Search Results (11)

A promising direction for the creation of new biologically active derivatives of the alkaloid lupinine is the synthesis of “hybrid molecules” that combine a fragment of the alkaloid and the pharmacophore of 1,2,3-triazole in their structure. From a biological perspective, this work presents the first X-ray diffraction study of a single crystal of (1S,9aR)-1-({4-[4-(Benzyloxy)-3-methoxyphenyl]-1H-1,2,3-triazol-1-yl}methyl)octahydro-2H-quinolizine, a new, recently synthesized 1,2,3-triazole derivative of lupinine. A comparison of theoretically predicted and experimentally observed structural parameters was carried out. The FTIR spectroscopy study and vibrational properties calculations allowed us to interpret the FTIR absorption spectrum and localize specific vibrational modes in quinolizidine, 1,2,3-triazole, and benzene rings. Such information can be fruitful for further characterization of the synthesis process and products. The molecular docking of the compound was performed. It was shown that the studied molecules are capable of interacting with the Mpro binding site via non-covalent and hydrophobic interactions with subsites S3 (Met165, Glu166, Leu167, Pro168) and S5 (Gln189, Thr190, Gln192), which ensure the stabilization of the Mpro substrate. Blocking of the active site of the enzyme in the region of the oxyanion hole does not occur, but stable stacking interactions with the π-system of one of the catalytic amino acids, His41, are observed. Full article

The pathogenesis of a bacterial infection is a multistep process typically involving bacterial attachment to the host, toxin production, and/or invasion, followed by inflammation. For many bacteria, the invasion of human cells is a key step in the spread of infection and evasion of host immunity. Fusion of host cell membranes during bacterial penetration is a necessary step in invasion. The aim of this study was to evaluate the plant alkaloids, such as piperine, tabersonine, and lupinine, which have the potential to inhibit membrane fusion, fighting bacterial infection. Despite previous data on lupinine’s inhibition of membrane fusion, it has no effect on invasion or on the synthesis of the proinflammatory cytokines. This was likely due to the synthesis of the surface protein OmpX, which was a virulence factor for S. proteamaculans and can neutralize the effect of lupinine on the host cell membrane. Piperine and tabersonine inhibit invasion and proinflammatory cytokine synthesis in response to bacterial infection. However, tabersonine is toxic to eukaryotic cells. This makes it necessary to select an optimal concentration of tabersonine that suppresses invasion but is nontoxic to human cells. Therefore, piperine holds the greatest prospects for clinical use: it inhibits bacterial invasion while remaining nontoxic to human cells even at higher concentrations. Full article

This study presents the results of a study of the synthesis and properties of 2-hydroxy-β-cyclodextrin functionalized by silver nanoparticles and its loading with a bioactive component. As a reducing agent and stabilizer, 2-Hydroxy-β-cyclodextrin (2gβCD) was used in the production of silver nanoparticles. The use of 2gβCD-AgNPs in loading molecules of the plant alkaloid lupinine (Lup) and its acetyl derivative (Lac) with bactericidal properties were studied. The formation of Lup-2gβCD-AgNPs and Lac-2gβCD-AgNPs was confirmed by UV spectroscopy and X-ray diffraction spectroscopy (XRD). Transmission electron microscopy (TEM) showed that the synthesized AgNPs had a spherical shape. ¹H-, ¹³C-NMR nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy (FT-IR) confirmed the reduction and encapsulation of AgNPs by 2gβCD. Thermographic data show that the obtained Lup and its derivative inclusion complexes reduced energy barriers. This makes them promising components for thermosensitive functional materials. Encapsulated complexes of Lup and its acetate inclusion with silver nanoparticles demonstrated significantly (p < 0.05) higher antibacterial, cytotoxic, and moderately pronounced analgesic activity. Full article

Quinolizidine derivatives are an important class of substances that are used in the pharmaceutical industry. In previous studies, the synthesis of these substances is carried out using lupinine azide (IUPAC: 1-(azidomethyl)octahydro-2H-quinolizine), which is often used to obtain new biologically active compounds. In this regard, its structural characterization is critically important. In this work, the conformational diversity of the molecular structure of this compound has been studied. It is shown that the structure with the axial position of the methyl azide group contains a number of low-energy conformer states with energies higher than the ground state by 0.15–0.60 kcal/mol. Such structural ambiguity should manifest itself in the chemical reactions and biological activity of lupinine azide. The spectroscopic properties of the conformers were studied by modeling chemical shifts for carbon and hydrogen atoms, as well as by simulating IR absorption spectra. An analysis of the most specific spectroscopic features of all of the conformers was carried out. Based on the correlation of the theoretical results and the experimental spectroscopic data, a conclusion was made for the first time regarding the most probable conformational states in the solution. Full article

