan SC, Mansor SM
    Molecules, 2015 Mar 18;20(3):4915-27.
    PMID: 25793541 DOI: 10.3390/molecules20034915
    Varied pharmacological responses have been reported for mitragynine in the literature, but no supportive scientific explanations have been given for this. These studies have been undertaken without a sufficient understanding of the physicochemical properties of mitragynine. In this work a UV spectrophotometer approach and HPLC-UV method were employed to ascertain the physicochemical properties of mitragynine. The pKa of mitragynine measured by conventional UV (8.11 ± 0.11) was in agreement with the microplate reader determination (8.08 ± 0.04). Mitragynine is a lipophilic alkaloid, as indicated by a logP value of 1.73. Mitragynine had poor solubility in water and basic media, and conversely in acidic environments, but it is acid labile. In an in vitro dissolution the total drug release was higher for the simulated gastric fluid but was prolonged and incomplete for the simulated intestinal fluid. The hydrophobicity, poor water solubility, high variability of drug release in simulated biological fluids and acid degradable characteristics of mitragynine probably explain the large variability of its pharmacological responses reported in the literature. The determined physicochemical properties of mitragynine will provide a basis for developing a suitable formulation to further improve its solubility, stability and oral absorption for better assessment of this compound in preclinical studies.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/isolation & purification*; Secologanin Tryptamine Alkaloids/chemistry*
  5. Liew SY, Khaw KY, Murugaiyah V, Looi CY, Wong YL, Mustafa MR, et al.
    Phytomedicine, 2015 Jan 15;22(1):45-8.
    PMID: 25636869 DOI: 10.1016/j.phymed.2014.11.003
    Nine monoterpenoid indole alkaloids; naucletine (1), angustidine (2), nauclefine (3), angustine (4), naucline (5), angustoline (6), harmane (7), 3,14-dihydroangustoline (8), strictosamide (9) and one quinoline alkaloid glycoside; pumiloside (10) from Nauclea officinalis were tested for cholinesterase inhibitory activity. All the alkaloids except for pumiloside (10) showed strong to weak BChE inhibitory effect with IC50 values ranging between 1.02-168.55 μM. Angustidine (2), nauclefine (3), angustine (4), angustoline (6) and harmane (7) showed higher BChE inhibiting potency compared to galanthamine. Angustidine (2) was the most potent inhibitor towards both AChE and BChE. Molecular docking (MD) studies showed that angustidine (2) docked deep into the bottom gorge of hBChE and formed hydrogen bonding with Ser 198 and His 438. Kinetic study of angustidine (2) on BChE suggested a mixed inhibition mode with an inhibition constant (Ki) of 6.12 μM.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/isolation & purification; Secologanin Tryptamine Alkaloids/pharmacology*
  6. Yusoff M, Hamid H, Houghton P
    Molecules, 2014 Jan 20;19(1):1201-11.
    PMID: 24448061 DOI: 10.3390/molecules19011201
    Quaternary alkaloids are the major alkaloids isolated from Tinospora species. A previous study pointed to the necessary presence of quaternary nitrogens for strong acetylcholinesterase (AChE) inhibitory activity in such alkaloids. Repeated column chromatography of the vine of Tinospora crispa extract led to the isolation of one new protoberberine alkaloid, 4,13-dihydroxy-2,8,9-trimethoxydibenzo[a,g]quinolizinium (1), along with six known alkaloids-dihydrodiscretamine (2), columbamine (3), magnoflorine (4), N-formylannonaine (5), N-formylnornuciferine (6), and N-trans-feruloyltyramine (7). The seven compounds were isolated and structurally elucidated by spectroscopic analysis. Two known alkaloids, namely, dihydrodiscretamine and columbamine are reported for the first time for this plant. The compounds were tested for AChE inhibitory activity using Ellman's method. In the AChE inhibition assay, only columbamine (3) showed strong activity with IC50 48.1 µM. The structure-activity relationships derived from these results suggest that the quaternary nitrogen in the skeleton has some effect, but that a high degree of methoxylation is more important for acetylcholinesterase inhibition.
    Matched MeSH terms: Berberine Alkaloids/isolation & purification; Berberine Alkaloids/chemistry
  7. Singh D, Narayanan S, Vicknasingam B
    Brain Res Bull, 2016 09;126(Pt 1):41-46.
    PMID: 27178014 DOI: 10.1016/j.brainresbull.2016.05.004
    INTRODUCTION: The objective of the paper was to highlight the differences in the traditional and non-traditional users of kratom in the South East Asian and Western contexts.

