Bioactivity of essential oils from Artemisia against Diaphania hyalinata and its selectivity to beneficial insects

The demand for effective insecticides in pest control with low toxicity to the non-target organisms, such as natural enemies and pollinators, is increasing steadily. A good alternative for synthetic insecticides is natural compounds, including essential oils (EO). This work assessed toxicity of essential oils extracted from Artemisia annua, A. absinthium, A. camphorata, A. dracunculus and A. vulgaris against the melonworm Diaphania hyalinata (Linnaeus, 1758) (Lepidoptera: Crambidae) larvae, a pest of Cucurbitaceae, and their selectivity for fire ant Solenopsis saevissima (Smith) (Hymenoptera: Formicidae) and jataí bee Tetragonisca angustula (Latreille) (Meliponinae). The plants were grown in a greenhouse with mineral fertilization and were used for EO extraction. The insects in the bioassay belonged to the second instar of D. hyalinata and adult forms of S. saevissima and T. angustula. Essential oil from A. annua induced a high mortality rate in D. hyalinata (96 %) over a 48 h period. The same essential oil was selective for predator S. saevissima (42 % mortality) and pollinator T. angustula (74 % mortality), while causing high mortality in D. hyalinata. The insecticidal activity of A. annua oil was attributed to the synergism of its constituents viz., camphor and 1,8-cineole. Therefore, this essential oil contains constituents that are promising for effective use as insecticide due to its high toxicity and rapid action against D. hyalinata as well as low toxicity for predator and pollinator.(AU)

Chemical composition of the essential oil of Psidium guajava leaves and its toxicity against Sclerotinia sclerotiorum / Composição química do óleo essencial de folhas de Psidium guajava e sua toxicidade contra Sclerotinia sclerotiorum

Globally, the fungus Sclerotinia sclerotiorum is considered as one of the most important phytopathogens,since it affects the production of several economically important crops. Further, it is difficult to control,thus increasing the use of pesticides. Therefore, the search for new substances, especially thoseextracted from plants, has received special attention to control this plant pathogen. The objective ofthe present study was to evaluate the yield and chemical composition of the essential oil extracted fromthe fresh leaves of guava collected during the rainy and dry seasons, and also to evaluate its toxicityagainst S. sclerotiorum. The experiment was a completely randomized design with five treatmentsand six replicates. The essential oil was extracted by hydrodistillation of the leaves and analyzed bygas chromatography-flame ionization detector and gas chromatography-mass spectrometry. The maincompounds identified in the essential oil were trans-caryophyllene and α-humulene. The essential oilat a concentration of 300 μL exhibited 90% inhibition of the mycelial growth of S. sclerotiorum. Thisconfirmed the antifungal potential of the essential oil of the guava leaves during both the samplingseasons.(AU)

O fungo Sclerotinia sclerotiorum é considerado um dos fitopatógenos mais importantes no mundo,pois afeta a produção de diversas culturas de importância econômica, e possui difícil controle,aumentando, assim, a necessidade de crescentes aplicações de defensivos agrícolas. Dessa forma, abusca de novas substâncias, principalmente aquelas extraídas de plantas, tem recebido especial atençãocomo forma de controle desse fitopatógeno. Com este trabalho, objetivou-se avaliar o rendimento, acomposição química e a toxicidade frente a S. sclerotiorum do óleo essencial extraído de folhas innatura de goiabeira coletadas na época das chuvas e da seca. O delineamento utilizado foi inteiramentecasualizado, com cinco tratamentos e seis repetições. O óleo essencial foi extraído por hidrodestilaçãodas folhas e analisado por CG-DIC e CG-EM. Os compostos majoritários identificados no óleo essencial foram o trans-cariofileno e α-humuleno. O óleo essencial possibilitou taxa de inibição micelial de S.sclerotiorum acima de 90% com o tratamento de 300 μL, confirmando o potencial antifúngico do óleoessencial de folhas de goiabeira em ambas as épocas de coleta avaliadas.(AU)

Chemical composition of the essential oil of Psidium guajava leaves and its toxicity against Sclerotinia sclerotiorum / Composição química do óleo essencial de folhas de Psidium guajava e sua toxicidade contra Sclerotinia sclerotiorum

