Displaying publications 21 - 40 of 129 in total

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  1. Achike FI, Kwan CY
    Acta Pharmacol Sin, 2002 Aug;23(8):698-704.
    PMID: 12147191
    In an attempt to pharmacologically characterize the Chinese antihypertensive drug, tetrandrine, we observed in rat-tail arteries, an unusual contraction in tissues that were stimulated with high [KCl] and not those stimulated with phenylephrine. The characteristics of this contraction were studied.
    Matched MeSH terms: Alkaloids/pharmacology*
  2. Chear NJ, León F, Sharma A, Kanumuri SRR, Zwolinski G, Abboud KA, et al.
    J Nat Prod, 2021 04 23;84(4):1034-1043.
    PMID: 33635670 DOI: 10.1021/acs.jnatprod.0c01055
    Ten indole and oxindole alkaloids (1-10) were isolated from the freshly collected leaves of Malaysian Mitragyna speciosa (Kratom). The chemical structures of these compounds were established on the basis of extensive 1D and 2D NMR and HRMS data analysis. The spectroscopic data of mitragynine oxindole B (4) are reported herein for the first time. The spatial configuration of mitragynine oxindole B (4) was confirmed by single-crystal X-ray diffraction. Simultaneous quantification of the isolated alkaloids in the M. speciosa leaf specimens collected from different locations in the northern region of Peninsular Malaysia was also performed using UPLC-MS/MS. The oxindole alkaloids (1-4) and the indole alkaloid (10) were assessed for binding affinity at opioid receptors. Corynoxine (1) showed high binding affinity to μ-opioid receptors with a Ki value of 16.4 nM. Further, corynoxine (1) was 1.8-fold more potent than morphine in rats subjected to a nociceptive hot plate assay. These findings have important implications for evaluating the combined effects of the minor oxindole alkaloids in the overall therapeutic activity of M. speciosa.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  3. Tan CH, Sim DSY, Lim SH, Mohd Mohidin TB, Mohan G, Low YY, et al.
    Planta Med, 2022 Nov;88(14):1325-1340.
    PMID: 35100653 DOI: 10.1055/a-1755-5605
    Two iboga-vobasine bisindoles, 16'-decarbomethoxyvoacamine (1: ) and its 19,20-dihydro derivative, 16'-decarbomethoxydihydrovoacamine (2: ) from Tabernaemontana corymbosa exhibited potent cytotoxicity against the human colorectal adenocarcinoma HT-29 cells in our previous studies. Bisindoles 1: and 2: selectively inhibited the growth of HT-29 cells without significant cytotoxicity to normal human colon fibroblasts CCD-18Co. Treatment with bisindoles 1: and 2: suppressed the formation of HT-29 colonies via G0/G1 cell cycle arrest and induction of mitochondrial apoptosis. Owing to its higher antiproliferative activity, bisindole 2: was chosen for the subsequent studies. Bisindole 2: inhibited the formation of HT-29 spheroids (tumor-like cell aggregates) in 3D experiments in a dose-dependent manner, while an in vitro tubulin polymerization assay and molecular docking analysis showed that bisindole 2: is a microtubule-stabilizing agent which is predicted to bind at the β-tubulin subunit at the taxol-binding site. The binding resulted in the generation of ROS, which consequently activated the oxidative stress-related cell cycle arrest and apoptotic pathways, viz., JNK/p38, p21Cip1/Chk1, and p21Cip1/Rb/E2F, as shown by microarray profiling.
    Matched MeSH terms: Indole Alkaloids/pharmacology
  4. Muktar MR, Osman N, Awang K, Hazni H, Qureshi AK, Hadi AH, et al.
    Molecules, 2011 Dec 28;17(1):267-74.
    PMID: 22205092 DOI: 10.3390/molecules17010267
    A new indole alkaloid; neonaucline (1), along with six known compounds-Cadamine (2), naucledine (3), harmane, benzamide, cinnamide and blumenol A-were isolated from the leaves of Ochreinauclea maingayii (Rubiaceae). In addition to that of compound 1, (13)C-NMR data of cadamine (2) and naucledine (3) were also reported. Structural elucidations of these alkaloids were performed using spectroscopic methods especially 1D- and 2D-NMR, IR, UV and LCMS-IT-TOF. The excellent vasorelaxant activity on isolated rat aorta was observed for the alkaloids 1-3 after injection of each sample at 1 × 10(-5) M.
    Matched MeSH terms: Indole Alkaloids/pharmacology
  5. Kam TS, Tan SJ, Ng SW, Komiyama K
    Org. Lett., 2008 Sep 4;10(17):3749-52.
