Fungicidal and anti-aflatoxigenic effects of the essential oil of Cymbopogon citratus (DC.) Stapf. (lemongrass) against Aspergillus flavus Link. isolated from stored rice

Characterization and antimicrobial activity of essential oils extracted from lemongrass (Cymbopogon flexuosus) using microwave-assisted hydro distillation

Lemongrass (Cymbopogon flexuosus) essential oil (LGEO) contains α-citral, β-citral and other phytochemicals extracted using various methods. This research extracted essential oils using steam distillation (SD) and microwave-assisted hydro distillation (MAHD) to maximize quantity and purity. LGEO was tested for antibacterial properties. LGEO was extracted using SD and compared to MAHD output based on oil production and chemical composition. We performed GCMS to characterize LGEO. Fourier transform infrared spectroscopy (FTIR) used for quantum chemical analysis. Spectroscopic analysis showed that SD extracted secondary metabolites (ethyl-linalool, isogeranial, β-citral, α-citral, geranyl acetate, and caryophyllene) yielded 9.7 %, 11.5 %, 35.4 %, 13.4 %, 6.4 %, and 6.4 %, respectively, while MAHD yielded 10.2 %, 13.4 %, 43.2 %, 17.3 %, 6.9 %, and 7.3 %. MAHD extracted α and β citral content was better than SD extraction technique. FTIR spectroscopy and quantum chemistry analysis showed extracted oil chemical composition, electronic structure of α and β citral isomers. In the disc-diffusion experiment, both extracts were effective against Gram-positive and Gram-negative bacteria and harmful fungi. LGEO from SD and MAHD extraction (30 mg/mL) demonstrated disc diffusion assay antibacterial efficacy against microorganisms. The two extracts effectively inhibited microorganisms with MIC values of 3.75 and 7.5 μg/mL. It can be concluded that, LGEO have greater antimicrobial activity in MAHD extraction.

Repellency, Fumigant Toxicity, Antifeedent and Residual Activities of Coridothymus capitatus and Its Main Component Carvacrol against Red Flour Beetle

Tribolium castaneum is a challenging pest of stored products, causing significant economic losses. The present study explored the efficacy of Coridothymus capitatus essential oil and its primary constituent, carvacrol, as eco-friendly alternatives for managing this pest. To evaluate their insecticidal potential, repellency, fumigant toxicity, and antifeedant properties, progeny inhibition assays were performed. Carvacrol exhibited superior repellency compared to the essential oil, achieving a 92% repellency rate at 2 mg/cm2. Both compounds demonstrated significant fumigant toxicity against T. castaneum, with LC50 values of 168.47 and 106.5 μL/L for the essential oil and carvacrol, respectively, after 24 h. Carvacrol also outperformed the essential oil in antifeedant activity, inducing an 80.7% feeding deterrence at 1.17 mg/g. Moreover, both treatments effectively suppressed the development of the pest's progeny. These results collectively underscore the potent insecticidal properties of C. capitatus essential oil and carvacrol, particularly carvacrol, as promising candidates for the sustainable management of T. castaneum in stored product protection.

Ethnobotanical uses, phytochemistry and bioactivities of Cymbopogon plants: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Cymbopogon (Poaceae) plants have been used for various purposes by many indigenous peoples in all continents. In particular, almost all species in the genus have traditionally been used as folk medicine to treat ailments. Traditional application records indicated that Cymbopogon might be used extensively to treat cold, dizziness, headache, loss of appetite, abdominal pain, rheumatism, diarrhea, whole grass for cold, sore throat, tracheitis and others.

AIMS OF THE REVIEW

Despite several research confirmed that Cymbopogon includes a range of active components, no review has been undertaken to consolidate information on its traditional uses, phytochemistry, pharmacology, and/or quality control. Thus this article aims to update a comprehensive review about the traditional uses, phytochemistry, pharmacology, cultivation techniques, economic benefits, trade, threats, and future conservation implications of Cymbopogon species. It may provide informative data for future development and further investigation of this important plant group.

MATERIALS AND METHODS

Traditional medicinal books and ethnomedicinal publications related to Cymbopogon from 1992 to 2023 were collated to investigate its ethnobotanical, phytochemical and pharmacological information. The online databases including Google Scholar, SciFinder, Web of Science, Scopus, Springer Link, PubMed, Wiley, China National Knowledge Infrastructure (CNKI), Baidu Scholar, and WanFang Database were screened.

RESULTS

Cymbopogon (Gramineae or Poaceae) plants have been grown worldwide. Traditional Chinese medicine and other medicinal systems believes that Cymbopogon has the effect of relieve a cough, analgesia, treating dizziness, traumatic injury and can relieve abdominal pain. A total of 153 compounds, including flavonoids, terpenoids, fatty acid and other compounds were isolated or identified from Cymbopogon species by phytochemical studies. The extracts or compounds from Cymbopogon have exhibited numerous biological activities such as antibacterial, antiinflammatory, antiviral, antineoplastic, antiarrhythmic, antidiabetic and other activities. The rich contents of citronellal, citronellol and geraniol found in Cymbopogon also provide significant nutritional benefits.

CONCLUSION

Based on their traditional uses, phytochemicals, and pharmacological activities, Cymbopogon plants are potential medicinal and edible resources with diverse pharmacological effects. Due to various advantages of this group, they possess huge application potential in food and pharmaceutical industries, and animal husbandry. Among them, citronella is very important in terms of economic development. Further comprehensive research to evaluate the medicinal properties of Cymbopogon species will be necessary for future development.

