Chitosan based encapsulation of Valeriana officinalis essential oil as edible coating for inhibition of fungi and aflatoxin B1 contamination, nutritional quality improvement, and shelf life extension of Citrus sinensis fruits.

In this study, a novel chitosan nanoemulsion coating embedded with Valeriana officinalis essential oil (Ne-VOEO) was synthesized in order to improve the postharvest quality of Citrus sinensis fruits against infesting fungi, and aflatoxin B1 (AFB1) mediated nutritional deterioration. The developed nanoemulsion was characterized through SEM, FTIR, XRD, and DLS analyses. The nanoemulsion showed controlled delivery of VOEO responsible for effective inhibition of Aspergillus flavus, A. niger, A. versicolor, Penicillium italicum, and Fusarium oxysporum growth at 6.5, 5.0, 4.0, 5.5, and 3.5 µL/mL, respectively and AFB1 production at 5.0 µL/mL. The biochemical and molecular mechanism of aflatoxigenic A. flavus inhibition, and AFB1 diminution was associated with impairment in ergosterol biosynthesis, methylglyoxal production, and stereo-spatial binding of valerianol in the cavity of Ver-1 protein. During in vivo investigation, Ne-VOEO coating potentially restrained the weight loss, and respiratory rate of C. sinensis fruits with delayed degradation of soluble solids, titrable acidity, pH, and phenolic contents along with maintenance of SOD, CAT, APX activities (p < 0.05) and sensory attributes under specific storage conditions. Based on overall findings, Ne-VOEO nanoemulsion could be recommended as green, and smart antifungal coating agent in prolonging the shelf-life of stored fruits with enhanced AFB1 mitigation.

Silicon nanoforms in crop improvement and stress management.

Although, silicon - the second most abundant element in the earth crust could not supersede carbon (C) in the competition of being the building block of life during evolution, yet its presence has been reported in some life forms. In case of the plants, silicon has been reported widely to promote the plant growth under normal as well as stressful situations. Nanoform of silicon is now being explored for its potential to improve plant productivity and its tolerance against various stresses. Silicon nanoparticles (SiNPs) in the form of nanofertilizers, nanoherbicides, nanopesticides, nanosensors and targeted delivery systems, find great utilization in the field of agriculture. However, the mechanisms underlying their uptake by plants need to be deciphered in detail. Silicon nanoformss are reported to enhance plant growth, majorly by improving photosynthesis rate, elevating nutrient uptake and mitigating reactive oxygen species (ROS)-induced oxidative stress. Various studies have reported their ability to provide tolerance against a range of stresses by upregulating plant defense responses. Moreover, they are proclaimed not to have any detrimental impacts on environment yet. This review includes the up-to-date information in context of the eminent role of silicon nanoforms in crop improvement and stress management, supplemented with suggestions for future research in this field.

Mechanistic investigations on antifungal and antiaflatoxigenic activities of chemically characterised Carum carvi L. essential oil against fungal infestation and aflatoxin contamination of herbal raw materials.

This study aimed to investigate the efficiency of chemically characterised Carum carvi essential oil (CcEO) against aflatoxin B1 (AFB1) producing strain of Aspergillus flavus (AF-LHP-WS-4) causing deterioration of herbal raw materials (HRM). GC-MS analysis of the EO revealed the presence of carvone (69.85%) as a dominant component. CcEO caused complete suppression of A. flavus growth and AFB1 secretion at 0.7 and 0.6 µL/mL, respectively. The investigation on antifungal mode of action showed that CcEO inhibited fungal growth via abrogating ergosterol biosynthesis and triggered efflux of vital cellular ions. The inhibition of AFB1 biosynthesis was attributed to the inhibition of cellular methylglyoxal (MG) biosynthesis. In addition, CcEO showed remarkable antioxidant activity (IC50 = 10.564 µL/mL) against DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals. Based on overall results, it can be concluded that the CcEO may be recommended as potential antifungal agent for protection of HRM from fungal infestation and AFB1 contamination.

Assessment of nanoencapsulated Cananga odorata essential oil in chitosan nanopolymer as a green approach to boost the antifungal, antioxidant and in situ efficacy.

