Displaying publications 41 - 60 of 335 in total

Abstract:
Sort:
  1. Ezeoke MC, Krishnan P, Sim DS, Lim SH, Low YY, Chong KW, et al.
    Phytochemistry, 2018 Feb;146:75-81.
    PMID: 29247894 DOI: 10.1016/j.phytochem.2017.12.003
    From the leaves of Elaeocarpus tectorius (Lour.) Poir. four previously undescribed phenethylamine-containing alkaloids were isolated, namely, tectoricine, possessing an unprecedented isoquinuclidinone ring system incorporating a phenethylamine moiety, tectoraline, representing a rare alkamide incorporating two phenethylamine moieties, and tectoramidines A and B, representing the first naturally occurring trimeric and dimeric phenethylamine alkaloids incorporating an amidine function. The structures of these alkaloids were established by detailed spectroscopic analysis. The absolute configuration of tectoricine was determined by comparison of the experimental and calculated ECD spectra. Plausible biosynthetic pathways to the four alkaloids are proposed.
    Matched MeSH terms: Alkaloids/isolation & purification; Alkaloids/chemistry*
  2. Lee FK, Chan NJ, Krishnan P, Datu Abdul Salam DS, Chee XW, Muhamad A, et al.
    J Nat Prod, 2024 Apr 26;87(4):675-691.
    PMID: 38442031 DOI: 10.1021/acs.jnatprod.3c00707
    Schwarzinicines A-D, a series of alkaloids recently discovered from Ficus schwarzii, exhibit pronounced vasorelaxant activity in rat isolated aorta. Building on this finding, a concise synthesis of schwarzinicines A and B has been reported, allowing further investigations into their biological properties. Herein, a preliminary exploration of the chemical space surrounding the structure of schwarzinicine A (1) was carried out aiming to identify structural features that are essential for vasorelaxant activity. A total of 57 analogs were synthesized and tested for vasorelaxant activity in rat isolated aorta. Both efficacy (Emax) and potency (EC50) of these analogs were compared. In addition to identifying structural features that are required for activity or associated with potency enhancement effect, four analogs showed significant potency improvements of up to 40.2-fold when compared to 1. Molecular dynamics simulation of a tetrameric 44-bound transient receptor potential canonical-6 (TRPC6) protein indicated that 44 could potentially form important interactions with the residues Glu509, Asp530, Lys748, Arg758, and Tyr521. These results may serve as a foundation for guiding further structural optimization of the schwarzinicine A scaffold, aiming to discover even more potent analogs.
    Matched MeSH terms: Alkaloids/pharmacology; Alkaloids/chemistry
  3. Müller CP, Yang Y, Singh D, Lenz B, Müller E
    Nervenarzt, 2024 Sep;95(9):824-829.
    PMID: 39085520 DOI: 10.1007/s00115-024-01721-6
    BACKGROUND: Kratom/ketum is a psychoactive herbal preparation that has been used for a long time as a remedy and performance-enhancing substance in Southeast Asia. The advancement of globalization is making kratom increasingly more available in the western world, where it is becoming increasingly more used.

    OBJECTIVE: The current research on kratom and its ingredients is presented.

    MATERIAL AND METHODS: An overview of the use and effects of kratom is exemplary given on the basis of reports. The instrumentalization of the drug and its consequences up to the development of addiction are discussed.

    RESULTS: Consumption is accompanied by several instrumentalizeable effects so that kratom is used as a therapeutic substance in the self-management of pain, anxiety and depression as well as other substance addictions. Another benefit comes from the performance-enhancing effects on physical work and in a social context. Consumption is usually well controlled, rarely escalates and has few and mostly mild aversive side effects. The danger arises from consumption particularly when there is an escalation of the dose and from mixed consumption with other psychoactive substances. The main alkaloid mitragynine and the more potent 7‑hydroxy-mitragynine are considered mainly responsible for the effect. Both have a complex pharmacology that involves partial µ‑opioid receptor agonism.

