Antifungal activity of Tagetes patula extracts on some phytopathogenic fungi: ultrastructural evidence on Pythium ultimum

Photoantimicrobials in agriculture

Classical approaches for controlling plant pathogens may be impaired by the development of pathogen resistance to chemical pesticides and by limited availability of effective antimicrobial agents. Recent increases in consumer awareness of and/or legislation regarding environmental and human health, and the urgent need to improve food security, are driving increased demand for safer antimicrobial strategies. Therefore, there is a need for a step change in the approaches used for controlling pre- and post-harvest diseases and foodborne human pathogens. The use of light-activated antimicrobial substances for the so-called antimicrobial photodynamic treatment is known to be effective not only in a clinical context, but also for use in agriculture to control plant-pathogenic fungi and bacteria, and to eliminate foodborne human pathogens from seeds, sprouted seeds, fruits, and vegetables. Here, we take a holistic approach to review and re-evaluate recent findings on: (i) the ecology of naturally-occurring photoantimicrobials, (ii) photodynamic processes including the light-activated antimicrobial activities of some plant metabolites, and (iii) fungus-induced photosensitization of plants. The inhibitory mechanisms of both natural and synthetic light-activated substances, known as photosensitizers, are discussed in the contexts of microbial stress biology and agricultural biotechnology. Their modes-of-antimicrobial action make them neither stressors nor toxins/toxicants (with specific modes of poisonous activity), but a hybrid/combination of both. We highlight the use of photoantimicrobials for the control of plant-pathogenic fungi and quantify their potential contribution to global food security.

Evaluation of the antifungal photodynamic activity of Thymophylla pentachaeta extracts against Candida albicans and its virulence factors

BACKGROUND

Candida albicans is one of the most common causative of opportunistic infections. Treatment of candidiasis is challenging considering the few antifungal drugs available and the increase in resistance. Antimicrobial photodynamic therapy (aPDT) is a recently developed therapeutic option that combines a non-toxic photosensitizer (PS) and light to kill the microbial pathogens. Targeting virulence, defined as the ability of a pathogen to cause overt disease, represents another attractive target for the development of novel antifungal agents. Thymophylla pentachaeta (DC.) Small var. belenidium (DC.) is an endemic plant from Argentina in which the presence of thiophenes, biologically active compounds whose antifungal activity is enhanced by irradiation with Ultraviolet A (UVA), have been already described.

PURPOSE

The purpose of this study was to evaluate the photodynamic antifungal activity of hexane (Hex), dichloromethane (DCM), ethyl acetate (EtOAc) and methanol (MeOH) extracts from T. pentachaeta var. belenidium and their inhibitory effects on C. albicans virulence factors as well as biofilm formation and eradication.

STUDY DESIGN/METHODS

Antifungal photodynamic activity of Hex, DCM, EtOAc and MeOH extracts from different parts of the plant were assessed with the microbroth dilution, bioautography and the time-kill assays, under light and darkness conditions. The capacities of the most active extracts of inhibiting Candida virulence factors (adherence to epithelial cells, germ tube and pseudomycelium formation and hydrolytic enzyme secretion) were assessed. In addition, the activity against biofilm formation and eradication has been investigated by reaction with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) that quantifies living cells in these structures.

RESULTS

Hex and DCM extracts from T. pentachaeta roots exhibited high photodynamic antifungal activity against C. albicans [Minimal fungicide concentrations (MFCs)= 7.8 µg/ml] under UVA light irradiation. Chemical analysis of active extracts (Hex and DCM from roots) revealed the presence of photoactive thiophenes. Both extracts generate reactive oxygen species through type I and II mechanisms. These extracts, at sub-inhibitory concentrations, under light conditions decreased the adherence of C. albicans to Buccal Epithelial Cells (BEC), inhibited germ tube formation and reduced esterase production. Finally, they demonstrated activity against preformed biofilms submitted to irradiation (MFCs= 3.91 µg/ml and 15.63 µg/ml for Hex and DCM extracts, respectively).

