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1.
Proc Natl Acad Sci U S A ; 117(3): 1678-1688, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31915293

RESUMO

Primary human hepatocytes (PHHs) are an essential tool for modeling drug metabolism and liver disease. However, variable plating efficiencies, short lifespan in culture, and resistance to genetic manipulation have limited their use. Here, we show that the pyrrolizidine alkaloid retrorsine improves PHH repopulation of chimeric mice on average 10-fold and rescues the ability of even poorly plateable donor hepatocytes to provide cells for subsequent ex vivo cultures. These mouse-passaged (mp) PHH cultures overcome the marked donor-to-donor variability of cryopreserved PHH and remain functional for months as demonstrated by metabolic assays and infection with hepatitis B virus and Plasmodium falciparum mpPHH can be efficiently genetically modified in culture, mobilized, and then recultured as spheroids or retransplanted to create highly humanized mice that carry a genetically altered hepatocyte graft. Together, these advances provide flexible tools for the study of human liver disease and evaluation of hepatocyte-targeted gene therapy approaches.


Assuntos
Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Hepatopatias/genética , Alcaloides de Pirrolizidina/farmacologia , Animais , Transplante de Células , Quimera , Modelos Animais de Doenças , Feminino , Terapia Genética , Hepatite B , Vírus da Hepatite B , Hepatócitos/transplante , Proteínas de Homeodomínio/genética , Humanos , Hidrolases/genética , Subunidade gama Comum de Receptores de Interleucina/genética , Fígado/patologia , Hepatopatias/patologia , Malária , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos Knockout , Plasmodium falciparum
2.
Food Chem Toxicol ; 129: 391-398, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31054999

RESUMO

Pyrrolizidine alkaloids (PAs) are hepatotoxic and specifically damage hepatic sinusoidal endothelial cells (HSECs) via cytochrome P450 enzymes (CYPs)-mediated metabolic activation. Due to the lack of CYPs in HSECs, currently there is no suitable cell model for investigating PA-induced HSEC injury. This study aimed to establish a two-layer transwell co-culture model that mimics hepatic environment by including HepaRG hepatocytes and HSECs to evaluate cytotoxicity of PAs on their major target HSECs. In this model, PAs were metabolically activated by CYPs in HepaRG hepatocytes to generate reactive pyrrolic metabolites, which react with co-cultured HSECs leading to HSEC damage. Three representative PAs, namely retrorsine, monocrotaline, and clivorine, induced significant concentration-dependent cytotoxicity in HSECs in the co-culture model, but did no cause obvious cytotoxicity directly in HSECs. Using the developed co-cultured model, further mechanism studies of retrorsine-induced HSEC damage demonstrated that the reactive pyrrolic metabolite generated by CYP-mediated bioactivation in HepaRG hepatocytes caused formation of pyrrole-protein adducts, reduction of GSH content, and generation of reactive oxygen species in HSECs, leading to cell apoptosis. The established co-culture model is reliable and applicable for cytotoxic assessment of PA-induced HSEC damage and offers a novel platform for screening toxicity of different PAs on their target cells.


Assuntos
Hepatócitos/efeitos dos fármacos , Alcaloides de Pirrolizidina/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Técnicas de Cocultura , Glutationa/metabolismo , Hepatócitos/metabolismo , Hepatócitos/patologia , Humanos , Técnicas In Vitro , Espécies Reativas de Oxigênio/metabolismo
3.
PLoS One ; 14(4): e0215065, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30973947