Globally, the fungus Sclerotinia sclerotiorum is considered as one of the most important phytopathogens,since it affects the production of several economically important crops. Further, it is difficult to control,thus increasing the use of pesticides. Therefore, the search for new substances, especially thoseextracted from plants, has received special attention to control this plant pathogen. The objective ofthe present study was to evaluate the yield and chemical composition of the essential oil extracted fromthe fresh leaves of guava collected during the rainy and dry seasons, and also to evaluate its toxicityagainst S. sclerotiorum. The experiment was a completely randomized design with five treatmentsand six replicates. The essential oil was extracted by hydrodistillation of the leaves and analyzed bygas chromatography-flame ionization detector and gas chromatography-mass spectrometry. The maincompounds identified in the essential oil were trans-caryophyllene and α-humulene. The essential oilat a concentration of 300 μL exhibited 90% inhibition of the mycelial growth of S. sclerotiorum. Thisconfirmed the antifungal potential of the essential oil of the guava leaves during both the samplingseasons.

O fungo Sclerotinia sclerotiorum é considerado um dos fitopatógenos mais importantes no mundo,pois afeta a produção de diversas culturas de importância econômica, e possui difícil controle,aumentando, assim, a necessidade de crescentes aplicações de defensivos agrícolas. Dessa forma, abusca de novas substâncias, principalmente aquelas extraídas de plantas, tem recebido especial atençãocomo forma de controle desse fitopatógeno. Com este trabalho, objetivou-se avaliar o rendimento, acomposição química e a toxicidade frente a S. sclerotiorum do óleo essencial extraído de folhas innatura de goiabeira coletadas na época das chuvas e da seca. O delineamento utilizado foi inteiramentecasualizado, com cinco tratamentos e seis repetições. O óleo essencial foi extraído por hidrodestilaçãodas folhas e analisado por CG-DIC e CG-EM. Os compostos majoritários identificados no óleo essencial foram o trans-cariofileno e α-humuleno. O óleo essencial possibilitou taxa de inibição micelial de S.sclerotiorum acima de 90% com o tratamento de 300 μL, confirmando o potencial antifúngico do óleoessencial de folhas de goiabeira em ambas as épocas de coleta avaliadas.

Natural Abenquines and Their Synthetic Analogues Exert Algicidal Activity against Bloom-Forming Cyanobacteria.

Abenquines are natural quinones, produced by some Streptomycetes, showing the ability to inhibit cyanobacterial growth in the 1 to 100 µM range. To further elucidate their biological significance, the synthesis of several analogues (4f-h, 5a-h) allowed us to identify some steric and electronic requirements for bioactivity. Replacing the acetyl by a benzoyl group in the quinone core and also changing the amino acid moiety with ethylpyrimidinyl or ethylpyrrolidinyl groups resulted in analogues 25-fold more potent than the natural abenquines. The two most effective analogues inhibited the proliferation of five cyanobacterial strains tested, with IC50 values ranging from 0.3 to 3 µM. These compounds may be useful leads for the development of an effective strategy for the control of cyanobacterial blooms.

Chemical Variability and Biological Activities of Eucalyptus spp. Essential Oils.

Many plant species produce mixtures of odorous and volatile compounds known as essential oils (EOs). These mixtures play important roles in Nature and have been utilized by mankind for different purposes, such as pharmaceuticals, agrochemicals, aromatherapy, and food flavorants. There are more than 3000 EOs reported in the literature, with approximately 300 in commercial use, including the EOs from Eucalyptus species. Most EOs from Eucalyptus species are rich in monoterpenes and many have found applications in pharmaceuticals, agrochemicals, food flavorants, and perfumes. Such applications are related to their diverse biological and organoleptic properties. In this study, we review the latest information concerning the chemical composition and biological activities of EOs from different species of Eucalyptus. Among the 900 species and subspecies of the Eucalyptus genus, we examined 68 species. The studies associated with these species were conducted in 27 countries. We have focused on the antimicrobial, acaricidal, insecticidal and herbicidal activities, hoping that such information will contribute to the development of research in this field. It is also intended that the information described in this study can be useful in the rationalization of the use of Eucalyptus EOs as components for pharmaceutical and agrochemical applications as well as food preservatives and flavorants.