CONCLUSION

Taking together, results demonstrated the strong photodynamic effects of T. pentachaeta root extracts under UVA irradiation, making them valuable alternatives to the already established antifungal drugs against C. albicans.

Photodynamic activity of Tagetes minuta extracts against superficial fungal infections

Candida and dermatophyte species are the most common causes of superficial mycoses because their treatment can be difficult due to limitations of current antifungal drugs in terms of toxicity, bioavailability, interactions, narrow-spectrum activity, and development of resistance. Photodynamic therapy (PDT) involves the topical administration of a photosensitizer in combination with light of an appropriate wavelength and molecular oxygen that produces reactive oxygen species (ROS), which promote damage to several vital components of the microorganism. Tagetes species are known as a source of thiophenes, biologically active compounds whose antifungal activity is enhanced by irradiation with UVA. The present investigation evaluated Tagetes minuta extracts as a photosensitizer on growth of Candida and dermatophytes and their effect on Candida virulence factors. T. minuta root hexane and dichloromethane extracts demonstrated high photodynamic antifungal activity. Bioautographic assays and chromatographic analysis revealed the presence of five thiophenes with reported photodynamic antifungal activities under UVA. Analysis of ROS production indicated that both type I and II reactions were involved in the activity of the extracts. In addition, the extracts inhibited virulence factors of Candida, such as adherence to epithelial surfaces and germ tube formation and showed efficacy against different Candida morphologies: budding cells, cells with germ tube and biofilms. Results suggested that PDT with T. minuta extracts might become a valuable alternative to the already established antifungal drugs for the treatment of superficial fungal infections.

Traditional uses, Phyto-chemistry and pharmacological activities of Tagetes Patula L

ETHNO-PHARMACOLOGICAL RELEVANCE

Tagetes patula L. an important medicinal plant of Asteraceae family is worldwide distributed and reported for its folkloric use in various disorders like skin, eye problems, injury and stomach issues by different communities of China, Nepal, India, Bangladesh and Pakistan.

AIM OF THIS REVIEW

The present review has focused the ethnomedicinal and traditional uses of T. patula with special reference to Asian countries. Chemical constituents and pharmacological aspects of T. patula was explored. After reading the review the researchers may able to find new insights to further investigate this plant.

REVISION OF LITERATURE

Google scholar, PubMed, and Science direct, were the major search engines used to get relevant information based on articles and books.

RESULTS

and Discussion: The ethno-botanical aspects were recorded, the pharmacological aspects like antioxidant, anti-inflammatory, antimicrobial, anti-parasitic and anti-diabetic potentials evaluated both in vivo and in vitro is described. The toxicity or allergic manifestation with the use of the plant is also a section in the article. It is a rich source for thiophene derivatives, flavonoids, carotenoids, terpenes and terpenoids. Various gaps were pointed out for researchers that need to be investigated.

CONCLUSION

Various traditional uses have been reported in Asian countries that need to be scientifically investigated in depth and several pharmacological activities have been reported for the T. patula but more detailed and mechanism-based studies linked to a particular lead compound need to be targeted in future.

New antibacterial thiophenes from Eclipta prostrata

Three new thiophene derivatives, ecliprostins A-C (1-3), have been isolated from the aerial parts of a Compositae medicinal plant Eclipta prostrata, and structures of them have been elucidated by comprehensive spectroscopic analyses. Both ecliprostins A (1) and B (2) feature an acetylenic bithiophenyl backbone and also incorporate an isovalerate moiety, while ecliprostin C (3) is a symmetrical dimer of compound 1 and represents the first example bonded via an ether bridge among the very limited natural dimers. All three compounds show antibacterial activity against Staphylococcus aureus.

