How gamma radiation affects antimicrobial potential of medicinal plants: Mentha x piperita L. as a case study

Medicinal plants are being used by the food and pharmaceutic industries to extract relevant compounds. To be used in these industries as raw materials, it is required the non-presence of microorganisms. Therefore, it is essential that they undergo a decontamination process before entering processing lines, and these methods should not compromise their bioactive properties. In this context a non-thermal technology, gamma irradiation, was used as a decontamination procedure. For this purpose, samples of Mentha piperita L. (peppermint) was irradiated using a 60Co experimental chamber, at the doses of 1, 5, and 10 kGy. The hydroethanolic extracts were then further evaluated through the virucidal efficacy assay, using two enteric viruses – human adenovirus type-5 (HAdV-5) and murine norovirus type-1 (MNV-1, as a human norovirus surrogate). The antibacterial activity was evaluated against a set of Gram-positive and Gram-negative bacteria. For the virucidal activity, data suggested that the irradiation treatment of all species can preserve the natural properties of the plant against enteric viral pathogens. The hydroethanolic extracts of peppermint reveal a low antibacterial potential for all the tested bacteria. However, antibacterial activity of gamma irradiated samples did not affect this bioactivity for none of the microbial agents tested. Validation of antimicrobial potential of medicinal plants, after gamma irradiation processing, are scarce in the literature. This study allowed defining the influence of this treatment on the bioactive properties of peppermint.Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013), C2TN (UID/Multi/04349/2013), grant to A. Fernandes (SFRH/BPD/114753/2016) and L. Barros contract; European Structural and Investment Funds (ESIF) (Regional Operational Program Norte 2020, Project ValorNatural®); Rural Development Program (Project MicoCoating, PDR2020-101-031472); International Atomic Energy Agency (IAEA) Coordinated Research Project D61024 DEXAFI.info:eu-repo/semantics/publishedVersio

Effects of gamma radiation on the bioactivity of medicinal and aromatic plants: Mentha × piperita L., Thymus vulgaris L. and Aloysia citrodora Paláu as case studies

Irradiation is a feasible and safe decontamination technique, being applied to several types of foods including edible and medicinal plants. The aim of this study was to evaluate the effects of different gamma radiation doses (1, 5 and 10 kGy) on the individual profile of phenolic compounds determined by HPLC-DAD-ESI/MS, and the bioactive potential (cytotoxic, virucidal, and antimicrobial activities) of Aloysia citrodora Paláu (lemon verbena), Mentha × piperita L. (peppermint) and Thymus vulgaris L. (thyme). The observed cytotoxic activity varied with the plant and with the applied dose, being higher in Thymus vulgaris irradiated with 10 kGy. The virucidal activity was also dependent on the radiation dose, but was preserved with irradiation treatment. Gamma rays had no effect on the antimicrobial activity of the studied plants. Otherwise, the effects of gamma radiation on the phenolic profile were heterogeneous, with an increase in some compounds and decrease in others, depending on the species and on the radiation dose.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and the FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013), C2TN (UID/Multi/04349/2013), L. Barros and R. C. Calhelha contracts. The authors are grateful to the FEDER-Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_6_E.info:eu-repo/semantics/publishedVersio

Padrões de inactivação microbiana em hortelã-pimenta por radiação gama

As plantas podem ser utilizadas como aditivos alimentares e em benefício da saúde, como ingredientes em formulações de alimentos funcionais e nutracêuticos. Um dos principais problemas associado ao seu consumo e comercialização é a sua contaminação microbiana, que pode ocorrer ao longo da colheita, no processamento e na distribuição. Deste modo, torna-se necessário encontrar uma solução viável para a conservação de plantas comestíveis ou medicinais e que cumpra as normas de segurança alimentar e farmacêutica. Actualmente, o processamento de ervas e especiarias por radiação ionizante é reconhecido como uma tecnologia segura e eficaz na descontaminação e desinfecção microbiana. Porém, a maioria dos estudos em irradiação de plantas incide nos efeitos da tecnologia nas propriedades químicas das plantas. O objectivo específico deste trabalho foi estudar os padrões de inactivação por radiação gama da microbiota de Mentha x piperita (hortelã-pimenta). A metodologia seguida baseou-se na determinação da carga microbiana (bactérias mesófilas e fungos filamentosos) de amostras secas de hortelã-pimenta antes e após irradiação a várias doses de radiação gama (1,5 kGy a 10 kGy), recorrendo a métodos convencionais de cultura. As irradiações foram efectuadas num equipamento de 60Co a um débito de dose de 1,2 kGy/h. Os resultados obtidos indicaram uma cinética de inactivação não-linear (côncava) para a população bacteriana das plantas, e uma curva de sobrevivência linear para a população de fungos filamentosos. A análise da contaminação diferencial das amostras indicou após irradiação a 10 kGy, um decréscimo de 3 log em relação à carga bacteriana inicial de 5 log UFC/g, e uma redução de 2 log para a população fúngica inicial de 4 UFC/g. De referir, que não foi detectada a presença de coliformes totais nas amostras irradiadas a partir dos 1,5 kGy. As eficiências máximas de inactivação observadas nas condições do estudo foram de 99,9% para a população bacteriana e de 99% para a população fúngica. Assim, este estudo sugere a tecnologia de irradiação, como um tratamento promissor e mais amigo do ambiente, pretendendo-se validar a sua aplicação na descontaminação/desinfecção microbiana de plantas secas com interesse alimentar e medicinal, sobre as quais este tipo de processamento e seus efeitos não se encontra documentado.PRODER - Projecto AROMAP e FCT (Portugal) RECI/AAG-TEC/0400/2012 pelo apoio financeiro à execução do trabalho e à empresa “MaisErvas - Aromáticas e Medicinais” (Portugal), pela disponibilização das amostras