In this study, a comparative efficacy of Cananga odorata EO (CoEO) and its nanoencapsulated formulation into chitosan nanoemulsion (CoEO-CsNe) against a toxigenic strain of Aspergillus flavus (AF-M-K5) were investigated for the first time in order to determine its efficacy in preservation of stored food from fungal, aflatoxin B1 (AFB1) contamination and lipid peroxidation. GC and GC-MS analysis of CoEO revealed the presence of linalool (24.56%) and benzyl acetate (22.43%) as the major components. CoEO was encapsulated into chitosan nanoemulsion (CsNe) through ionic-gelation technique and characterized by High Resolution-Scanning Electron Microscopy (HR-SEM), Fourier Transform Infrared spectroscopy (FTIR), and X-Ray Diffraction (XRD) analysis. The CoEO-CsNe during in vitro investigation against A. flavus completely inhibited the growth and AFB1 production at 1.0 µL/mL and 0.75 µL/mL, respectively. Additionally, CoEO-CsNe showed improved antioxidant activity against DPPH• and ABTS•+ with IC50 value 0.93 and 0.72 µL/mL, respectively. Further, CoEO-CsNe suppressed fungal growth, AFB1 secretion and lipid peroxidation in Arachis hypogea L. during in situ investigation without causing any adverse effect on seed germination. Overall results demonstrated that the CoEO-CsNe has potential of being utilized as a suitable plant based antifungal agent to improve the shelf-life of stored food against AFB1 and lipid peroxidation mediated biodeterioration.

Assessment of chemically characterized Salvia sclarea L. essential oil and its combination with linalyl acetate as novel plant based antifungal, antiaflatoxigenic and antioxidant agent against herbal drugs contamination and probable mode of action.

The present investigation reports antifungal and antiaflatoxigenic efficacy of Salvia sclarea essential oil (SSEO) and its combination with Linalyl acetate (LA) (1:1) against herbal drug deteriorating molds and aflatoxin B1 contamination. GC-MS analysis of SSEO showed Linalyl Acetate (LA) (61.33%) and Linalool (LL) (17.59%) as major components. The SSEO and LA combination displayed better antifungal and antiaflatoxigenic activity as compared to SSEO and LA used individually. SSEO and LA combination was effective in reduction of ergosterol and enhanced leakage of vital ions and UV-absorbing materials in a dose dependent manner. The combination caused significant reduction in cellular methylglyoxal content, an aflatoxin inducer suggesting its future application for development of aflatoxin resistant herbal drug varieties through green transgenics. The combination also showed pronounced antioxidant activity as compared to SSEO and LA used separately. Interestingly, the combination showed significant in situ protection of Picrorhiza kurroa rhizomes against mould infestation.

Zingiber zerumbet L. essential oil-based chitosan nanoemulsion as an efficient green preservative against fungi and aflatoxin B1 contamination.

The present study envisages the potential application of chitosan-coated Zingiber zerumbet essential oil nanoemulsion (ZEO-CsNE) as green antimicrobial preservative against Aspergillus flavus, aflatoxin B1 (AFB1 ), and lipid peroxidation of stored functional foods. GC-MS analysis of ZEO exhibited the abundance of cis-geraniol (15.53%) as the major component. ZEO-CsNE showed biphasic release profile during in vitro release study conducted for 10 days. The ZEO-CsNE inhibited the growth of A. flavus (strain AF-LHP-SH1) and AFB1 production at 1.0 and 0.8 µL/mL, respectively. Interestingly, considerable reduction in ergosterol biosynthesis followed by enhanced leakage of vital cellular contents and methylglyoxal inhibition represents novel antifungal and antiaflatoxigenic mechanism of action, respectively. Further, ZEO-CsNE inhibited lipid peroxidation and AFB1 production in postharvest Salvia hispanica seeds during in situ trial and presented favorable safety profile (median lethal dose [LD50 ] = 29,114 µL/kg) for male mice. Based on overall observations, ZEO-CsNE could be recommended as a green antimicrobial substitute of synthetic preservatives for in vitro and in situ protection of functional food samples. PRACTICAL APPLICATION: Food industries are facing enormous amount of burden coming from fungal and aflatoxin contamination that can cause severe adverse effects to humans. Essential oils (EOs) are well known for their food preservative efficacy; however, some limitations such as oxidative instability in open system may limit their application directly into food system. The encapsulation of the EOs into polymeric matrix could provide a barrier that will protect the EOs from degradation. This research could provide a basis for utilization of EO after encapsulation into chitosan nanoemulsion for industrial-scale application for preservation of stored functional foods from fungal and aflatoxin contamination.

