Combined effect of high pressure treatment and anti-microbial bio-sourced materials on microorganisms' growth in model food during storage

Antimicrobial bio-sourced films based on poly(lactic acid) containing either carvacrol or allyl isothiocyanate (AITC) were prepared and their antimicrobial properties were assessed on Botrytis cinerea during storage and after a high pressure (HP) “pasteurisation-like” treatment (up to 800 MPa at ambient temperature). A dry process (extrusion + thermomoulding) was used to shape the material. The high temperature encountered during film processing dramatically decreased the carvacrol and AITC content in the film, leading to a less efficient antimicrobial activity. The use of β-cyclodextrin (β-CD) to encapsulate the active compounds before film processing proved to be efficient to protect the AITC against thermal degradation and to control its release from the films during its use. PLA-based films containing either AITC or β-CD encapsulated AITC showed a significant activity against B. cinerea. An effective combination between the antimicrobial activity of AITC-based films and the high pressure treatment was observed on a model food system (PDA) inoculated with N × 10⁴ (N ~ 1–9) conidia of B. cinerea. An HP treatment of only 300 MPa associated with an antimicrobial PLA/β-CD system providing an initial quantity of active agents equivalent to 4 mg of AITC/L of air (i.e. almost 2 folds lower than the minimal inhibition concentration of the active packaging used alone, which was determined to be equal to 10 mg/L of air in the same conditions) was found more efficient (total inhibition of B. cinerea growth during 10 days) than an 800 MPa HP treatment used alone (increase of the lag phase growth of 3.3 days).

Industrial relevance

The consumer demand for “fresh like” product containing reduced amount of preservatives without compromising human and environmental safety needs the development of new preservation strategies. As a consequence, the concept of “hurdle technologies” has risen up. The combined effect of HP treatment and volatile antimicrobial packaging allowed the use of lower individual treatment intensities to inhibit B. cinerea growth. Combining such “hurdles” is of relevance in the context of development of low-cost and eco-friendly food technologies.     

Recovery of allyl isothiocyanate from steam distillation condensate using adsorption

This paper describes the results of a study on use of the adsorption–regeneration technique for recovery of dissolved allyl isothiocyanate(AITC) which is present in significant quantities in steam distillation condensate of mustard essential oil (MEO). Equilibrium and dynamic breakthrough studies were carried out. The adsorbents used were polymeric adsorbents: Amberlite XAD‐2, Amberlite XAD‐4, Amberlite XAD‐7, NPA‐1 and NPA‐2. The results obtained indicate that Amberlite XAD‐4 is the best amongst these various adsorbents. AITC recoveries in excess of 95% were obtained, indicating the feasibility of this approach. Further, since no chemical reactions are involved the recovered AITC retains its ‘natural’ origin. © 2000 Society of Chemical Industry     

Activation of Drosophila melanogaster TRPA1 Isoforms by Citronellal and Menthol

Background: The transient receptor potential ankyrin 1 (TRPA1) cation channels function as broadly-tuned sensors of noxious chemicals in many species. Recent studies identified four functional TRPA1 isoforms in Drosophila melanogaster (dTRPA1(A) to (D)), but their responses to non-electrophilic chemicals are yet to be fully characterized. Methods: We determined the behavioral responses of adult flies to the mammalian TRPA1 non-electrophilic activators citronellal and menthol, and characterized the effects of these compounds on all four dTRPA1 channel isoforms using intracellular Ca²⁺ imaging and whole-cell patch-clamp recordings. Results: Wild type flies avoided citronellal and menthol in an olfactory test and this behavior was reduced in dTrpA1 mutant flies. Both compounds activate all dTRPA1 isoforms in the heterologous expression system HEK293T, with the following sensitivity series: dTRPA1(C) = dTRPA1(D) > dTRPA1(A) ≫ dTRPA1(B) for citronellal and dTRPA1(A) > dTRPA1(D) > dTRPA1(C) > dTRPA1(B) for menthol. Conclusions: dTrpA1 was required for the normal avoidance of Drosophila melanogaster towards citronellal and menthol. All dTRPA1 isoforms are activated by both compounds, but the dTRPA1(B) is consistently the least sensitive. We discuss how these findings may guide further studies on the physiological roles and the structural bases of chemical sensitivity of TRPA1 channels.     

