RESUMO
Muscodor yucatanensis, an endophytic fungus, was isolated from the leaves of Bursera simaruba (Burseraceae) in a dry, semideciduous tropical forest in the Ecological Reserve El Eden, Quintana Roo, Mexico. We tested the mixture of volatile organic compounds (VOCs) produced by M. yucatanensis for allelochemical effects against other endophytic fungi, phytopathogenic fungi and fungoids, and plants. VOCs were lethal to Guignardia mangifera, Colletotrichum sp., Phomopsis sp., Alternaria solani, Rhizoctonia sp., Phytophthora capsici, and P. parasitica, but had no effect on Fusarium oxysporum, Xylaria sp., the endophytic isolate 120, or M. yucatanensis. VOCs inhibited root elongation in amaranth, tomato, and barnyard grass, particularly those produced during the first 15 days of fungal growth. VOCs were identified by gas chromatography/mass spectrometry and included compounds not previously reported from other Muscodor species and the previously reported compounds octane, 2-methyl butyl acetate, 2-pentyl furan, caryophyllene, and aromadendrene. We also evaluated organic extracts from the culture medium and mycelium of M. yucatanensis on the same endophytes, phytopathogens, and plants. In general, extracts inhibited plants more than endophytic or phytopathogens fungi. G. mangifera was the only organism that was significantly stimulated by both extracts regardless of concentration. Compounds in both organic extracts were identified by gas chromatography/mass spectrometry. We discuss the possible allelopathic role that metabolites of M. yucatanensis play in its ecological interactions with its host plant and other organisms.
Assuntos
Bursera/química , Feromônios/farmacologia , Raízes de Plantas/efeitos dos fármacos , Compostos Orgânicos Voláteis/farmacologia , Xylariales/química , Meios de Cultivo Condicionados/metabolismo , Relação Dose-Resposta a Droga , Cromatografia Gasosa-Espectrometria de Massas , México , Feromônios/classificação , Feromônios/isolamento & purificação , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Fatores de Tempo , Compostos Orgânicos Voláteis/classificação , Compostos Orgânicos Voláteis/isolamento & purificaçãoRESUMO
Chemical investigation of the mycelium of Edenia gomezpompae, a newly discovered endophytic fungus isolated from the leaves of Callicarpa acuminata (Verbenaceae) collected from the ecological reserve El Eden, Quintana Roo, Mexico, resulted in the isolation of four naphthoquinone spiroketals, including three new compounds and palmarumycin CP2 (4). We elucidated the structures of the metabolites by extensive NMR spectroscopy studies, including DEPT, COSY, NOESY, HSQC, HMBC, and chiroptical methods. The trivial names proposed for these compounds are preussomerin EG1 (1), preussomerin EG2 (2) and preussomerin EG3 (3). In addition, the X-ray data for 4 were obtained. The bioactivity of the mycelial organic extracts and the pure compounds was tested against three endophytic fungi (Colletotrichum sp., Phomopsis sp., and Guignardia manguifera) isolated from the same plant species (C. acuminata, Verbenaceae) and against four economically important phytopathogenic microorganisms (two fungoid oomycetes, Phythophtora capsici and Phythophtora parasitica, and the fungi Fusarium oxysporum and Alternaria solani). Spiroketals 1-3 displayed significant growth inhibition against all the phytopathogens. IC50 values for the four phytopathogens were from 20 to 170 microg/ml. Palmarumycin CP2 (4) was not bioactive against any of the fungi tested. Compound 1 showed the strongest bioactivity. The acetylated derivatives of preussomerin EG1 (1), 1a and 1b, were obtained and their biological activity was tested on endophytes and phytopathogens. Preussomerin EG1 1, 1a and 1b exhibited significant bioactivity against all microorganisms tested with the exception of Alternaria solani. This is the first report of allelochemicals with antifungal activity from the newly discovered endophytic fungus E. gomezpompae.