Improvement of in vitro and in situ antifungal, AFB1 inhibitory and antioxidant activity of Origanum majorana L. essential oil through nanoemulsion and recommending as novel food preservative.

Origanum majorana essential oil (OmEO) encapsulated into chitosan nanoemulsion is being reported as a novel preservative of stored food items against fungi, aflatoxin B1 (AFB1) contamination and lipid peroxidation. The major component of OmEO identified through GC-MS was terpinen-4-ol (28.92%). HR-SEM, FTIR and XRD analyses confirmed successful encapsulation of OmEO into chitosan nanoemulsion (OmEO-CsNe). The results showed remarkable improvement in efficacy after nanoencapsulation, since OmEO-CsNe completely inhibited the growth and AFB1 production by Aspergillus flavus at 1.0 µL/mL, which was 2.5 and 1.5 µL/mL, respectively for OmEO. The inhibition of ergosterol followed by release of cellular ions and 260 and 280 nm absorbing materials demonstrated plasma membrane as possible antifungal target. Inhibition of methylglyoxal confirmed antiaflatoxigenic mode of action. OmEO-CsNe showed enhanced antioxidant activity (IC50 = 14.94 and 5.53 µL/mL for DPPH and ABTS, respectively) and caused in situ inhibition of lipid peroxidation and AFB1 production in maize (third most important staple crop after wheat and rice) without altering their sensory attributes and presented safety profile (LD50 = 11,889 µL/kg) when tested on mice. The findings indicate that the encapsulation considerably enhances the performance of OmEO, therefore can be recommended as a promising antifungal agent to extend the shelf-life of food items.

Fabrication, characterization and practical efficacy of Myristica fragrans essential oil nanoemulsion delivery system against postharvest biodeterioration.

The present study deals with encapsulation of Myristica fragrans essential oil (MFEO) into chitosan nano-matrix, their characterization and assessment of antimicrobial activity, aflatoxin inhibitory potential, safety profiling and in situ efficacy in stored rice as environment friendly effective preservative to control the postharvest losses of food commodities under storage. Surface morphology of MFEO-chitosan nanoemulsion as well as encapsulation of MFEO was confirmed through SEM, FTIR and XRD analysis. In vitro release characteristics with biphasic burst explained controlled volatilization from nanoencapsulated MFEO. Unencapsulated MFEO exhibited fungitoxicity against 15 food borne molds and inhibited aflatoxin B1 secretion by toxigenic Aspergillus flavus LHP R14 strain. In contrast, nanoencapsulated MFEO showed better fungitoxicity and inhibitory effect on aflatoxin biosynthesis at lower doses. In situ efficacy of unencapsulated and nanoencapsulated MFEO on stored rice seeds exhibited effective protection against fungal infestation, aflatoxin B1 contamination, and lipid peroxidation. Both the unencapsulated and nanoencapsulated MFEO did not affect the germination of stored rice seeds confirming non-phytotoxic nature. In addition, negligible mammalian toxicity of unencapsulated MFEO (LD50 = 14,289.32 µL/kg body weight) and MFEO loaded chitosan nanoemulsion (LD50 = 9231.89 µL/kg body weight) as revealed through favorable safety profile recommend the industrial significance of nanoencapsulated MFEO as an effective green alternative to environmentally hazardous synthetic pesticides for protection of food commodities during storage.

Assessment of chemically characterised Myristica fragrans essential oil against fungi contaminating stored scented rice and its mode of action as novel aflatoxin inhibitor.