Characterization and Antifungal Activity of Lemongrass Essential Oil-Loaded Nanoemulsion Stabilized by Carboxylated Cellulose Nanofibrils and Surfactant

Nanocellulose is an emerging green, biodegradable and biocompatible nanomaterial with negligible toxicities. In this study, a carboxylated nanocellulose (i.e., 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidized cellulose nanofibril (TEMPO-CNF)) was prepared from corn stover and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and differential scanning calorimetry (DSC)/thermogravimetric analysis (TGA). Corn stover-derived TEMPO-CNF was explored as an emulsion co-stabilizer together with Tween 80 for lemongrass essential oil-loaded emulsions. Droplet size, phase behavior and thermodynamic stability of oil-in-water emulsions stabilized by Tween 80 and TEMPO-CNF were investigated. The optimal nanoemulsion stabilized by this binary stabilizer could achieve a mean particle size of 19 nm, and it did not form any phase separation against centrifugal forces, freeze-thaw cycles and at least 30 days of room temperature storage. The nanoencapsulated essential oil had better inhibition activity against the mycelial growth of Aspergillus flavus than pure essential oil. Results from this study demonstrate the potential of using agricultural byproduct-derived nanomaterial as nanoemulsion stabilizers for essential oils with good emulsion thermodynamic stability as well as enhanced antifungal activities.

Green Synthesis of Zinc Oxide Nanoparticles Using Cymbopogon citratus Extract and Its Antibacterial Activity

Excessive use of antimicrobial medications including antibiotics has led to the emerging menace of antimicrobial resistance, which, as per the World Health Organization (WHO), is among the top ten public health threats facing humanity, globally. This necessitates that innovative technologies be sought that can aid in the elimination of pathogens and hamper the spread of infections. Zinc oxide (ZnO) has multifunctionality owing to its extraordinary physico-chemical properties and functionality in a range of applications. In this research, ZnO nanoparticles (NPs) were synthesized from zinc nitrate hexahydrate, by a green synthesis approach using Cymbopogon citratus extract followed by characterization of the NPs. The obtained X-ray diffraction peaks of ZnO NPs matched with the standard JCPDS card (no. 89-510). The particles had a size of 20-24 nm, a wurtzite structure with a high crystallinity, and hexagonal rod-like shape. UV-Vis spectroscopy revealed absorption peaks between 369 and 374 nm of ZnO NPs synthesized from C. citratus extract confirming the formation of ZnO. Fourier transform infrared confirmed the ZnO NPs as strong absorption bands were observed in the range of 381-403 cm-1 corresponding to Zn-O bond stretching. Negative values of the highest occupied molecular orbital-lowest unoccupied molecular orbital for ZnO NPs indicated the good potential to form a stable ligand-protein complex. Docking results indicated favorable binding interaction between ZnO and DNA gyrase subunit b with a binding energy of -2.93 kcal/mol. ZnO NPs at various concentrations inhibited the growth of Escherichia coli and Staphylococcus aureus. Minimum inhibitory concentration values of ZnO NPs against E. coli and S. aureus were found to be 92.07 ± 0.13 and 88.13 ± 0.35 μg/mL, respectively, at a concentration of 2 mg/mL. AO/EB staining and fluorescence microscopy revealed the ability of ZnO NPs to kill E. coli and S. aureus cells. Through the findings of this study, it has been shown that C. citratus extract can be used in a green synthesis approach to generate ZnO NPs, which can be employed as alternatives to antibiotics and a tool to eliminate drug-resistant microbes in the future.

Nanomaterials in food industry for the protection from mycotoxins: an update

The storage of food grains against the fungal infection has been a great challenge to the farmers, but nanotechnology provides a solution to address this problem. The application of nanotechnology for the storage of food grains replaces synthetic fungicides in agriculture. Inorganic nanoparticles such as silver and zinc oxide are well-known for their antifungal activity. Green synthesized nanoparticles show enhanced antimicrobial activity than the chemically synthesized nanoparticles. Extracts and essential oils derived from plants exhibit very good antifungal properties. The synthesized nanoparticles can be impregnated in packaging materials, which are used to store food grains. Natural materials are having advantages like non-toxicity and easier to degrade and are suitable for food safety. This overview discusses the nanomaterials-mediated protection of food materials from mycotoxin and its releases into the open environment.

Isoborneol as a natural sporulation quenching agent to control Aspergillus flavus

In an effort to seek natural antisporulating agents used in the control of Aspergillus flavus, 54 essential oil compounds were employed to evaluate their antisporulating activity against A. flavus at the concentration of 100 μg/mL. The results indicated that isoborneol could inhibit spore production at 100 μg/mL. The light microscopy and scanning electron microscopy (SEM) observations revealed that A. flavus did not produce any conidia, vesicles, phialides and conidiophores after treatment with isoborneol at 80 μg/mL, confirming the effectiveness of isoborneol. The in vivo bioassay results demonstrated that isoborneol could prevent the peanuts from A. flavus contamination by inhibiting the sporulation when treated with isoborneol at concentrations higher than 100 μg/mL. RT-qPCR results suggested that isoborneol exerts its antisporulating activity by suppressing the fluG expression. These results proved that isoborneol could be used as a natural and safe antisporulating agent for commercial applications to control spore infections of A. flavus.

Antioxidant Activity and Phenolic Content of Sonication- and Maceration-Assisted Ethanol and Acetone Extracts of Cymbopogon citratus Leaves

Cymbopogon citratus is a medicinal and well-known aromatic plant which is usually used as a substitute for green-tea with extraordinary phytomedicinal potential. It is of great importance because it offers several promising health effects. The objective of the study was to investigate the antioxidant activity and total phenolic content of lemongrass leaves extracted by maceration and ultrasound-assisted extraction techniques. Different concentrations of both acetone and ethanol (50% and 70%) as solvents were tested for their radical scavenging activity against the stable free radical DPPH in quantization using a spectrophotometric assay. The ultrasound-assisted extraction technique had advantageous results in the polyphenols extraction yield (26.68%), TPC (61 mg GAE/g of extract) and DPPH (73.85%) compared to the maceration technique. Overall, the results were significant from 50% ethanol and the DPPH results were more significant from 70% ethanol than other concentrations. It is concluded that the ultrasound-assisted extraction is a better extraction technique for polyphenols than other conventional techniques.

