Lourivaldo S. Santos

Biologically active polyketides produced by Penicillium janthinellum isolated as an endophytic fungus from fruits of Melia azedarach

Penicillium janthinellum, isolated as an endophytic fungus from fruits of Melia azedarach, was cultivated over 20 days on ground and autoclaved white corn, where the known polyketides citrinin, emodin, 1,6,8-trihydroxy-3-hydroxymethylanthraquinone, and a new modified anthraquinone, named janthinone, were produced and isolated by classical chromatographic procedures and identified by MS and 1D and 2D NMR spectroscopic data. The antibacterial properties of these polyketides were investigated. Citrinin inhibited 100% of Leishmania growth after 48h at a concentration of 40 mg mL-1.

Potencial alelopático de Myrcia guianensis

The use of fire and mowing as weed methods have proved inefficient. Although more efficient, synthetic chemical herbicides are usually related to environmental problems. Thus, the search for natural herbicides has become a priority matter. Based on these facts, research was conducted on Myrcia guianensis (pedra-ume-caa) including the isolation and identification of chemical substances with allelophatic activity. The allelophatic effects of extracts, fractions, essential oils, and isolated chemical substances (gallic acid and protocatechuic acid) on germination and radicle and hypocotyl growth of weed species Mimosa pudica (malicia) and Senna obtusifolia (mata-pasto) were analyzed. Extracts and fractions were analyzed at a concentration of 1%, essential oils at 15, 30, 45, 60 ppm and the isolated chemical substances at 15, 30, 45, 60 ppm. Malicia showed more sensitivity to the allelophatic effects of extracts and fractions. The essential oil inhibited the germination of M. pudica but stimulated that of S. obtusifolia. The allelophatic effects of the chemical substances were concentration dependent and the strongest activity was observed at 60 ppm.

Metodologias empregadas em estudos de avaliação da atividade alelopática em condições de laboratório: revisão crítica

Nas ultimas decadas, tem proliferado a formacao de grupos de pesquisa dedicados aos estudos na area de alelopatia, em diferentes partes do mundo. O Brasil nao ficou imune a essa tendencia; prova disso sao os numeros cada vez maiores de artigos cientificos publicados em periodicos nacionais e internacionais. O fato de a alelopatia ser uma ciencia relativamente jovem, podendo ser considerada em sua fase juvenil de desenvolvimento, tem propiciado a proliferacao de tecnicas de estudos diversificadas e muitas vezes carentes de embasamento. Adicionalmente, essa peculiaridade dificulta o entendimento das grandezas expressas e do valor biologico que os resultados apresentados podem significar. Uniformizar os procedimentos e, sem duvida alguma, ponto de partida quando se pensa na dimensao que a alelopatia pode representar em futuro proximo. Neste trabalho, foram revisados criticamente os protocolos pertinentes aos processos empregados nos bioensaios desenvolvidos para caracterizar as propriedades alelopaticas de extratos brutos e de substâncias quimicas. Ao mesmo tempo, os pontos fortes e as limitacoes de cada procedimento sao apresentados.

Chemical constituents and allelopathic and antioxidant activities of Alchorneopsis floribunda Müll. Arg. (Euphorbiaceae)

Chemical investigation of extracts from the stems and leaves of Alchorneopsis floribunda Müll. Arg., collected in the Amazon region, was performed. The main isolated compounds were triterpenes (α-amyrin, β-amyrin, lupeol, betulin, betulinic acid, uvaol, erythrodiol and oleanolic acid) and phenolic acid derivatives from 4-hydroxybenzoic acid (gallic and protocatechuic acids and isocorilagin). In the germination assays, high inhibitory allelopathic effects of the extracts and isocorilagin were observed and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of isocorilagin was higher than those of the standards used (Trolox and butylated hydroxyanisole). This is the first chemical study of the genus Alchorneopsis (Euphorbiaceae).

C25 steroid epimers produced by Penicillium janthinellum, a fungus isolated from fruits Melia azedarach

A plant-derived fungus, Penicillium janthinellum, obtained from Melia azedarach, produced ergosterol and ergosterol 5a,8a-peroxide along with a mixture of rare C25 steroid epimers. The C25 steroids, named neocyclocitrinols, shows exactly the same tetracyclic ring system present in cyclocitrinol, which was isolated from a sponge-derived Penicillium citrinum, with the same bicyclo [4:4:1] skeleton at A/B rings, but showing different side chains. The P. janthinellum was cultivated over white corn and the three steroids were isolated by several silica gel based chromatographic procedures and identified by extensive NMR methods, mainly 1H - 13C correlations and 1H - 1H COSY and TOCSY. The biosynthetic origin of the cyclocitrinols is also discussed.