The study reports chemically characterised Myristica fragrans essential oil (MFEO) as plant based food preservative against fungal and aflatoxin B1 (AFB1) contamination of scented rice varieties. The chemical profile of MFEO revealed elemicin (27.08%), myristicine (21.29%) and thujanol (18.55%) as major components. The minimum inhibitory and minimum aflatoxin inhibitory concentrations of MFEO were 2.75 and 1.5 mg/ml, respectively. The MFEO was efficacious against a broad spectrum of food deteriorating fungi. MFEO caused decrease in ergosterol content of fungal plasma membrane and enhanced leakage of cellular ions, depicting plasma membrane as the site of action. The MFEO caused reduction in cellular methylglyoxal content, the aflatoxin inducer. This is the first report on MFEO as aflatoxin suppressor. The essential oil may be recommended as plant based food preservative after large scale trials and reduction in methylglyoxal suggests its application for development of aflatoxin resistant varieties through green transgenics.

Nanoencapsulated Illicium verum Hook.f. essential oil as an effective novel plant-based preservative against aflatoxin B1 production and free radical generation.

The study reports efficacy of Illicium verum essential oil (IvEO) against food borne moudls and its nanoencapsulation for enhancing antifungal and antiaflatoxigenic potency. Chemical characterization of the IvEO showed anethole (89.12%) as major compound followed by estragole (4.859%). The IvEO showed broad fungitoxic spectrum against common food borne moulds. It's minimum inhibitory concentration (MIC) and minimum aflatoxin B1 inhibitory concentration (MAIC) against aflatoxigenic strain Aspergillus flavus LHP-PV-1 were 0.7, and 0.5 µL/mL respectively. Morphological observations of treatment sets by SEM and TEM along with decrease in ergosterol content and enhanced leakage of Ca2+, K+ and Mg2+ ions denoted fungal cell membrane as site of action. The IvEO showed promising free radical scavenging activity and favourable safety profile with high LD50 value on mice. The IvEO also exhibited considerable protection of Pistacia vera from fungal contamination and complete protection from aflatoxin B1 contamination in storage containers. Nanoencapsulated IvEO in gel form and lyophilized form exhibited enhanced efficacy as fungal inhibitor and aflatoxin suppressor. The chemically characterised IvEO may be recommended as plant based preservative having favourable safety and its nanocapsules may be of industrial significance as shelf life enhancer of food items. This is the first report on in situ antiaflatoxigenic efficacy and nanoencapsulation of IvEO.

Chemically characterized Mentha cardiaca L. essential oil as plant based preservative in view of efficacy against biodeteriorating fungi of dry fruits, aflatoxin secretion, lipid peroxidation and safety profile assessment.

The study reports Mentha cardiaca essential oil (EO) as plant based preservative against fungal and aflatoxin contamination of stored dry fruits. Mycoflora analysis of the dry fruits revealed Aspergillus favus LHP-PV-1 as the most aflatoxigenic isolate with highest Aflatoxin B1 content. M. cardiaca EO showed broad fungitoxic spectrum inhibiting the tested moulds contaminating dry fruits. It's minimum inhibitory concentration (MIC), minimum aflatoxin inhibitory concentration (MAIC) and minimum fungicidal concentration (MFC) against A. favus LHP-PV-1 were recorded to be 1.25, 1.0 and 2.25 µL/mL respectively. The EO caused decrease in ergosterol content and enhanced leakage of Ca2+, K+ and Mg2+ ions from treated fungal cells, depicting fungal plasma membrane as the site of antifungal action. The EO showed promising DPPH free radical scavenging activity (IC50 value:15.89 µL/mL) and favourable safety profile with LD50 value (7133.70 mg/kg body wt.) when estimated through acute oral toxicity on mice. Carvone (61.62%) was recorded as the major component of the oil during chemical characterisation through GC-MS. Based on strong antifungal, antiaflatoxigenic and antioxidant potential, the chemically characterised M. cardiaca EO may be recommended as safe plant based preservative and shelf life enhancer of food items. This is the first report on antifungal and antiaflatoxigenic activity of M. cardiaca EO.

Efficacy of Mentha spicata essential oil in suppression of Aspergillus flavus and aflatoxin contamination in chickpea with particular emphasis to mode of antifungal action.