    PMID: 18683934 DOI: 10.1021/ol801354s
    A cytotoxic bisindole alkaloid possessing an unprecedented structure in which two indole moieties are bridged by an aromatic spacer unit has been isolated from Alstonia angustifolia. The structure was established by analysis of the spectroscopic data and confirmed by X-ray diffraction analysis. A possible biogenetic pathway from pyrocatechuic acid and pleiocarpamine is presented.
    Matched MeSH terms: Indole Alkaloids/pharmacology
  6. Mohtar M, Johari SA, Li AR, Isa MM, Mustafa S, Ali AM, et al.
    Curr Microbiol, 2009 Aug;59(2):181-6.
    PMID: 19475447 DOI: 10.1007/s00284-009-9416-9
    Increased prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has become a major threat to the health sector worldwide due to their virulence, limited therapeutic options and their distribution in both hospital and community settings. Discovery and development of new anti-MRSA agents as alternatives to the very few antibiotics left in the armamentarium are, thus, urgently required. Recently, an efflux mechanism in MRSA has been identified as one of the main contributors of resistance towards various structurally unrelated antibiotics. The potential of reserpine (a phytoalkaloid) as efflux pump inhibitor (EPI) against various microbes remains limited as the concentration needed for inhibition is toxic to humans. This study therefore aimed to evaluate 13 alkaloid compounds as potential inhibitory agents and/or potential EPIs against a panel of three MRSA isolates which not only differ in their susceptibility to vancomycin (amongst the last drugs available to treat serious MRSA infection), but also exhibited active efflux activity. Results indicated berberine's moderate inhibitiory activity against two MRSA isolates scoring a minimum inhibitory concentration (MIC) value of 125 microg/ml. Notable efflux inhibitory activity (ranging from two- to eightfold Ethidium Bromide MIC reduction) meanwhile was detected from quinine, piperine and harmaline using reserpine as the positive control. Findings from this study support the opinion that a vast number of potential phytocompounds with pharmacological potential await discovery. Therapeutic application of these compounds, however, warrants further investigation to ascertain their pharmacodynamics and safety aspects.
    Matched MeSH terms: Alkaloids/pharmacology*
  7. Lim KH, Hiraku O, Komiyama K, Kam TS
    J Nat Prod, 2008 Sep;71(9):1591-4.
    PMID: 18778099 DOI: 10.1021/np800435c
    Seven new indole alkaloids of the Aspidosperma type, jerantinines A-G (1-7), were isolated from a leaf extract of the Malayan Tabernaemontana corymbosa. The structures were established using NMR and MS analysis. Five of the alkaloids isolated and two derivatives (1-5, 8, 9) displayed pronounced in vitro cytotoxicity against human KB cells (IC50 < 1 microg/mL).
    Matched MeSH terms: Indole Alkaloids/pharmacology*
  8. Gan CY, Low YY, Etoh T, Hayashi M, Komiyama K, Kam TS
    J Nat Prod, 2009 Dec;72(12):2098-103.
    PMID: 20035556 DOI: 10.1021/np900576b
    Seven new indole alkaloids of the Strychnos type, leuconicines A-G (1-7), and a new eburnan alkaloid, (-)-eburnamaline (8), were isolated from the stem-bark extract of two Malayan Leuconotis species. The structures of these alkaloids were established using NMR and MS analysis and in the case of 8 also by partial synthesis. Alkaloids 1-5 reversed multidrug resistance in vincristine-resistant KB cells.
    Matched MeSH terms: Indole Alkaloids/pharmacology
  9. Jantan I, Raweh SM, Yasin YH, Murad S
    Phytother Res, 2006 Jun;20(6):493-6.
    PMID: 16619347
    Six aporphine and one phenanthrenoid alkaloids isolated from Aromadendron elegans Blume were investigated for their ability to inhibit arachidonic acid (AA), collagen and ADP induced platelet aggregation in human whole blood. The antiplatelet activity of the compounds was measured in vitro by the Chrono Log whole blood aggregometer using an electrical impedance method. Of the compounds tested, (-)-N-acetylnornuciferine, (-)-N-acetylanonaine and 1-(N-acetyl-N-methylamino)ethyl-3,4,6-trimethoxy-7-hydroxyphenanthrene showed strong inhibition on platelet aggregation caused by all three inducers. (-)-N-acetylanonaine was the most effective antiplatelet compound as it inhibited both arachidonic acid, collagen and ADP-induced platelet aggregation with IC(50) values of 66.1, 95.1 and 80.6 microm, respectively.
    Matched MeSH terms: Alkaloids/pharmacology*
  10. Qureshi AK, Mukhtar MR, Hirasawa Y, Hosoya T, Nugroho AE, Morita H, et al.
    Chem Pharm Bull (Tokyo), 2011;59(2):291-3.