RESUMO

The primary goal of cattle genomics is the identification of genome-wide polymorphism associated with economically important traits. The bovine genome sequencing project was completed in 2009. Since then, using massively parallel sequencing technologies, a large number of Bos taurus cattle breeds have been resequenced and scanned for genome-wide polymorphisms. As a result, a substantial number of single nucleotide polymorphisms (SNPs) have been discovered across European Bos taurus genomes, whereas extremely less number of SNPs are cataloged for Bos indicus breeds. In this study, we performed whole-genome resequencing, reference-based mapping, functional annotation and gene enrichment analysis of 20 sires representing eleven important Bos indicus (indicine) breeds of Pakistan. The breeds sequenced here include: Sahiwal, Red Sindhi, Tharparkar and Cholistani (tropically adapted dairy and dual purpose breeds), Achai, Bhagnari, Dajal and Lohani (high altitude adapted dual and drought purpose breeds); Dhanni, Hisar Haryana and Gabrali (dairy and light drought purpose breeds). A total of 17.4 billion QC passed reads were produced using BGISEQ-500 next generation sequencing platform to generate 9 to 27-fold genome coverage (average ~16×) for each of the 20 sequenced sires. A total of 67,303,469 SNPs were identified, of which 3,850,365 were found novel and 1,083,842 insertions-deletions (InDels) were detected across the whole sequenced genomes (491,247 novel). Comparative analysis using coding region SNPs revealed a close relationship between the best milking indicine breeds; Red Sindhi and Sahiwal. On the other hand, Bhagnari and Tharparkar being popular for their adaptation to dry and extremely hot climates were found to share the highest number of SNPs. Functional annotation identified a total of 3,194 high-impact (disruptive) SNPs and 745 disruptive InDels (in 275 genes) that may possibly affect economically important dairy and beef traits. Functional enrichment analysis was performed and revealed that high or moderate impact variants in wingless-related integration site (Wnt) and vascular smooth muscle contraction (VSMC) signaling pathways were significantly over-represented in tropically adapted heat tolerant Pakistani-indicine breeds. On the other hand, vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1 (HIF-1) signaling pathways were found over-represented in highland adapted Pakistani-indicine breeds. Similarly, the ECM-receptor interaction and Jak-STAT signaling pathway were significantly enriched in dairy and beef purpose Pakistani-indicine cattle breeds. The Toll-like receptor signaling pathway was significantly enriched in most of the Pakistani-indicine cattle. Therefore, this study provides baseline data for further research to investigate the molecular mechanisms of major traits and to develop potential genomic markers associated with economically important breeding traits, particularly in indicine cattle.


Assuntos
Cruzamento/métodos , Bovinos/genética , Genoma , Genômica/métodos , Polimorfismo de Nucleotídeo Único , Alcaloides de Pirrolizidina/farmacologia , Sequenciamento Completo do Genoma/veterinária , Animais , Bovinos/classificação , Genótipo , Mutação INDEL , Anotação de Sequência Molecular , Paquistão , Fenótipo , Seleção Genética
4.
Glycobiology ; 29(7): 530-542, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-30976784

RESUMO

The endoplasmic reticulum (ER) contains both α-glucosidases and α-mannosidases which process the N-linked oligosaccharides of newly synthesized glycoproteins and thereby facilitate polypeptide folding and glycoprotein quality control. By acting as structural mimetics, iminosugars can selectively inhibit these ER localized α-glycosidases, preventing N-glycan trimming and providing a molecular basis for their therapeutic applications. In this study, we investigate the effects of a panel of nine iminosugars on the actions of ER luminal α-glucosidase I and α-glucosidase II. Using ER microsomes to recapitulate authentic protein N-glycosylation and oligosaccharide processing, we identify five iminosugars that selectively inhibit N-glycan trimming. Comparison of their inhibitory activities in ER microsomes against their effects on purified ER α-glucosidase II, suggests that 3,7a-diepi-alexine acts as a selective inhibitor of ER α-glucosidase I. The other active iminosugars all inhibit α-glucosidase II and, having identified 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) as the most effective of these compounds, we use in silico modeling to understand the molecular basis for this enhanced activity. Taken together, our work identifies the C-3 substituted pyrrolizidines casuarine and 3,7a-diepi-alexine as promising "second-generation" iminosugar inhibitors.


Assuntos
Arabinose/farmacologia , Retículo Endoplasmático/enzimologia , Inibidores de Glicosídeo Hidrolases/farmacologia , Imino Furanoses/farmacologia , Alcaloides de Pirrolizidina/farmacologia , Álcoois Açúcares/farmacologia , alfa-Glucosidases/metabolismo , Animais , Arabinose/química , Cães , Inibidores de Glicosídeo Hidrolases/química , Humanos , Imino Furanoses/química , Camundongos , Microssomos/efeitos dos fármacos , Microssomos/metabolismo , Alcaloides de Pirrolizidina/química , Álcoois Açúcares/química
5.
BMC Vet Res ; 15(1): 99, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30909906