The present study reports in vivo antifungal and antiaflatoxigenic efficacy of Mentha spicata essential oil (EO) against toxigenic Aspergillus flavus strain LHP(C)-D6 in chickpea food system up to 12 months of storage. In addition, the mode of antifungal action of EO was also determined to understand the mechanism of fungal growth inhibition. The in vivo study with different concentrations of M. spicata EO showed dose-dependent decrease in fungal colony count as well as aflatoxin B1 concentration. The EO caused >50% protection in inoculated sets and >70% protection in uninoculated sets of chickpea food system against A. flavus at 1.0 µL mL(-1) air concentration. However, at the same concentration, EO caused 100% inhibition to aflatoxin B1 production in both sets when analyzed through high-performance liquid chromatography (HPLC). The antifungal target of EO in fumigated cells of A. flavus was found to be the plasma membrane when analyzed through electron microscopic observations and ions leakage test. The EO fumigated chickpea seeds showed 100% seed germination and seedling growth after 12 months of storage. Based on these observations, M. spicata EO can be recommended as plant-based preservative for safe protection of food commodities during storage conditions against fungal and most importantly mycotoxin contaminations.

LIB spectroscopic and biochemical analysis to characterize lead toxicity alleviative nature of silicon in wheat (Triticum aestivum L.) seedlings.

The responses of wheat seedling treated with silicon (Si; 10 µM) and lead (Pb; 100 µM) for 7 days have been investigated by analyzing growth, Pb uptake, chlorophyll fluorescence, oxidative stress, antioxidants and nutrients regulation. Results indicated that, Pb significantly (P<0.05) declined growth of seedlings which was accompanied by uptake of Pb. Under Pb stress, fluorescence parameters: Fv/Fm ratio and qP were significantly (P<0.05) decreased while NPQ was increased. Si addition alleviated Pb-induced decrease in growth and alterations in photosynthesis, and also significantly (P<0.05) lowered Pb uptake. Under Pb treatment, oxidative stress markers: hydrogen peroxide and lipid peroxidation were enhanced while DPPH(•) scavenging capacity and total phenolic compounds (TPCs) were decreased significantly, however, Si addition improved the status of antioxidants. The non-protein thiols (NP-SH) showed enhanced level under Pb stress. Pb stress considerably disturbed status of the nutrients as decrease in Ca, P, Mg, Zn and Ni contents while an increase in K, S, B, Cu, Fe, Mn and Na contents were noticed. Si addition maintained status of all the nutrients remarkably. The quickest method of element analysis: LIBS spectra revealed significantly lower uptake of Pb in seedlings grown under Si and Pb combination and same was correlated with the data of AAS. Overall results pointed out that excess Pb uptake disturbed status of nutrients, photosynthetic performance, antioxidant capacity, hence severe oxidative damage to lipids occurred. Further, Si supplementation successfully regulated these parameters by inhibiting Pb uptake hence maintained growth of wheat seedlings. Similar pattern of data recorded by the LIBS, AAS and ICAP-AES confirmed that LIBS may be one of the promising and authentic tools to monitor the mineral and metal distribution in the plants without hampering or disturbing the environment due to its eco-friendly and non-invasive nature.

Efficacy of chemically characterized Piper betle L. essential oil against fungal and aflatoxin contamination of some edible commodities and its antioxidant activity.

The study investigates fungal contamination in some dry fruits, spices and areca nut and evaluation of the essential oil (EO) of Piper betle var. magahi for its antifungal, antiaflatoxigenic and antioxidant properties. A total of 1651 fungal isolates belonging to 14 species were isolated from the samples and Aspergillus was recorded as the dominant genus with 6 species. Eleven aflatoxin B(1) (AFB(1)) producing strains of A. flavus were recorded from the samples. Eugenol (63.39%) and acetyleugenol (14.05%) were the major components of 32 constituents identified from the Piper betle EO through GC and GC-MS analysis. The minimum inhibitory concentration (MIC) of P. betle EO was found 0.7 microl/ml against A.flavus. The EO reduced AFB(1) production in a dose dependent manner and completely inhibited at 0.6 microl/ml. This is the first report on efficacy of P. betle EO as aflatoxin suppressor. EO also exhibited strong antioxidant potential as its IC(50) value (3.6 microg/ml) was close to that of ascorbic acid (3.2 microg/ml) and lower than that of the synthetic antioxidants such as butylated hydroxytouene (BHT) (7.4 microg/ml) and butylated hydroxyanisole (BHA) (4.5 microg/ml). P. betle EO thus exhibited special merits possessing antifungal, aflatoxin suppressive and antioxidant characters which are desirable for an ideal preservative. Hence, its application as a plant based food additive in protection and enhancement of shelf life of edible commodities during storage and processing is strongly recommended in view of the toxicological implications by synthetic preservatives.

