RESUMO
The boom in visible light photoredox catalysis (VLPC) research has demonstrated that this novel synthetic approach is here to stay. VLPC enables reactive radical intermediates to be catalytically generated at ambient temperature, a feat not generally allowed through traditional pyrolysis- or radical initiator-based methodologies. VLPC has vastly extended the range of substrates and reaction schemes that have been traditionally the domain of radical reactions. In this review the photophysics background of VLPC will be briefly discussed, followed by a report on recent inroads of VLPC into decarboxylative couplings and radical C-H functionalization of aromatic compounds. The bulk of the review will be dedicated to advances in synergistic catalysis involving VLPC, namely the combination of photoredox catalysis with organocatalysis, including ß-functionalization of carbonyl groups, functionalization of weak aliphatic C-H bonds, and anti-Markovnikov hydrofunctionalization of alkenes; dual catalysis with gold or with nickel, photoredox catalysis as an oxidation promoter in transition metal catalysis, and acid-catalyzed enantioselective radical addition to π systems.
RESUMO
An anticancer-bioassay guided isolation of the ethanol extract and fractions of two plants from the Peruvian rainforest, Mikania decora and Cremastosperma microcarpum, led to the characterization of one abundant diterpene, ent-pimara-8(14),15-dien-19-oic acid (1), three thymol derivatives, 10-acetoxy-8,9-dehydro-6-methoxythymol butyrate (2), 10-acetoxy-8,9-epoxy-6-methoxythymol isobutyrate (3), and acetylschizoginol (4), as well as one neolignan, (±)-trans-dehydrodiisoeugenol (5). Only the latter was isolated from C. microcarpum. These compounds exhibited significant cytotoxic activity against a panel of human tumor cell lines. Compounds 3 and 4 were also investigated for their in vitro antileishmanial and trypanocidal activity against Leishmania amazonensis axenic amastigotes and Trypanosoma cruzi trypomastigotes.
Assuntos
Annonaceae/química , Anti-Infecciosos/farmacologia , Mikania/química , Extratos Vegetais/química , Animais , Anti-Infecciosos/química , Linhagem Celular Tumoral , Sobrevivência Celular , Diterpenos/química , Diterpenos/farmacologia , Feminino , Humanos , Leishmania/efeitos dos fármacos , Lignanas/química , Lignanas/farmacologia , Macrófagos/efeitos dos fármacos , Masculino , Camundongos , Testes de Sensibilidade Parasitária , Peru , Folhas de Planta/química , Raízes de Plantas/química , Caules de Planta/química , Timol/química , Timol/farmacologia , Árvores , Trypanosoma cruzi/efeitos dos fármacosRESUMO
A pharmacological screening of the ethanol extract and fractions of two Peruvian medicinal plants, Plagiochila disticha and Ambrosia peruviana, led to the isolation and characterization of three ENT-2,3-secoaromadendrane-type sesquiterpenoids, named plagiochiline A ( 1), I ( 2), and R ( 3), as well as of two pseudoguaianolids, damsin ( 4) and confertin ( 5), which exhibited significant cytotoxic activity against a panel of human tumor cell lines. Compounds 1, 4, and 5 were also investigated for their in vitro antileishmanial, trypanocidal, and antituberculosis activity against Leishmania amazonensis axenic amastigotes and Trypanosoma cruzi trypomastigotes, as well as against MDR and sensitive strains of Mycobacterium tuberculosis, respectively.
Assuntos
Anti-Infecciosos/isolamento & purificação , Antineoplásicos Fitogênicos/isolamento & purificação , Asteraceae/química , Azulenos/isolamento & purificação , Compostos de Epóxi/isolamento & purificação , Piranos/isolamento & purificação , Sesquiterpenos/isolamento & purificação , Linhagem Celular Tumoral , Avaliação Pré-Clínica de Medicamentos , Humanos , Peru , Plantas Medicinais/químicaRESUMO
A multidisciplinary and international team of scientists was assembled in the early 1990s to conduct an ethnobotanical study of plants used by the Aguaruna people of the Peruvian Amazon forest. The initial ethnobotanical project, carried out under the auspices of an International Cooperative Biodiversity Grant (ICBG), led to the collection of approximately 4000 plant species. Some members of the original team of scientists have continued this collaboration by focusing on potential sources of new anticancer, anti-infective, and wound-healing agents. This effort has uncovered several secondary metabolites representing a wide variety of chemical diversity. In this short review we describe some bioactive compounds of interest as part of our continuing collaboration.