    DISCUSSION: Epidemiological, clinical and neurochemical studies have shown that kratom only has a limited addictive drug profile, which might suggest a medical use as a remedy or substitute in addiction treatment.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids/pharmacology; Secologanin Tryptamine Alkaloids/therapeutic use
  4. Yeap JS, Saad HM, Tan CH, Sim KS, Lim SH, Low YY, et al.
    J Nat Prod, 2019 11 22;82(11):3121-3132.
    PMID: 31642315 DOI: 10.1021/acs.jnatprod.9b00712
    A methanol extract of the stem bark of the Malayan Alstonia penangiana provided seven new bisindole alkaloids, comprising six macroline-sarpagine alkaloids (angustilongines E-K, 1-6) and one macroline-pleiocarpamine bisindole alkaloid (angustilongine L, 7). Analysis of the spectroscopic data (NMR and MS) of these compounds led to the proposed structures of these alkaloids. The macroline-sarpagine alkaloids (1-6) showed in vitro growth inhibitory activity against a panel of human cancer cell lines, inclusive of KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, HCT 116, and A549 cells (IC50 values: 0.02-9.0 μM).
    Matched MeSH terms: Alkaloids/chemical synthesis*; Alkaloids/pharmacology*; Indole Alkaloids/chemical synthesis*; Indole Alkaloids/pharmacology*
  5. Deguchi J, Shoji T, Nugroho AE, Hirasawa Y, Hosoya T, Shirota O, et al.
    J Nat Prod, 2010 Oct 22;73(10):1727-9.
    PMID: 20836516 DOI: 10.1021/np100458b
    Eucophylline (1), a new tetracyclic vinylquinoline alkaloid, was isolated from the bark of Leuconotis eugenifolius together with leucophyllidine (2). The structure and absolute configuration of 1 were elucidated on the basis of 2D NMR correlations and simulated CD analysis. Leucophyllidine (2) showed iNOS inhibitory activity and decreased the iNOS protein expression dose-dependently.
    Matched MeSH terms: Alkaloids/isolation & purification*; Alkaloids/pharmacology; Alkaloids/chemistry; Indole Alkaloids/isolation & purification; Indole Alkaloids/pharmacology; Indole Alkaloids/chemistry
  6. Mukhtar MR, Hadi AH, Rondeau D, Richomme P, Litaudon M, Mustafa MR, et al.
    Nat Prod Res, 2008;22(11):921-6.
    PMID: 18629705 DOI: 10.1080/14786410701642821
    The phytochemical study of the bark of Malaysian Phoebe scortechinii (Lauraceae) has resulted in the isolation and identification of two new proaporphine alkaloids; (+)-scortechiniine A (1) and (+)-scortechiniine B (2) together with two known proaporphines; (-)-hexahydromecambrine A (3), (-)-norhexahydromecambrine A (4), and one aporphine; norboldine (5). Structural elucidations of these alkaloids were performed using spectroscopic methods especially 1D and 2D (1)H and (13)C NMR.
    Matched MeSH terms: Alkaloids/chemistry*
  7. Mukhtar MR, Hadi AH, Litaudon M, Awang K
    Fitoterapia, 2004 Dec;75(7-8):792-4.
    PMID: 15567268
    Five morphinoid alkaloids have been isolated from Dehaasia longipedicellata, namely (-) pallidine, a new alkaloid (+) pallidinine (1), (+)-milonine, (-) 8,14-dehydrosalutaridine and (-) sinoacutine.
    Matched MeSH terms: Alkaloids/chemistry*
  8. Husain K, Jantan I, Said IM, Aimi N, Takayama H
    J Asian Nat Prod Res, 2003 Mar;5(1):63-7.
    PMID: 12608641
    Two new indole alkaloids with the methyl chanofruticosinate skeletal system viz., methyl 3-oxo-12-methoxy-N1-decarbomethoxy-14,15-didehydrochanofruticosinate (1) and methyl 3-oxo-11,12-methylenedioxy-N-decarbomethoxy-14,15-didehydrochanofruticosinate (2), together with four known compounds, methyl 12-methoxy-N1-decarbomethoxychanofruticosinate, methyl 12-methoxychanofruticosinate, methyl 11,12-dimethoxychanofruticosinate and methyl 11,12-methylenedioxy-N1-decarbomethoxychanofruticosinate, were isolated in continuing studies on the leaves of Kopsia flavida Blume. The structures of the new indole alkaloids were assigned by NMR spectral data using various 2D-techniques.
    Matched MeSH terms: Alkaloids/chemistry*
  9. Kopp B, Bauer WP, Bernkop-Schnürch A
    J Ethnopharmacol, 1992 Feb;36(1):57-62.
    PMID: 1501494
    An investigation of nine Malaysian dart poisons has confirmed that their main active components are cardenolides from Antiaris toxicaria (Pers.) Lesch. and alkaloids probably from different forms of Strychnos ignatii P. Bergius. It is not possible to determine the ethnic origin of the poisons from the results of the analyses on their own. Two new cardiac glycosides have been isolated and their structures determined as 12 beta-hydroxycannogenin 3 beta-O-beta-D-deoxygulopyranoside and 3 beta-O-alpha-L-rhamnopyranoside, respectively.
    Matched MeSH terms: Alkaloids/toxicity
  10. Liu S, Dang M, Lei Y, Ahmad SS, Khalid M, Kamal MA, et al.
    Curr Pharm Des, 2020;26(37):4808-4814.
    PMID: 32264807 DOI: 10.2174/1381612826666200407161842
    BACKGROUND: Alzheimer's disease (AD) is the most well-known reason for disability in persons aged greater than 65 years worldwide. AD influences the part of the brain that controls cognitive and non-cognitive functions.