    PMID: 21297315
    Two new indole alkaloids, neolamarckines A and B (1, 2) were isolated from the leaves of Neolamarckia cadamba (Rubiaceae). Structural elucidation of 1 and 2 was performed by combination of 2D-NMR and circular dichroism (CD) spectra, and chemical correlations. Neolamarckine A (1) showed inhibition of inducible nitric oxide synthase (iNOS) dose dependently.
    Matched MeSH terms: Indole Alkaloids/pharmacology
  11. 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/pharmacology*
  12. Ramli RA, Lie W, Pyne SG
    J Nat Prod, 2014 Apr 25;77(4):894-901.
    PMID: 24606395 DOI: 10.1021/np400978x
    Four new stichoneurine-type alkaloids, stichoneurines F and G (1-2) and sessilistemonamines E and F (3-4), have been isolated from the root extracts of Stichoneuron caudatum. The structures and relative configurations of these alkaloids have been determined by spectroscopic methods and molecular modeling experiments. Compounds 1-4 were tested for their acetylcholinesterase (AChE) inhibitory activities against human AChE. Compound 3 showed significant inhibitory activity with an IC50 value of 9.1±0.15 μM.
    Matched MeSH terms: Alkaloids/pharmacology*
  13. Ismail NIW, Jayabalan N, Mansor SM, Müller CP, Muzaimi M
    Addict Biol, 2017 Jul;22(4):967-976.
    PMID: 26990882 DOI: 10.1111/adb.12385
    Kratom (Mitragyna speciosa) is a widely abused herbal drug preparation in Southeast Asia. It is often consumed as a substitute for heroin, but imposing itself unknown harms and addictive burdens. Mitragynine is the major psychostimulant constituent of kratom that has recently been reported to induce morphine-like behavioural and cognitive effects in rodents. The effects of chronic consumption on non-drug related behaviours are still unclear. In the present study, we investigated the effects of chronic mitragynine treatment on spontaneous activity, reward-related behaviour and cognition in mice in an IntelliCage® system, and compared them with those of morphine and Δ-9-tetrahydrocannabinol (THC). We found that chronic mitragynine treatment significantly potentiated horizontal exploratory activity. It enhanced spontaneous sucrose preference and also its persistence when the preference had aversive consequences. Furthermore, mitragynine impaired place learning and its reversal. Thereby, mitragynine effects closely resembled that of morphine and THC sensitisation. These findings suggest that chronic mitragynine exposure enhances spontaneous locomotor activity and the preference for natural rewards, but impairs learning and memory. These findings confirm pleiotropic effects of mitragynine (kratom) on human lifestyle, but may also support the recognition of the drug's harm potential.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology*
  14. Mishan MA, Choo YM, Winkler J, Hamann MT, Karan D
    Eur J Pharmacol, 2025 Mar 05;990:177295.
    PMID: 39863145 DOI: 10.1016/j.ejphar.2025.177295
    Manzamine A, a natural compound derived from various sponge genera, features a β-carboline structure and exhibits a range of biological activities, including anti-inflammatory and antimalarial effects. Its potential as an anticancer agent has been explored in several tumor models, both in vitro and in vivo, showing effects through mechanisms such as cytotoxicity, regulation of the cell cycle, inhibition of cell migration, epithelial-to-mesenchymal transition (EMT), autophagy, and apoptosis through multi-target interactions of E2F transcriptional factors, ribosomal S6 kinases, androgen receptor (AR), SIX1, GSK-3β, v-ATPase, and p53/p21/p27 cascades. This systematic review evaluates existing literature on the potential application of this marine alkaloid as a novel cancer therapy, highlighting its promising ability to inhibit cancer cell growth while causing minimal side effects.
    Matched MeSH terms: Indole Alkaloids/pharmacology
  15. 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
  16. Ahmad H, Ahmad S, Ali M, Latif A, Shah SAA, Naz H, et al.
    Bioorg Chem, 2018 08;78:427-435.
    PMID: 29698893 DOI: 10.1016/j.bioorg.2018.04.008
    Three new norditerpenoids alkaloids, 1β-hydroxy,14β-acetyl condelphine (1), jadwarine-A (2), jadwarine-B (3) along with two known alkaloids isotalatizidine hydrate (4) and dihydropentagynine (5) were isolated from medicinal plant Delphinium denudatum. The structures of natural products 1-5 were established on the basis of HR-EIMS, 1H and 13C NMR (1D & 2D) spectroscopic data as well as by comparison from literature data. The structures of compound 1 and 4 were also confirmed by single crystal X-ray diffraction studies. In-vitro AChE and BChE enzyme inhibitory activities of compounds 1-5 and molecular docking studies were performed to investigate the possible molecular inhibitory mechanism of the isolated natural products. Compound 2, 4 and 5 showed competitive inhibitory effects by inhibiting AChE and BChE, respectively, while 1 and 3 showed non-competitive inhibition. This work is the first report that provides a supporting evidence about the use of constituents of Delphinium denudatum in cerebral dementia and Alzheimer diseases.