Assuntos
Antifúngicos/farmacologia , Ascomicetos/química , Compostos de Epóxi/farmacologia , Fungos/efeitos dos fármacos , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Naftalenos/farmacologia , Compostos de Espiro/farmacologia , Antifúngicos/isolamento & purificação , Antifúngicos/metabolismo , Ascomicetos/metabolismo , Bioensaio , Cristalografia por Raios X , Meios de Cultivo Condicionados/química , Relação Dose-Resposta a Droga , Compostos de Epóxi/isolamento & purificação , Compostos de Epóxi/metabolismo , Fungos/crescimento & desenvolvimento , Compostos Heterocíclicos de 4 ou mais Anéis/isolamento & purificação , Compostos Heterocíclicos de 4 ou mais Anéis/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Modelos Moleculares , Conformação Molecular , Naftalenos/isolamento & purificação , Naftalenos/metabolismo , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Compostos de Espiro/isolamento & purificação , Compostos de Espiro/metabolismo , Estereoisomerismo , Verbenaceae/microbiologiaRESUMO
Aqueous leachates and a CHCl3-MeOH (1:1) extract of roots of Stauranthus perforatus showed a significant phytotoxic effect on Amaranthus hypochondriacus and Echinochloa crus-galli. Bioassay-directed fractionation of the active organic extract led to the isolation and characterization of ten secondary metabolites, which included two pyranocoumarins [xanthyletin (1) and 3-(1',1'-dimethylallyl)-xanthyletin (2)], four furanocoumarins [chalepensin (3), ammirin (4), chalepin (5) and 2'-isopropyl-psoralene (6)], two lignans [asarinin (7) and fargesin (8)], one sesquiterpene [4,5-epoxi-beta-caryophyllene (9)], and one alkamide [pellitorine (10)]. From these compounds, 2'-isopropyl-psoralene (6) or anhydromarmesin, is reported for the first time as a natural product, whereas compounds 4-10 are now reported as being present in S. perforatus. Metabolites 1, 3-5 and 10 caused significant inhibition of radicle growth of A. hypochondriacus and E. crus-galli. Furthermore, in a greenhouse experiment the decomposition of the leaves and roots in the soil had a significant inhibitory effect on the growth of weeds. The allelopathic action of the decomposition of roots was evident up to the sixth week of the experiment. The effect of leaves was comparable to that of DPCA (dimethyl tetrachloroterephthalate), a commercial herbicide. Finally different concentrations of Stauranthus root powder were combined with maize kernels and used to feed corn weevil. The treatments resulted in high mortality of this insect.
Assuntos
Feromônios/química , Feromônios/isolamento & purificação , Rutaceae/química , Árvores/química , Animais , Bioensaio , México , Estrutura Molecular , Feromônios/farmacologia , Feromônios/toxicidade , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Rutaceae/efeitos dos fármacos , Rutaceae/crescimento & desenvolvimento , Árvores/efeitos dos fármacos , Árvores/crescimento & desenvolvimentoRESUMO
The allelochemical potential of Callicarpa acuminata (Verbenaceae) was investigated by using a biodirected fractionation study as part of a long-term project to search for bioactive compounds among the rich biodiversity of plant communities in the Ecological Reserve El Eden, Quintana Roo, Mexico. Aqueous leachate, chloroform-methanol extract, and chromatographic fractions of the leaves of C. acuminata inhibited the root growth of test plants (23-70%). Some of these treatments caused a moderate inhibition of the radial growth of two phytopathogenic fungi, Helminthosporium longirostratum and Alternaria solani (18-31%). The chloroform-methanol (1:1) extract prepared from the leaves rendered five compounds: isopimaric acid (1), a mixture of two diterpenols [sandaracopimaradien-19-ol (3) and akhdarenol (4)], alpha-amyrin (5), and the flavone salvigenin (6)]. The phytotoxicity exhibited by several fractions and the full extract almost disappeared when pure compounds were evaluated on the test plants, suggesting a synergistic or additive effect. Compounds (4), (5), and the semisynthetic derivative isopimaric acid methyl ether (2) had antifeedant effects on Leptinotarsa decemlineata. Compound 5 was most toxic to this insect, followed by (2), (4), and (6) with moderate to low toxicity. No correlation was found between antifeedant and toxic effects on this insect, suggesting that different modes of action were involved. All the test compounds were cytotoxic to insect Sf9 cells while (6), (4), and (1) also affected mammalian Chinese Hamster Ovary (CHO) cells. Compound 5 showed the strongest selectivity against insect cells. This study contributes to the knowledge of the defensive chemistry and added value of C. acuminata.