Effect of Citrus reticulata and Cymbopogon citratus essential oils on Aspergillus flavus growth and aflatoxin production on Asparagus racemosus.

Essential oils extracted from Citrus reticulata and Cymbopogon citratus were tested in vitro against the toxigenic strain of Aspergillus flavus, isolated from the tuberous roots of Asparagus racemosus, used in preparation of herbal drugs. The essential oils completely inhibited the growth of A. flavus at 750 ppm and also exhibited a broad fungitoxic spectrum against nine additional fungi isolated from the roots. Citrus reticulata and Cymbopogon citratus essential oils completely inhibited aflatoxin B(1) production at 750 and 500 ppm, respectively. During in vivo investigation, the incidence of fungi and aflatoxin B(1) production decreased considerably in essential oil-treated root samples. The findings thus indicate possible exploitation of the essential oils as effective inhibitor of aflatoxin B(1) production and as post-harvest fungitoxicant of traditionally used plant origin for the control of storage fungi. These essential oils may be recommended as plant-based antifungals as well as aflatoxin B(1) suppressors in post-harvest processing of herbal samples.

Chemical composition, antifungal and antiaflatoxigenic activities of Ocimum sanctum L. essential oil and its safety assessment as plant based antimicrobial.

The study deals with the efficacy of Ocimum sanctum essential oil (EO) and its major component, eugenol against the fungi causing biodeterioration of food stuffs during storage. O. sanctum EO and eugenol were found efficacious in checking growth of Aspergillus flavus NKDHV8; and, their minimum inhibitory concentrations (MICs) were recorded as 0.3 and 0.2 microl ml(-1), respectively. The O. sanctum EO and eugenol also inhibited the aflatoxin B1 production completely at 0.2 and 0.1 microl ml(-1), respectively. Both of these were found superior over some prevalent synthetic antifungals and exhibited broad fungitoxic spectrum against 12 commonly occurring fungi. The LD50 value of O. sanctum EO on mice was found to be 4571.43 microl kg(-1) suggesting its non-mammalian toxic nature. The findings of present study reveals the possible exploitation of O. sanctum EO and eugenol as plant based safe preservatives against fungal spoilage of food stuffs during storage.

Efficacy of Lippia alba (Mill.) N.E. Brown essential oil and its monoterpene aldehyde constituents against fungi isolated from some edible legume seeds and aflatoxin B1 production.

The present study deals with evaluation of antifungal properties of Lippia alba essential oil (EO) and two of its monoterpene aldehyde constituents against legume-contaminating fungi. Seventeen different fungal species were isolated from 11 varieties of legumes, and aflatoxigenic isolates of Aspergillus flavus were identified. Hydrodistillation method was used to extract the EO from fresh leaves. The GC and GC-MS analysis of EO revealed the monoterpene aldehydes viz. geranial (22.2%) and neral (14.2%) as the major components. The antifungal activity of EO, geranial and neral was evaluated by contact assay on Czapek's-dox agar. The EO (0.25-1 microL/mL) and its two constituents (1 microL/mL) showed remarkable antifungal effects against all the fungal isolates (growth inhibition range 32.1-100%). Their minimal inhibitory (MIC) and fungicidal (MFC) concentrations for A. flavus were lower than those of the systemic fungicide Bavistin. Aflatoxin B(1) (AFB(1)) production by three isolates of A. flavus was strongly inhibited even at the lower fungistatic concentration of EO and its constituents. There was no adverse effect of treatments on seed germination, and rather, there was enhanced seedling growth in the EO-treated seeds. It is concluded that L. alba EO and two of its constituents could be safely used as effective preservative for food legumes against fungal infections and mycotoxins.