Cytotoxic and genotoxic action of Tagetes patula flower methanol extract and patuletin using the Allium test

Tagetes patula is used to treat cancer patients in alternative healthcare systems. However, its cytotoxic and genotoxic effects have not been reported. Therefore, themethanol extract of T. patula flower, the ethyl acetate fraction, and the pure compound patuletin were evaluatedusing the Allium test.The methanol extract and fraction contained ~3% and ~36% patuletin, respectively, with ~98% purity. The methanol extract caused inhibition of Allium root growth displaying an IC₅₀ value of ~500 µg/mL, while the fraction and patuletin were more potent by ~2 and ~5 times, respectively. The Allium root tips demonstrated a decline in prophase, metaphase, anaphase, and telophase stages with concomitant decrease in percent mitotic index in the methanol extract (~5.64), fraction, and patuletin (~4) as compared to the control (~7.61). However, in only methanol extract-treated root tips, an increase in metaphase stage was noted. In addition, the methanol extract predominantly induced c-type, misaligned, and multipolar chromosomal abnormalities while the fraction and patuletin displayed fragments and sticky chromosomes. The fraction and patuletin also produced micronuclei (~2%). In conclusion, T. patula flower methanol extract and ethyl acetate fraction are cytotoxicand genotoxic, which most likely could be due to the patuletin. Further preclinical and clinical studies are required to justify its clinical use.

Inhibitory effects of leaf extract of Lawsonia inermis on Curvularia lunata and characterization of novel inhibitory compounds by GC-MS analysis

•

Isolation of active principle compound was found maximum in acetone extract of L. inermis leaf.

•

Phytochemical tests suggest that carbohydrate, steroids, volatile oils, flavonoids, and tannins were found to be present in acetone extract of L. inermis leaf.

•

In vitro assay of antifungal activity of all column fractions fraction no. F1 which exhibited most significant antifungal activity against the test fungus.

•

GC–MS analysis of column fraction showed the occurrence of total 6 constituents.

•

The obtained constituents are hexacosane, octadecane, docosane, heptacosane methyl, octacosane, and tetracosane.

Plants produce a high diversity of natural products with a prominent function in the protection against microbial pathogens on the basis of their toxic effect on growth and reproduction. In the present study, effect of partially purified acetone fraction of L. inermis leaves on various cytomorphological parameters i.e. mycelium width, conidial size, etc. of test fungi and fraction was subjected to confirming the presence of primary and secondary metabolites by rapid qualitative phytochemical tests, chromatographic methods such as TLC, column chromatography, GC–MS, etc. which were responsible for the inhibition of growth of test pathogen conidial size of Curvularia lunata decreased up to 64.76% at 0.039 μg/ml concentration of the extract. Mycelial width of C. lunata increased up to 55.91% at 0.312 μg/ml concentration of the extract. Carbohydrate, steroids, volatile oils, flavonoids, and tannins were found to be present in acetone extract of L. inermis leaf. Total of 7 bands were observed in TLC fingerprinting of L. inermis acetone fraction. Total of 10 fractions were collected from the column chromatography. Fractions which show the most significant antifungal activity against the test fungus was subjected to further GC–MS analysis for the separation and identification of active principle. GC–MS analyses show the presence of total 6 constituents i.e. hexacosane, octadecane, docosane, heptacosane methyl, octacosane, and tetracosane.

Comparison of the Fungistatic Activity of Selected Essential Oils Relative to Fusarium graminearum Isolates

The aim of the study was to determine the chemical composition of lemon, rosewood, geranium and rosemary oils, and compare their effect on the sensitivity of Fusarium graminearum ZALF 24 and Fusarium graminearum ZALF 339 isolated from infected cereals. The tested oils were added to Potato Dextrose Agar (PDA) medium at concentrations of 0.125%, 0.25%, 0.5%, 1.0% and 2.0%. The activity of the oils on inhibition of the linear growth of mycelium was evaluated by measuring the growth of fungal colonies (growth index), while the fungistatic activity was evaluated on the basis of the percentage growth inhibition of a fungal colony and calculated according to Abbott's formula. The sensitivity of the test strains was variable and depended on the type and concentration of the tested oils. Geranium and rosewood oils in all of the concentrations completely inhibited the growth of the used isolates. In contrast, lemon oil relative to F. graminearum ZALF 339 showed the highest activity at a concentration of 1.0% and rosemary oil, 0.5%. The highest activity against F. graminearum ZALF 24 was shown by the oils of rosemary and lemon at concentrations from 1.0% to 2.0%. The susceptibility of Fusarium graminearum isolates was differentiated and depended on the type and concentration of tested oils.