    METHOD: A literature survey of published kratom studies among humans was conducted. Forty published studies relevant to the objective were reviewed.

    RESULTS: Apart from the differences in the sources of supply, patterns of use and social acceptability of kratom within these two regions, the most interesting finding is its evolution to a recreational drug in both settings and the severity of the adverse effects of kratom use reported in the West. While several cases of toxicity and death have emerged in the West, such reports have been non-existent in South East Asia where kratom has had a longer history of use. We highlight the possible reasons for this as discussed in the literature. More importantly, it should be borne in mind that the individual clinical case-reports emerging from the West that link kratom use to adverse reactions or fatalities frequently pertained to kratom used together with other substances. Therefore, there is a danger of these reports being used to strengthen the case for legal sanction against kratom. This would be unfortunate since the experiences from South East Asia suggest considerable potential for therapeutic use among people who use drugs.

    CONCLUSION: Despite its addictive properties, reported side-effects and its tendency to be used a recreational drug, more scientific clinical human studies are necessary to determine its potential therapeutic value.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/adverse effects*; Secologanin Tryptamine Alkaloids/therapeutic use*
  8. Feng X, Jiang G, Xia Z, Hu J, Wan X, Gao JM, et al.
    Org. Lett., 2015 Sep 18;17(18):4428-31.
    PMID: 26315849 DOI: 10.1021/acs.orglett.5b02046
    The first enantioselective synthesis of (-)-conolutinine was achieved in 10 steps. The synthesis featured a catalytic asymmetric bromocyclization of tryptamine to forge the tricycle intermediate. Hydration of an alkene catalyzed by Co(acac)2 was also employed as a key step to diastereoselectively introduce the tertiary alcohol moiety. The absolute configuration of (-)-conolutinine was established to be (2S,5aS,8aS,13aR) based on this asymmetric total synthesis.
    Matched MeSH terms: Indole Alkaloids/chemical synthesis*; Indole Alkaloids/chemistry
  9. Islam F, Bibi S, Meem AFK, Islam MM, Rahaman MS, Bepary S, et al.
    Int J Mol Sci, 2021 Nov 23;22(23).
    PMID: 34884440 DOI: 10.3390/ijms222312638
    Several coronaviruses (CoVs) have been associated with serious health hazards in recent decades, resulting in the deaths of thousands around the globe. The recent coronavirus pandemic has emphasized the importance of discovering novel and effective antiviral medicines as quickly as possible to prevent more loss of human lives. Positive-sense RNA viruses with group spikes protruding from their surfaces and an abnormally large RNA genome enclose CoVs. CoVs have already been related to a range of respiratory infectious diseases possibly fatal to humans, such as MERS, SARS, and the current COVID-19 outbreak. As a result, effective prevention, treatment, and medications against human coronavirus (HCoV) is urgently needed. In recent years, many natural substances have been discovered with a variety of biological significance, including antiviral properties. Throughout this work, we reviewed a wide range of natural substances that interrupt the life cycles for MERS and SARS, as well as their potential application in the treatment of COVID-19.
    Matched MeSH terms: Alkaloids/therapeutic use; Alkaloids/chemistry
  10. Gan CY, Robinson WT, Etoh T, Hayashi M, Komiyama K, Kam TS
    Org. Lett., 2009 Sep 3;11(17):3962-5.
    PMID: 19708704 DOI: 10.1021/ol9016172
    A cytotoxic bisindole alkaloid possessing an unprecedented structure constituted from the union of an eburnan half and a novel vinylquinoline alkaloid has been isolated from Leuconotis griffithii. The structure was established by analysis of the spectroscopic data and confirmed by X-ray diffraction analysis. A possible biogenetic pathway to the novel quinolinic coupling partner is presented from an Aspidosperma precursor.
    Matched MeSH terms: Indole Alkaloids/chemical synthesis*; Indole Alkaloids/isolation & purification; Indole Alkaloids/pharmacology*; Indole Alkaloids/chemistry
  11. Subramaniam G, Hiraku O, Hayashi M, Koyano T, Komiyama K, Kam TS
    J Nat Prod, 2007 Nov;70(11):1783-9.
    PMID: 17939738
    Eleven new indole alkaloids, in addition to the previously reported rhazinal (1), and 14 other known alkaloids, were obtained from the Malayan Kopsia singapurensis, viz., kopsiloscines A-F (2-7), 16-epikopsinine (8), kopsilongine- N-oxide (9), 16-epiakuammiline (10), aspidophylline A (11), and vincophylline (12). The structures of these alkaloids were determined using NMR and MS analyses. Rhazinal (1), rhazinilam (17), and rhazinicine (18) showed appreciable cytotoxicity toward drug-sensitive as well as vincristine-resistant KB cells, while kopsiloscines A (2), B (3), and D (5) and aspidophylline A (11) were found to reverse drug-resistance in drug-resistant KB cells.
    Matched MeSH terms: Alkaloids/classification; Alkaloids/isolation & purification*; Alkaloids/pharmacology*; Alkaloids/chemistry
  12. Salhi N, Mohammed Saghir SA, Terzi V, Brahmi I, Ghedairi N, Bissati S
    Biomed Res Int, 2017;2017:7526291.
    PMID: 29226147 DOI: 10.1155/2017/7526291
    Aim: This study investigated the antifungal properties of aqueous extracts obtained from indigenous plants that grow spontaneously in the Northern Sahara of Algeria. The activities of these plants in controlling two fungal species that belong to Fusarium genus were evaluated in an in vitro assay.