Harvest time on the content and chemical composition of essential oil from leaves of guava / Horário de coleta sobre o teor e a composição química do óleo essencial das folhas de goiabeira

ABSTRACT: The essential oil plants contents can be affected by several factors. For example, in certain plants, collection time has been observed to affect the content and chemical composition of the essential oil obtained from the plant. The objective of this study was to evaluate the effect of collection time on the content and chemical composition of the essential oil from guava ( Psidium guajava L.) leaves. Leaves were collected at different times of the day and the content and chemical composition of their essential oil was determined. Collection time did not qualitatively affect the chemical composition of the essential oil. However, concentration of certain substances in the oil, such as α-humulene and trans-caryophyllene, did significantly vary at different collection times. The main constituents of the essential oil of Psidium guajava are limonene (2.2-4.4%), trans-caryophyllene (18.1-17.1%), α-humulene (26.3-20.4%), aromadendrene (7.6-12.2%), α-selinene (7.3-11.3%), caryophyllene oxide (3.7-3.3%), humulene epoxide II (4.1-1.9%), and selin-11-en-4α-ol (7.2-11.1%). Leaves collected at 7:00 AM had higher essential oil production, with a content of 0.38% (d.b.), whereas leaves collected at 7:00 PM had lower essential oil production, 0.24% (d.b.). Chemical analysis showed that sesquiterpene compounds represented the highest concentration (62.0%), and monoterpenoids and monoterpenes represented the lowest concentrations (1.1 and 2.2%, respectively). Chemical classes that underwent major changes with respect to collection time were monoterpenes, sesquiterpenes, and sesquiterpenoids (2.2-4.4%, 63.8-61.7%, and 15.9-13.2%, respectively).

RESUMO: Existem fatores que podem afetar o conteúdo de óleo essencial das plantas, sendo o horário de coleta um deles. Assim, observa-se que o teor e a composição química de óleo essencial podem variar em certas plantas de acordo com horário de coleta. O objetivo deste trabalho foi avaliar o efeito do horário de coleta sobre o conteúdo e a composição química do óleo essencial das folhas de goiabeira ( Psidium guajava ). Folhas de Psidium guajava foram coletadas em diferentes horários do dia para determinar teor e composição química de seu óleo essencial. O óleo essencial não apresentou variação qualitativa da composição química em relação ao horário de coleta das folhas de Psidium guajava , mas alterou a concentração das substâncias, entre elas o α-humuleno e o trans-cariofileno. Os constituintes principais do óleo essencial das folhas de Psidium guajava são o limoneno (2,2-4,4%), trans-cariofileno (18,1-17,1%), α-humuleno (26,3-20,4%), aromadendreno (7,6-12,2%), α-selineno (7,3-11,3%), óxido de cariofileno (3,7-3,3%) epóxido de humuleno II (4,1-1,9%) e o selin-11-en-4α-ol (7,2-11,1%). No entanto, a maior produção de óleo essencial, foi obtida com as folhas coletadas às 19h, apresentando conteúdo de 0,38% (b.s.) e a mais baixa produção às 07h, apresentando conteúdo de 0,24% (b.s.). Através da análise química, identificou-se que compostos sesquiterpênicos apresentaram uma maior concentração (62,0%) e os monoterpenos e monoterpenoides foram os que apresentaram menor concentração (2,2 e 1,1%, respectivamente). As classes que sofreram maiores mudanças em relação ao horário de coleta foram os monoterpenos (2,2-4,4%) e os sesquiterpenos e os sesquiterpenoides (63,8-61,7% e 15,9-13,2%, respectivamente).

Harvest time on the content and chemical composition of essential oil from leaves of guava / Horário de coleta sobre o teor e a composição química do óleo essencial das folhas de goiabeira

The essential oil plants contents can be affected by several factors. For example, in certain plants, collection time has been observed to affect the content and chemical composition of the essential oil obtained from the plant. The objective of this study was to evaluate the effect of collection time on the content and chemical composition of the essential oil from guava ( Psidium guajava L.) leaves. Leaves were collected at different times of the day and the content and chemical composition of their essential oil was determined. Collection time did not qualitatively affect the chemical composition of the essential oil. However, concentration of certain substances in the oil, such as alpha-humulene and trans-caryophyllene, did significantly vary at different collection times. The main constituents of the essential oil of Psidium guajava are limonene (2.2-4.4%), trans-caryophyllene (18.1-17.1%), alpha-humulene (26.3-20.4%), aromadendrene (7.6-12.2%), alpha-selinene (7.3-11.3%), caryophyllene oxide (3.7-3.3%), humulene epoxide II (4.1-1.9%), and selin-11-en-4-ol (7.2-11.1%). Leaves collected at 7:00 AM had higher essential oil production, with a content of 0.38% (d.b.), whereas leaves collected at 7:00 PM had lower essential oil production, 0.24% (d.b.). Chemical analysis showed that sesquiterpene compounds represented the highest concentration (62.0%), and monoterpenoids and monoterpenes represented the lowest concentrations (1.1 and 2.2%, respectively). Chemical classes that underwent major changes with respect to collection time were monoterpenes, sesquiterpenes, and sesquiterpenoids (2.2-4.4%, 63.8-61.7%, and 15.9-13.2%, respectively).(AU)