A methanolic extract of Zanthoxylum bungeanum modulates secondary metabolism regulator genes in Aspergillus flavus and shuts down aflatoxin production

Aflatoxin B1 (AFB1) is a food-borne toxin produced by Aspergillus flavus and a few similar fungi. Natural anti-aflatoxigenic compounds are used as alternatives to chemical fungicides to prevent AFB1 accumulation. We found that a methanolic extract of the food additive Zanthoxylum bungeanum shuts down AFB1 production in A. flavus. A methanol sub-fraction (M20) showed the highest total phenolic/flavonoid content and the most potent antioxidant activity. Mass spectrometry analyses identified four flavonoids in M20: quercetin, epicatechin, kaempferol-3-O-rhamnoside, and hyperoside. The anti-aflatoxigenic potency of M20 (IC₅₀: 2-4 µg/mL) was significantly higher than its anti-proliferation potency (IC₅₀: 1800-1900 µg/mL). RNA-seq data indicated that M20 triggers significant transcriptional changes in 18 of 56 secondary metabolite pathways in A. flavus, including repression of the AFB1 biosynthesis pathway. Expression of aflR, the specific activator of the AFB1 pathway, was not changed by M20 treatment, suggesting that repression of the pathway is mediated by global regulators. Consistent with this, the Velvet complex, a prominent regulator of secondary metabolism and fungal development, was downregulated. Decreased expression of the conidial development regulators brlA and Medusa, genes that orchestrate redox responses, and GPCR/oxylipin-based signal transduction further suggests a broad cellular response to M20. Z. bungeanum extracts may facilitate the development of safe AFB1 control strategies.

Antifungal and physicochemical properties of Ocimum essential oil loaded in poly(lactic acid) nanofibers

Poly(lactic acid) (PLA) nanofibers containing different proportions of the essential oils from Ocimum basilicum L. and Ocimum gratissimum L. were prepared by the solution blow spinning method. The essential oils were extracted by hydrodistillation and characterized by gas chromatography. MEV, contact angle, DSC, and FTIR were used to characterize the nanofibers. The effect of bioative nanofibers on the growth of the fungus and on the production of ochratoxin A were evaluated using the fumigation test. Linalool, 1.8-cineole and camphor were the principal components of the essential oil from O. basilicum, and eugenol was the principal constituent in the oil from O. gratissimum. An increase in the average diameter of the nanofibers was observed with the addition of the essential oils. The essential oils acted as a plasticizer, resulting in a reduction in the crystallinity of the PLA. The encapsulation of essential oils in PLA nanofibers was verified by FTIR. An effective antifungal and antimicotoxygenic activity against Aspergillus ochraceus and Aspergillus westerdjikiae was observed for the bioative nanofibers. These results confirm the potential of PLA nanofibers containing the essential oils for the control of toxigenic fungi that cause the deterioration of food and are harmful to human health.

Antifungal and Antiaflatoxinogenic Effects of Cymbopogon citratus, Cymbopogon nardus, and Cymbopogon schoenanthus Essential Oils Alone and in Combination

The antifungal and antiaflatoxinogenic activities of the essential oils (EOs) from the leaves of Cymbopogon schoenanthus, Cymbopogon citratus, Cymbopogon nardus, and their pair combinations were investigated. Antifungal susceptibility and the efficacy of paired combinations of EOs were assessed using agar microdilution and checkerboard methods, respectively. Identification and quantification of chemical components of the EOs were carried out by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector (GC-MS and GC-FID), respectively. Aflatoxins were separated and identified by High-Performance Liquid Chromatography (HPLC) and then quantified by spectrofluorescence. The EO of C. nardus exhibited the highest inhibitory activity against Aspergillus flavus and Aspergillus parasiticus. The combination of C. citratus and C. nardus and that of C. nardus and C. schoenanthus exhibited a synergistic effect against Aspergillus flavus and Aspergillus, respectively. Both C. citratus and C. schoenanthus EOs totally inhibited the synthesis of aflatoxin B1 at 1 µL/mL. C. citratus blocked the production of aflatoxins B2 and G2 at 0.5 µL/mL. Both C. citratus and C. schoenanthus totally hampered the production of the aflatoxin G1 at 0.75 µL/mL. The combination of C. citratus and C. schoenanthus completely inhibited the production of the four aflatoxins. The study shows that the combinations can be used to improve their antifungal and antiaflatoxinogenic activities.

Lemongrass essential oil and its major constituent citral isomers modulate adipogenic gene expression in 3T3-L1 cells

