Excito-repellent and Pesticide-Likeness Properties of Essential Oils on Carpophilus dimidiatus (Fabricius) (Nitidulidae) and Oryzaephilus mercator (L.) (Silvanidae).

Carpophilus dimidiatus (Fabricius) (Nitidulidae) and Oryzaephilus mercator (L.) (Silvanidae) are insect pests that cause severe damage in important walnut growing regions in the northwest of Argentina. The current management approaches for these pests involve the use of unsafe phosphorus pesticides whose overuse have led to farmworker poisoning, pest resistance issues, and environmental contamination. Plant extracts, particularly essential oils, are an alternative source of insect control agents. Excito-repellent essential oils can be used to develop ecofriendly tools for managing the pest population without affecting quality and visual appearance of the stored walnuts. Laboratory studies were conducted to assess the excito-repellent effects of C. dimidiatus and O. mercator of 12 essential oils derived from aromatic plants used as food additives and traditional medicine in Argentina: Aloysia citrodora (AC), Aloysia gratissima (AG), Aloysia gratissima var. Gratissima (AGG), Blepharocalyx salicipholius (BS), Hyptis mutabilis (HM), Lippia junelliana (LJ), Lippia turbinata (LT), Mentha x piperita (MP), Minthostachys mollis (MM), Minthostachys verticillata (MV), Origanum vulgare(OV), and Rosmarinus officinalis (RO). The most bioactive EOs (ERijk ≥ 70%) were Aloysia gratissima var. Gratissima (AGG), Minthostachys verticillata, and Lippia junelliana. Their bioactivity profile and chemical space, characterized from GC-MS measures, Generalized Estimating Equations, and Hierarchical Cluster Analysis, revealed that they are mixtures of very functionalized molecules with physicochemical properties similar to those of insecticides with low residual property that enter the insect body through the respiratory system by inhalation. The AGG, MV, and LJ oils are promising as protective agents of walnut products. In our laboratory, studies of their formulations for use in integrated pest management programs are still ongoing.

Chemical composition and larvicidal activity of essential oils from Peganum harmala, Nepeta cataria and Phellodendron amurense against Aedes aegypti (Diptera: Culicidae).

Essential oils from aerial parts of the herbs Peganum harmala and Nepeta cataria, and leaves of the tree Phellodendron amurense were analyzed by GC-FID and GC-MS, and their larvicidal activities were assayed on the early fourth instar larvae of Aedes aegypti. The major constituents of the oils were limonene (14.5%) and thymol (11.5%) in P. harmala, thymol (46.5%), 4aα,7α,7aß-nepetalactone (18.3%) and 4aα,7ß,7aα-neptalactone (19.7%) in N. cataria, eugenol (14.5%) andγ-eudesmol (9.5%) in P. amurense.The oil of N. cataria had a strong larvicidal activity (LC50 < 50 µg/mL; LC90 < 86.8 µg/mL) on A. aegypti while the remaining oils showed a moderated killing effect. The larvicidal activity of N. cataria oil was associated to the contents of 1,8-cineol, camphor, 4aα,7α,7aß-Nepetalactone, 4aα,7ß,7aα-Nepetalactone and thymol. Our results indicate that the oil of N. catariadeserves to be used as a source of larvicidal agents against A. aegypti.

Antifungal activity of 4-hydroxy-3-(3-methyl-2-butenyl)acetophenone against Candida albicans: evidence for the antifungal mode of action.

The main secondary metabolite of Senecio nutans is 4-hydroxy-3-(3-methyl-2-butenyl)acetophenone (4HMBA). The antifungal activity of this compound and three derivatives was assessed using Candida albicans. 4HMBA exhibited the highest antifungal activity among the assayed compounds. The Fractional Inhibitory Concentration (FIC = 0.133) indicated a synergistic fungicidal effect of 4HMBA (5 mg L(-1)) and fluconazole (FLU) (0.5 mg L(-1)) against the C. albicans reference strain (ATCC 10231). Microscopy showed that 4HMBA inhibits filamentation and reduces cell wall thickness. Our findings suggest that 4HMBA is an interesting compound to diminish resistance to commercial fungistatic drugs such as fluconazole.