Tagetes spp. Essential Oils and Other Extracts: Chemical Characterization and Biological Activity

Tagetes (marigold) is native to America, and its cultivation currently extends to other countries in Africa, Asia, and Europe. Many species of this genus, such as T. minuta, T. erecta, T. patula, and T. tenuifolia, are cultivated as ornamental plants and studied for their medicinal properties on the basis of their use in folk medicine. Different parts of the Tagetes species are used as remedies to treat various health problems, including dental, stomach, intestinal, emotional, and nervous disorders, as well as muscular pain, across the world. Furthermore, these plants are studied in the field of agriculture for their fungicidal, bactericidal, and insecticidal activities. The phytochemical composition of the extracts of different Tagetes species parts are reported in this work. These compounds exhibit antioxidant, antiinflammatory, and enzyme inhibitory properties. Cultivation and the factors affecting the chemical composition of Tagetes species are also covered. In the current work, available literature on Tagetes species in traditional medicine, their application as a food preservative, and their antimicrobial activities are reviewed.

Surface characterisation and reaction kinetics of silver nanoparticles mediated by the leaf and flower extracts of French marigold (Tagetes patula)

In this study, French marigold's leaf and flower were used for the synthesis of silver nanoparticles (SNPs) in order to explore their potentials towards bioreduction of Ag⁺ to Agᵒ. The as-synthesised SNPs were characterised using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction, transmission electron microscopy, and zeta-potential analysis. The results obtained showed that the particles are polydispersed with sizes in the range 15.8-42.8 nm. The bioreduction was believed to be due to the amides, aldehyde functional groups, and essential oils present in the extracts as confirmed by the FTIR analysis. The growth mechanism involved in the reaction was studied which revealed oriented attachment (OA) onwards Ostwald ripening in the case of the flower-mediated synthesis and typical OA in the leaf-mediated synthesis. The studied kinetics of the particle formation showed that the reaction is possibly a pseudo-first-order reaction with some diffusion-controlled mechanism which is driven by high surface area to volume ratio in both the leaf- and flower-mediated synthesis.

Antifungal photosensitive activity of Porophyllum obscurum (Spreng.) DC.: Correlation of the chemical composition of the hexane extract with the bioactivity

We report Porophyllum obscurum as a source of new photosensitizers with potential use in Photodynamic Therapy as an alternative for oropharyngeal candidiasis treatment. The antifungal photosensitive activity of different extracts from P. obscurum was evaluated by using microdilution and bioautographic assays. The Minimum Fungicidal Concentration for hexanic extract under UV-A irradiation was 0.98μg/mL, but it was inactive in experiments without irradiation. The bioassay-guided fractionation of this extract led to the isolation of four thiophenes responsible for the photosensitive activity: 2,2':5'2″terthiophene, 5-(3-buten-1-ynyl)-2,2'-bithiophene, 5-(4-acetoxy-1-butenyl)-2,2'- bithiophene and 5-(4-hydroxy-1-butenyl)-2,2'- bithiophene, with Minimum Fungicidal Concentrations ranging 0.24-7.81μg/mL under UV-A irradiation. The activity of the hexanic extract was evaluated against 25 clinical strains of Candida spp. isolates as etiological agents of oropharyngeal candidiasis. No differences in susceptibility were observed in strains resistant and susceptible to conventional antifungal drugs. Qualitative and quantitative chemical analyses of seven samples of P. obscurum collected in four different phenological stages were carried out showing that full flowering stage possesses the highest thiophenes content. These data also allowed us to establish a correlation between the thiophene composition of the different extracts and their antifungal photosensitive activity, according to a second order polynomial model with the equation: y=11.2603-0.6831*x+0.0108*x². The thiophenes isolated were the responsible of antifungal photosensitive activity and can be used for the future standardization of the extract. Results showed that P. obscurum hexanic extract could be potentially developed as an Herbal Medicinal Product to be applied as a photosensitizer in Photodynamic Therapy.

