“Polyphenols from Rosemary: Effect on phytophatogenic viruses”

SICILIANO F.; MARANO M.R.; MORENO S.

Malta

Simposio; III International Conference on Polyphenols Applications in Nutrition and Health – Satellite Symposium on Natural Antioxidants and Polyphenols: Valorization from Fruit & Vegetable Wastes.; 2006

International Society of Antioxidant in Nutrition and Health

There is increasing interest in the bioactive compounds of plant products. Studies of the antimicrobial activity of phenolic compounds usually concern in vitro bioassays against more or less common human pathogens and /or food storage microbes.  Previously, the effect of organic and water rosemary extracts on the growth of several Gram positive and negative bacteria was investigated and the antimicrobial rosemary extracts efficacy was associated with a specific polyphenols composition (Moreno, S. et al., Free Radical Research, 2006, 40: 223-231.). In this study we also showed that an organic rosemary extract strongly inhibited the growth of the phytopatogenic bacteria Xanthomonas campestris pv campestris with a minimal inhibitory concentration of 1 µg/ml and a minimal bactericide concentration of 60 µg/ml. The effect of these secondary metabolites on phytophatogenic microorganism has rarely been examined; here we evaluated the biological action of secondary metabolites present in non-volatile fraction of rosemary extract as well as pure polyphenols against a tobacco necrosis virus (TNV). Main active components in the rosemary preparations, carnosic acid and rosmarinic acid were also studied. The plant disease caused by tobacco necrosis virus is found worldwide. The virus is known to infect more than 150 types of herbaceous, dicotyledonous plants including many vegetables, flowers, and weeds. Infection by tobacco mosaic virus causes serious losses on several crops including tomatoes, peppers, and many ornamentals. The virus almost never kills plants but lowers the quality and quantity of the crop, particularly when the plants are infected while young. Unlike fungicidal chemicals used to control fungal diseases, to date there are no efficient chemical treatments that protect plant parts from virus infection. Thus, control of tobacco necrosis virus is primarily focused on reducing and eliminating sources of the virus and limiting the spread by insects. Tobacco necrosis virus is the most persistent plant virus known. It has been known to survive up to 50 years in dried plant parts. Antiviral action was tested by the infection of Nicotiana tabacum cv Petit Havana with TNV. Plants were sprayed with different concentrations of rosemary extracts, previously and after the infections, until the symptoms appear. Our results showed that rosemary extracts inhibits the growth of TNV, decreasing significantly the number and size of lesions in Nicotiana tabacum. These extracts are able to inhibit TNV virus infection at very low concentrations. Therefore, the rosemary preparations possess antioxidant properties and antiviral properties. Our results are relevant for the development of environmentally benign and toxicologically safe pest management agents.