Antifungal activity of extracts from Justicia species against Fusarium graminearum.

Fusarium graminearum causes destructive ear rot diseases in maize and wheat. New antifungals are essential to combat this pathogen, and aerial parts of Justicia species (Acanthaceae) are a potential source. We investigated the antifungal activity of extracts from stems and leaves of five Justicia species native to Northwest Argentina. The aerial parts were subjected to sequential extractions with dichloromethane, ethyl acetate, and methanol. The resulting extracts were tested by the disc diffusion method against F. graminearum strains. Only the leaf and stem extracts from J. xylosteoides displayed inhibitory effects, with the dichloromethane leaf extract as the most active. The compounds involved were identified as the lignans hinokinin, savinin, and isohibalactone. Both the dichloromethane extract and hinokinin synergised with tebuconazole, and inhibited deoxynivalenol biosynthesis. The identified compounds warrant further research as additives to azole fungicides for F. graminearum control.

Chemical composition and insecticidal activity of essential oils from cultivated and native aromatic plants of Argentina against Carpophilus dimidiatus (Fabricius) (Nitidulidae) and Oryzaephilus mercator (L.) (Silvanidae).

Essential oils from aerial parts of six aromatic plants were analysed by GC-MS. The major compounds identified were γ-terpinene (11.5%), cuminaldehyde (26.6%) and γ-terpinen-7-al (40.6%) in Cuminum cyminum, trans-anethol (95.2%) in Pimpinella anisum, α-pinene (11.6%), limonene (21.0%), ß-caryophyllene (22.3%) and α-humulene (16.7%) in Lippia integrifolia, limonene (40.8%) and artemisia ketone (19.3%) in Lippia junelliana, trans-ß-ocimene (15.6%), 4-ethyl-4-methyl-1-hexene (24.5%), trans-tagetone (20.5%) and verbenone (27.2%) in Tagetes minuta, 1,8-cineole (17.9%),elixene (10.3%) and spathulenol (13.8%) in Aloysia gratissima. Oils with strong insecticidal activity on Carpophilus dimidiatus and Oryzaephilus mercator were from P. anisum (LC50 = 4 µl/L; LC100 = 10 µl/L) and T. minuta (LC50=10.19-12.57 µl/L; LC100=20 µl/L). Scents of C. cyminum and L. junelliana were strong insecticides on O. mercator (LC50=7.02-7.17 µl/L; LC100=10.00-20.00 µl/L). The insecticidal activity was associated to the whole content of C10 molecules and oxygenated constituents. The P. anisum oil is promising as protective agent of nut products.

Fusaric acid detoxification: a strategy of Gliocladium roseum involved in its antagonism against Fusarium verticillioides.

Fungal co-culture has several biotechnological applications including the discovery or the enhanced production of secondary metabolites. It is also a powerful tool aiding to elucidate the involvement of secondary metabolism in fungus-fungus interactions. The aim of this work was to investigate secondary metabolites produced when Fusarium verticillioides is co-cultured with Gliocladium roseum. Secreted metabolites were analyzed by HPLC-MS, and fusaric acid (FA) was quantified by HPLC-DAD. Four FA derivatives were identified only in the F. verticillioides-G. roseum co-culture. Mass spectrometry and one- and two-dimensional NMR spectra indicated that they were 5-butylpyridine-2-carboxylic acid methyl ester (5B2CAM), 4-(5-butylpicolinamido) butanoic acid (45BBA), methyl 4-(5-butylpicolinamido) butanoate (M45BBA), and bis(5-butyl-2-pyridinecarboxylate-N1,O2)-copper (B52P). 45BBA and M45BBA are reported for the first time and were FA biotransformation products generated by G. roseum. The antifungal activity of 5B2CAM, 45BBA, and M45BBA was evaluated in vitro against Botrytis cinerea and Aspergillus niger. They were less fungitoxic than FA, with 45BBA as the least toxic. Our results suggest that the effective antagonism exerted by G. roseum against F. verticillioides is due, at least in part, to its detoxifying ability against FA.

Synthesis and Evaluation of New Halogenated GR24 Analogs as Germination Promotors for Orobanche cumana.