Existem fatores que podem afetar o conteúdo de óleo essencial das plantas, sendo o horário de coleta um deles. Assim, observa-se que o teor e a composição química de óleo essencial podem variar em certas plantas de acordo com horário de coleta. O objetivo deste trabalho foi avaliar o efeito do horário de coleta sobre o conteúdo e a composição química do óleo essencial das folhas de goiabeira ( Psidium guajava ). Folhas de Psidium guajava foram coletadas em diferentes horários do dia para determinar teor e composição química de seu óleo essencial. O óleo essencial não apresentou variação qualitativa da composição química em relação ao horário de coleta das folhas de Psidium guajava , mas alterou a concentração das substâncias, entre elas o alfa-humuleno e o trans-cariofileno. Os constituintes principais do óleo essencial das folhas de Psidium guajava são o limoneno (2,2-4,4%), trans-cariofileno (18,1-17,1%), alfa-humuleno (26,3-20,4%), aromadendreno (7,6-12,2%), alfa-selineno (7,3-11,3%), óxido de cariofileno (3,7-3,3%) epóxido de humuleno II (4,1-1,9%) e o selin-11-en-4-ol (7,2-11,1%). No entanto, a maior produção de óleo essencial, foi obtida com as folhas coletadas às 19h, apresentando conteúdo de 0,38% (b.s.) e a mais baixa produção às 07h, apresentando conteúdo de 0,24% (b.s.). Através da análise química, identificou-se que compostos sesquiterpênicos apresentaram uma maior concentração (62,0%) e os monoterpenos e monoterpenoides foram os que apresentaram menor concentração (2,2 e 1,1%, respectivamente). As classes que sofreram maiores mudanças em relação ao horário de coleta foram os monoterpenos (2,2-4,4%) e os sesquiterpenos e os sesquiterpenoides (63,8-61,7% e 15,9-13,2%, respectivamente).(AU)

Effect of natural and artificial drying of leaf biomassof Psidium guajava on the content and chemical composition of essential oil / Efeito da secagem natural e artificial da biomassa foliar de psidium guajava sobre o teor e a composição química do óleo essencial

Psidium guajava L. is native to Central and South America. It is widely distributed and well adapted to Brazil, a producer of essential oils rich in terpenes. The objective of this study was to evaluate the effects of natural and artificial drying on the content and chemical composition of the essential oil of guava leaves (Psidium guajava L.) grown in Rio Verde (GO). The two treatments consisted of drying fresh leaves either naturally in the shade or artificially at 40C. Chemical composition was analyzed qualitatively and quantitatively by gas coupled with mass spectrometer chromatography (GC/MS) and gas chromatography using a flame ionizer (GC-FID), respectively. The method of drying changed the content and chemical composition of the essential oil of guava leaves. Drying in the shade reduced the content and altered the constituents of the essential oil, whereas drying in an oven at 40C, despite having reduced the amounts of the constituents, exhibited the highest essential oil content and increased the concentration of certain major constituents as compared to that in the natural shade drying method. The major components found in the essential oil of leaves regardless of the drying processes were trans-caryophyllene, ?-humulene, aromadendrene, ?-selinene, and selin-11-en-4?-ol. According to reports in the literature, these compounds possess fungicidal, insecticidal, antimicrobial, and anti-inflammatory activity, among others beneficial actions.(AU)

