title: Antibacterial activities of naturally occurring compounds against Mycobacterium avium subsp. paratuberculosis.
abstract: The antibacterial activities of 18 naturally occurring compounds (including essential oils and some of their isolated constituents, apple and green tea polyphenols, and other plant extracts) against three strains of Mycobacterium avium subsp. paratuberculosis (a bovine isolate [NCTC 8578], a raw-milk isolate [806R], and a human isolate [ATCC 43015]) were evaluated using a macrobroth susceptibility testing method. M. avium subsp. paratuberculosis was grown in 4 ml Middlebrook 7H9 broth containing 10% oleic acid-albumin-dextrose-catalase, 0.05% Tween 80 (or 0.2% glycerol), and 2 microg/ml mycobactin J supplemented with five concentrations of each test compound. The changes in the optical densities of the cultures at 600 nm as a measure of CFU were recorded at intervals over an incubation period of 42 days at 37 degrees C. Six of the compounds were found to inhibit the growth of M. avium subsp. paratuberculosis. The most effective compound was trans-cinnamaldehyde, with a MIC of 25.9 microg/ml, followed by cinnamon oil (26.2 microg/ml), oregano oil (68.2 microg/ml), carvacrol (72.2 microg/ml), 2,5-dihydroxybenzaldehyde (74 microg/ml), and 2-hydroxy-5-methoxybenzaldehyde (90.4 microg/ml). With the exception of carvacrol, a phenolic compound, three of the four most active compounds are aldehydes, suggesting that the structure of the phenolic group or the aldehyde group may be important to the antibacterial activity. No difference in compound activity was observed between the three M. avium subsp. paratuberculosis strains studied. Possible mechanisms of the antimicrobial effects are discussed.
authors.affiliation: Institute of Agri-Food and Land Use, School of Biological Sciences, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, United Kingdom. ywong04@qub.ac.uk
authors.forename: Stella Y Y
authors.initials: SY
authors.lastname: Wong
authors.forename: Irene R
authors.initials: IR
authors.lastname: Grant
authors.forename: Mendel
authors.initials: M
authors.lastname: Friedman
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Elliott
authors.forename: Chen
authors.initials: C
authors.lastname: Situ
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D018533:Biomass; D002417:Cattle; D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D006801:Humans; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D016927:Mycobacterium avium subsp. paratuberculosis / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D013053:Spectrophotometry
chemical_list: D000995:Antitubercular Agents; D003470:Culture Media; D010936:Plant Extracts