In vitro photodynamic inactivation of conidia of the phytopathogenic fungus Colletotrichum graminicola with cationic porphyrins

Photodynamic inactivation (PDI) is an efficient approach for the elimination of a series of microorganisms; however, PDI involving phytopathogenic filamentous fungi is scarce in the literature. In the present study, we have demonstrated the photoinactivating properties of five cationic meso-(1-methyl-4-pyridinio)porphyrins on conidia of the phytopathogen Colletotrichum graminicola. For this purpose, photophysical properties (photostability and (1)O2 singlet production) of the porphyrins under study were first evaluated. PDI assays were then performed with a fluence of 30, 60, 90 and 120 J cm(-2) and varying the porphyrin concentration from 1 to 25 μmol L(-1). Considering the lowest concentration that enabled the best photoinactivation, with the respective lowest effective irradiation time, the meso-(1-methyl-4-pyridinio)porphyrins herein studied could be ranked as follows: triple-charged 4 (1 μmol L(-1) with a fluence of 30 J cm(-2)) > double-charged-trans2 (1 μmol L(-1) with 60 J cm(-2)) > tetra-charged 5 (15 μmol L(-1) with 90 J cm(-2)) > mono-charged 1 (25 μmol L(-1) with 120 J cm(-2)). Double-charged-cis-porphyrin 3 inactivated C. graminicola conidia in the absence of light. Evaluation of the porphyrin binding to the conidia and fluorescence microscopic analysis were also performed, which were in agreement with the PDI results. In conclusion, the cationic porphyrins herein studied were considered efficient photosensitizers to inactivate C. graminicola conidia. The amount and position of positive charges are related to the compounds' amphiphilicity and therefore to their photodynamic activity.

Antifungal, antiradical and cytotoxic activities of extractives obtained from Tagetes patula L. (Asteraceae), a potential acaricide plant species

Tagetes patula L. shows a complex chemical composition, ranging from glycosylated flavonoids and thiophenes in extracts until terpenoids in the essential oil. In the present study, due to this rich flavonoidic constitution, its antioxidant potential was determined, having shown values of antiradical percentage superior to reference compounds, mainly the extracts prepared with flowers. Previous studies performed emphasized the acaricide potential of T. patula and thus, the present study aimed to verify the action of extractives obtained from aerial parts on growth of entomopathogenic fungi related to biological control of brown dog tick Rhipicephalus sanguineus and the action against pathogenic fungi closely associated with pets. None of the samples inhibited the growth of strains of Beauveria bassiana or Metarhizium anisopliae, enabling feasible future studies of synergism on acaricide activity of formulations containing fungi and extracts. The antimicrobial activity of ethanolic extract of flowers (FlEtOH70%) against Microsporum canis and Trichophyton rubrum was significant (193.3 μg/mL and 253.9 μg/mL, respectively), as well as ethanolic extract from aerial parts (APEtOH70%) against T. rubrum (312.5 μg/mL). In order to ensure the safety of a topical formulation containing the extractives of T. patula, the cytotoxic potential of these samples were tested in murine macrophages cells. At higher concentrations all extracts were quite lethal, with IC50 ranging from 210.96 μg/mL to 468.75 μg/mL for APEtOH70% and FlEtOH70%, respectively. These results suggest that the application of a product containing T. patula extractives in the control of ticks could be used, at principle, only on the environment.