Psidium guajava L. é uma planta nativa da América Central e do Sul, que está amplamente distribuída e bem adaptada no território brasileiro, produtora de óleo essencial rico em terpenos. O objetivo deste estudo foi avaliar o efeito da secagem natural e artificial sobre o teor e a composição química do óleo essencial das folhas de goiabeira (Psidium guajava L.), cultivada em Rio Verde (GO). Os tratamentos avaliados foram: folhas frescas; secagem natural à sombra e secagem em estufa a 40ºC. A composição química qualitativa e quantitativa foi analisada por cromatografia gasosa acoplada ao espectrômetro de massa (CG/MS) e cromatógrafo gasoso com ionizador de chama (CG-FID), respectivamente. O tipo de secagem alterou o teor e a constituição química do óleo essencial das folhas de goiabeira. A secagem a sombra reduziu o teor e a quantidade de constituintes do óleo essencial, enquanto a secagem em estufa a 40ºC apesar de ter reduzido a quantidade de constituintes, apresentou o maior teor de óleo essencial e aumentou a concentração de alguns constituintes majoritários em relação à secagem natural a sombra. Os componentes majoritários encontrados tanto no óleo essencial das folhas in natura quanto no óleo essencial obtido das folhas submetidas aos processos de secagem foram trans-cariofileno, ?-humuleno, aromadendreno, ?-selineno e o selin-11-en-4?-ol, e segundo relatos na literatura segundo relatos na literatura estes compostos possuem atividades fungicidas, inseticidas, antimicrobianas, anti-inflamatórias, entre outras.(AU)

Effect of natural and artificial drying of leaf biomassof Psidium guajava on the content and chemical composition of essential oil / Efeito da secagem natural e artificial da biomassa foliar de psidium guajava sobre o teor e a composição química do óleo essencial

Psidium guajava L. is native to Central and South America. It is widely distributed and well adapted to Brazil, a producer of essential oils rich in terpenes. The objective of this study was to evaluate the effects of natural and artificial drying on the content and chemical composition of the essential oil of guava leaves (Psidium guajava L.) grown in Rio Verde (GO). The two treatments consisted of drying fresh leaves either naturally in the shade or artificially at 40C. Chemical composition was analyzed qualitatively and quantitatively by gas coupled with mass spectrometer chromatography (GC/MS) and gas chromatography using a flame ionizer (GC-FID), respectively. The method of drying changed the content and chemical composition of the essential oil of guava leaves. Drying in the shade reduced the content and altered the constituents of the essential oil, whereas drying in an oven at 40C, despite having reduced the amounts of the constituents, exhibited the highest essential oil content and increased the concentration of certain major constituents as compared to that in the natural shade drying method. The major components found in the essential oil of leaves regardless of the drying processes were trans-caryophyllene, ?-humulene, aromadendrene, ?-selinene, and selin-11-en-4?-ol. According to reports in the literature, these compounds possess fungicidal, insecticidal, antimicrobial, and anti-inflammatory activity, among others beneficial actions.

Psidium guajava L. é uma planta nativa da América Central e do Sul, que está amplamente distribuída e bem adaptada no território brasileiro, produtora de óleo essencial rico em terpenos. O objetivo deste estudo foi avaliar o efeito da secagem natural e artificial sobre o teor e a composição química do óleo essencial das folhas de goiabeira (Psidium guajava L.), cultivada em Rio Verde (GO). Os tratamentos avaliados foram: folhas frescas; secagem natural à sombra e secagem em estufa a 40ºC. A composição química qualitativa e quantitativa foi analisada por cromatografia gasosa acoplada ao espectrômetro de massa (CG/MS) e cromatógrafo gasoso com ionizador de chama (CG-FID), respectivamente. O tipo de secagem alterou o teor e a constituição química do óleo essencial das folhas de goiabeira. A secagem a sombra reduziu o teor e a quantidade de constituintes do óleo essencial, enquanto a secagem em estufa a 40ºC apesar de ter reduzido a quantidade de constituintes, apresentou o maior teor de óleo essencial e aumentou a concentração de alguns constituintes majoritários em relação à secagem natural a sombra. Os componentes majoritários encontrados tanto no óleo essencial das folhas in natura quanto no óleo essencial obtido das folhas submetidas aos processos de secagem foram trans-cariofileno, ?-humuleno, aromadendreno, ?-selineno e o selin-11-en-4?-ol, e segundo relatos na literatura segundo relatos na literatura estes compostos possuem atividades fungicidas, inseticidas, antimicrobianas, anti-inflamatórias, entre outras.

The fungal phytotoxin alternariol 9-methyl ether and some of its synthetic analogues inhibit the photosynthetic electron transport chain.