RESUMO

BACKGROUND: Haemonchosis affects sheep husbandry and its treatment is often compromised due to the development of anthelminthic resistance. Plant-derived bioactive compounds have been studied as alternative to control Haemonchus contortus. The objective of this study was to evaluate the effect of Senecio brasiliensis extracts on H. contortus egg hatching and infective larvae migration. RESULTS: The aqueous extract from dried and fresh plant and alkaloid-enriched fraction of the previously dried leaves of S. brasiliensis inhibited H. contortus egg hatching. The main plant compound in alkaloid fraction was integerrimine, a pyrrolizidine alkaloid (PA). However, the aqueous extract from dried plant displayed higher efficacy when compared to their alkaloid enriched or non-polar fractions, meaning that, although PAs contributed to the ovicidal effect, other compounds in the plant can also contribute to their effect. Furthermore, the aqueous extract from dried plant also had higher efficacy than aqueous extract from fresh plant in larvae migration inhibition. Finally, extract from dried plant presented low in vitro cytotoxic effect. CONCLUSION: Taken together our results suggest a good anthelmintic effect of S. brasiliensis, especially when aqueous extract is prepared from dried plant. Further in vivo studies should be performed focused on forms of administration of this extract in rearing sheep.


Assuntos
Anti-Helmínticos/farmacologia , Haemonchus/efeitos dos fármacos , Extratos Vegetais/farmacologia , Folhas de Planta , Senécio , Animais , Técnicas In Vitro , Larva/efeitos dos fármacos , Óvulo/efeitos dos fármacos , Folhas de Planta/química , Alcaloides de Pirrolizidina/farmacologia , Senécio/química
6.
Mol Nutr Food Res ; 63(12): e1801206, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30900802

RESUMO

SCOPE: Pyrrolizidine alkaloids (PAs) are common phytotoxins. Intoxication can lead to liver damage. Previous studies showed PA-induced apoptosis in liver cells. However, the exact role of the extrinsic apoptotic pathway has not been investigated yet. This study aims to analyze whether the PA representative lasiocarpine sensitizes human liver cells toward extrinsic Fas-mediated apoptosis. METHODS AND RESULTS: HepG2 cells with limited xenobiotic metabolic activity are used to analyze metabolism-dependent effects. External in vitro metabolism is simulated using rat or human liver enzymes. Additionally, metabolically competent HepaRG cells are used to confirm the observed effects in a human liver cell system with internal xenobiotic metabolism. Metabolized lasiocarpine decreases cell viability and induces Fas receptor gene expression in both cell lines. Increased Fas receptor protein expression on the cell surface is demonstrated by flow cytometry. The addition of a Fas ligand-simulating antibody induces apoptosis. Induction of extrinsic Fas-mediated apoptosis is verified by Western blotting for cleaved caspase 8, the initiator caspase of extrinsic apoptosis. All effects are dependent on lasiocarpine metabolism. CONCLUSION: The results demonstrate that metabolically metabolized lasiocarpine sensitizes human liver cells toward Fas-mediated apoptosis. They broaden our knowledge on the hepatotoxic molecular mechanisms of PA as widely distributed food contaminants.


Assuntos
Apoptose/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Alcaloides de Pirrolizidina/farmacologia , Receptor fas/fisiologia , Ativação Metabólica , Animais , Caspase 8/fisiologia , Proteína Ligante Fas/farmacologia , Células Hep G2 , Hepatócitos/fisiologia , Humanos , Masculino , Alcaloides de Pirrolizidina/farmacocinética , Ratos , Ratos Wistar
7.
Molecules ; 24(3)2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30704105

RESUMO

Pyrrolizidine alkaloids (PAs) are heterocyclic secondary metabolites with a typical pyrrolizidine motif predominantly produced by plants as defense chemicals against herbivores. They display a wide structural diversity and occur in a vast number of species with novel structures and occurrences continuously being discovered. These alkaloids exhibit strong hepatotoxic, genotoxic, cytotoxic, tumorigenic, and neurotoxic activities, and thereby pose a serious threat to the health of humans since they are known contaminants of foods including grain, milk, honey, and eggs, as well as plant derived pharmaceuticals and food supplements. Livestock and fodder can be affected due to PA-containing plants on pastures and fields. Despite their importance as toxic contaminants of agricultural products, there is limited knowledge about their biosynthesis. While the intermediates were well defined by feeding experiments, only one enzyme involved in PA biosynthesis has been characterized so far, the homospermidine synthase catalyzing the first committed step in PA biosynthesis. This review gives an overview about structural diversity of PAs, biosynthetic pathways of necine base, and necic acid formation and how PA accumulation is regulated. Furthermore, we discuss their role in plant ecology and their modes of toxicity towards humans and animals. Finally, several examples of PA-producing crop plants are discussed.