Obesity is a predisposing factor to diseases such as diabetes mellitus, hypertension, and coronary artery disease. Lemongrass essential oil (LEO), from Cymbopogon flexuosus, possesses numerous therapeutic properties including modulation of obesity in vivo. This experiment investigated the effect of LEO and its major components citral (3,7-dimethyl-2,6-octadienal), citral dimethyl acetal (1,1-dimethoxy-3,7-dimethylocta-2,6-diene), and citral diethyl acetal (1,1-diethoxy-3,7-dimethylocta-2,6-diene) in modulation of adipogenesis and genetic expression in adipocytes. Adipogenesis was induced from murine 3T3-L1 preadipocytes procured from ATCC and maintained in Dulbecco's modified Eagle's medium (DMEM) enriched with calf serum. Differentiation was conducted using DMEM enriched with 10% fetal bovine serum, Dexamethasone 0.25 µM, 3-isobutyl-methylxanthine 0.5 mM, and insulin 10 mg/ml for 2 days, followed by 5 days of insulin 10 mg/ml alone. Samples were subjected to experimental treatments at a concentration of 2.5 × 10^-3 . Intracellular triglycerides were quantified and photomicrographs were obtained following Oil red O (ORO) staining procedure. Total ribonucleic acid was extracted and expression of genes effecting in lipid metabolism were quantitated using real-time polymerase chain reaction. ORO staining procedure and spectrophotometric analysis demonstrated decreased lipid accumulation following treatments. LEO and its major constituents significantly inhibited expression of sterol response binding protein 2, cluster of differentiation 36, fatty acid binding protein 4, and peripilin. These results indicate modulation of lipid accumulation through decreased lipid uptake, increased lipolysis, decreased differentiation, and downregulated lipid biosynthesis. This investigation suggests that LEO and its constituents exert effects on adipocyte metabolism and are important for understanding metabolic disease. Further investigation is required to elucidate the degree that each mechanism implicated contributes to the observed effect.

Antiaflatoxigenic potential of essential oils of spices – a review

Mycotoxins are important food contaminants posing a significant threat to food and feed safety and public health. Among the mycotoxins, aflatoxins are deemed to be a more significant contaminant due to their potent carcinogenic, and hepatotoxic effects, and their levels are highly regulated in the international food trade. Phytochemicals are considered a major source of natural antifungal agents. The volatile nature of essential oil of plants makes them ideal candidates for antifungal agents due to their ability to distribute in free air spaces in closed containers and penetrate through heterogeneous food materials. In these, essential oils in spices attain special attention due to their commercial availability and low toxicity. This article reviews the antiaflatoxigenic capacity of spice essential oils and the effect of essential oil composition on the activity and mechanism of antifungal action and is expected to be useful for the planning of further research in the subject area.

Staphylococcus saprophyticus L-38 produces volatile 3,3-dimethyl-1,2-epoxybutane with strong inhibitory activity against Aspergillus flavus germination and aflatoxin production

Controlling proliferation and aflatoxin production by Aspergillus flavus is a pressing challenge for global food safety and security. Marine bacterium Staphylococcus saprophyticus strain L-38 showed excellent antifungal activity toward A. flavus in vitro and in vivo. In sealed, non-contact confrontation assays, L-38 completely inhibited conidial germination and mycelial growth of A. flavus through the production of volatile organic compounds (VOCs). Gas chromatography-mass spectrometry identified 3,3-dimethyl-1,2-epoxybutane (3-DE) as the most abundant VOC (32.61% of total peak area, 78% matching). Exposure of A. flavus cultures to synthetic 3-DE similarly demonstrated strong inhibition of growth. Moreover, culture of L-38 in a sealed chamber with maize or peanuts artificially inoculated with A. flavus, at high water activity, resulted in significant inhibition of A. flavus germination and aflatoxin biosynthesis. Scanning electron microscopy of these samples revealed severe damage to conidial cells and hyphae compared to samples not exposed to L-38. L-38 also showed broad and effective antifungal activity toward eight other phytopathogenic fungi including Aspergillus niger, Fusarium verticillioides, Fusarium graminearum, Sclerotinia sclerotiorum, Rhizoctonia solani, Alternaria alternata, Monilinia fructicola, and Botrytis cinerea. This work introduces S. saprophyticus L-38 as a potential biocontrol agent and demonstrates the efficacy of the volatile 3-DE in the control of A. flavus and other destructive plant pathogens for post-harvest food safety.

Anxiolytic Effect of Essential Oils and Their Constituents: A Review

Essential oils are usually used in aromatherapy to alleviate anxiety symptoms. In comparison to traditional drugs, essential oils have fewer side effects and more diversified application ways, including inhalation. This review provides a comprehensive overview of studies on anxiolytic effects of essential oils in preclinical and clinical trials. Most of the essential oils used in clinical studies have been proven to be anxiolytic in animal models. Inhalation and oral administration were two common methods for essential oil administration in preclinical and clinical trials. Massage was only used in the clinical trials, while intraperitoneal injection was only used in the preclinical trails. In addition to essential oils that are commonly used in aromatherapy, essential oils from many folk medicinal plants have also been reported to be anxiolytic. More than 20 compounds derived from essential oils have shown an anxiolytic effect in rodents, while two-thirds of them are alcohols and terpenes. Monoamine neurotransmitters, amino acid neurotransmitters, and the hypothalamic-pituitary-adrenal axis are thought to play important roles in the anxiolytic effects of essential oils.

Essential oils and their bioactive compounds as green preservatives against fungal and mycotoxin contamination of food commodities with special reference to their nanoencapsulation

Fungal and mycotoxin contamination of stored food items is of utmost concern throughout the world due to their hazardous effects on mammalian systems. Most of the synthetic chemicals used as preservatives have often been realised to be toxic to humans and also cause adverse environmental effects. In this respect, use of different plant products especially essential oils (EOs) and their bioactive compounds has been recognized as a green strategy and safer alternatives to grey synthetic chemicals in view of their long traditional use. The current nanoencapsulation technology has strengthened the prospective of EOs and their bioactive compounds in food preservation by enhancing their bioactivity and mitigating other problems regarding their large-scale application. Although, the antimicrobial potential of EOs and their bioactive compounds has been reviewed time to time by different food microbiologists, but very less is known about their mode of action. Based on these backgrounds, the present article provides an account on the antifungal and antimycotoxigenic mode of action of EOs as well as their bioactive compounds. In addition, the article also deals with the application of currently used nanoencapsulation approach to improve the stability and efficacy of EOs and their bioactive compounds against mycotoxigenic fungi causing deterioration of stored food items so as to recommend their large-scale application for safe preservation and enhancement of shelf life of food items during storage.