Photodynamic inactivation of oropharyngeal Candida strains

Oropharyngeal candidiasis (OPC) is an infection frequent in immunocompromised patients. Photodynamic therapy is an alternative to conventional treatments, based on the utilization of compounds that inhibit or kill microorganisms only under the effect of light, process known as Photodynamic Inactivation (PDI). In the present study, PDI of Candida spp. by the natural product α-terthienyl (α-T) was investigated following the guidelines of CLSI M27-A3, under UV-A light irradiation. The optimal values of two variables, exposure irradiation time (ET) and distance to the irradiation source (DIS) were established by employing Design Expert Software (DES). For this purpose, a panel of Candida strains isolated from OPC (C. albicans, C. tropicalis, C. parapsilosis and C. krusei) was employed and optimal values were 5 min (ET) and between 6.06 and 6.43 cm (DIS) with a desirability factor of 0.989. α-T plus UV-A light in the optimal conditions caused a complete reduction in viable cells in 5 min which was demonstrated by viable cells reduction assays and confocal microscopy after vital staining (propidium iodide/fluorescein diacetate). The germ tube formation of C. albicans was inhibited by α-T at sub-inhibitory concentrations. Results showed that α-T plus UV-A light could constitute an alternative for OPC treatments at the optimal conditions determined here.

A quantitative ethnopharmacological documentation of natural pharmacological agents used by pediatric patients in Mauritius

The pediatric population constitutes the most vulnerable patients due to a dearth of approved drugs. Consequently, there is a pressing need to probe novel natural pharmacological agents in an endeavour to develop new drugs to address pediatric illnesses. To date, no studies have explored the use of natural therapies for pediatric health care in Mauritius. Parents (n = 325) from different regions of the island were interviewed. Quantitative indexes such as fidelity level (FL), informant consensus factor (F IC), and use-value (UV) were calculated. Thirty-two plants were reported to be used by pediatric patients. Gastrointestinal disorders (F IC = 0.97) encompassing regurgitation, infantile colic, and stomach aches were the most common ailments managed with herbs. Matricaria chamomilla used for infantile colic and its pharmacological properties has previously been documented for pediatric patients. Product from A. mellifera (UV = 0.75) was the most utilized zootherapy for managing cough. Most plants and animal products reported in this study have bioactive constituents supported by existing scientific literature but their use for the pediatric population is scant. The present ethnopharmacological study has opened new perspectives for further research into their pharmacology, which can subsequently support and facilitate timely pediatric medicinal product development.

Anti-oxidative and anti-inflammatory effects of Tagetes minuta essential oil in activated macrophages

OBJECTIVE

To investigate antioxidant and anti-inflammatory effects of Tagetes minuta (T. minuta) essential oil.

METHODS

In the present study T. minuta essential oil was obtained from leaves of T. minuta via hydro-distillation and then was analyzed by gas chromatography-mass spectrometry. The anti-oxidant capacity of T. minuta essential oil was examined by measuring reactive oxygen, reactive nitrogen species and hydrogen peroxide scavenging. The anti-inflammatory activity of T. minuta essential oil was determined through measuring NADH oxidase, inducible nitric oxide synthase and TNF-α mRNA expression in lipopolysacharide-stimulated murine macrophages using real-time PCR.

RESULTS

Gas chromatography-mass spectrometry analysis indicated that the main components in the T. minuta essential oil were dihydrotagetone (33.86%), E-ocimene (19.92%), tagetone (16.15%), cis-β-ocimene (7.94%), Z-ocimene (5.27%), limonene (3.1%) and epoxyocimene (2.03%). The T. minuta essential oil had the ability to scavenge all reactive oxygen/reactive nitrogen species radicals with IC50 12-15 µg/mL, which indicated a potent radical scavenging activity. In addition, T. minuta essential oil significantly reduced NADH oxidase, inducible nitric oxide synthaseand TNF-α mRNA expression in the cells at concentrations of 50 µg/mL, indicating a capacity of this product to potentially modulate/diminish immune responses.

CONCLUSIONS

T. minuta essential oil has radical scavenging and anti-inflammatory activities and could potentially be used as a safe effective source of natural anti-oxidants in therapy against oxidative damage and stress associated with some inflammatory conditions.