Orobanche and Striga are parasitic weeds extremely well adapted to the life cycle of their host plants. They cannot be eliminated by conventional weed control methods. Suicidal germination induced by strigolactones (SLs) analogs is an option to control these weeds. Here, we reported two new halogenated (+)-GR24 analogs, named 7-bromo-GR24 (7BrGR24) and 7-fluoro-GR24 (7FGR24), which were synthesized using commercially available materials following simple steps. Both compounds strongly promoted seed germination of Orobanche cumana. Their EC50 values of 2.3±0.28×10-8M (7BrGR24) and 0.97±0.29×10-8M (7FGR24) were 3- and 5-fold lower, respectively, than those of (+)-GR24 and rac-GR24 (EC50=5.1±1.32-5.3±1.44×10-8; p<0.05). The 7FGR24 was the strongest seed germination promoter tested, with a stimulation percentage of 62.0±9.1% at 1.0×10-8M and 90.9±3.8% at 1.0×10-6M. It showed higher binding affinity (IC50=0.189±0.012µM) for the SL receptor ShHTL7 than (+)-GR24 (IC50=0.248±0.032µM), rac-GR24 (IC50=0.319±0.032µM), and 7BrGR24 (IC50=0.521±0.087µM). Molecular docking experiments indicated that the binding affinity of both halogenated analogs to the strigolactone receptor OsD14 was similar to that of (+)-GR24. Our results indicate that 7FGR24 is a promising agent for the control of parasitic weeds.

Antifungal activity of Bignoniaceae plants on Aspergillus carbonarius and Aspergillus niger.

Twenty four extracts from Bignoniaceae plants of northwest Argentina were tested for antifungal activity against Aspergillus species responsible of the grape black rot. Stems and leaves of Amphilophium cynanchoides, Macfadyena cynanchoides, Tecoma stans and Jacaranda mimosifolia were separately extracted with solvents of increasing polarity to obtain the dichloromethane (fCH2Cl2), ethyl acetate (fEtOAc) and methanol extracts (fMeOH). The fCH2Cl2 from stem of M. cynanchoides had the lowest IC50 (1.0-1.2 mg/mL) and MID values (0.6-1.2 mg) and the highest ID values (5.0-6.8 mm) on A. niger and A. carbonarius. The main contributors of the antifungal activity of fCH2Cl2 were identified as lapachol (MIC = 0.25-1.00 mg/ml) and 1-hydroxy-4-methylanthraquinone (MIC = 0.0625-0.125 mg/mL). These compounds synergized the antifungal activity of sodium metabisulfite and showed an additive effect in mixtures with propiconazol. They might be used as additives of commercial antifungals to protect grapes against A. niger and A. carbonarius.

Antifungal and antimycotoxigenic metabolites from native plants of northwest Argentina: isolation, identification and potential for control of Aspergillus species.

Extracts from aerial parts of Prosopis ruscifolia, Bidens pilosa, Cercidium praecox and Phoradendron liga were assayed against toxigenic Aspergillus species. They were obtained by sequential extraction of the aerial parts with hexane (fHex), dichloromethane (fDCM), ethyl acetate (fEtOAc) and methanol (fMeOH). The fMeOH from P. ruscifolia showed the highest antifungal spectrum (MIC = 750-1500 µg mL-1; MID = 50-200 µg; DI = 1.7-3.0 mm). Indolizidine alkaloids (juliflorine and juliprosine) and tryptamine were identified with strong (MIC = 188 µg mL-1) and moderate antifungal activities (MIC = 750 µg mL-1), respectively, towards A. parasiticus and A. flavus. The fMeOH, the indolizidine alkaloids and tryptamine synergized the fungitoxic effect of potassium sorbate and propiconazole. They completely suppressed the biosynthesis of aflatoxins at concentrations of 47, 94 and 375 µg mL-1, respectively. Our results indicate that fMeOH and its identified alkaloids are promisory additives of commercial antifungals and are antiaflatoxigenic agents at concentrations below of those required for complete suppression of fungal growth.

Chemical composition and antifungal activity of essential oils from Senecio nutans, Senecio viridis, Tagetes terniflora and Aloysia gratissima against toxigenic Aspergillus and Fusarium species.