Assuntos
Alcaloides de Pirrolizidina/metabolismo , Alcaloides de Pirrolizidina/farmacologia , Alquil e Aril Transferases/metabolismo , Amina Oxidase (contendo Cobre)/metabolismo , Vias Biossintéticas , Cobre/metabolismo , Produtos Agrícolas/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Ácidos Dicarboxílicos/química , Modelos Moleculares , Conformação Molecular , Estrutura Molecular
8.
J Nat Prod ; 82(2): 358-367, 2019 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-30714734

RESUMO

Hyacinthacines C1 and C4 are natural products that were isolated from Hyacinthoides non-scripta and Scilla socialis in 1999 and 2007, respectively. Despite their different 1H NMR and 13C NMR spectroscopic data, these compounds have been assigned the same structures, including absolute configurations. This work details the total synthesis of natural (+)-hyacinthacine C1, whose structure is confirmed as being the C-6 epimer of that reported. The synthetic strategy focused on inverting the configuration at C-1 of the final hyacinthacines via operating the inversion at the corresponding carbon atom in three previously synthesized intermediates. To do this, the advanced intermediates were subjected to Swern oxidation, followed by a stereoselective reduction with L-Selectride. This approach led to the synthesis of (+)-5 -epi-hyacinthacine C1 (15), the corrected structure for (+)-hyacinthacine C1 (19), (+)-6,7-di- epi-hyacinthacine C1 (23), and (+)-7- epi-hyacinthacine C1 (29). Glycosidase inhibition assays revealed that (+)-hyacinthacine C1 (19) proved the most active, with IC50 values of 33.7, 55.5, and 78.2 µM, against the α-glucosidase of rice, human lysosome, and rat intestinal maltase, respectively.


Assuntos
Alcaloides de Pirrolizidina/síntese química , Animais , Glicosídeo Hidrolases/antagonistas & inibidores , Humanos , Alcaloides de Pirrolizidina/química , Alcaloides de Pirrolizidina/farmacologia , Ratos , Estereoisomerismo
9.
J Chem Ecol ; 45(2): 116-127, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30221331

RESUMO

Plants produce an extremely diverse array of metabolites that mediate many aspects of plant-environment interactions. In the context of plant-herbivore interactions, it is as yet poorly understood how natural backgrounds shape the bioactivity of individual metabolites. We tested the effects of a methanol extract of Jacobaea plants and five fractions derived from this extract, on survival of western flower thrips (WFT). When added to an artificial diet, the five fractions all resulted in a higher WFT survival rate than the methanol extract. In addition, their expected combined effect on survival, assuming no interaction between them, was lower than that of the methanol extract. The bioactivity was restored when the fractions were combined again in their original proportion. These results strongly suggest synergistic interactions among the fractions on WFT survival rates. We then tested the effects of two pyrrolizidine alkaloids (PAs), free base retrorsine and retrorsine N-oxide, alone and in combination with the five shoot fractions on WFT survival. The magnitude of the effects of the two PAs depended on the fraction to which they were added. In general, free base retrorsine was more potent than retrorsine N-oxide, but this was contingent on the fraction to which these compounds were added. Our results support the commonly held, though seldom tested, notion that the efficacy of plant metabolites with respect to plant defence is dependent on their phytochemical background. It also shows that the assessment of bioactivity cannot be decoupled from the natural chemical background in which these metabolites occur.


Assuntos
Compostos Fitoquímicos/química , Alcaloides de Pirrolizidina/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Asteraceae/química , Asteraceae/metabolismo , Cromatografia Líquida de Alta Pressão , Flores/química , Flores/metabolismo , Compostos Fitoquímicos/farmacologia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Brotos de Planta/química , Brotos de Planta/metabolismo , Alcaloides de Pirrolizidina/química , Espectrometria de Massas em Tandem , Tisanópteros/fisiologia
10.
J Chem Ecol ; 45(2): 136-145, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30284188