    OBJECTIVE: The study focuses on the screening of natural compounds for the inhibition of AChE and BuChE using a computational methodology.

    METHODS: We performed a docking-based virtual screening utilizing the 3D structure of AChE and BuChE to search for potential inhibitors for AD. In this work, a screened inhibitor Ajmalicine similarity search was carried out against a natural products database (Super Natural II). Lipinski rule of five was carried out and docking studies were performed between ligands and enzyme using 'Autodock4.2'.

    RESULTS: Two phytochemical compounds SN00288228 and SN00226692 were predicted for the inhibition of AChE and BuChE, respectively. The docking results revealed Ajmalicine, a prominent natural alkaloid, showing promising inhibitory potential against AChE and BuChE with the binding energy of -9.02 and -8.89 kcal/mole, respectively. However, SN00288228- AChE, and SN00226692-BuChE were found to have binding energy -9.88 and -9.54 kcal/mole, respectively. These selected phytochemical compounds showed better interactions in comparison to Ajmalicine with the target molecule.

    CONCLUSION: The current study verifies that SN00288228 and SN00226692 are more capable inhibitors of human AChE and BuChE as compared to Ajmalicine with reference to ΔG values.

    Matched MeSH terms: Secologanin Tryptamine Alkaloids*
  11. Javed Iqbal M, Quispe C, Javed Z, Sadia H, Qadri QR, Raza S, et al.
    Front Mol Biosci, 2020;7:624494.
    PMID: 33521059 DOI: 10.3389/fmolb.2020.624494
    Cancer is a multifactorial disease characterized by complex molecular landscape and altered cell pathways that results in an abnormal cell growth. Natural compounds are target-specific and pose a limited cytotoxicity; therefore, can aid in the development of new therapeutic interventions for the treatment of this versatile disease. Berberine is a member of the protoberberine alkaloids family, mainly present in the root, stem, and bark of various trees, and has a reputed anticancer activity. Nonetheless, the limited bioavailability and low absorption rate are the two major hindrances following berberine administration as only 0.5% of ingested berberine absorbed in small intestine while this percentage is further decreased to 0.35%, when enter in systemic circulation. Nano-based formulation is believed to be an ideal candidate to increase absorption percentage as at nano scale level, compounds can absorb rapidly in gut. Nanotechnology-based therapeutic approaches have been implemented to overcome such problems, ultimately promoting a higher efficacy in the treatment of a plethora of diseases. This review present and critically discusses the anti-proliferative role of berberine and the nanotechnology-based therapeutic strategies used for the nano-scale delivery of berberine. Finally, the current approaches and promising perspectives of latest delivery of this alkaloid are also critically analyzed and discussed.
    Matched MeSH terms: Alkaloids; Berberine Alkaloids
  12. Lee MJ, Ramanathan S, Mansor SM, Tan SC
    Anal Biochem, 2020 06 15;599:113733.
    PMID: 32302607 DOI: 10.1016/j.ab.2020.113733
    An enzyme-linked immunosorbent assay for detection of mitragynine, other closely related Kratom alkaloids and metabolites was developed using polyclonal antibodies. Mitragynine was conjugated to a carrier protein, cationized-bovine serum albumin using Mannich reaction. The synthesized antigen was injected into rabbits to elicit specific polyclonal antibodies against mitragynine. An enzyme conjugate was synthesized for evaluating its performance with the antibodies produced. The assay had an IC50 of 7.3 ng/mL with a limit of detection of 15 ng/mL for mitragynine. Antibody produced have high affinity for mitragynine (100%), other closely related Kratom alkaloids such as paynantheine (54%), speciociliatine (63%), 7α-hydroxy-7H-mitragynine (83%) and cross-reacted with metabolites 9-O-demethyl mitragynine (79%), 16-carboxy mitragynine (103%), 9-O-demethyl mitragynine sulfate (263%), 9-O-demethyl mitragynine glucuronide (60%), 16-carboxy mitragynine glucuronide (60%), 9-O-demethyl-16-carboxy mitragynine sulfate (270%) and 17-O-demethyl-16,17-dihydro mitragynine glucuronide (34%). It showed cross-reactivity less than 0.01% to reserpine, codeine, morphine, caffeine, methadone, amphetamine, and cocaine. Ten-fold dilution urine was used in the assay to reduce the matrix effects. The recovery ranged from 83% to 112% with variation coefficients in intraday and interday less than 8% and 6%, respectively. The ELISA turned out to be a convenient tool to diagnose mitragynine, other closely related Kratom alkaloids and metabolites in human urine samples.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids/urine*
