Effects of Oakmoss and its Components on <i>Acanthamoeba</i><i> castellanii</i> ATCC 30234 and the Uptake of <i>Legionella pneu</i><i>mophila</i> JCM 7571 (ATCC 33152) into <i><i>A. castellanii</i></i>

Abstract

Acanthamoeba castellanii, a ubiquitous organism in water environments, is pathogenic toward humans and also is a host for bacteria of the genus Legionella, a causative agent of legionellosis. Oakmoss, a natural fragrance ingredient, and its components are antibacterial agents specifically against the genus Legionella. In the present study, oakmoss and its components were investigated for their amoebicidal activity against A. castellanii ATCC 30234 and the inhibitory effect on the uptake of L. pneumophila JCM 7571 ATCC 33152 into A. castellanii. The oakmoss and its components 3-hydroxy-5-methylphenyl 2,4-dihydroxy-6-methylbenzoate 5 , and 6,8-dihydroxy-3-pentyl-1H-isochromen-1-one 12 exhibited high amoebicidal activity IC 50 values 10.5 2.3, 16.3 4.0 and 17.5 2.8 µg/mL, respectively after 48 h of treatment, which were equivalent to that of the reference compound, chlorhexidine gluconate. Pretreatment of L. pneumophila with sub-minimal inhibitory concentration of oakmoss, compound 5, 3-hydroxy-5-methylphenyl 2-hydroxy-4-methoxy-6-methylbenzoate 10 and 8-2,4-dihydroxy-6-pentylphenoxy -6-hydroxy-3-pentyl-1H-isochromen-1-one 14 obviously reduced the uptake of L. pneumophila into A. castellanii p 0.05 . The inhibitory effect of compound 5 on the uptake of L. pneumophila was almost equivalent to that of ampicillin used as a reference. Thus, the oakmoss and its components were considered to be good candidates for disinfectants against not only genus Legionella but also A. castellanii.

Drug Discovery against Acanthamoeba Infections: Present Knowledge and Unmet Needs

“…Traditionally many drugs with biological activity were discovered from natural compounds. Among a plethora of natural compounds tested, a few examples include Ipomoea spp., Kaempferia galanga, Cananga odorata [101], oakmoss (a natural fragrance ingredient) [102], a hexane fraction of Pterocaulon polystachyum (Asteraceae) [103], ethyl acetate extract of Limouni olive leaf [104], resveratrol and curcuminoids [105] were found to be amoebicidal. Of note, resveratrol is of high interest for further investigation because it can prevent amoeba binding to the human brain microvascular endothelial cells (hBMECs) and it is selective to A. castellanii, but not the hBMECs [105].…”

Effects of Fragrance Ingredients on the Uptake of <i>Legionella pneumophila</i> into <i>Acanthamoeba castellanii</i>

“…Further, the effects of these fragrance ingredients on L. pneumophila uptake into A. castellanii were evaluated. L. pneumophila uptake experiments were performed using a partially modified method of Nomura et al 2015 . A. castellanii suspension 1 10 5 cells/ mL were inoculated into a 96-well microtiter plate Sumitomo Bakelite Co. Ltd., Tokyo, Japan .…”