Antifungal Volatile Organic Compounds from the Endophyte Nodulisporium sp. Strain GS4d2II1a: a Qualitative Change in the Intraspecific and Interspecific Interactions with Pythium aphanidermatum.

This study demonstrates volatile organic compounds (VOCs) production as one of the defense mechanisms of the antagonistic endophyte Nodulisporium sp. GS4d2II1a, and the volatile changes in two times of the fungal growth; and, as result of its intra and interspecific interactions with the plant pathogen Pythium aphanidermatum. The antifungal activity of the volatile and diffusible metabolites was evaluated by means of three types of antagonism bioassays and by organic extract agar dilution. VOCs were obtained by gas chromatography coupled to mass spectrometry from 3- and 5-day Nodulisporium sp. cultures, as well as from its interspecific in vitro antagonistic interaction with the oomycete P. aphanidermatum, and its intraspecific Nodulisporium sp.-Nodulisporium sp. interaction. The GS4d2II1a strain completely inhibited the growth of two fungi and seven oomycetes by replacing their mycelia in simple antagonism bioassays and by producing in vitro volatile and diffusible metabolites that acted synergistically in multiple antagonism bioassays. Additionally, VOCs inhibited the growth of three oomycetes and one fungus in antagonism bioassays using divided plates. A total of 70 VOCs were detected, mainly including mono and sesquiterpenes, especially eucalyptol and limonene. Multiple correspondence analysis revealed four different volatile profiles, showing that volatiles changed with the fungus age and its intra and interspecific interactions. The metabolites produced by Nodulisporium sp. GS4d2II1a could be useful for biological control of fungal and oomycetes plant pathogens of economically important crops.

HPLC determination of the major active flavonoids and GC-MS analysis of volatile components of Dysphania graveolens (Amaranthaceae).

INTRODUCTION: Dysphania graveolens is used mainly in Mexican traditional medicine against gastrointestinal ailments. Previous investigations revealed that its flavonoids are important active principles; however, there is not a reliable and accurate analytical method for determining these compounds in the crude drug or preparations of the plant. In addition, its volatile chemical composition remains unknown. OBJECTIVE: The main goals were to develop a validated HPLC method for quantifying the active flavonoids (pinostrobin (1), pinocembrin (2) and chrysin (3)) of D. graveolens and to establish its volatile composition. METHODOLOGY: Separation was carried out on a Licrospher100 RP18 column with a linear gradient acetonitrile 0.1% formic acid and aqueous 0.1% formic acid. Accuracy was determined by spiking the crude drug with the standards, the recoveries were between 99% and 101%. A systematic description of the volatile components of D. graveolens was assessed via GC-MS using headspace solid-phase microextraction (HS-SPME) and hydrodistillation extraction methods. RESULTS: The developed HPLC method represented a powerful technique for the quality control of D. graveolens allowing the quantification of the three active flavonoids. For each compound a linear response was evaluated within the range of 0.5-2.0 mg/mL for pinostrobin (1), 0.25-1.25 mg/mL for pinocembrin (2) and 0.05-0.5 mg/mL for chrysin (3). According to SPME the major components in D. graveolens were p-cymene (84.85%) and eucalyptol (11.26%). On the other hand, the essential oil had eucalyptol (42.89%) and p-cymene (16.51%) and did not contain ascaridol. Thus the most relevant volatile components in the species were monoterpenoids.

Chemical composition and antimicrobial and spasmolytic properties of Poliomintha longiflora and Lippia graveolens essential oils.

UNLABELLED: In the present study, we reported a comparative analysis of the chemical composition and pharmacological properties of the essential oils obtained from 2 Mexican oreganos, Poliomintha longiflora and Lippia graveolens. The gas chromatography-mass spectrometry (GC-MS) profiles of the oils showed high amounts of oxygenated monoterpenes, mainly carvacrol (%[mg/100 g dry matter]) (18.36 [459.0] in P. longiflora and 13.48 [164.7] in L. graveolens). In addition, these oils contained marked quantities of p-cymene (14.09 [352.2] and 7.46 [37.3], respectively), ß-caryophyllene oxide, ß-caryophyllene, and carvacrol acetate. Headspace analyses of the leaves of both species using different coated fibers revealed that γ-terpinene, eucalyptol, and p-cymene were the principal light volatile components. Chromatographic fingerprints and a suitable analytical method for quantifying the main components of both essences were established using high-performance liquid chromatography (HPLC) as analytical tool. The essential oils of both species were not toxic in the acute toxicity studies in mice performed according to the Lorke procedure (DL(50) > 5000 mg/kg). The oils and the major constituents, carvacrol and p-cymene, displayed a moderate in vitro antibacterial activity, with minimum inhibitory concentration values ranging from 128 to 512 µg/mL. In addition, these samples demonstrated a marginal antispasmodic activity in vivo and provoked a concentration-dependent inhibition of the carbachol- and histamine-induced contractions using the isolated guinea-pig ileum preparation. In particular, p-cymene exerts good selective inhibitory activity on the carbachol-induced contractions (IC(50) = 9.85 µg/mL). PRACTICAL APPLICATION: The analytical methods using GC-MS and HPLC techniques will be useful for establishing quality control as well as preclinical pharmacological and toxicological parameters of the crude drug P. longiflora, which is widely used as substitute of L. graveolens for medicinal and flavorings purposes. This overall information will be also useful for elaborating scientific and pharmacopoeic monographs of this very Mexican medicinal plant.

Allelochemical effects of volatile compounds and organic extracts from Muscodor yucatanensis, a tropical endophytic fungus from Bursera simaruba.

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.