  13. Sim YS, Chong ZY, Azizi J, Goh CF
    PMID: 35700649 DOI: 10.1016/j.jchromb.2022.123316
    Mitragynine is a promising candidate for pain relief and opiate replacement but the investigations for drug delivery are lacking. This study aims to investigate the potential of mitragynine to be delivered through the skin with an emphasis on developing and validating a gradient HPLC-UV analytical method to determine mitragynine in the samples collected during in vitro skin permeation studies. The optimised method involves a gradient elution using a C18 column with a mobile phase comprising acetonitrile and 0.1 %v/v of formic acid (0-1 min: 30:70 to 70:30 (v/v) and hold up to 4 min; 4-6 min: return to 30:70 (v/v) and hold up to 10 min) at a flow rate of 1.2 mL/min. This method was validated based on the standards set by the International Council on Harmonisation guidelines. The method showed mitragynine elution at ∼ 4 min with adequate linearity (R2 ≥ 0.999 for concentration ranges of 0.5-10 and 10-175 μg/mL) and acceptable limits of detection and quantification at 0.47 and 1.43 μg/mL, respectively. The analytical performance is robust with excellent precision and accuracy. This method was used to evaluate the in vitro skin permeation of mitragynine (5 %w/v) from simple solvent systems over 48 hr. The results showed a cumulative amount of mitragynine permeated at ∼ 11 μg/cm2 for dimethyl sulfoxide and ∼ 4 μg/cm2 for propylene glycol. The study not only addressed the issues of the currently available HPLC-UV methods that limit the direct application but also affirmed the potential of mitragynine to be delivered through the skin.
    Matched MeSH terms: Secologanin Tryptamine Alkaloids*
  14. Tan SJ, Lim JL, Low YY, Sim KS, Lim SH, Kam TS
    J Nat Prod, 2014 Sep 26;77(9):2068-80.
    PMID: 25211145 DOI: 10.1021/np500439u
    A total of 20 new indole alkaloids comprising mainly oxidized derivatives of macroline- (including alstofonidine, a macroline indole incorporating a butyrolactone ring-F), pleiocarpamine-, and sarpagine-type alkaloids were isolated from the bark and leaf extracts of Alstonia angustifolia. The structures and relative configurations of these alkaloids were determined using NMR and MS analyses and in some instances confirmed by X-ray diffraction analyses. Alkaloids 3, 7, 35, and 41 showed moderate to weak activity, while 21 showed strong activity in reversing multidrug resistance in vincristine-resistant KB cells.
    Matched MeSH terms: Alkaloids; Indole Alkaloids/isolation & purification*; Indole Alkaloids/chemistry
  15. 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/isolation & purification*; Alkaloids/pharmacology*; Alkaloids/chemistry
  16. Low YY, Hong FJ, Lim KH, Thomas NF, Kam TS
    J Nat Prod, 2014 Feb 28;77(2):327-38.
    PMID: 24428198 DOI: 10.1021/np400922x
    Several transformations of the seco Aspidosperma alkaloid leuconolam were carried out. The based-induced reaction resulted in cyclization to yield two epimers, the major product corresponding to the optical antipode of a (+)-meloscine derivative. The structures and relative configuration of the products were confirmed by X-ray diffraction analysis. Reaction of leuconolam and epi-leuconolam with various acids, molecular bromine, and hydrogen gave results that indicated that the structure of the alkaloid, previously assigned as epi-leuconolam, was incorrect. This was confirmed by an X-ray diffraction analysis, which revealed that epi-leuconolam is in fact 6,7-dehydroleuconoxine. Short partial syntheses of the diazaspiro indole alkaloid leuconoxine and the new leuconoxine-type alkaloids leuconodines A and F were carried out.
    Matched MeSH terms: Indole Alkaloids/chemical synthesis; Indole Alkaloids/metabolism; Indole Alkaloids/chemistry*
  17. 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/isolation & purification; Indole Alkaloids/pharmacology; Indole Alkaloids/chemistry*
  18. 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/isolation & purification*; Indole Alkaloids/pharmacology; Indole Alkaloids/chemistry
  19. 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/isolation & purification; Indole Alkaloids/pharmacology; Indole Alkaloids/chemistry*
  20. 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/isolation & purification*; Indole Alkaloids/pharmacology*; Indole Alkaloids/chemistry
Filters
Contact Us

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

External Links