RESUMO

In this study we investigated the effect of methyl jasmonate (MeJA) application on pyrrolizidine alkaloid (PA) concentration and composition of two closely related Jacobaea species. In addition, we examined whether MeJA application affected herbivory of the polyphagous leaf feeding herbivore Spodoptera exigua. A range of concentrations of MeJA was added to the medium of Jacobaea vulgaris and J. aquatica tissue culture plants grown under axenic conditions. PA concentrations were measured in roots and shoots using LC-MS/MS. In neither species MeJA application did affect the total PA concentration at the whole plant level. In J. vulgaris the total PA concentration decreased in roots but increased in shoots. In J. aquatica a similar non-significant trend was observed. In both Jacobaea species MeJA application induced a strong shift from senecionine- to erucifoline-like PAs, while the jacobine- and otosenine-like PAs remained largely unaffected. The results show that MeJA application does not necessarily elicits de novo synthesis, but rather leads to PA conversion combined with reallocation of certain PAs from roots to shoots. S. exigua preferred feeding on control leaves of J. aquatica over MeJA treated leaves, while for J. vulgaris both the control and MeJA treated leaves were hardly eaten. This suggests that the MeJA-induced increase of erucifoline-like PAs can play a role in resistance of J. aquatica to S. exigua. In J. vulgaris resistance to S. exigua may already be high due to the presence of jacobine-like PAs or other resistance factors.


Assuntos
Acetatos/química , Ciclopentanos/química , Oxilipinas/química , Alcaloides de Pirrolizidina/química , Acetatos/metabolismo , Acetatos/farmacologia , Animais , Asteraceae/química , Asteraceae/metabolismo , Cromatografia Líquida de Alta Pressão , Ciclopentanos/metabolismo , Ciclopentanos/farmacologia , Herbivoria/efeitos dos fármacos , Oxilipinas/metabolismo , Oxilipinas/farmacologia , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Brotos de Planta/química , Brotos de Planta/metabolismo , Alcaloides de Pirrolizidina/metabolismo , Alcaloides de Pirrolizidina/farmacologia , Spodoptera/efeitos dos fármacos , Spodoptera/fisiologia , Espectrometria de Massas em Tandem
11.
J Chem Ecol ; 45(2): 109-115, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30079442

RESUMO

This mini-review summarizes over 40 years of research on quinolizidine (QAs) and pyrrolizidine alkaloids (PAs). Emphasis is on the chemical ecology of both groups of alkaloids, which serve as general defense compounds against herbivores for the plants producing them. For QAs and PAs, a number of insects (aphids, moths, beetles) have acquired tolerance. These specialists store the alkaloids and use them as defense chemicals against predators. In some PA sequestering moths, the adaptation is even more intricate and advanced. PAs can function as a morphogen to induce the formation of male coremata, inflatable organs that dissipate pheromones. In these insects, PAs are additionally used as a precursor for male pheromones. Female moths utilize their own PAs and those obtained from males via the spermatophore as nuptial gift, to transfer them to the eggs that thus become chemically protected. Novel genomic technologies will allow deeper insights in the molecular evolution of these two classes of alkaloids in plant-insect interactions.


Assuntos
Alcaloides de Pirrolizidina/química , Quinolizidinas/química , Animais , Lupinus/química , Lupinus/metabolismo , Mariposas/fisiologia , Feromônios/química , Feromônios/metabolismo , Plantas/química , Plantas/metabolismo , Comportamento Predatório/efeitos dos fármacos , Alcaloides de Pirrolizidina/metabolismo , Alcaloides de Pirrolizidina/farmacologia , Quinolizidinas/metabolismo , Quinolizidinas/farmacologia
12.
Mol Pharmacol ; 95(3): 269-285, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30567956

RESUMO

Quinone reductase 2 (QR2, E.C. 1.10.5.1) is an enzyme with a feature that has attracted attention for several decades: in standard conditions, instead of recognizing NAD(P)H as an electron donor, it recognizes putative metabolites of NADH, such as N-methyl- and N-ribosyl-dihydronicotinamide. QR2 has been particularly associated with reactive oxygen species and memory, strongly suggesting a link among QR2 (as a possible key element in pro-oxidation), autophagy, and neurodegeneration. In molecular and cellular pharmacology, understanding physiopathological associations can be difficult because of a lack of specific and powerful tools. Here, we present a thorough description of the potent, nanomolar inhibitor [2-(2-methoxy-5H-1,4b,9-triaza(indeno[2,1-a]inden-10-yl)ethyl]-2-furamide (S29434 or NMDPEF; IC50 = 5-16 nM) of QR2 at different organizational levels. We provide full detailed syntheses, describe its cocrystallization with and behavior at QR2 on a millisecond timeline, show that it penetrates cell membranes and inhibits QR2-mediated reactive oxygen species (ROS) production within the 100 nM range, and describe its actions in several in vivo models and lack of actions in various ROS-producing systems. The inhibitor is fairly stable in vivo, penetrates cells, specifically inhibits QR2, and shows activities that suggest a key role for this enzyme in different pathologic conditions, including neurodegenerative diseases.