    Materials and Methods: Fresh aerial parts of four plant species (Artemisia herba alba, Cotula cinerea, Asphodelus tenuifolius, and Euphorbia guyoniana) were collected for the preparation of aqueous extracts. Two levels of dilution (10% and 20%) of the pure extracts were evaluated against Fusarium graminearum and Fusarium sporotrichioides.

    Results: The results of this study revealed that the A. herba alba, C. cinerea, A. tenuifolius, and E. guyoniana aqueous extracts are effective at both concentrations of 10% and 20% for the Fusarium mycelia growth inhibition. In particular, A. tenuifolius extract is effective against F. graminearum, whereas F. sporotrichioides mycelium growth is strongly affected by the E. guyoniana 20% extract. The phytochemical characterization of the compositions of the aqueous extracts has revealed that the presence of some chemical compounds (tannins, flavonoids, saponins, steroids, and alkaloids) is likely to be responsible for the antifungal activities sought.

    Conclusion: The antifungal properties of A. herba alba, C. cinerea, A. tenuifolius, and E. guyoniana make these plants of potential interest for the control of fungi affecting both wheat yield and safety.

    Matched MeSH terms: Alkaloids/pharmacology; Alkaloids/chemistry
  13. Hassan Z, Suhaimi FW, Ramanathan S, Ling KH, Effendy MA, Müller CP, et al.
    J. Psychopharmacol. (Oxford), 2019 07;33(7):908-918.
    PMID: 31081443 DOI: 10.1177/0269881119844186
    BACKGROUND: Mitragynine is the major alkaloid of Mitragyna speciosa (Korth.) or Kratom, a psychoactive plant widely abused in Southeast Asia. While addictive effects of the substance are emerging, adverse cognitive effects of this drug and neuropharmacological actions are insufficiently understood.

    AIMS: In the present study, we investigated the effects of mitragynine on spatial learning and synaptic transmission in the CA1 region of the hippocampus.

    METHODS: Male Sprague Dawley rats received daily (for 12 days) training sessions in the Morris water maze, with each session followed by treatment either with mitragynine (1, 5, or 10 mg/kg; intraperitoneally), morphine (5 mg/kg; intraperitoneally) or a vehicle. In the second experiment, we recorded field excitatory postsynaptic potentials in the hippocampal CA1 area in anesthetized rats and assessed the effects of mitragynine on baseline synaptic transmission, paired-pulse facilitation, and long-term potentiation. Gene expression of major memory- and addiction-related genes was investigated and the effects of mitragynine on Ca2+ influx was also examined in cultured primary neurons from E16-E18 rats.

    RESULTS/OUTCOMES: Escape latency results indicate that animals treated with mitragynine displayed a slower rate of acquisition as compared to their control counterparts. Further, mitragynine treatment significantly reduced the amplitude of baseline (i.e. non-potentiated) field excitatory postsynaptic potentials and resulted in a minor suppression of long-term potentiation in CA1. Bdnf and αCaMKII mRNA expressions in the brain were not affected and Ca2+ influx elicited by glutamate application was inhibited in neurons pre-treated with mitragynine.