Essential oils from aerial parts of Senecio nutans, Senecio viridis, Tagetes terniflora and Aloysia gratissima were analysed by GC-MS and their antifungal activities were assayed on toxigenic Fusarium and Aspergillus species. Sabinene (27.6 ± 0.1%), α-phellandrene (15.7 ± 0.3%), o-cymene (9.6 ± 0.2%) and ß-pinene (6.1 ± 0.2%) in S. nutans, 9,10-dehydrofukinone (92.7 ± 0.2%) in S. viridis, ß-thujone (36.1 ± 0.1%), α-thujone (32.2 ± 0.2%), 1,8-cineol (10.7 ± 0.1%) and sabinene (6.2 ± 0.2%) in A. gratissima, and cis-tagetone (33.6 ± 0.2%), cis-ß-ocimene (17.1 ± 0.2%), trans-tagetone (17.0 ± 0.1%), cis-ocimenone (8.0 ± 0.2%) and trans-ocimenone (8.2 ± 0.1%) in T. terniflora. The oils showed moderate antifungal activity (1.2 mg/mL > MIC >0.6 mg/mL) on the Fusarium species and a weak effect on Aspergillus species. The antifungal activity was associated on F. verticillioides to the high content of cis-tagetone, trans-tagetone, cis-ß-ocimene, cis-ocimenone, trans-ocimenone and on F. graminearum due to the total content of oxygenated sesquiterpenes and 9,10- dehydrofukinone. The oil of S. viridis synergized the effect of fungicides and food preservatives on F. verticillioides.[Formula: see text].

Antifungal activity and toxicity studies of flavanones isolated from Tessaria dodoneifolia aerial parts.

Tessaria dodoneifolia [Asteraceae] is traditionally employed in Northwestern Argentina for fungal infections treatment. We report the antifungal activity guided isolation and identification of substances from aerial parts of this species, both individually and in combination with fluconazole (FLU), against Candida albicans strains. Two antifungal flavanones were identified as naringenin (NAR) and pinocembrin (PIN). These compounds could individually inhibit the growth of C. albicans strains. Combinations of NAR and PIN with FLU were synergistic against the FLU resistant and sensitive C. albicans strains. Genotoxic and cytotoxic evaluations were also performed. NAR, PIN and their combinations with FLU did not have a genotoxic effect on Bacillus subtilis rec strains. Finally, these compounds did not show cytotoxicity at concentrations below 80 µg/mL.

Purification and characterization of an exo-polygalacturonase from Pycnoporus sanguineus.

The present work describes the purification and characterization of a novel extracellular polygalacturonase, PGase I, produced by Pycnoporus sanguineus when grown on citrus fruit pectin. This substrate gave enhanced enzyme production as compared to sucrose and lactose. PGase I is an exocellular enzyme releasing galacturonic acid as its principal hydrolysis product as determined by TLC and orcinol-sulphuric acid staining. Its capacity to hydrolyze digalacturonate identified PGase I as an exo-polygalacturonase. SDS-PAGE showed that PGase I is an N-glycosidated monomer. The enzyme has a molecular mass of 42kDa, optimum pH 4.8 and stability between pH 3.8 and 8.0. A temperature optimum was observed at 50-60 degrees C, with some enzyme activity retained up to 80 degrees C. Its activation energy was 5.352calmol(-1). PGase I showed a higher affinity towards PGA than citric pectin (Km=0.55+/-0.02 and 0.72+/-0.02mgml(-1), respectively). Consequently, PGase I is an exo-PGase, EC 3.2.1.82.

Influence of water activity and temperature on growth and production of trichothecenes by Fusarium graminearum sensu stricto and related species in maize grains.