Influenza is a disease of significant morbidity and mortality. The number of anti-influenza drugs is small; many of them stimulate the appearance of resistant strains. This article presents the results of assessing the antiviral activity of 1,2,3-triazole-containing derivatives of alkaloid lupinine for their ability to suppress the reproduction of orthomyxoviruses (influenza viruses: A/Vladivostok/2/09 (H1N1) and A/Almaty/8/98 (H3N2)). The ability of (1S,9aR)-1-[(1,2,3-triazol-1-yl)-methyl]octahydro-1H-quinolizines with aryl-, 4-((4-formylphenoxy)methyl)- or 4-((3-tert-butyl-5-ethyl-2-hydroxy-benzoyloxy)methyl)- substituents at the C-4 position of the triazole ring to reduce the infectivity of the virus when processing virus-containing material was established, indicating good prospects for the studied compounds as virucidal agents affecting extracellular virions. The experimental results demonstrated that the triazolyl lupinine derivatives exhibited varying degrees of affinity for both hemagglutinin and neuraminidase proteins. Furthermore, these compounds demonstrated inhibitory effects on the replication of influenza viruses with different antigenic subtypes. The obtained biological data are in agreement with the results of molecular docking, which showed strong binding energies of the investigated compounds under study with biological targets—hemagglutinin and neuraminidase proteins. Following the evaluation of antiviral efficacy among the studied triazolyl derivatives of lupinine, four compounds have been identified for subsequent comprehensive in vitro and in vivo investigations to further elucidate their antiviral properties. Full article

Fourteen quinolizidine derivatives, structurally related to the alkaloids lupinine and cytisine and previously studied for other pharmacological purposes, were presently tested for antiarrhythmic, and other cardiovascular effects on isolated guinea pig heart tissues in comparison to well-established reference drugs. According to their structures, the tested compounds are assembled into three subsets: (a) N-(quinolizidinyl-alkyl)-benzamides; (b) 2-(benzotriazol-2-yl)methyl-1-(quinolizidinyl)alkyl-benzimidazoles; (c) N-substituted cytisines. All compounds but two displayed antiarrhythmic activity that was potent for compounds 4, 1, 6, and 5 (in ascending order). The last compound (N-(3,4,5-trimethoxybenzoyl)aminohomolupinane) was outstanding, exhibiting a nanomolar potency (EC₅₀ = 0.017 µM) for the increase in the threshold of ac-arrhythmia. The tested compounds shared strong negative inotropic activity; however, this does not compromise the value of their antiarrhythmic action. On the other hand, only moderate or modest negative chronotropic and vasorelaxant activities were commonly observed. Compound 5, which has high antiarrhythmic potency, a favorable cardiovascular profile, and is devoid of antihypertensive activity in spontaneously hypertensive rats, represents a lead worthy of further investigation. Full article

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by progressive memory loss and cognitive impairment due in part to a severe loss of cholinergic neurons in specific brain areas. AD is the most common type of dementia in the aging population. Although several acetylcholinesterase (AChE) inhibitors are currently available, their performance sometimes yields unexpected results. Thus, research is ongoing to find potentially therapeutic AChE inhibitory agents, both from natural and synthetic sources. Here, we synthesized 13 new lupinine triazole derivatives and evaluated them, along with 50 commercial lupinine-based esters of different carboxylic acids, for AChE inhibitory activity. The triazole derivative 15 [1S,9aR)-1-((4-(4-(benzyloxy)-3-methoxyphenyl)-1H-1,2,3-triazol-1-yl)methyl)octahydro-2H-quinolizine)] exhibited the most potent AChE inhibitory activity among all 63 lupinine derivatives, and kinetic analysis demonstrated that compound 15 was a mixed-type AChE inhibitor. Molecular docking studies were performed to visualize interaction between this triazole derivative and AChE. In addition, a structure-activity relationship (SAR) model developed using linear discriminant analysis (LDA) of 11 SwissADME descriptors from the 50 lupinine esters revealed 5 key physicochemical features that allowed us to distinguish active versus non-active compounds. Thus, this SAR model could be applied for design of more potent lupinine ester-based AChE inhibitors. Full article