环糊精包埋强化异硫氰酸烯丙酯抑菌效果的研究

异硫氰酸烯丙酯具有很强且广谱的杀菌作用,但强烈的气味及挥发性限制了其在食品防腐上的广泛应用.本论文利用β-环糊精对异硫氰酸烯丙酯进行分子包埋,通过控制释放方式,提高了异硫氰酸烯丙酯的抑菌效果,改善了刺激的气味;同时将液态油转变为固体粉末,方便了其在实际领域中的应用.     

Allyl Isothiocyanate (AITC) Induces Apoptotic Cell Death In Vitro and Exhibits Anti-Tumor Activity in a Human Glioblastoma GBM8401/luc2 Model

Some clinically used anti-cancer drugs are obtained from natural products. Allyl isothiocyanate (AITC), a plant-derived compound abundant in cruciferous vegetables, has been shown to possess an anti-cancer ability in human cancer cell lines in vitro, including human brain glioma cells. However, the anti-cancer effects of AITC in human glioblastoma (GBM) cells in vivo have not yet been examined. In the present study, we used GBM8401/luc2 human glioblastoma cells and a GBM8401/luc2-cell-bearing animal model to identify the treatment efficacy of AITC. Here, we confirm that AITC reduced total cell viability and induced cell apoptosis in GBM8401/luc2 cells in vitro. Furthermore, Western blotting also showed that AITC induced apoptotic cell death through decreased the anti-apoptotic protein BCL-2, MCL-1 expression, increased the pro-apoptotic protein BAX expression, and promoted the activities of caspase-3, -8, and -9. Therefore, we further investigated the anti-tumor effects of AITC on human GBM8401/luc2 cell xenograft mice. The human glioblastoma GBM8401/luc2 cancer cells were subcutaneously injected into the right flank of BALB/c nude mice to generate glioblastoma xenograft mice. The animals were randomly divided into three groups: group I was treated without AITC (control); group II with 0.1 mg/day of AITC; and group III with 0.2 mg/day of AITC every 3 days for 27 days. Bodyweight, and tumor volume (size) were recorded every 3 days. Tumors exhibiting Luc2 intensity were measured, and we quantified intensity using Living Image software on days 0, 12, and 24. After treatment, tumor weight from each mouse was recorded. Tumor tissues were examined for histopathological changes using H&E staining, and we analyzed the protein levels via immunohistochemical analysis. Our results indicate that AITC significantly inhibited tumor growth at both doses of AITC due to the reduction in tumor size and weight. H&E histopathology analysis of heart, liver, spleen, and kidney samples revealed that AITC did not significantly induce toxicity. Body weight did not show significant changes in any experiment group. AITC significantly downregulated the protein expression levels of MCL-1, XIAP, MMP-9, and VEGF; however, it increased apoptosis-associated proteins, such as cleaved caspase-3, -8, and -9, in the tumor tissues compared with the control group. Based on these observations, AITC exhibits potent anti-cancer activity in the human glioblastoma cell xenograft model via inhibiting tumor cell proliferation and the induction of cell apoptosis. AITC may be a potential anti-GBM cancer drug that could be used in the future.     

Release of Allyl Isothiocyanate from Mustard Seed Meal Powder

Allyl isothiocyanate (AITC) is a wide‐spectrum antimicrobial compound found in mustard seeds, produced when their tissues are disrupted. The formation of AITC in mustard seed is mediated by the myrosinase enzyme which catalyzes the release of volatile AITC from a glucosinolate—sinigrin. Since water is a substrate in the reaction, humidity from the air can be used to activate the release of AITC from mustard seed. In this study, defatted and partially defatted mustard seed meals were ground into powders with particle size ranging from 5 to 300 μm. The mustard seed meal powder (MSMP) samples were enclosed within hermetically sealed glass jars wherein the headspace air was adjusted to 85% or 100% relative humidity at 5, 20, or 35 °C. Data from gas chromatography analysis showed that AITC release rate and amount increased with increasing relative humidity and temperature. Moreover, the release rate can be manipulated by particle size and lipid content of the MSMP samples. The amount of AITC released ranged from 2 to 17 mg/g MSMP within 24 h under the experimental conditions tested. In view of the antimicrobial properties of AITC, the mustard meal powder may be used as a natural antimicrobial material for extending the shelf life of food products.     