    Matched MeSH terms: Alkaloids/pharmacology*
  17. Prozialeck WC, Avery BA, Boyer EW, Grundmann O, Henningfield JE, Kruegel AC, et al.
    Int J Drug Policy, 2019 08;70:70-77.
    PMID: 31103778 DOI: 10.1016/j.drugpo.2019.05.003
    Kratom (Mitragyna speciosa) is a tree-like plant indigenous to Southeast Asia. Its leaves, and the teas brewed from them have long been used by people in that region to stave off fatigue and to manage pain and opioid withdrawal. Evidence suggests kratom is being increasingly used by people in the United States and Europe for the self-management of opioid withdrawal and treatment of pain. Recent studies have confirmed that kratom and its chemical constituents have potentially useful pharmacological actions. However, there have also been increasing numbers of reports of adverse effects resulting from use of kratom products. In August 2016, the US Drug Enforcement Administration announced plans to classify kratom and its mitragynine constituents as Schedule I Controlled Substances, a move that triggered a massive response from pro-kratom advocates. The debate regarding the risks, and benefits and safety of kratom continues to intensify. Kratom proponents tout kratom as a safer and less addictive alternative to opioids for the management of pain and opioid addiction. The anti-kratom faction argues that kratom, itself, is a dangerous and addictive drug that ought to be banned. Given the widespread use of kratom and the extensive media attention it is receiving, it is important for physicians, scientists and policy makers to be knowledgeable about the subject. The purpose of this commentary is to update readers about recent developments and controversies in this rapidly evolving area. All of the authors are engaged in various aspects of kratom research and it is our intention to provide a fair and balanced overview that can form the basis for informed decisions on kratom policy. Our conclusions from these analyses are: (a) User reports and results of preclinical studies in animals strongly suggest that kratom and its main constituent alkaloid, mitragynine may have useful activity in alleviating pain and managing symptoms of opioid withdrawal, even though well-controlled clinical trials have yet to be done. (b) Even though kratom lacks many of the toxicities of classic opioids, there are legitimate concerns about the safety and lack of quality control of purported "kratom" products that are being sold in the US. (c) The issues regarding the safety and efficacy of kratom and its mitragynine constituent can only be resolved by additional research. Classification of the Mitragyna alkaloids as Schedule I controlled substances would substantially impede this important research on kratom.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology
  18. 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/pharmacology*
  19. Leong Bin Abdullah MFI, Tan KL, Mohd Isa S, Yusoff NS, Chear NJY, Singh D
    PLoS One, 2020;15(6):e0234639.
    PMID: 32525924 DOI: 10.1371/journal.pone.0234639
    BACKGROUND AND AIM: Kratom, or Mitragyna speciosa Korth., is a tropical plant that has been reported to exhibit opioid-like effects. Although opioids have been demonstrated to alter the lipid profile of regular users, data on the lipid-altering effects of kratom are scarce. This study aimed to compare the fasting lipid profile of regular kratom users to that of healthy subjects who do not use kratom. It also determined the association between various characteristics of kratom users and the serum triglycerides, total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels of regular kratom users.

    METHODS: A total of 200 participants (n = 100 kratom users and n = 100 healthy subjects who do not use kratom) were recruited for this analytical cross-sectional study. Data on sociodemographic status, kratom use characteristics, cigarette smoking, physical activity, body mass index (BMI), fasting serum lipid profile, and liver function were collected from all participants.

    RESULTS: The liver parameters of the study participants were within normal range. The serum total cholesterol and LDL of kratom users were significantly lower than those of healthy subjects who do not use kratom. There were no significant differences in the serum triglyceride and HDL levels. However, higher average daily frequency of kratom use and increasing age were associated with increased serum total cholesterol among kratom users. Other kratom use characteristics such as age of first kratom intake, duration of kratom use, and quantity of daily kratom intake were not associated with increased serum triglyceride, total cholesterol, LDL, and HDL levels.

    CONCLUSIONS: Our findings suggest regular kratom consumption was not linked to elevated serum lipids, except when there is a higher frequency of daily kratom intake. However, the study was limited by the small sample size, and hence a more comprehensive study with larger sample size is warranted to confirm the findings.

    Matched MeSH terms: Alkaloids/pharmacology*
  20. 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/pharmacology*
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