Alternariol and monomethylalternariol are natural phytotoxins produced by some fungal strains, such as Nimbya and Alternaria. These substances confer virulence to phytopathogens, yet no information is available concerning their mode of action. Here we show that in the micromolar range alternariol 9-methyl ether is able to inhibit the electron transport chain (IC50 = 29.1 ± 6.5 µM) in isolated spinach chloroplasts. Since its effectiveness is limited by poor solubility in water, several alternariol analogues were synthesized using different aromatic aldehydes. The synthesized 6H-benzo[c]cromen-6-ones, 5H-chromene[4,3-b]pyridin-5-one, and 5H-chromene[4,3-c]pyridin-5-one also showed inhibitory properties, and three 6H-benzo[c]cromen-6-ones were more effective (IC50 = 12.8-22.8 µM) than the lead compound. Their addition to the culture medium of a cyanobacterial model strain was found to inhibit algal growth, with a relative effectiveness that was consistent with their activity in vitro. In contrast, the growth of a nonphotosynthetic plant cell culture was poorly affected. These compounds may represent a novel lead for the development of new active principles targeting photosynthesis.

Organocatalysis in the three-component Povarov reaction and investigation by mass spectrometry.

A diastereoselective three-component cascade reaction, catalyzed by p-sulfonic acid calix[4]arene, provides a unique method to access diverse julolidine derivatives in high yields. Additionally, the reaction was also monitored by mass spectrometry and the mechanistic pathway uncovered.

Efeito da adubação mineral na produção de biomassa e no teor e composição do óleo essencial do capim-citronela / Effect of mineral fertilization on the production of biomass and the content and composition of the essential oil of grass citronella

Este trabalho teve por objetivos avaliar o efeito de quatro doses de adubo mineral na produção de biomassa, no teor e na composição do óleo essencial do capim-citronela (Cymbopogon nardus) em cinco épocas de colheita. Na avaliação da produção de biomassa do capim-citronela foi adotado o delineamento experimental em blocos casualizados, em esquema de parcela subdividida, com cinco repetições. As parcelas foram constituídas por quatro doses de adubo mineral com fertilizantes NPK (0, 50, 100 e 150% da dose recomendada); a recomendação de adubação mineral foi de 100 kg ha-1 P205, 40 hg ha-1 K2O e 50 kg ha-1 N fornecidos por superfosfato simples, cloreto de potássio e sulfato de amônio respectivamente; as subparcelas por cinco épocas de avaliação (60, 88, 116, 144 e 172 dias após o transplante). O óleo essencial foi obtido por hidrodestilação e a identificação dos compostos do óleo essencial por CG/EM. A adubação mineral de 150 % da dose recomendada propiciou as maiores taxas de crescimento em todas as variáveis analisadas. Os maiores teores de óleo essencial foram obtidos nas doses de 100% (1,59%) e 150% de NPK (1,67%). Foram identificados dez compostos químicos no óleo essencial do capim-citronela, entre monoterpenos e sesquiterpenos. Os compostos majoritários do óleo essencial foram o citronelal, o geraniol e o elemol. O teor e a composição do óleo essencial do capim-citronela variaram conforme a dose de adubo mineral utilizado.

This study aimed to evaluate the effect of four doses of mineral fertilization in biomass production, the content and composition of essential oil of citronella grass (Cymbopogon nardus) in five harvest seasons. In the evaluation of the production of biomass of citronella grass was adopted the statistical design in block randomized in a subdivided plot scheme, with five repetitions. The plots consisted by four levels of mineral fertilization with fertilizers NPK (0, 50, 100 and 150% of the recommended dose) the recommendation of mineral fertilizer was 100 kg ha-1 P205, 40 hg ha-1 K2O and 50 kg N ha-1 provided by superphosphate, potassium chloride and ammonium sulfate, respectively; the subplots for five harvest times (60, 88, 116, 144 and 172 days after transplant). The extraction of essential oil of citronella grass was made by hydrodistillation and the identification of compounds of the essential oil by GC/MS. The mineral fertilizer of 150% of the recommended dose propitiated the biggest taxes of growth in all the analyzed variable. The biggest essential oil content was obtained in the doses of 100% (1.59%) and 150% of NPK (1.67%). Ten chemical compounds were identified in essential oil of citronella grass, between monoterpenes and sesquiterpenes. The majority compounds of the essential oil were the citronellal, geraniol and elemol. The content and the composition of the essential oil of citronella grass varied depending on the dose of mineral fertilizer used.