Fusarium meridionale and F. boothii cause Gibberella Ear Rot (GER) in maize. This study determined the effects of temperature (5-35 °C) and water activity (0.90-0.995 aw) on the growth, and deoxynivalenol (DON) and nivalenol (NIV) production of F. meridionale and F. boothii strains in maize grains. Fusarium graminearum sensu stricto strains from wheat were also tested. The three Fusarium species grew best at 0.995 aw and 25 °C. Growth was absent or marginal at 0.90 aw regardless of temperature. F. meridionale and F. boothii were sensitive to 30 °C and more affected by water stress than F. graminearum sensu stricto. The highest DON levels were at 0.995-0.97 aw and 30 °C and at 0.97 aw and 20 °C for F. graminearum sensu stricto, and at 0.995-0.97 aw and 20 °C for F. boothii. Fusarium meridionale reached maximum NIV accumulation at 0.995 aw and 20 °C. This produced DON at negligible levels compared to the other two Fusarium species. Growth of F. meridionale and F. boothii was well adapted to the usual autumn high humidity and mild temperatures associated with GER in northwest Argentina. Control strategies during grain development should be taken into account to reduce the risk of the presence of DON and NIV in the harvested grains.

Phytochemical and biological study of phenolic components from Geoffroea decorticans stem bark / Estudio fitoquímico y biológico de los componentes fenólicos de la corteza de Geoffroea decorticans

The stem bark of Geoffroea decorticans (Gill.ex Hook. etArn.) Burk. was used medicinally to cure several skin affections; however, phytochemical and biological antecedents were not found. Analyses of purified methanolic extract from G. decorticans bark (PFGB), realized by silylation derivatization for GC/MS, C18-CC and HPLC followed by two-dimensional TLC and UV-Vis spectroscopy, allowed to characterize nine phenolic compounds, among these, two methoxy flavonoids. Antibacterial assays of PFGB showed the highest activity (MICs = 125 µg/mL) against Staphylococcus aureus (25923) and Enterococcus faecalis (29212) ATCC strains. Moreover, PFGB showed the highest intracellular antioxidant activity at low concentration (5 µg/mL), evaluated by using the fluorescent DA-H2DCF probe on lymphocyte culture; cytotoxic effects on lymphocytes activated or not by LPS were not observed, through Trypan Blue Exclusion and MTT colorimetric assays. The results obtained from the ethnomedicinal approach of this work contribute to the scientific validation of the vulnerary medicinal use of G. decorticans.

La corteza de Geoffroea decorticans (Gill.ex Hook. EtArn.) Burk. se utiliza con fines medicinales para curar diferentes afecciones de la piel; sin embargo, no encontramos antecedentes fitoquímicos y biológicos que validen las propiedades medicinales atribuidas. Analizamos el extracto metanólico purificado de corteza de G. decorticans (PFGB), por CG-EM de la muestra derivatizada por sililación, C18-CC y HPLC seguido de CCF bidimensional, y espectroscopia UV-Vis; estos métodos nos permitieron caracterizar nueve compuestos fenólicos, entre estos, dos metoxi-flavonoides. Los ensayos antibacterianos de PFGB mostraron mayor actividad (CIMs = 125 µg/mL) contra las cepas ATCC de Staphylococcus aureus (25923) y Enterococcus faecalis (29212). Además, PFGB evidenció la mayor actividad antioxidante intracelular a baja concentración(5 µg/mL), evaluada en cultivo de linfocitos, mediante el uso de sonda fluorescente DA-H2DCF; no se observaron efectos citotóxicos sobre linfocitos activados o no por LPS, a través de ensayos colorimétricos con MTT y test de exclusión con azul Tripán. Los resultados obtenidos del abordaje etnomedicinal de este trabajo, contribuyen con la validación científica del uso medicinal vulnerario de G. decorticans.

Chemical composition and antifungal activity of essential oils from medicinal plants of Kazakhstan.