Antimicrobial Efficiency of Essential Oils from Traditional Medicinal Plants of Asir Region, Saudi Arabia, over Drug Resistant Isolates

Antimicrobial resistance (AMR) is a recurring global problem, which constantly demands new antimicrobial compounds to challenge the resistance. It is well known that essential oils (EOs) have been known for biological activities including antimicrobial properties. In this study, EOs from seven aromatic plants of Asir region of southwestern Saudi Arabia were tested for their antimicrobial efficacy against four drug resistant pathogenic bacterial isolates (Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Streptococcus typhimurium) and one fungal isolate (Candida albicans). Chemical compositions of EOs were determined by gas chromatography-mass spectrometry (GC-MS). The results revealed that EOs from Mentha cervina, Ocimum basilicum, and Origanum vulgare proved most active against all isolates with inhibitory zone range between 17 and 45 mm. The lowest minimum inhibitory concentration (MIC) of 0.025mg/ml was observed for Staph. aureus and Streptococcus pyogenes with EO of Origanum vulgare. All the three EOs showed significant anticandida activity. The results related to EOs from Mentha cervina, Ocimum basilicum, and Origanum vulgare demonstrated significant antimicrobial efficacy against drug resistant microorganisms.

Probiotics and plant-derived compounds as eco-friendly agents to inhibit microbial toxins in poultry feed: a comprehensive review

Some of pathogenic bacteria and fungi have the ability to produce fetal toxins which may be the direct causes of cytotoxicity or cellular dysfunction in the colonization site. Biological and non-biological environmental factors, challenge and microbes influence the effect of toxins on these pathogens. Modern research mentions that many natural materials can reduce the production of toxins in pathogenic microbes. However, researches that explain the mechanical theories of their effects are meager. This review aimed to discuss the ameliorative potential role of plant-derived compounds and probiotics to reduce the toxin production of food-borne microbes either in poultry bodies or poultry feedstuff. Moreover, studies that highlight their own toxicological mechanisms have been discussed. Adding natural additives to feed has a clear positive effect on the enzymatic and microbiological appearance of the small intestine without any adverse effect on the liver. Studies in this respect were proposed to clarify the effects of these natural additives for feed. In conclusion, it could be suggested that the incorporation of probiotics, herbal extracts, and herbs in the poultry diets has some beneficial effects on productive performance, without a positive impact on economic efficiency. In addition, the use of these natural additives in feed has a useful impact on the microbiological appearance of the small intestine and do not have any adverse impacts on intestinal absorption or liver activity as evidenced by histological examination.

Prospective of Essential Oils of the Genus Mentha as Biopesticides: A Review

Mentha is a genus from the family Lamiaceae, whose essential oils has long been used in various forms such as in management of plant pathogens and insect pests, in traditional medicine as well as in culinary and cosmetics. Its major chemical components such as menthol, carvone have now been successfully commercialized in the industry as antimicrobials/insecticidal agents. Current review focuses on chemical composition of essential oils of some Mentha species from different geographical regions with their insecticidal (repellent, antifeedant, and ovicidal) and antimicrobial efficacies against bacterial, fungal plant pathogens and insects of stored products. Reports of the researchers on chemical analysis of essential oils of Mentha species revealed that most of the oils being rich in pulegone, menthon, menthol, carvone, 1, 8-cineole, limonene and β-caryophyllene. Reviewed literature revealed that, essential oils from different Mentha species possess potential antimicrobial activity against plant pathogens and have insecticidal activity against stored product insects. Thus, antimicrobial and insecticidal properties of essential oils of Mentha species offer the prospect of using them as natural pesticides with a commercial value, having social acceptance due to its sustainability and being environment friendly.

Chemical Composition and In Vitro Antimicrobial Efficacy of Sixteen Essential Oils against Escherichia coli and Aspergillus fumigatus Isolated from Poultry

Escherichia coli and Aspergillus fumigatus are two pathogens largely present among poultry. They can cause mild or severe forms of disease, and are associated with significant economic losses. The aim of the present study was to investigate the chemical composition and the in vitro antimicrobial activity of sixteen essential oils (EOs) and five mixtures against E. coli and A. fumigatus strains previously isolated from poultry. The study was performed with the following EOs: Aloysiatryphilla, Boswelliasacra, Cinnamomum zeylanicum, Citrus aurantium, Citrus bergamia, Citrus limon, Citrus reticulata, Cymbopogon citratus, Eucalyptus globulus, Lavandula hybrida, Litsea cubeba, Ocimum basilicum, Melaleuca alternifolia, Mentha piperita, Pelargoniumgraveolens, and Syzygium aromaticum. Moreover, the following mixtures were also tested: L. cubeba and C. citratus (M1), L. cubeba and A. triphylla (M2), A. triphylla and C. citratus (M3), A. triphylla, C.citratus and L. cubeba (M4), S. aromaticum and C. zeylanicum (M5). One hundred and ninety-one compounds were identified in the tested EOs and mixtures. MIC determination found good anti-E. coli activity with C. zeylanicum (2.52 mg/mL), C. citratus (1.118 mg/mL), L. cubeba (1.106 mg/mL), M. piperita (1.14 mg/mL) and S. aromaticum (1.318 mg/mL) EOs. Among the mixtures, M5 showed the best result with a MIC value of 2.578 mg/mL. The best antimycotic activity was showed by A. triphylla (0.855 mg/mL), followed by C. citratus (0.895 mg/mL), while C. aurantium, M. piperita, B. sacra and P. graveolens did not yield any antifungal effect at the highest dilution. The mixtures exhibited no antifungal activity at all. This study shows promising results in order to use EOs in the environment for disinfection purposes in poultry farms and/or in hatcheries.

