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Matos O.,Ip Inia Instituto Nacional Of Investigacao Agraria
Acta Horticulturae | Year: 2012

Aromatic plants are economically important due their flavouring, pharmacological or industrial utilities. The bioactivity of several substances synthesized by plants is triggered by absorption of solar light. Studies have been developed aiming to protect crops against pests and diseases by using this new type of natural substances whose activity is enhanced or started by the absorption of light. Natural photopesticides can act as potent herbicides and can control viruses, bacteria, algae, nematodes, yeasts and fungi. Present work relates to a large number of aromatic plants subjected to extraction procedures in the search of their potential as source for new natural photoactive plant products. The species Althaea officinalis, Calamintha baetica, Coriandrum sativum, Cuminum cyminum, Chelidonium majus, Ephedra fragilis, Juniperus comunnis, Laurus nobilis, Mentha pulegium, Origanum vulgare, Picris spinifera, Sambucus nigra, Satureja montana, Syzygium aromaticum and Thymus sp., traditionally used as spices or for medicinal purposes, were analysed for their photoactive potential. Plants were extracted in water or organic solvents, while essential oils were obtained by hydrodistillation. Both essential oils and extracts prepared were tested against the phytopathogenic fungi Aspergillus flavus, A. niger, Botrytis cinerea, Cladosporium cucumerinum, Fusarium culmorum; plant extracts were also tested on the bacteria Erwinia carotovora and Pseudomonas aeruginosa. For irradiation a sun light simulator was used. Effects of plants oil and extracts were detected, by comparing the microorganisms growth inhibition on the plates irradiated to those kept under dark. Strong photoactivity was observed to C. majus and C. cyminum both against fungi and bacteria; C. baetica, O. vulgare, P. spinifera and S. montana were very active, while L. nobilis was only slightly active. Good results observed for this set of plants enhances their antimicrobial properties and their photoactive potential. Source

Matos O.C.,Ip Inia Instituto Nacional Of Investigacao Agraria | Santos M.,Ip Inia Instituto Nacional Of Investigacao Agraria | Ramos P.,Ip Inia Instituto Nacional Of Investigacao Agraria | Graca Barreiro M.,Ip Inia Instituto Nacional Of Investigacao Agraria
Acta Horticulturae | Year: 2011

Aromatic plants can play a determinant role in several domains of agriculture being recognized as useful for food preservation, preventing molds and pest attacks that affect the quality of fresh fruits. Post-harvest deterioration of fruits due to water loss, senescence and development of physiological disorders and fungal attack cause decay in quality and economic losses. In the present work the extracts of a set of aromatic plants were assayed for their capability to control fungi affecting cold stored fruits. Assays were performed in vitro and in vivo using the 'Rocha' pear cultivar kept in cold chambers. Botrytis cinerea and Penicillium expansum, two main pathogens responsible for postharvest rots, were used as biological targets. Even though low concentrations were used, promising results were achieved, from the in vitro tests performed with extracts or oils of eight aromatic plants. Significant mycelia growth reduction of both fungi was obtained mainly with Origanum vulgare, Coriandrum sativum and Mentha pulegium. Successful in vivo assays were performed with O. vulgare either for preventing or to treat fungal infections. From tests performed with standard compounds corresponding to the main constituents of such aromatic plants, positive results were also obtained mainly with caprilic acid, benzoic acid and pulegone. The present work is a positive contribution to the knowledge on biological potentialities of aromatic plants and their helpfulness to the development of harmless strategies to post-harvest control of fruit rots. Source

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