    CONCLUSIONS/INTERPRETATION: These data suggest that high doses of mitragynine (5 and 10 mg/kg) cause memory deficits, possibly via inhibition of Ca2+ influx and disruption of hippocampal synaptic transmission and long-term potentiation induction.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/administration & dosage; Secologanin Tryptamine Alkaloids/toxicity*
  14. Obeng S, Kamble SH, Reeves ME, Restrepo LF, Patel A, Behnke M, et al.
    J Med Chem, 2020 01 09;63(1):433-439.
    PMID: 31834797 DOI: 10.1021/acs.jmedchem.9b01465
    Selected indole-based kratom alkaloids were evaluated for their opioid and adrenergic receptor binding and functional effects, in vivo antinociceptive effects, plasma protein binding, and metabolic stability. Mitragynine, the major alkaloid in Mitragyna speciosa (kratom), had higher affinity at opioid receptors than at adrenergic receptors while the vice versa was observed for corynantheidine. The observed polypharmacology of kratom alkaloids may support its utilization to treat opioid use disorder and withdrawal.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/metabolism; Secologanin Tryptamine Alkaloids/pharmacology*
  15. Ekeuku SO, Pang KL, Chin KY
    Drug Des Devel Ther, 2020;14:4963-4974.
    PMID: 33235437 DOI: 10.2147/DDDT.S280520
    Palmatine is a naturally occurring isoquinoline alkaloid with various pharmacological properties. Given its antioxidant and anti-inflammatory properties, palmatine may be able to impede the effects of metabolic syndrome (MetS) and its related diseases triggered by inflammation and oxidative stress. This review summarises the existing literature about the effects of palmatine supplementation on MetS and its complications. The evidence shows that palmatine could protect against MetS, and cardiovascular diseases, osteoporosis and osteoarthritis, which might be associated with MetS. These protective effects are mediated by the antioxidant and anti-inflammatory properties of palmatine. Although preclinical experiments have demonstrated the efficacy of palmatine against MetS and its related diseases, no human clinical trials have been performed to validate these effects. This research gap should be bridged to validate the efficacy and safety of palmatine supplementation in protecting humans against MetS and its related diseases.
    Matched MeSH terms: Berberine Alkaloids/adverse effects; Berberine Alkaloids/pharmacology*
  16. Suhaimi FW, Hassan Z, Mansor SM, Müller CP
    Neurosci Lett, 2021 02 06;745:135632.
    PMID: 33444671 DOI: 10.1016/j.neulet.2021.135632
    Mitragynine is the main alkaloid isolated from the leaves of Mitragyna speciosa Korth (Kratom). Kratom has been widely used to relieve pain and opioid withdrawal symptoms in humans but may also cause memory deficits. Here we investigated the changes in brain electroencephalogram (EEG) activity after acute and chronic exposure to mitragynine in freely moving rats. Vehicle, morphine (5 mg/kg) or mitragynine (1, 5 and 10 mg/kg) were administered for 28 days, and EEG activity was repeatedly recorded from the frontal cortex, neocortex and hippocampus. Repeated exposure to mitragynine increased delta, but decreased alpha powers in both cortical regions. It further decreased delta power in the hippocampus. These findings suggest that acute and chronic mitragynine can have profound effects on EEG activity, which may underlie effects on behavioral activity and cognition, particularly learning and memory function.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/administration & dosage*; Secologanin Tryptamine Alkaloids/isolation & purification
  17. Mok SL, Yoganathan K, Lim TM, Kam TS
    J Nat Prod, 1998 Mar;61(3):328-32.
    PMID: 9544563
    Intravenous injection of the aspidofractinine alkaloid, kopsingine (1, 0.2-10.0 mg/kg) from Kopsia teoi, produced dose-related decreases in the mean arterial blood pressure and heart rate in anesthetized spontaneously hypertensive rats, which were similar to those seen in normotensive controls. Minor modifications in the molecular structure of kopsingine, as in kopsaporine (2, the 12-demethoxy derivative of kopsingine) and 14,15-dihydrokopsingine (4), did not significantly alter the hypotensive responses, whereas a more drastic change in the structure, as in the heptacyclic kopsidine A (3) and the 3-to-17 oxo-bridged compound 5, resulted in an increase in blood pressure. The antihypertensive effects of kopsingine (1) and its congeners (2 and 4) along with the pressor effects produced by the heptacyclic oxo-bridged compounds (5 and 3) could be ascribed to central as well as peripheral actions.