Impact of storage environment on respiration, dry matter losses and fumonisin B1 contamination of stored paddy and brown rice

The objective of this study was to compare the effect of different storage moisture conditions (0.90 and 0.95 water activity, aw) and temperatures (25, 30 °C) on (1) respiration rates (CO2; R), (2) dry matter loss (DML) of paddy and brown rice, (3) inoculation of both rice types with Fusarium verticillioides under these storage conditions on R, DML, and (4) effects on fumonisin B1 (FB1) contamination of these rice types. There was an increase in temporal CO2 production with wetter and warmer conditions in naturally contaminated rice. Higher R and consequently, percentage (%) DML were generally observed for brown rice (up to 21%) while in paddy rice this was only up to 3.5% DML. The FB1 production in paddy rice was low and similar in all treatments regardless of aw × temperature conditions. In the dehusked brown rice there were higher levels of contamination with FB1, with a maximum at 0.95 aw and 25 °C. A significant correlation between %DMLs and FB1 contamination was obtained (R=0.7454, P<0.01). These results suggest that monitoring of CO2 may provide an early indication of fungal activity in moist rice and help in evaluating the relative risk of spoilage and potential for mycotoxin contamination.

Facile one‐pot hydrothermal synthesis of stable and biocompatible fluorescent carbon dots from lemon grass herb

Luminescent carbon‐based nanomaterials hold great promise due to their stable photo‐physical behaviour, biocompatibility and lower toxicity. This work involves economic and facile one‐pot green synthesis of water‐soluble nanostructures from lemon grass (LGNS) [Cymbopogon citratus (DC) Stapf ] as carbon source. High‐resolution transmission electron microscopy confirmed the formation of LGNS with lattice spacing of 0.23 nm matching low‐dimensional graphitic structures. The strong absorption exhibited at 278 nm could be attributed to л‐states of sp2 /sp3 hybridisation in carbon nanostructures. Fluorescence spectroscopy of LGNS exhibited strong excitation‐dependent emission properties over a broad range of wavelengths from 300 to 600 nm. Quantitatively, these LGNS were estimated to have quantum yield of 23.3%. Biomass derived LGNS could be potentially exploited for wide variety of applications like bioimaging, up‐conversion, drug delivery and optoelectronic devices. To this extent, synthesised LGNS were used to image yeast cells via multicolour/multi‐excitation fluorescence imaging.

Citral, a Monoterpene Inhibits Adipogenesis Through Modulation of Adipogenic Transcription Factors in 3T3-L1 Cells

Obesity is considered as a major global human health problem which significantly increases the risk for development of type 2 diabetes. Citral, a bioactive compound widely found in a variety of foods that are consumed daily. In this study, we investigated the inhibitory effect of citral against adipogenic genes in 3T3-L1 cells. The mouse fibroblast 3T3-L1 pre-adipocytes were differentiated into adipocytes using adipogenic cocktail (5 g/ml insulin, 0.5 mM isobutylmethylxanthine and 10 M dexamethasone). Differentiation of adipocytes was evaluated by assessing triglyceride accumulation assay and cell viability by MTT assay. The PI3K/AKT signaling, adipogenic specific transcription factors (PPARγ, SREBP-1c, FAS and CPD) and inflammatory genes (TNF-α, IL-6 and MCP-1) were analyzed by western blotting and reverse transcriptase PCR in differentiated 3T3-L1 cell lines. In this study, triglyceride accumulation was increased in adipogenic cocktail induced 3T3-L1 cells, whereas treatment of citral significantly decreased levels of triglyceride accumulation in concentration dependent manner. Further, MTT assay shows that there was no reduction of cell viability during the differentiation of 3T3-L1 cells. The differentiated 3T3-L1 cell significantly increases the expression of PI3K/AKT, adipogenic transcription factors (PPARγ, SREBP-1c, FAS and CPD) and inflammatory biomarkers (TNF-α, IL-6 and MCP-1). Conversely, cells were treated with citral significantly suppress the expression of PI3K/AKT, PPARγ, SREBP-1c, FAS, CPD, TNF-α, IL-6 and MCP-1 in dose dependent manner. Thus, citral exhibits beneficial effects to inhibit adipogenesis in 3T3-L1 adipocytes through the modulation of adipogenic transcription factors and inflammatory markers.

Effects of Medicinal Plant Extracts and Photosensitization on Aflatoxin Producing Aspergillus flavus (Raper and Fennell)

This study was undertaken with an aim of exploring the effectiveness of medicinal plant extracts in the control of aflatoxin production. Antifungal properties, photosensitization, and phytochemical composition of aqueous and organic extracts of fruits from Solanum aculeastrum, bark from Syzygium cordatum, and leaves from Prunus africana, Ocimum lamiifolium, Lippia kituiensis, and Spinacia oleracea were tested. Spores from four-day-old cultures of previously identified toxigenic fungi, UONV017 and UONV003, were used. Disc diffusion and broth dilution methods were used to test the antifungal activity. The spores were suspended in 2 ml of each extract separately and treated with visible light (420 nm) for varying periods. Organic extracts displayed species and concentration dependent antifungal activity. Solanum aculeastrum had the highest zones of inhibition diameters in both strains: UONV017 (mean = 18.50 ± 0.71 mm) and UONV003 (mean = 11.92 ± 0.94 mm) at 600 mg/ml. Aqueous extracts had no antifungal activity because all diameters were below 8 mm. Solanum aculeastrum had the lowest minimum inhibitory concentration at 25 mg/ml against A. flavus UONV017. All the plant extracts in combination with light reduced the viability of fungal conidia compared with the controls without light, without extracts, and without both extracts and light. Six bioactive compounds were analyzed in the plant extracts. Medicinal plant extracts in this study can control conidia viability and hence with further development can control toxigenic fungal spread.