Antibacterial activity of the alkaloid-enriched extract from Prosopis juliflora pods and its influence on in vitro ruminal digestion.

The purpose of this study was to assess the in vitro antimicrobial activity of alkaloid-enriched extracts from Prosopis juliflora (Fabaceae) pods in order to evaluate them as feed additives for ruminants. As only the basic chloroformic extract (BCE), whose main constituents were juliprosopine (juliflorine), prosoflorine and juliprosine, showed Gram-positive antibacterial activity against Micrococcus luteus (MIC = 25 µg/mL), Staphylococcus aureus (MIC = 50 µg/mL) and Streptococcus mutans (MIC = 50 µg/mL), its influence on ruminal digestion was evaluated using a semi-automated in vitro gas production technique, with monensin as the positive control. Results showed that BCE has decreased gas production as efficiently as monensin after 36 h of fermentation, revealing its positive influence on gas production during ruminal digestion. Since P. juliflora is a very affordable plant, this study points out this alkaloid enriched extract from the pods of Prosopis juliflora as a potential feed additive to decrease gas production during ruminal digestion.

Induction of G2/M arrest, caspase activation and apoptosis by α-santonin derivatives in HL-60 cells.

Sesquiterpene lactones (SLs) are natural products with a variety of biological activities. Previously, we demonstrated the cytotoxic effects of three new α-santonin derivatives on different tumor cell lines with low toxic effects upon peripheral human leukocytes. Here, we evaluated the mechanism of action triggered by these derivatives. HL-60 cell cycle determined after 24h treatment revealed a significant inhibition on cell-cycle progression and leading to an increasing of cells in G2/M [7.6% and 9.0% for compound 3% and 9.0% and 8.6% for compound 4 (1 and 2 µM, respectively)]. However, after 48 h exposure, all compounds caused G2/M reduction and a significant DNA fragmentation. Compounds 2, 3 and 4 were able to induce apoptosis on leukemia cells, which was corroborated by phosphatidyserine externalization and activation of caspases-3 and -7 after 24h exposure. None of the derivatives analyzed caused depolarization of mitochondrial membrane within 24h of incubation, suggesting the involvement of the extrinsic apoptotic pathway in the death process. The antiproliferative action of these compounds is related to the DNA synthesis inhibition and cell cycle arrest, which probably lead to apoptosis activation. Therefore, these santonin derivatives are promising lead candidates for development of new cytotoxic agents.

Chemical characterization of volatile compounds of Lantana camara L. and L. radula Sw. and their antifungal activity.

A comparative study of the chemical composition of essential oils of two very similar species of the Verbenaceae family (Lantana camara and L. radula) revealed that the main components of essential oil of L. camara were germacrene-D (19.8%) and E-caryophyllene (19.7%), while those of L. radula were E-caryophyllene (25.3%), phytol (29.2%) and E-nerolidol (19.0%). We have hypothesized that the observed differences could contribute to the differentiated reaction of the two species of Lantana to the attack of the phytopathogenic fungi Corynespora cassiicola. An experiment, involving C. cassiicola cultivation in culture media containing volatile oils of the two species demonstrated that the oils of L. radula were more fungistatic than the oils of L. camara, in accordance with the in vivo observations. It is likely that E-nerolidol and phytol, only found in the oil of L. radula, play a significant role in the effects of L. radula on C. cassiicola.

Seasonal variation in the chemical composition and antimicrobial activity of volatile oils of three species of Leptospermum (Myrtaceae) grown in Brazil.

This study investigates the seasonal variation of three species of Leptospermum (Myrtaceae) grown in Brazil. The chemical composition of the volatile oils of L. flavescens and L. petersonii did not show any significant seasonal variation in the major components, while for Leptospermum madidum subsp. sativum the levels of major constituents of the volatile oils varied with the harvest season. Major fluctuations in the composition of L. madidum subsp. sativum oil included α-pinene (0-15.2%), ß-pinene (0.3-18.5%), α-humulene (0.8-30%), 1,8-cineole (0.4-7.1%) and E-caryophyllene (0.4-11.9%). Levels of ß-pinene (0.3-5.6%), terpinen-4-ol (4.7-7.2%) and nerolidol (55.1-67.6%) fluctuated seasonally in the L. flavescens oil. In L. petersonii, changes were noted for geranial (29.8-32.8%), citronellal (26.5-33.9%) and neral (22.7-23.5%). The activity of the volatile oils against the tested bacteria differed, depending on season the oils were obtained. In general, the volatile oils were more active against Gram-positive bacteria.

