title: Anti-encystment and amoebicidal activity of Lonicera japonica Thunb. and its major constituent chlorogenic acid in vitro.
abstract: OBJECTIVE
  To examine the acanthamoebicidal effects of ethyl acetate, aqueous and butanol fractions of dried flower buds of Lonicera japonica (L. japonica) Thunb. (Flos Lonicerae) in vitro.
  
  
  METHODS
  Acanthamoeba triangularis isolates were obtained from environmental water samples and identified by PCR. They were exposed to ethyl acetate, water and butanol fractions of L. japonica Thunb. at concentrations ranging from 0.5 mg/mL to 1.5 mg/mL. The extracts were evaluated for growth inhibition at 24, 48 and 72 h, respectively. Chlorogenic acid at a concentration of 1 mg/mL was examined for inhibition of encystment.
  
  
  RESULTS
  Ethyl acetate fraction at a concentration of 1.5 mg/mL evoked a significant reduction of trophozoite viability by 48.9% after 24 h, 49.2% after 48 h and 33.7% after 72 h chlorogenic acid, the major active constituent of L. japonica Thunb. at the concentration of 1 mg/mL reduced the cysts/trophozoite ratio by 100% after 24 h, 84.0% after 48 h and 72.3% after 72 h. This phenolic compound at concentration of 1 mg/mL concurrent with 0.6% hydrogen peroxide inhibited hydrogen peroxide-induced encystment by 92.8% at 72 h.
  
  
  CONCLUSIONS
  Results obtained from this study show that ethyl acetate fraction at 1.5 mg/mL is the most potent fraction of L. japonica Thunb. and its major constituent chlorogenic acid showed the remarkable inhibition of encystment at a concentration of 1 mg/mL.
authors.affiliation: Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Tooba
authors.initials: T
authors.lastname: Mahboob
authors.affiliation: Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Abdul-Majid
authors.initials: AM
authors.lastname: Azlan
authors.affiliation: Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Tian-Chye
authors.initials: TC
authors.lastname: Tan
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Chandramathi
authors.initials: C
authors.lastname: Samudi
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Shamala Devi
authors.initials: SD
authors.lastname: Sekaran
authors.affiliation: Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia. Electronic address: veeranoot@um.edu.my.
authors.forename: Veeranoot
authors.initials: V
authors.lastname: Nissapatorn
authors.affiliation: School of Pharmacy, University of Nottingham Malaysia Campus, Jalan 56000 Semenyih, Kuala Lumpur, Malaysia.
authors.forename: Christophe
authors.initials: C
authors.lastname: Wiart
keywords: Acanthamoeba spp.; Amoebicidal; Chlorogenic acid; Encystment; Lonicera japonica Thunb.