Assuntos
Piridinas/farmacologia , Alcaloides de Pirrolizidina/farmacologia , Quinona Redutases/antagonistas & inibidores , Animais , Linhagem Celular Tumoral , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Células Hep G2 , Humanos , Masculino , Camundongos , NAD(P)H Desidrogenase (Quinona)/metabolismo , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo
13.
Curr Org Synth ; 16(4): 498-522, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31984928

RESUMO

BACKGROUND: The inherent glycosidase inhibitory activity and potentially therapeutic value of the polyhydroxylated pyrrolizidine alkaloids containing a hydroxymethyl substituent at the C-3 position have been well documented. Belonging to this class, the naturally occurring hyacinthacine C-type alkaloids are of general interest among iminosugar researchers. Their selective micromolar α -glycosidase inhibitory ranges (10 - 100 µM) suggest that these azasugars are potential leads for treating type II diabetes. However, the structures of hyacinthacine C1, C3 and C4 are insecure with hyacinthacine C5 being recently corrected. OBJECTIVE: This review presents the hyacinthacine C-type alkaloids: their first discovery to the most recent advancements on the structures, biological activities and total synthesis. CONCLUSION: The hyacinthacine C-type alkaloids are of exponentially increasing interest and will undoubtedly continue to be reported as synthetic targets. They represent a challenging but rewarding synthetic feat for the community of those interested in accessing biologically active iminosugars. Since 2009, ten total syntheses have been employed towards accessing similarly related products but only three have assessed the glycosidase inhibitory activity of the final products. This suggests the need for an accessible and universal glycosidase inhibitory assay so to accurately determine the structure-activity relationship of how the hyacinthacine C-type alkaloids inhibit specific glycosidases. Confirming the correct structures of the hyacinthacine C-type alkaloids as well as accessing various analogues continues to strengthen the foundation towards a marketable treatment for type II diabetes and other glycosidase related illnesses.


Assuntos
Inibidores de Glicosídeo Hidrolases/síntese química , Inibidores de Glicosídeo Hidrolases/isolamento & purificação , Glicosídeo Hidrolases/antagonistas & inibidores , Alcaloides de Pirrolizidina/síntese química , Alcaloides de Pirrolizidina/isolamento & purificação , Castanospermum/química , Inibidores de Glicosídeo Hidrolases/história , Inibidores de Glicosídeo Hidrolases/farmacologia , Heliotropium/química , História do Século XX , História do Século XXI , Estrutura Molecular , Alcaloides de Pirrolizidina/história , Alcaloides de Pirrolizidina/farmacologia
14.
Org Biomol Chem ; 16(48): 9430-9439, 2018 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-30511067

RESUMO

Four pairs of new spiropyrrolizidine oxindole enantiomers (1a/1b-4a/4b) were isolated from the leaves of Isatis indigotica Fortune. Their structures and absolute configurations were elucidated by a combination of NMR spectroscopic analyses, experimental and calculated electronic circular dichroism (ECD) and the assistance of quantum chemical predictions (QCP) of 13C NMR chemical shifts. Notably, all the isolated spiropyrrolizidine oxindoles are reported as natural products for the first time. The biosynthetic pathway of these unique structures was proposed to be formed by cycloaddition reaction. In addition, all the compounds were evaluated for their inhibitory effects on ß-amyloid aggregation by ThT assay, and the optically pure compounds 1a/1b and 2a/2b exhibited better Aß1-42 aggregation inhibition potency (85.8% and 73.6%, 71.5% and 75.8%, respectively) at a concentration of 20 µM, compared with the positive control curcumin (57.0%). The difference of the inhibitory pattern caused by chirality was also explained by molecular docking studies.