Assuntos
Plantas Medicinais/química , Etnobotânica , Humanos , Medicina Tradicional , Estrutura Molecular , PeruRESUMO
The antiproliferative bioassay-guided fractionation of five Peruvian plants, Doliocarpus dentatus, Picramnia sellowii, Strychnos mitscherlichii, Iryanthera juruensis, and Croton alnifolius, led to the isolation and identification of their different major cytotoxic constituents, betulinic acid (1), nataloe-emodin (2), bisnordihydrotoxyferine (4), 2',4'-dihydroxy-6'-methoxy-3,4-methylenedioxydihydrochalcone (5), and 2',4'-dihydroxy-4,6'-dimethoxydihydrochalcone (6) and 12-O-tetradecanoylphorbol-13-acetate (7), respectively. Eight human tumor cell lines and two nontumorigenic cell lines were used in this investigation. Their in vitro activity against Mycobacterium tuberculosis is also reported.
Assuntos
Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Plantas Medicinais/química , Strychnos/química , Triterpenos/isolamento & purificação , Triterpenos/farmacologia , Antineoplásicos Fitogênicos/química , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Triterpenos Pentacíclicos , Peru , Triterpenos/química , Células Tumorais Cultivadas , Ácido BetulínicoRESUMO
Purification of a CHCl3-soluble extract from seeds of the Mexican medicinal arborescent morning glory, Ipomoea intrapilosa, by means of preparative-scale recycling HPLC, yielded seven new resin glycosides, intrapilosins I-VII (1-7). Their structures were established through the interpretation of their NMR spectroscopic and FABMS data. All pentasaccharides were found to be macrolactones of the known operculinic acid A with different fatty acids esterifying the same positions: C-2 on the second rhamnose unit and C-3 and C-4 on the third rhamnose moiety. The lactonization site of the aglycon could be placed at C-2 of the second saccharide. The fatty acid components of 1-7 were identified as (+)-(2S)-methylbutanoic, octanoic (caprylic), dodecanoic (lauric), and trans-cinnamic. The less common (-)-(2R)-methylbutanoic acid was also isolated as one of the saponification-liberated residues from intrapilosin IV (4). The presence of the (2R)- and (2S)-methylbutanoyl enantiomers bonded to the same oligosaccharide core in intrapilosins IV (4) and V (5) represents an example of diastereoisomerism due to a chiral esterifying moiety in the resin glycoside mixtures of a morning glory species.
Assuntos
Ipomoea/química , Oligossacarídeos/química , Oligossacarídeos/isolamento & purificação , Plantas Medicinais/química , Resinas Vegetais/química , Glicosídeos/análise , México , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Sementes/química , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
Anredera diffusa is used as a wound-healing agent in traditional Peruvian medicine. Acid hydrolysis of the bioactive ethanolic extract, followed by in vivo activity-guided fractionation, yielded oleanolic acid, with a wound-healing activity equivalent to 42.9% (p < 0.01) above the control. The highest cicatrizant activity in mice was obtained by applying 40 microg of oleanolic acid per gram of body weight.
Assuntos
Caryophyllaceae/química , Ácido Oleanólico , Plantas Medicinais/química , Cicatrização/efeitos dos fármacos , Animais , Medicina Tradicional , Camundongos , Estrutura Molecular , Ácido Oleanólico/análogos & derivados , Ácido Oleanólico/química , Ácido Oleanólico/isolamento & purificação , Ácido Oleanólico/farmacologia , PeruRESUMO
A versatile microplate bioassay for quick and sensitive determination of antibacterial activity was developed for use in screening medicinal plants and identification of their active principles. This assay can be used to determine minimum inhibitory concentrations for small quantities of organic or water-soluble plant extracts. Bioassay-guided fractionation of the stem and leaves of Peperomia galioides using this method found fractions containing grifolin and grifolic acid, which inhibited growth of Staphylococcus aureus and Staphylococcus epidermidis.
Assuntos
Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Peperomia , Plantas Medicinais , Antibacterianos/isolamento & purificação , Testes de Sensibilidade Microbiana/estatística & dados numéricos , Peru , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Folhas de Planta , Caules de Planta , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/crescimento & desenvolvimentoRESUMO
Extracts of eight medicinal plants from the Callejon de Huaylas in Peru were screened for antibacterial activity in eighteen bacterial strains by the agar-diffusion method; six of these were active against a variety of bacteria.