Essential Oils: Sources of Antimicrobials and Food Preservatives

Aromatic and medicinal plants produce essential oils in the form of secondary metabolites. These essential oils can be used in diverse applications in food, perfume, and cosmetic industries. The use of essential oils as antimicrobials and food preservative agents is of concern because of several reported side effects of synthetic oils. Essential oils have the potential to be used as a food preservative for cereals, grains, pulses, fruits, and vegetables. In this review, we briefly describe the results in relevant literature and summarize the uses of essential oils with special emphasis on their antibacterial, bactericidal, antifungal, fungicidal, and food preservative properties. Essential oils have pronounced antimicrobial and food preservative properties because they consist of a variety of active constituents (e.g., terpenes, terpenoids, carotenoids, coumarins, curcumins) that have great significance in the food industry. Thus, the various properties of essential oils offer the possibility of using natural, safe, eco-friendly, cost-effective, renewable, and easily biodegradable antimicrobials for food commodity preservation in the near future.

Chemical Compositions of Ligusticum chuanxiong Oil and Lemongrass Oil and Their Joint Action against Aphis citricola Van Der Goot (Hemiptera: Aphididae)

In order to develop novel botanical insecticides, the joint action of Ligusticum chuanxiong oil (LCO) and lemongrass oil (LO) against Aphis citricola van der Goot was determined systematically indoors and outdoors. The chemical profiles of LCO and LO as determined by gas chromatography-mass spectrometry (GC-MS) analysis revealed that the main compounds from LCO were (Z)-ligustilide (44.58%) and senkyunolide A (26.92%), and that of LO were geranial (42.16%) and neral (32.58%), respectively. The mixture of LCO and LO showed significant synergy against A. citricola, with a common-toxicity coefficient (CTC) value of 221.46 at the optimal ratio of LCO to LO (4:1, w:w). Based on the results of solvents and emulsifiers screening, L. chuanxiong oil·Lemongrass oil 20% emulsifiable concentrate (20% LCO·LO EC) was developed, and its stability was confirmed with tests of cold and thermal storage. Field trials indicated that the insecticidal activity of the diluted 20% LCO·LO EC (1000 fold dilution) was comparable to conventional pesticide (20% imidacloprid EC) on A. citricola seven days after application. Thus, the mixture of LCO and LO has the potential to be further developed as a botanical pesticide.

ROS Involves the Fungicidal Actions of Thymol against Spores of Aspergillus flavus via the Induction of Nitric Oxide

Aspergillus flavus is a well-known pathogenic fungus for both crops and human beings. The acquisition of resistance to azoles by A. flavus is leading to more failures occurring in the prevention of infection by A. flavus. In this study, we found that thymol, one of the major chemical constituents of the essential oil of Monarda punctate, had efficient fungicidal activity against A. flavus and led to sporular lysis. Further studies indicated that thymol treatment induced the generation of both ROS and NO in spores, whereas NO accumulation was far later than ROS accumulation in response to thymol. By blocking ROS production with the inhibitors of NADPH oxidase, NO generation was also significantly inhibited in the presence of thymol, which indicated that ROS induced NO generation in A. flavus in response to thymol treatment. Moreover, the removal of either ROS or NO attenuated lysis and death of spores exposed to thymol. The addition of SNP (exogenous NO donor) eliminated the protective effects of the inhibitors of NADPH oxidase on thymol-induced lysis and death of spores. Taken together, it could be concluded that ROS is involved in spore death induced by thymol via the induction of NO.

Evaluation of antioxidant and antifungal properties of the traditional plants against foodborne fungal pathogens

OBJECTIVE

To determine the antioxidant and antifungal activities of the essential oils from five aromatic herbs, including Thymus vulgaris, Chamaemelum nobile, Ziziphora clinopodioides, Zingiber officinale and Cuminum cyminum, against different Aspergillus and Penicillium species.

METHODS

The oils were subjected to screening for their possible antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The susceptibility test for the oils was carried out in terms of minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) using microdilution method.

RESULTS

The values of the essential oils in DPPH assay were as follows: T. vulgaris (450.11±5.23 μg/mL), Ch. nobile (602.73±4.8 μg/mL), Ziz. clinopodioides (1238.82±9.3 μg/mL), Cu. cyminum (1255.52±8.92 μg/mL) and Zin. officinale (5595.06±8.24 μg/mL). Our findings also indicated a strong activity against tested fungi for the oil of T. vulgaris (1250 μg/mL), followed by Cu. cyminum (1416 μg/mL), Zin. officinale (1833 μg/mL), Ziz. clinopodioides (2166 μg/mL) and Ch. nobile (3750 μg/mL). This study confirmed the excellent antifungal and antioxidant properties of the essential oils, especially T. vulgaris, against foodborne pathogenic fungi.

CONCLUSION

Owing to their strong protective features, these oils could be used in ethno-medicine as preventers of lipid peroxidation and cellular damage, and in food industries as preservers of foodstuffs against spoilage fungi. Also, they could be the candidates to develop new antibiotics and disinfectants to control infective agents.

Nation-Based Occurrence and Endogenous Biological Reduction of Mycotoxins in Medicinal Herbs and Spices

Medicinal herbs have been increasingly used for therapeutic purposes against a diverse range of human diseases worldwide. Moreover, the health benefits of spices have been extensively recognized in recent studies. However, inevitable contaminants, including mycotoxins, in medicinal herbs and spices can cause serious problems for humans in spite of their health benefits. Along with the different nation-based occurrences of mycotoxins, the ultimate exposure and toxicities can be diversely influenced by the endogenous food components in different commodities of the medicinal herbs and spices. The phytochemicals in these food stuffs can influence mold growth, mycotoxin production and biological action of the mycotoxins in exposed crops, as well as in animal and human bodies. The present review focuses on the occurrence of mycotoxins in medicinal herbs and spices and the biological interaction between mold, mycotoxin and herbal components. These networks will provide insights into the methods of mycotoxin reduction and toxicological risk assessment of mycotoxin-contaminated medicinal food components in the environment and biological organisms.