Assuntos
Isatis/química , Oxindois/química , Alcaloides de Pirrolizidina/química , Compostos de Espiro/química , Peptídeos beta-Amiloides/metabolismo , Humanos , Simulação de Acoplamento Molecular , Oxindois/isolamento & purificação , Oxindois/farmacologia , Fragmentos de Peptídeos/metabolismo , Agregados Proteicos/efeitos dos fármacos , Alcaloides de Pirrolizidina/isolamento & purificação , Alcaloides de Pirrolizidina/farmacologia , Compostos de Espiro/isolamento & purificação , Compostos de Espiro/farmacologia , Estereoisomerismo
15.
Med Sci Monit ; 24: 7444-7450, 2018 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-30335732

RESUMO

BACKGROUND Spinal cord injury (SCI) is an injury-triggered event that is associated with permanent neurologic deficit. The deficit instigated by SCI leads to medical co-morbidity, not only affecting sensory and motor capabilities, but also having an impact on the physiological and economic condition of the patient. Against this backdrop, the present study was carried out to investigate the effect of lycopsamine, a plant-derived alkaloid in SCI rats. MATERIAL AND METHODS The traumatic SCI injury in rats was created using a force-calibrated weight-drop device. The Basso-Beattie-Bresnahan (BBB) locomotor rating scale was used to investigate the functional consequences of SCI. DAPI (4',6-diamidino-2-phenylindole) and Tunnel staining were used to detect apoptosis. Western blot and qRT-PCR was used to examine the protein and gene expressions, respectively. RESULTS The results revealed that lycopsamine significantly (p<0.01) improved locomotory function in SCI rats. Lycopsamine also significantly (p<0.01) decreased the lesion area of the SCI rats. Investigation of the effect of lycopsamine on cell death following SCI revealed that lycopsamine reduces apoptotic cell death following SCI. The lycopsamine-induced reduction in apoptosis was allied with downregulation of calpain, cleaved caspase 3 and 9, and Bax. However, the expression of BCl-2 was significantly upregulated. Furthermore, lycopsamine significantly (p<0.01) upregulated the expression of interleukin-10 (IL-10) and decreased the expression of tumor necrosis factor-α (TNF-α). CONCLUSIONS Lycopsamine exerts protective effects in PCI rats by improving functional recovery and suppressing apoptosis.


Assuntos
Alcaloides de Pirrolizidina/farmacologia , Traumatismos da Medula Espinal/tratamento farmacológico , Animais , Apoptose/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Interleucina-10/metabolismo , Masculino , Substâncias Protetoras/metabolismo , Alcaloides de Pirrolizidina/metabolismo , Ratos , Ratos Sprague-Dawley , Recuperação de Função Fisiológica/fisiologia , Medula Espinal/patologia , Traumatismos da Medula Espinal/patologia , Fator de Necrose Tumoral alfa/efeitos dos fármacos
16.
Alkaloids Chem Biol ; 80: 1-314, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30001795

RESUMO

Naturally occurring pyrrolizidine alkaloids (PAs) are isolated from plants and other sources. The interest of the scientific community in these compounds owes itself to their high toxicity and biological activity, as well as to the challenge of synthesizing their pyrrolizidine scaffold. This review encompasses a wide range of topics found in the literature from 1995 to date, including the occurrence, biosynthesis, toxicity (hepatotoxicity, genotoxicity, and tumorigenicity), biological activity, and pharmacological properties (glycosidase inhibitory activity) of these secondary metabolites. Particular attention is given to the chemistry of PAs, addressing general strategies for formal and total syntheses via amino-based substrates, pyrroles, and pyrrolidine-based derivatives.


Assuntos
Alcaloides de Pirrolizidina/química , Alcaloides de Pirrolizidina/farmacologia , Animais , Antibacterianos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Apocynaceae/química , Apocynaceae/metabolismo , Asteraceae/química , Asteraceae/metabolismo , Técnicas de Química Sintética , Inibidores Enzimáticos/farmacologia , Glicosídeo Hidrolases/antagonistas & inibidores , Estrutura Molecular , Alcaloides de Pirrolizidina/metabolismo , Alcaloides de Pirrolizidina/toxicidade
17.
Phytochemistry ; 153: 147-155, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29980107