The composition of essential oils from leaves of Kazakhstan medicinal plants was analysed by GC-MS. The major compounds identified were 1,8-cineole (34.2%), myrcene (19.1%) and α-pinene (9.4%) in Ajania fruticulosa; 1,8-cineole (21.0%), ß-thujone (11.0%), camphor (8.5%), borneol (7.3%) and α-thujone (6.5%), in Achillea nobilis; camphor (47.3%), 1,8-cineole (23.9%), camphene (9.8%) and ß-thujone (6.0%) in Artemisia terrae-albae; 1,8-cineole(55.8%) and ß-pinene (6.2%) in Hyssopus ambiguus; α-thuyene(46.3%) and δ-cadinene(6.3%) in Juniperus sibirica; sabinene (64%) in Juniperus sabina; and α-pinene (51.5%), ß-phellandrene (11.2%) and δ-cadinene (6.3%) in Pinus sibirica. The essential oils did not show antifungal effect (MIC > 1.20 mg/mL) on Aspergillus carbonarius and Aspergillus niger, while the oils from A. nobilis, A. terrae-albae, H. ambiguus and J. sabina exhibited moderate and moderate to weak antimicrobial activities on Fusarium verticillioides (MIC = 0.60 mg/mL) and Fusarium graminearum (MIC = 0.60-1.20 mg/mL), respectively. A principal component analysis associated the antifungal activity (r2 > 0.80, p = 0.05) with the presence of borneol, camphor, camphene, 1,8-cineole,α- and ß-thujone, and of the oxygenated monoterpenes.

Antifungal activity and cytotoxicity of extracts and triterpenoid saponins obtained from the aerial parts of Anagallis arvensis L.

ETHNOPHARMACOLOGICAL RELEVANCE: Anagallis arvensis L. (Primulaceae) is used in argentinean northwestern traditional medicine to treat fungal infections. We are reporting the isolation and identification of compounds with antifungal activity against human pathogenic yeast Candida albicans, and toxicity evaluation. AIM OF THE STUDY: to study the antifungal activity of extracts and purified compounds obtained form A. arvensis aerial parts, alone and in combinations with fluconazole (FLU), and to study the toxicity of the active compounds. MATERIALS AND METHODS: Disk diffusion assays were used to perform an activity-guided isolation of antifungal compounds from the aerial parts of A. arvensis. Broth dilution checkerboard and viable cell count assays were employed to determine the effects of samples and combinations of FLU + samples against Candida albicans. The chemical structures of active compounds were elucidated by spectroscopic analysis. Genotoxic and haemolytic effects of the isolated compounds were determined. RESULTS: Four triterpenoid saponins (1-4) were identified. Anagallisin C (AnC), exerted the highest inhibitory activity among the assayed compounds against C. albicans reference strain (ATCC 10231), with MIC-0 =1µg/mL. The Fractional Inhibitory Concentration Index (FICI=0.129) indicated a synergistic effect between AnC (0.125µg/mL) and FLU (0.031µg/mL) against C. albicans ATCC 10231. AnC inhibited C. albicans 12-99 FLU resistant strain (MIC-0 =1µg/mL), and the FICI=0.188 indicated a synergistic effect between AnC (0.125µg/mL) and fluconazole (16µg/mL). The combination AnC+ FLU exerted fungicidal activity against both C. albicans strains. AnC exerted inhibitory activity against C. albicans ATCC 10231 sessile cells (MIC50=0.5µg/mL and MIC80=1µg/mL) and against C. albicans 12-99 sessile cells (MIC50=0.75µg/mL and MIC80=1.25µg/mL). AnC exerted haemolytic effect against human red blood cells at 15µg/mL and did not exerted genotoxic effect on Bacillus subtilis rec strains. CONCLUSIONS: The antifungal activity and lack of genotoxic effects of AnC give support to the traditional use of A. arvensis as antifungal and makes AnC a compound of interest to expand the available antifungal drugs.

Chemical composition and antimicrobial activity of essential oils from Acantholippia deserticola, Artemisia proceriformis, Achillea micrantha and Libanotis buchtormensis against phytopathogenic bacteria and fungi.

Essential oils from aerial parts of Acantholippia deserticola, Artemisia proceriformis, Achillea micrantha and Libanotis buchtormensis were analysed by GC-MS. The major compounds identified were ß-thujone (66.5 ± 0.2%), and trans-sabinyl acetate (12.1 ± 0.2%) in A. deserticola; α-thujone (66.9 ± 0.4%) in A. proceriformis; 1,8-cineole (26.9 ± 0.5%), and camphor (17.7 ± 0.3%) in A. micrantha and cis-ß-ocimene (23.3 ± 0.3%), and trans-ß-ocimene (18.4 ± 0.2%) in L. buchtormensis. The oils showed a weak antimicrobial effect (MIC100 > 1.5 mg/ml) on most phytopathogens tested. A moderate antimicrobial activity (MIC100 between 0.5 and 1.5 mg/ml) was displayed by the oils of A. deserticola, A. micrantha and L. buchtormensis on Septoria tritici and by the oil of A. deserticola on Septoria glycine. The antimicrobial activity was associated to the contents of ß-thujone, trans-sabinyl acetate and trans-sabinol. Our results indicate that the tested essential oils have little inhibitory potency not suitable for use as plant protection products against the phytopathogens assayed.