Antifungal activity of plant extracts against Colletotrichum lagenarium, the causal agent of anthracnose in cucumber

BACKGROUND

Colletotrichum lagenarium is an important plant-pathogenic fungus that causes anthracnose of cucumber, a disease that is widespread under both greenhouse and field cultivation. To find a promising method for the control of this disease, extracts of eight plants from China were screened in the study presented here.

RESULTS

The results showed that the extract of Cinnamomum camphora (L.) Presl had significantly greater inhibitory activity against C. lagenarium than the other seven plant extracts tested in vitro. At 5 days after inoculation in a potted seedling experiment, C. camphora extract demonstrated 95% control of C. lagenarium at a concentration of 16 mg mL⁻¹, and the MIC₅₀ was 2.596 mg mL⁻¹. Microscopic observation showed that this extract had a significant impact on the morphology of the fungus, leading to shorter hyphae that were more branched; this observation was associated with the inhibition of mycelial growth. Stability assays revealed that the extract was relatively stable at 80 °C, under acidic conditions and when exposed to light and short periods of UV radiation.

CONCLUSION

These results demonstrated that the extract from C. camphora could be used as a potent phytochemical fungicide.

Thiophene occurrence in different Tagetes species: agricultural biomasses as sources of biocidal substances

BACKGROUND

Tagetes species produce thiophenes, polyacetylenic compounds that possess strong biocidal activity, thus making Tagetes plants very useful for suppressing nematode populations in the soil and as sources of natural pesticides. In the present study, Tagetes species (T. erecta, T. filifolia, T. lucida, T. minuta, T. patula and T. tenuifolia) grown in northern Italy were evaluated for their morphophenological parameters and thiophene pattern in different plant parts (roots, shoots and flowers).

RESULTS

Roots had the highest diversity and contents of thiophenes (from 64 to 100% of the total thiophene amount), with 5-(3-buten-1-ynyl)-2,2'-bithienyl (BBT) as the main component followed by 5-(4-acetoxy-1-butynyl)-2,2'-bithienyl (BBTOAc), 2,2':5',2''-terthienyl (alpha-T) and 5-(4-hydroxy-1-butynyl)-2,2'-bithienyl (BBTOH). Tagetes lucida and T. tenuifolia possessed the highest amounts of total thiophenes (6717.3 and 6452.5 mg kg(-1) dry weight respectively), while T. minuta had the highest total thiophene yield (518.8 mg m(-2)), with BBT accounting for 98% of the total.

CONCLUSION

Considering both thiophene concentrations and biomass yields, T. minuta and T. lucida appeared to be the most promising Tagetes species, with high potential for use as biocidal crops for the implementation of pest control practices that are less harmful to human health and natural resources.

Chemical composition and antifungal activity of Hyptis Suaveolens (L.) Poit leaves essential oil against Aspergillus species

This study aimed to identify the constituents of the essential oil from Hyptis suaveolens (L.) leaves using a Gas Chromatograph - Mass Spectrometer and assess its inhibitory effect on some potentially pathogenic Aspergilli (A. flavus, A. parasiticus, A. ochraceus, A. fumigatus and A. niger). Eucaliptol (47.64 %) was the most abundant component in the oil, followed for gama-ellemene (8.15 %), beta-pynene (6.55 %), (+)-3-carene (5.16 %), trans-beta-cariophyllene (4.69 %) and germacrene (4.86 %). The essential oil revealed an interesting anti-Aspergillus property characterized by a Minimum Inhibitory Concentration and Minimum Fungicidal Concentration of 40 and 80 µL/mL, respectively. The oil at 80 and 40 µL/mL strongly inhibited the mycelial growth of A. fumigatus and A. parasiticus along 14 days. In addition, at 10 and 20 µL/mL the oil was able to cause morphological changes in A. flavus as decreased conidiation, leakage of cytoplasm, loss of pigmentation and disrupted cell structure suggesting fungal wall degeneration. These findings showed the interesting anti-Aspergillus property of H. suaveolens leaves essential oil supporting its possible rational use as alternative source of new antifungal compounds to be applied in the aspergillosis treatment.