    Matched MeSH terms: Alkaloids/isolation & purification*; Alkaloids/pharmacology
  18. Wan Othman WNN, Liew SY, Khaw KY, Murugaiyah V, Litaudon M, Awang K
    Bioorg Med Chem, 2016 09 15;24(18):4464-4469.
    PMID: 27492195 DOI: 10.1016/j.bmc.2016.07.043
    Alzheimer's disease is the most common form of dementia among older adults. Acetylcholinesterase and butyrylcholinesterase are two enzymes involved in the breaking down of the neurotransmitter acetylcholine. Inhibitors for these enzymes have potential to prolong the availability of acetylcholine. Hence, the search for such inhibitors especially from natural products is needed in developing potential drugs for Alzheimer's disease. The present study investigates the cholinesterase inhibitory activity of compounds isolated from three Cryptocarya species towards acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Nine alkaloids were isolated; (+)-nornantenine 1, (-)-desmethylsecoantofine 2, (+)-oridine 3, (+)-laurotetanine 4 from the leaves of Cryptocarya densiflora BI., atherosperminine 5, (+)-N-methylisococlaurine 6, (+)-N-methyllaurotetanine 7 from the bark of Cryptocarya infectoria Miq., 2-methoxyatherosperminine 8 and (+)-reticuline 9 from the bark of Cryptocarya griffithiana Wight. In general, most of the alkaloids showed higher inhibition towards BChE as compared to AChE. The phenanthrene type alkaloid; 2-methoxyatherosperminine 8, exhibited the most potent inhibition against BChE with IC50 value of 3.95μM. Analysis of the Lineweaver-Burk (LB) plot of BChE activity over a range of substrate concentration suggested that 2-methoxyatherosperminine 8 exhibited mixed-mode inhibition with an inhibition constant (Ki) of 6.72μM. Molecular docking studies revealed that 2-methoxyatherosperminine 8 docked well at the choline binding site and catalytic triad of hBChE (butyrylcholinesterase from Homo sapiens); hydrogen bonding with Tyr 128 and His 438 residues respectively.
    Matched MeSH terms: Alkaloids/pharmacology*; Alkaloids/chemistry
  19. Mok JS, Chang P, Lee KH, Kam TS, Goh SH
    J Ethnopharmacol, 1992 Jun;36(3):219-23.
    PMID: 1434680
    Among several alkaloids, including dimeric indoles, isolated from Uncaria callophylla, gambirine which is an alkaloid unique to this plant, has been found to be another hypotensive principle from the plant. Intravenous injections of gambirine in the dose range of 0.2 to 10.0 mg/kg caused a dose-related fall in both systolic and diastolic blood pressures as well as heart rate. At all doses gambirine showed a prompt onset of action and at the higher doses (5.0-10 mg/kg), marked persistence of hypotension accompanied by severe bradycardia were observed. In addition, higher doses of gambirine produced a more marked decrease in diastolic than systolic pressure while at lower doses both decreased equally. It is suggested that the hypotensive effect of gambirine may be peripheral in origin and is associated, at least in part, with a cardiac action.
    Matched MeSH terms: Alkaloids/administration & dosage; Alkaloids/pharmacology*
  20. Singh D, Narayanan S, Vicknasingam B, Corazza O, Santacroce R, Roman-Urrestarazu A
    Hum Psychopharmacol, 2017 05;32(3).
    PMID: 28544011 DOI: 10.1002/hup.2582
    OBJECTIVE: Kratom (Mitragyna speciosa. Korth) is an indigenous medicinal plant of Southeast Asia. This review paper aims to describe the trends of kratom use in Southeast Asia.

    DESIGN: A literature review search was conducted through ScienceDirect, Scopus, ProMed and Google Scholar. Twenty-five articles illustrating kratom use in humans in Southeast Asia were reviewed.

    RESULTS: Kratom has long been used by rural populations in Southeast Asia as a remedy for common ailments, to fight fatigue from hard manual work, as a drink during social interaction among men, and in village religious functions. Studies based on self-reports suggest that prolonged kratom use does not result in serious health risks or impair social functioning. Two recent trends have also emerged: (a) Kratom is reportedly being used to ease withdrawal from opioid dependence in rural settings; whereas (b) in urban areas, adulterated kratom cocktails are being consumed by younger people to induce euphoria.

    CONCLUSIONS: Legal sanctions appear to have preceded serious scientific investigations into the claimed benefits of ketum. More objective-controlled trials and experiments on humans need to be conducted to validate self-report claims by kratom users in the community.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/adverse effects*; Secologanin Tryptamine Alkaloids/therapeutic use*
Filters
Contact Us

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

External Links