To rationalize the antiviral actions of plant alkaloids, the ability of 20 compounds to inhibit calcium-mediated fusion of lipid vesicles composed of phosphatidylglycerol and cholesterol was investigated using the calcein release assay and dynamic light scattering. Piperine, tabersonine, hordenine, lupinine, quinine, and 3-isobutyl-1-methylxanthine demonstrated the most potent effects (inhibition index greater than 50%). The introduction of phosphatidylcholine into the phosphatidylglycerol/cholesterol mixture led to significant changes in quinine, hordenine, and 3-isobutyl-1-methylxanthine efficiency. Comparison of the fusion inhibitory ability of the tested alkaloids, and the results of the measurements of alkaloid-induced alterations in the physical properties of model membranes indicated a potent relationship between a decrease in the cooperativity of the phase transition of lipids and the ability of alkaloids to prevent calcium-mediated vesicle fusion. In order to use this knowledge to combat the novel coronavirus pandemic, the ability of the most effective compounds to suppress membrane fusion induced by fragments of MERS-CoV and SARS-CoV/SARS-CoV-2 fusion peptides was studied using the calcein release assay and confocal fluorescence microscopy. Piperine was shown to inhibit vesicle fusion mediated by both coronavirus peptides. Moreover, piperine was shown to significantly reduce the titer of SARS-CoV2 progeny in vitro in Vero cells when used in non-toxic concentrations. Full article

The total contents and qualitative compositions of alkaloids in seeds of 10 Old World lupin species (73 accessions) were surveyed using gas chromatography. The obtained results, combined with those for three lupin crops, Lupinus angustifolius, Lupinus albus, and Lupinus luteus, provide the most complete and up-to-date overview of alkaloid profiles of 13 lupin species originating from the Mediterranean Basin. The qualitative alkaloid compositions served as useful supplementary tools of species discrimination. On the basis of the most abundant major alkaloids, lupanine, lupinine, and multiflorine, the Old World lupin species were divided into four groups. Those containing lupanine (L. angustifolius, L. albus, and Lupinus mariae-josephi), containing lupinine (Lupinus luteus, Lupinus hispanicus, and Lupinus × hispanicoluteus), containing lupinine and multiflorine (Lupinus atlanticus, Lupinus palaestinus, Lupinus anatolicus, Lupinus digitatus, Lupinus pilosus, and Lupinus cosentinii), and containing multiflorine (Lupinus micranthus). Within a given group, certain species can be, in most cases, further distinguished by the presence of other major alkaloids. The discrimination of species based on the total alkaloid content was found to be less reliable because of the significant intra-species variations, as well as the influences of environmental factors on the seed alkaloid content. Full article

Alkaloid profiles of 22 lupin genotypes belonging to three different cultivated species, Lupinus albus L., Lupinus luteus L., and Lupinus angustifolius L., collected from different Italian regions and grown in Sicily, were studied by gas chromatography mass spectrometry (GC-MS) to determine alkaloid composition. More than 30 alkaloids were identified. The lowest alkaloid concentration was observed in the L. albus Luxor, Aster, and Rosetta cultivars, and in all the varieties of L. luteus and L. angustifolius. The highest content was observed in all the landraces of L. albus. Surprisingly, the white lupin Lublanc variety and the commercial seeds of cv Multitalia had a high alkaloid content. The tested species and the different genotypes exhibited different alkaloid profiles: lupanine, 13α-hydroxylupanine, and albine were the main alkaloids in the analyzed L. albus seeds; angustifoline and 13α-tigloyloxylupanine were well-represented in L. albus landraces; sparteine and lupinine were typical of L. luteus; and lupanine, 13α-hydroxylupanine, and angustifoline were the main alkaloids in L. angustifolius seeds. The samples with the highest amounts of total alkaloids proved to be interesting from a pharmaceutical viewpoint. The alkaloid extracts showed significant activity on Klebsiella pneumoniae and Pseudomonas aeruginosa clinical isolates. Full article

Natural products are a prolific source for the identification of new biologically active compounds. In the present work, we studied the in vitro and in vivo antimalarial efficacy and ADME-Tox profile of a molecular hybrid (AM1) between 4-aminoquinoline and a quinolizidine moiety derived from lupinine (Lupinus luteus). The aim was to find a compound endowed with the target product profile-1 (TCP-1: molecules that clear asexual blood-stage parasitaemia), proposed by the Medicine for Malaria Venture to accomplish the goal of malaria elimination/eradication. AM1 displayed a very attractive profile in terms of both in vitro and in vivo activity. By using standard in vitro antimalarial assays, AM1 showed low nanomolar inhibitory activity against chloroquine-sensitive and resistant P. falciparum strains (range IC₅₀ 16–53 nM), matched with a high potency against P. vivax field isolates (Mean IC₅₀ 29 nM). Low toxicity and additivity with artemisinin derivatives were also demonstrated in vitro. High in vivo oral efficacy was observed in both P. berghei and P. yoelii mouse models with IC₅₀ values comparable or better than those of chloroquine. The metabolic stability in different species and the pharmacokinetic profile in the mouse model makes AM1 a compound worth further investigation as a potential novel schizonticidal agent. Full article