Synthesis and biological evaluation of 2,5-bis(alkylamino)-1,4-benzoquinones.

A series of twelve 2,5-bis(alkylamino)-1,4-benzoquinones were prepared in yields ranging from 9-58% via the reaction between p-benzoquinone and various amines. The structures of the synthesized compounds were confirmed by IR, 1H- and 13C-NMR and MS analyses. The phytotoxicity of the 2,5-bis(alkylamino)-1,4-benzoquinones was evaluated against two crop species, Cucumis sativus and Sorgum bicolor, at 1.0 x 10(-3) mol/L. In general, the quinones displayed inhibitory effects on the dicotyledonous species C. sativus (7-74%). On the other hand stimulatory effects were observed on S. bicolor (monocotyledonous). Similar results were observed in the biological assays carried out with the weed species Ipomoea grandifolia (dicotyledonous) and Brachiaria decumbens (monocotyledonous). In addition, the cytotoxicity of the 2,5-bis(alkylamino)-1,4-benzoquinones was assayed against HL-60 (leukemia), MDA-MB-435 (melanoma), SF-295 (brain) and HCT-8 (colon) human cancer cell lines and human peripheral blood mononuclear cells (PBMC), as representatives of healthy cells, using a MTT and an Alamar Blue assay. Compound 12 was the most active, displaying cytotoxicity against all cancer cell lines tested.

QSAR modeling of photosynthesis-inhibiting nostoclide derivatives.

BACKGROUND: A statistical model, built using the CODESSA software package, was developed to describe the relationship between the structure of nostoclide derivatives and their ability to interfere with the electron transport chain in the Hill reaction. RESULTS: A QSAR treatment was carried out on a series of compounds designed using the naturally occurring toxin nostoclides to correlate molecular descriptors with their in vitro biological activity (the ability to interfere with light-driven reduction of ferricyanide by isolated spinach chloroplast thylakoid membranes). The treatment using the CODESSA software package resulted in a three-parameter model with n = 19, R(2) = 0.83, F = 23.8 and R(2) (cv) = 0.72. In the proposed model, the Image of Onsager Kirkwood solvation energy, which gives a measure of the polarity of a given compound, is the most important descriptor. The model was internally validated. CONCLUSIONS: The results obtained in this study indicate that polarity, as expressed by the dipole moment, is the most relevant molecular property determining efficiency of photosynthetic inhibitory activity.

Synthesis and phytotoxic activity of new pyridones derived from 4-hydroxy-6-methylpyridin-2(1H)-one.

Commercial dehydroacetic acid was converted into 4-hydroxy-6-methylpyridin-2(1H)-one (3), which was then condensed with several aliphatic aldehydes to produce seven new title compounds in variable yields (35-92%). Reaction of 3 with alpha,beta-unsaturated aldehydes resulted in the formation of condensed pyran derivatives 4g' and 4h'. A mechanism is proposed to explain the formation of such compounds. The effects of all methylpyridin-2(1H)-one derivatives on the development of the dicotyledonous species Ipomoea grandifolia and Cucumis sativus and the monocotyledonous species Sorghum bicolor were evaluated. At the dose of 6.7 x 10(-8) mol a.i./g substrate the compounds showed some phytotoxic selectivity, being more active against the dicotyledonous species. These compounds can be used as lead structures for the development of more active phytotoxic products.

Synthesis and phytogrowth properties of oxabicyclic analogues related to helminthosporin.

This investigation describes the synthesis and biological evaluation of a series of oxabicyclic analogues related to the helminthosporins. Four oxabicycles were prepared by [4+3] cycloaddition of an oxyallyl carbocation, generated in situ from 2,4-dibromopentan-3-one, with selected furans. Functional group manipulations of the oxabicyclic architecture generated nine further derivatives. The phytotoxic properties of these oxabicycles were evaluated as their ability to interfere with the growth of Sorghum bicolor and Cucumis sativus seedlings. In both species, the most active compounds were oxabicycles possessing a carbonyl group conjugated with a double bond.