The potential of Origanum vulgare L. (Lamiaceae) essential oil in inhibiting the growth of some food-related Aspergillus species

Origanum vulgare L. (Lamiaceae) has been currently known for their interesting antimicrobial activity being regarded as alternative antimicrobial for use is food conservation systems. This study aimed to evaluate the effectiveness of O. vulgare essential oil in inhibiting the growth of some food-related Aspergillus species (A. flavus, A. parasiticus, A. terreus, A. ochraceus, A. fumigatus and A. niger). The essential oil revealed a strong anti-Aspergillus property providing an inhibition of all assayed mould strains. MIC values were between 80 and 20 μL/mL being found a MIC50 of 40 μL/mL. The essential oil at concentration of 80 and 40 μL/mL provided a fungicidal effect on A. flavus, A. fumigatus and A. niger noted by a total inhibition of the radial mycelial growth along 14 days of interaction. In addition, the essential oil was able to inhibit the mould spores germination when assayed at concentrations of 80 and 40 μL/mL. Our results showed the interesting anti-Aspergillus activity of O. vulgare essential oil supporting their possible use as anti-mould compound in food conservation.

Effects of Citrus sinensis (L.) Osbeck epicarp essential oil on growth and morphogenesis of Aspergillus niger (L.) Van Tieghem

Essential oils from different plant parts are known for their antimicrobial activity but the antifungal effects of essential oil from Citrus sinensis (L.) Osbeck epicarp on growth and morphogenesis of Aspergillus niger has not been observed so far. The mycelial growth was inhibited at 2.5 and 3.0 microg/ml of oil in Potato Dextrose Broth and Agar medium, respectively. These concentrations were fungicidal under the test conditions. The fungitoxicity of oil did not change even at exposure to 100 degrees C and autoclaving. The main changes observed under light and scanning electron microscopy after oil treatment were loss of cytoplasm in fungal hyphae, and budding of hyphal tip. The hyphal wall and its diameter became markedly thinner, distorted and resulted in cell wall disruption. The flattened and empty hyphal tips bifurcated into bud like structures. GC-MS studies of the oil revealed the presence of 10 chemical constituents. Limonene has been found to be major component (84.2%).

Primary flavonoids in marigold dye: extraction, structure and involvement in the dyeing process

Flavonoids extracted from marigold flowers were investigated for their dyeing potential. Patulitrin (1) and patuletin (2) were isolated and their structures established using NMR and HPLC-MS. These compounds were identified as the main flavonoids present in the dyeing bath. Following the dyeing process, it was demonstrated that aglycone 2 bound more strongly to wool fibres than its glucoside 1. Moreover, analysis focused on 1 and 2 dynamics during plant growth revealed that these components were only found in flowers during and after flowering. The influence of growing location was also investigated and it appeared that cultivation under Mediterranean conditions enhanced biosynthesis of 1 and 2 . Finally, several solvents were tested for their potential to extract the flavonoids: the use of a water-ethanol mixture gave a high extraction efficiency and allowed selective extraction of 1 and 2. The implications of these results are discussed in relation to the development of marigold as a potential dyeing plant.

Chicory extracts from Cichorium intybus L. as potential antifungals

In this work extracts from roots of the common vegetable Cichorium intybus L., highly appreciated for its bitter taste, were studied to investigate their possible biological activity on fungi from a variety of ecological environments: some are parasites on plants (phytopathogens) or of animals and humans (zoophilic and anthropophilic dermatophytes), others live on the soil and only seldom parasitize animals (geophilic dermatophytes). The extracts were ineffective on geophilic species and on tested phytopathogens, with the exception of Pythium ultimum, whereas they inhibited the growth of zoophilic and anthropophilic dermatophytes, in particular Trichophyton tonsurans var. sulfureum, whose treatment caused morphological anomalies, here observed by scanning electron microscopy. This behaviour is discussed on the basis of the presence in the chicory extract of the two main sesquiterpene lactones, 8-deoxylactucin and 11 beta,13-dihydrolactucin.