Constituents and Pharmacological Activities of Myrcia (Myrtaceae): A Review of an Aromatic and Medicinal Group of Plants

Myrcia is one of the largest genera of the economically important family Myrtaceae. Some of the species are used in folk medicine, such as a group known as “pedra-hume-caá” or “pedra-ume-caá” or “insulina vegetal” (insulin plant) that it is used for the treatment of diabetes. The species are an important source of essential oils, and most of the chemical studies on Myrcia describe the chemical composition of the essential oils, in which mono- and sesquiterpenes are predominant. The non-volatile compounds isolated from Myrcia are usually flavonoids, tannins, acetophenone derivatives and triterpenes. Anti-inflammatory, antinociceptive, antioxidant, antimicrobial activities have been described to Myrcia essential oils, while hypoglycemic, anti-hemorrhagic and antioxidant activities were attributed to the extracts. Flavonoid glucosides and acetophenone derivatives showed aldose reductase and α-glucosidase inhibition, and could explain the traditional use of Myrcia species to treat diabetes. Antimicrobial and anti-inflammatory are some of the activities observed for other isolated compounds from Myrcia.

Structure-Activity Relationship of Compounds which are Anti-Schistosomiasis Active

O metodo do orbital molecular AM1 foi empregado para calcular um conjunto de descritores moleculares para vinte neolignanas sinteticas com atividade anti-esquistossomose. O metodo de reconhecimento de padrao (analise de componentes principais ACP, analise de conglomerados AC e analise de discriminante) foi utilizado para obter a relacao entre a estrutura molecular e a atividade biologica. O conjunto de moleculas foi classificado em dois grupos de acordo com seus graus de atividade biologica. Estes resultados permitem que, projete-se racionalmente novos compostos, potenciais candidatos a sintese e a avaliacao biologica.

Dihydroflavonols from the leaves of Derris urucu (Leguminosae): structural elucidation and DPPH radical-scavenging activity

Derris urucu e uma planta da Amazonia com propriedades inseticida e ictiotoxica. Estudos com esta especie reportam a presenca de flavonoides, principalmente rotenoides, bem como de estilbenos. A partir do extrato etanolico das folhas de Derris urucu (Leguminosae), tres novos diidroflavonoides, denominados urucuol A (1), B (2) e C (3) e o diidroflavonol isotirumalina (4), foram isolados e identificados. As estruturas destes compostos foram elucidadas por uma extensiva analise espectroscopica de RMN uni e bidimensional, UV, IV e dados de EM, alem de comparacao com dados da literatura. Os compostos isolados (1-4) foram avaliados quanto ao seu potencial sequestrador do radical DPPH• e apresentaram baixo poder antioxidante quando comparados ao antioxidante comercial trans-resveratrol.

Atividade alelopática de chalcona sintética, de seus precursores e de cetonas e aldeídos relacionados

’dimetoxichalcona, em funcao dos precursores, ortoanisaldeido e 4-metoxiacetofenona, e de alteracoes nestes. Os bioensaios foram monitorados em condicoes controladas de 25 °C e fotoperiodo de 12 horas. Como plantas-teste foram utilizadas as plantas daninhas malicia (Mimosa pudica) e mata-pasto (Senna obtusifolia). A atividade alelopatica foi analisada em concentracoes fixas de 100, 200 e 300 mg L -1 . A chalcona foi obtida via reacao de condensacao entre a 4-metoxiacetofenona e o ortoanisaldeido. Os resultados indicaram que a atividade alelopatica esta relacionada, em principio, ao precursor A, 4-metoxiacetofenona. Mudancas nos precursores indicaram a possibilidade de aumentar a atividade alelopatica, em especial no precursor A. Ausencia do grupo CH 3 O propiciou reducao na atividade alelopatica, indicando ser importante para a atividade. A presenca de dois grupamentos OCH 3 no precursor da porcao B da chalcona aumentou para 62% a atividade do aldeido. Esses resultados indicam que alteracoes de substâncias com atividades alelopaticas sao uma possivel via para enfrentar os problemas atrelados aos processos de isolamento e identificacao de moleculas quimicas com atividade alelopatica, em especies de plantas. Palavras-chave: alelopatia, aleloquimico, germinacao, sintese de chalcona.

Chemical constituents of Aspergillus sp EJC08 isolated as endophyte from Bauhinia guianensis and their antimicrobial activity

The present work reports the isolation of five compounds from Aspergillus sp EJC08 isolated as endophytic from Bauhinia guianensis, a tipical plant of the Amazon. The compounds ergosterol (1), ergosterol peroxide (2), mevalolactone (3), monomethylsulochrin (4) and trypacidin A (5) were isolated by chromatographic procedures and identified by spectral methods of 1D and 2D NMR and MS. Compounds 3, 4 and 5 were tested against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus and showed good activity.