Isolation, identification and usefulness of antifungal compounds from Zuccagnia punctata for control of toxigenic ear rot pathogens.

Infusion, tincture and decoction of leaves of Zuccagnia punctata Cav. were assayed on growth of Fusarium verticillioides, F. graminearum sensu stricto, F. boothii, F. meridionale, F. subglutinans and F. thapsinum. The tincture showed the lowest IC50 on mycelial growth. A diethyl ether fraction of the tincture showed the highest antifungal activity in microdilution assays on F. verticillioides and F. graminearum. The antifungal constituents were separated by silica gel chromatography and identified as 2',4'-dihydroxychalcone, 2',4'-dihydroxy-3'-methoxychalcone and 7-hydroxy-3',4'-dimethoxyflavone. These chalcones had the lowest MIC and MFC values on F. verticillioides and F. graminearum sensu stricto. 2',4'-Dihydroxychalcone was mildly toxic and the remaining identified compounds were non-toxic in the brine shrimp assay. 2',4'-Dihydroxychalcone in mixtures with commercial food preservatives showed additive effects on F. graminearum sensu stricto and synergistic ones on F. verticillioides. 2',4'-Dihydroxy-3'-methoxychalcone showed synergistic effects in mixtures. Our results suggest that addition of chalcones to food preservatives allows reduction in the doses of the preservatives required for control of Fusarium species.

Essential oils from Schinus species of northwest Argentina: Composition and antifungal activity.

The composition of the essential oils from leaves (Sal) and fruits of S. areira (Saf), and fruits of S. fasciculatus (Sff) and S. gracilipes (Sgf) were analyzed by GC/MS. The major compounds identified were sabinene (26.0 +/- 0.5%), bicyclogermacrene (14.5 +/- 0.4%), and E-citral (6.7+/- 0.2%) in Sal oil, limonene (27.7 +/- 0.7%), sabinene (16.0+/- 0.5%), beta-phellandrene (14.6 +/- 0.8%) and bicyclogermacrene (8.1 +/- 0.2%) in Saf oil, sabinene (22.7 +/- 0.6%), alpha-phellandrene (18.7 +/- 0.3%), beta-phellandrene (15.7 +/- 0.4%), and bicyclogermacrene (8.1 +/- 0.2%) in Sff oil and beta-pinene (25.4 +/- 0.8%), alpha-pinene (24.7 +/- 0.7%), and sabinene (13.6 +/- 0.4%) in Sgf oil.The antifungal activity of the four oils was evaluated on strains of Fusarium verticillioides and F. graminearum, and the results compared with the effect of epoxyconazole, pyraclostrobin and thyme oil. The Sff oil had the highest antifungal activity among the Schinus oils tested, with MIC100 (F. graminearum) = 6 per thousand and MIC100 (F. verticillioides) = 12 per thousand. A principal component analysis suggests that 9 constituents (alpha-thujene, alpha-terpinene, p-cymene, gamma-terpinene, terpinolene, 1-terpineol, alpha-calacorene, alpha-phellandrene, and terpinen-4-ol) explain the higher antifungal effect of Sff. The MIC100s of Schinus oils were on average 30-60 and 8.5-17 fold lower than those obtained for thyme oil on F. verticillioides and F. graminearum, respectively. In the case of commercial fungicides, their MIC100s were three orders of magnitude lower than those of Schinus oils. The last ones showed an additive interaction when assayed in mixtures with the commecial fungicides and thyme oil. The results suggest that the doses of fungicides required for control of the Fusarium species can be reduced when they are assayed in mixtures with the Schinus oils.