Cymbopogon citratus industrial waste as a potential source of bioactive compounds

BACKGROUND

Cymbopogon citratus (Cc), commonly known as lemongrass, is a very important crop worldwide, being grown in tropical countries. It is widely used in the food, pharmaceutical, cosmetic and perfumery industries for its essential oil. Cc aqueous extracts are also used in traditional medicine. They contain high levels of polyphenols, which are known for their antioxidant and anti-inflammatory properties. Hydrodistillation of lemongrass essential oil produces an aqueous waste (CcHD) which is discarded. Therefore a comparative study between CcHD and Cc infusion (CcI) was performed to characterize its phytochemical profile and to research its antioxidant and anti-inflammatory potential.

RESULTS

HPLC-PDA/ESI-MS(n) analysis showed that CcI and CcHD have similar phenolic profiles, with CcHD presenting a higher amount of polyphenols. Additionally, both CcI and CcHD showed antioxidant activity against DPPH (EC50 of 41.72 ± 0.05 and 42.29 ± 0.05 µg mL(-1) respectively) and strong anti-inflammatory properties, by reducing NO production and iNOS expression in macrophages and through their NO-scavenging activity, in a dose-dependent manner. Furthermore, no cytotoxicity was observed.

CONCLUSION

The data of this study encourage considering the aqueous solution from Cc leaf hydrodistillation as a source of bioactive compounds, which may add great industrial value to this crop.

Mass spectrometric identification and toxicity assessment of degraded products of aflatoxin B1 and B2 by Corymbia citriodora aqueous extracts

This study explores the detoxification potential of Corymbia citriodora plant extracts against aflatoxin B1 and B2 (AFB1; 100 μg L(-1) and AFB2; 50 μg L(-1)) in In vitro and In vivo assays. Detoxification was qualitatively and quantitatively analyzed by TLC and HPLC, respectively. The study was carried out by using different parameters of optimal temperature, pH and incubation time period. Results indicated that C. citriodora leaf extract(s) more effectively degrade AFB1 and AFB2 i.e. 95.21% and 92.95% respectively than C. citriodora branch extract, under optimized conditions. The structural elucidation of degraded toxin products was done by LCMS/MS analysis. Ten degraded products of AFB1 and AFB2 and their fragmentation pathways were proposed based on molecular formulas and MS/MS spectra. Toxicity of these degraded products was significantly reduced as compared to that of parent compounds because of the removal of double bond in the terminal furan ring. The biological toxicity of degraded toxin was further analyzed by brine shrimps bioassay, which showed that only 17.5% mortality in larvae was recorded as compared to untreated toxin where 92.5% mortality was observed after 96hr of incubation. Therefore, our finding suggests that C. citriodora leaf extract can be used as an effective tool for the detoxification of aflatoxins.

Detection of Aspergillus flavus in stored peanuts using real-time PCR and the expression of aflatoxin genes in toxigenic and atoxigenic A. flavus isolates

Aspergillus flavus is the main species from section Flavi responsible for aflatoxin accumulation in stored peanuts. Rapid methods to detect A. flavus could help to prevent aflatoxins from entering the food chain. A real-time polymerase chain reaction (RTi-PCR) assay was standardized for rapid, specific, and sensitive detection of A. flavus in stored peanuts. A. flavus was detected in 53.6% and 50% of peanut samples by RTi-PCR and A. flavus and Aspergillus parasiticus agar culture, respectively, with 95% agreement between them. Twenty-two A. flavus isolates were screened using high-performance liquid chromatography for their capacity to produce aflatoxin AFB1 (B1). B1 was produced by >72% of the isolates. Sixteen isolates produced B1 at concentrations ranging from 1.64 to 109.18 μg/mL. Four aflatoxin biosynthetic pathway genes (aflD, aflM, aflP, and aflQ) were evaluated using PCR and reverse-transcription PCR in 22 A. flavus isolates from peanut kernels with the aim of rapidly and accurately differentiating toxigenic and atoxigenic isolates. The PCR amplification of genes did not correlate with aflatoxin production capability. The expression of aflD and aflQ was a good marker for differentiating toxigenic from atoxigenic isolates.

Use of selected essential oils to control aflatoxin contaminated stored cashew and detection of aflatoxin biosynthesis gene

Aspergillus spp. associated with cashew from the regions of Riyadh, Dammam, and Abha were isolated and three different culture media were used to qualitatively measure aflatoxin production by Aspergillus via UV light (365 nm), which was expressed as positive or negative. The obtained data showed that six isolates of A. flavus and four isolates of A. parasiticus were positive for aflatoxin production, while all isolates of A. niger were negative. Five commercially essential oils (thyme, garlic, cinnamon, mint, and rosemary) were tested to determine their influence on growth and aflatoxin production in A. flavus and A. parasiticus by performing high-performance liquid chromatography (HPLC). The results showed that the tested essential oils caused highly significant inhibition of fungal growth and aflatoxin production in A. flavus and A. parasiticus. The extent of the inhibition of fungal growth and aflatoxin production was dependent on the type and concentration of essential oils applied. The results indicate that cinnamon and thyme oils show strong antimicrobial potential. PCR was used with four sets of primer pairs for nor-1, omt-1, ver-1, and aflR genes, enclosed in the aflatoxin biosynthetic pathway. The interpretation of the results revealed that PCR is a rapid and sensitive method.