Effects of gamma irradiation on cytotoxicity and phenolic compounds of Thymus vulgaris L. and Mentha x piperita L.

The aim of the present study was to evaluate the effects of gamma irradiation on cytotoxicity and phenolic compounds of Thymus vulgaris L. and Menta × piperita L. (methanolic extracts), used in traditional medicine. Thirteen and fourteen phenolic compounds, including caffeoyl derivatives and flavonoid glycosides, were detected in T. vulgaris and Mentha piperita, respectively, none of which was affected by the irradiation dose used (10 kGy). Furthermore, the irradiation up to 10 kGy did not change the cytotoxic properties of peppermint samples on tumor cell lines (MCF-7, NCI-H460, HeLa and HepG2), whereas thyme samples irradiated at 10 kGy increased their cytotoxicity in the assayed tumor cell lines compared with samples submitted to 2 and 5 kGy. All in all, the dose of 10 kGy was considered as suitable to be applied for the purpose of disinfestation and microbial decontamination of these plants without modifying their phenolic composition and bioactive properties.The authors are grateful to Foundation for Science and Technology (FCT, Portugal) for financial support to CIMO (PEst-OE/AGR/ UI0690/2014), C2TN (RECI/AAG-TEC/0400/2012) R.C. Calhelha (SFRH/BPD/BPD/68344/2010) and L. Barros (SFRH/BPD/107855/ 2015). The authors are also grateful to Ministry of Agriculture, Portugal (Project AROMAP- PRODER/FEADER), for financial support of the work and E. Pereira and Andreia I. Pimenta grants, and to “MaisErvas - Aromáticas e Medicinais” company for providing the samples.info:eu-repo/semantics/publishedVersio

Effects of gamma radiation on cork wastewater: Antioxidant activity and toxicity

A comprehensive assessment of the toxicity and antioxidant activity of cork boiling wastewater and the effects of gamma radiation on these parameters was performed. Antioxidant activity was evaluated using different methodologies as DPPH radical scavenging activity, reducing power and inhibition of ß-carotene bleaching. The results have shown that gamma radiation can induce an increase on the antioxidant activity of cork boiling wastewater. Toxicity tests were performed to access the potential added value of the irradiated wastewaters and/or minimization of the impact for discharge in the environment. Two different methods for toxicity evaluation were followed, bacterial growth inhibition test and cytotoxicity assay, in order to predict the behavior of different cells (prokaryotic and eukaryotic) in the presence of cork wastewater. Non-treated cork boiling wastewater seemed to be non-toxic for prokaryotic cells (Pseudomonas fluorescens and Bacillus subtilis) but toxic for eukaryotic cells (A549 human cells and RAW264.7 mouse cells). The gamma radiation treatment at doses of 100 kGy appeared to increase the toxicity of cork compounds for all tested cells, which could be related to a toxic effect of radiolytic products of cork compounds in the wastewaters.This work was supported by Fundação para a Ciência e a Tecnologia (FCT, Portugal) through financial support of RECI/AAG-TEC/0400/2012 “Application of Ionizing Radiation for a Sustainable Environment” project. C2TN/IST authors gratefully acknowledge the FCT support through the UID/Multi/04349/2013 project. The authors are also grateful to International Atomic Energy Agency (Contract No. 16513) and to the cork industry (Amorim S.A) for allowing us to collect all the samples necessary for the accomplishment of this work.info:eu-repo/semantics/publishedVersio

Erratum for Oliveira et al., "K2 Capsule Depolymerase Is Highly Stable, Is Refractory to Resistance, and Protects Larvae and Mice from Acinetobacter baumannii Sepsis"

Volume 85, no. 17, e00934-19, 2019, https://doi.org/10.1128/AEM.00934-19. Page 10, Acknowledgments, lines 4 and 5: POCI-01-0145-FEDER-016678 should read POCI-01-0145-FEDER-016643.info:eu-repo/semantics/publishedVersio

The impact of gamma irradiation on the cytotoxic properties and phenolic composition of Thymus vulgaris L. and Menta x piperita L.