RESUMO

Seven pyrrolizidine alkaloids, nervosine X-XV and nervosine VII N-oxide, together with a reaction product, namely chloride-(N-chloromethyl nervosine VII), were isolated from Liparis nervosa. Their structures were elucidated by extensive spectroscopic analyses. Most of these compounds were investigated for their cytotoxicity in vitro against HCT116 human cancer cell line, and the results showed that chloride-(N-chloromethyl nervosine VII) induced tumor cell death in a dose-dependent manner. Furthermore, the mechanisms underlying its cytotoxicity were investigated, including apoptosis and autophagy. Apoptosis in HCT116 cells was associated with up-regulation of caspase-3 and -9 expressions by activation of the mitochondrial pathway. The autophagy inducing effect was associated with the regulation of autophagic markers, including LC3-II, p62, and Beclin 1. Mechanistic studies showed that JNK, ERK1/2, and p38 MAPKs signaling cascades play an important role in chloride-(N-chloromethyl nervosine VII) induced autophagy and apoptosis.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Orchidaceae/química , Alcaloides de Pirrolizidina/farmacologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Células HCT116 , Humanos , Conformação Molecular , Alcaloides de Pirrolizidina/química , Alcaloides de Pirrolizidina/isolamento & purificação , Relação Estrutura-Atividade , Células Tumorais Cultivadas
18.
Int J Mol Sci ; 19(6)2018 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-29874826

RESUMO

Pyrrolizidine alkaloids (PA) are widely distributed in plants throughout the world, frequently in species relevant for human consumption. Apart from the toxicity that these molecules can cause in humans and livestock, PA are also known for their wide range of pharmacological properties, which can be exploited in drug discovery programs. In this work we review the current body of knowledge regarding the chemistry, toxicology, pharmacology and food safety of PA.


Assuntos
Inocuidade dos Alimentos , Plantas/química , Alcaloides de Pirrolizidina/química , Alcaloides de Pirrolizidina/farmacologia , Animais , Descoberta de Drogas , Humanos , Plantas/toxicidade , Alcaloides de Pirrolizidina/toxicidade
19.
J Org Chem ; 83(10): 5558-5576, 2018 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-29701065

RESUMO

The total synthesis of natural (+)-hyacinthacine C5 was achieved, which allowed correction of its initially proposed structure, as well as six additional hyacinthacine C-type compounds. These compounds were readily accessible from two epimeric anti-1,2-amino alcohols. Keeping a common A-ring configuration, chemical manipulation occurred selectively on the B-ring of the hyacinthacine C-type products through methods of syn-dihydroxylation, SN2 ring-opening of a cyclic sulfate, and also employing either ( R)- or ( R, S)-α-methylallyl amine for the Petasis borono Mannich reaction. Our small analogue library was then assessed for its glycosidase inhibitory potency against a panel of glycosidases. (-)-6- Epi-hyacinthacine C5 and (+)-7- epi-hyacinthacine C5 (compound names are based on the corrected structure of hyacinthacine C5) proved most active, with inhibitory activities ranging between weak (IC50 = 130 µM) and moderate (IC50 = 9.9 µM) against the α-glucosidases of rat intestinal maltase, isomaltase, and sucrase, thus identifying potential new leads for future antidiabetic drug development.


Assuntos
Produtos Biológicos/farmacologia , Alcaloides de Pirrolizidina/farmacologia , alfa-Glucosidases/metabolismo , Animais , Produtos Biológicos/síntese química , Produtos Biológicos/química , Relação Dose-Resposta a Droga , Intestinos/enzimologia , Conformação Molecular , Alcaloides de Pirrolizidina/síntese química , Alcaloides de Pirrolizidina/química , Ratos , Estereoisomerismo , Relação Estrutura-Atividade
20.
J Org Chem ; 83(13): 7033-7041, 2018 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-29460633

RESUMO

A novel enantioselective approach to the synthesis of a compound collection inspired by natural pyrrolizidine alkaloids was developed, employing an enantioselectively catalyzed 1,3-dipolar cycloaddition as the key step. The cycloadducts were obtained with excellent enantio- and diastereoselectivity. Biological evaluation of the resulting compound collection revealed that the compound class has multiple bioactivities, including activity against Plasmodium falciparum 3D7 and inhibition of Hedgehog signaling.


Assuntos
Antimaláricos/síntese química , Antimaláricos/farmacologia , Alcaloides de Pirrolizidina/síntese química , Alcaloides de Pirrolizidina/farmacologia , Animais , Produtos Biológicos/química , Catálise , Linhagem Celular , Reação de Cicloadição , Proteínas Hedgehog/metabolismo , Camundongos , Camundongos Endogâmicos C3H , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Estereoisomerismo
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