不同药剂对书虱的毒力及其复配与联用增效作用

为书虱的抗性治理提供科学指导,本研究采用培养皿药膜法测定了4种储粮保护剂对5种书虱的触杀毒力,并采用广口瓶密闭熏蒸法测定了8种植物精油对嗜卷书虱的熏蒸活性。同时,评估了药剂复配及其与辣根素精油联用对嗜卷书虱的协同毒力。结果表明,书虱对马拉硫磷、甲基嘧啶磷、高效氯氰菊酯和溴氰菊酯均表现出较高敏感性,LD50在0.041～0.977 μg/cm2之间,可作为敏感基线使用;辣根素精油对书虱的熏蒸活性最高。马拉硫磷和溴氰菊酯复配配比为4:5时,增效作用最佳;而甲基嘧啶磷和高效氯氰菊酯配比在2:1时,增效作用最佳。此外,辣根素与甲基嘧啶磷或高效氯氰菊酯联用均具有增效作用。本研究不仅为书虱抗药性监测提供了药剂敏感基线,而且为书虱化学防治的减药增效和抗性治理提供了新的思路。     

Complexation of allyl isothiocyanate by α- and β-cyclodextrin and its controlled release characteristics

The complexation of allyl isothiocyanate (AITC) by α- and β-cyclodextrin (CD) and its controlled release characteristics were investigated in this paper. Almost 100% of inclusion capacity was achieved at the AITC/CD molar ratio of 2:1 using a coprecipitation method, combined with water washing. The controlled release behaviour of the incorporated AITC was significantly affected by relative humidity (RH) and the type of CD. The release was accelerated with increased RH, and the release rate of AITC in the α-CD-AITC complex was much slower than that in the β-CD-AITC complex. Subsequent analysis with GC demonstrated that the headspace concentration of AITC over β-CD-AITC complex in a hermetical system was significantly dependent on RH, and could finally be at a different equilibrium level at various storage times.     

Functional Transient Receptor Potential Ankyrin 1 and Vanilloid 1 Ion Channels Are Overexpressed in Human Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a common cancer with poor prognosis. Transient Receptor Potential Ankyrin 1 (TRPA1) and Vanilloid 1 (TRPV1) receptors are non-selective cation channels expressed on primary sensory neurons and epithelial and immune cells. TRPV1 mRNA and immunopositivity, as well as TRPA1-like immunoreactivity upregulation, were demonstrated in OSCC, but selectivity problems with the antibodies still raise questions and their functional relevance is unclear. Therefore, here, we investigated TRPA1 and TRPV1 expressions in OSCC and analyzed their functions. TRPA1 and TRPV1 mRNA were determined by RNAscope in situ hybridization and qPCR. Radioactive ₄₅Ca²⁺ uptake and ATP-based luminescence indicating cell viability were measured in PE/CA-PJ41 cells in response to the TRPA1 agonist allyl-isothiocyanate (AITC) and TRPV1 agonist capsaicin to determine receptor function. Both TRPA1 and TRPV1 mRNA are expressed in the squamous epithelium of the human oral mucosa and in PE/CA-PJ41 cells, and their expressions are significantly upregulated in OSCC compared to healthy mucosa. TRPA1 and TRPV1 activation (100 µM AITC, 100 nM capsaicin) induced ₄₅Ca²⁺-influx into PE/CA-PJ41 cells. Both AITC (10 nM–5 µM) and capsaicin (100 nM–45 µM) reduced cell viability, reaching significant decrease at 100 nM AITC and 45 µM capsaicin. We provide the first evidence for the presence of non-neuronal TRPA1 receptor in the OSCC and confirm the expression of TRPV1 channel. These channels are functionally active and might regulate cancer cell viability.     

异硫氰酸烯丙酯的分子包埋物在不同温度下的控制释放

本论文利用β-环糊精对异硫氰酸烯丙酯进行分子包埋,将液态油转变为固体的包合物粉末,同时对其释放特性进行研究。结果表明,异硫氰酸烯丙酯可以和β-环糊精形成包合物,包合物中异硫氰酸烯丙酯的释放速度与环境的相对湿度密切相关,释放过程可以用Avrami方程进行较好的拟和。环糊精的包埋释放反应是一个动态的可逆过程,在密闭体系中存在一个异硫氰酸烯丙酯的顶空平衡浓度。