Irradiation has been increasingly recognized as an effective decontamination technique, also ensuring the chemical and organoleptic quality of medicinal and aromatic plants 1 . The use of medicinal plants in the prevention and or treatment of several diseases has revealed satisfactory results as anti-inflammatory, antimutagenic, anti-cancer and antioxidant agents 2 . The aim of the present study was to evaluate the effects of gamma irradiation on the cytotoxic properties and phenolic composition of Thymus vulgaris L. and Menta x piperita L. (methanolic extracts). Phenolic compounds were analyzed by HPLC-DAD-ESI MS, while the cytotoxicity of the samples was assessed in MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), HeLa (cervical carcinoma), HepG2 (hepatocellular carcinoma) cell lines, as also in non-tumor cells (PLP2). Thirteen and fourteen phenolic compounds were detected in T. vulgaris and M. piperita, respectively, but none of them was affected by the irradiation up to a dose of 10 kGy. However, despite there were no changes in the cytotoxic properties of irradiated peppermint samples in tumor cell lines, the thyme samples irradiated with 10 kGy showed higher cytotoxicity in comparison with the samples submitted to other doses (2 and 5 kGy). This highlights that 10 kGy can be a suitable dose to ensure the sanitary treatment, without modifying the bioactive composition and properties of these aromatic plants

Assessment of gamma radiation effects on antioxidant activity of cork wastewater

Cork cooking wastewater results from the process of boiling cork planks. It is an aqueous and complex dark liquor with high concentration of phenolic compounds such as phenolic acids and tannins [1, 2], which are known for their high antioxidant activity. The aim of this work is to perform a compreensive assessment of the effects of gamma radiation on the antioxidant activity of cork cooking water. The irradiation experiments were carried out at room temperature in a Co-60 experimental equipment (Prescisa 22, Graviner, Lda, UK), with an activity of 140 Tbq (3.77 kCi) and at a dose rate of 1.5 kGy/h, located at the Centro de Ciências e Tecnologias Nucleares (Portugal). Samples of wastewater were irradiated at. three distinct. doses (10, 20 and 50 KGy) and the antioxidant activity was evaluated by in vitro assays based on different mechanisms of action: DPPH radical scavenging activity, reducing power and inhibition of β-carotene bleaching. Antioxidant capacity was compared with the physico-chemical characterization [3) of cork wastewater - Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS) and Total Phenolic Content. (TP) - when exposed to gamma radiation. The obtained results point out that gamma radiation induces changes in complex compounds leading to an increase in the antioxidant capacity. These results demonstrate the potential of this technology in order to increase the added value of cork wastewaters.We are grateful to FCT (Portugal) by the supporting of RECI/AAG-TEC/0400/2012 "Application of lonizing Radiation for a Sustainable Environment" project and to lnternational Atomic Energy Agency (Austria) by the supporting of CRP 1539 - F23029 "Radiation Treatment of Wastewater for Reuse with Particular Focus on Wastewaters Containing Organic Pollutants"' project.info:eu-repo/semantics/publishedVersio

Use of gamma radiation in sheep butter manufacturing process for shelf-life extension

Gamma-irradiated sheep cream (1 kGy) was used to produce butter that was analysed during refrigerated storage up to 90 days in shelf-life extension studies including sensory, microbiological and water content assessments. The water content of the sheep butter made with irradiated fermented cream was 10% higher than that of control butter. A slower increase in bacterial load during storage was detected for the butter manufactured with irradiated fermented sheep cream compared with control butter; however, fungi increased at similar rates in both cream-irradiated and control butters during storage. The sensory evaluation suggested, in general, the acceptance of the irradiated samples by the panellists. The microbiocidal potential of gamma radiation of fermented sheep cream was highlighted, but was not reflected in extension of shelf-life of the butter produced. The traditional manufacturing process itself was found to be a major vehicle for microbial contamination of this dairy product, preventing its shelf-life extension.info:eu-repo/semantics/publishedVersio

Effects of gamma radiation on phenolic composition of medicinal plants: Aloysia Citrodora L. and Mentha X Piperita L. Infusions

Irradiation is a food processing technique supported by several globally recognized organizations (FAO, WHO, IAEA), being suitable for several food matrices, prolonging not only the shelf life of the food, but also providing microbiological decontamination. This work aimed to evaluate the effects of gamma radiation on the phenolic composition of Aloysia citrodora L. and Mentha x piperita L. infusions. Gamma radiation treatment was performed in a 60Co chamber, applying doses between 1 and 10 kGy and the results were compared with the control sample (non-irradiated, 0 kGy). The phenolic profile was determined and identified by HPLC-DAD-ESI/MS. Radiation treatment (at a dose of 10 kGy) caused statistically significant effects on the phenolic profile in both infusions, evidencing an increase in most of detected compounds, namely the majority ones. The same irradiation dose also induced an increase on the content of total phenolic acids and total phenolic compounds [1]. The results of this study can contribute to a wider knowledge of the effects of gamma irradiation on relevant bioactive compounds of several aromatic and medicinal plants, being recommended its application in these matrices.The authors are grateful FCT, Portugal and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013) and C2TN (UID/Multi/04349/2013); and to FEDER Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_6_E.info:eu-repo/semantics/publishedVersio