ABSTRACT
Multipurpose contact lens disinfecting solutions (MPDS) are widely used to cleanse and disinfect microorganisms. However, disinfection efficacy of these MPDS against Acanthamoeba cyst remain insufficient. 2, 6-dichlorobenzonitrile (DCB), a cellulose synthesis inhibitor, is capable of increasing the amoebical effect against Acanthamoeba by inhibiting its encystation. In this study, we investigated the possibility of DCB as a disinfecting agent to improve the amoebicidal activity of MPDS against Acanthamoeba cyst. Eight commercial MPDS (from a to h) were assessed, all of which displayed insufficient amoebicidal activity against the mature cysts. Solution e, f, and h showed strong amoebicidal effect on the immature cysts. Amoebicidal efficacy against mature cysts remained inadequate even when the 8 MPDS were combined with 100 μM DCB. However, 4 kinds of MPDS (solution d, e, f, and h) including 100 μM DCB demonstrated strong amoebicidal activity against the immature cysts. The amoebicidal activity of solution d was increased by addition of DCB. Cytotoxicity was absent in human corneal epithelial cells treated with either DCB or mixture of DCB with MPDS. These results suggested that DCB can enhance the amoebicical activity of MPDS against Acanthamoeba immature cyst in vitro.
Subject(s)
Humans , Acanthamoeba , Cellulose , Disinfection , Epithelial Cells , In Vitro TechniquesABSTRACT
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.
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.
ABSTRACT
Objective To determine antiacanthamoebic activity of natural and marketed honey samples. Methods Natural honey samples were collected directly from the bee hive and marketed honey samples were purchased from the local market in Karachi, Pakistan. Both honey samples were tested for their flavonoid content (quercetin equivalent per gram of the extract) and phenolic content (gallic acid equivalent per gram). Furthermore, their antioxidant activity was determined by measuring 2,2-diphenyl-1-picrylhydrazyl. Using amoebistatic and amoebicidal assays, the effects of honey samples were tested against growth and viability of Acanthamoeba parasites. Results Natural honey exhibited potent amoebistatic and amoebicidal effects, in a concentration-dependent manner. Honey-treated Acanthamoeba castellanii showed loss of acanthopodia, following which amoebae detached, rounded up, reduced in size, decreased in cytoplasmic mass and they were observed floating in the culture medium. Importantly, honey-treated amoebae did not revive when inoculated in fresh growth medium, however, glycerol-treated amoebae exhibited viable trophozoite and active growth. In contrast, marketed honey samples varied in their efficacy against Acanthamoeba castellanii. The proportion of flavonoid, as determined by quercetin measurements and the proportion of phenolic, as determined by gallic acid measurements was higher in natural honey compared with marketed honey. Similarly, the antioxidant activity, as determined by 2,2-diphenyl-1-picrylhydrazyl scavenging activity was higher in natural honey vs. marketed honey. Conclusions This study shows that natural honey has antiacanthamoebic properties and possesses higher flavonoid, phenolic and antioxidant properties compared with the marketed honey. These findings are of concern to the public, health officials, and to the manufacturers regarding production of honey for medical applications.
ABSTRACT
Objective: To determine antiacanthamoebic activity of natural and marketed honey samples. Methods: Natural honey samples were collected directly from the bee hive and marketed honey samples were purchased from the local market in Karachi, Pakistan. Both honey samples were tested for their flavonoid content (quercetin equivalent per gram of the extract) and phenolic content (gallic acid equivalent per gram). Furthermore, their anti-oxidant activity was determined by measuring 2,2-diphenyl-1-picrylhydrazyl. Using amoebistatic and amoebicidal assays, the effects of honey samples were tested against growth and viability of Acanthamoeba parasites. Results: Natural honey exhibited potent amoebistatic and amoebicidal effects, in a concentration-dependent manner. Honey-treated Acanthamoeba castellanii showed loss of acanthopodia, following which amoebae detached, rounded up, reduced in size, decreased in cytoplasmic mass and they were observed floating in the culture medium. Importantly, honey-treated amoebae did not revive when inoculated in fresh growth medium, however, glycerol-treated amoebae exhibited viable trophozoite and active growth. In contrast, marketed honey samples varied in their efficacy against Acantha-moeba castellanii. The proportion of flavonoid, as determined by quercetin measurements and the proportion of phenolic, as determined by gallic acid measurements was higher in natural honey compared with marketed honey. Similarly, the antioxidant activity, as determined by 2,2-diphenyl-1-picrylhydrazyl scavenging activity was higher in natural honey vs. marketed honey. Conclusions: This study shows that natural honey has antiacanthamoebic properties and possesses higher flavonoid, phenolic and antioxidant properties compared with the marketed honey. These findings are of concern to the public, health officials, and to the manufacturers regarding production of honey for medical applications.
ABSTRACT
Acanthamoeba is a free-living protozoan widely distributed in the environment, occurring in vegetative trophozoite and resistance cyst stages during its life cycle. It constitutes an etiological agent of Acanthamoeba keratitis, a disease that may cause severe ocular inflammation and blindness. New drugs can be developed from molecules found in plants and thus help in its difficult treatment. Acanthospermum australe (Asteraceae), a plant used in folk medicine, had its effect tested on Acanthamoeba polyphaga. Aqueous and ethanolic extracts of A. austral were obtained from aerial parts for infusion and static maceration, respectively. Concentrations of 10, 5, 2.5, 1.25 and 0.625 mg/ml of the extract were tested against Acanthamoeba polyphaga trophozoites. The cytotoxic effect of the extracts was tested in mammalian cells using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. RESULTS: The 10 mg/ml concentration of ethanolic extract was lethal to 100% of the A. polyphaga trophozoites in 24 h and both extracts presented cytotoxic effect against mammalian cells. These findings suggest that the A. austral ethanolic extract may have compounds with relevance to the development of new amoebicidal drugs.
Acanthamoeba é um protozoário de vida livre amplamente distribuído no ambiente, ocorrendo sob a forma trofozoítica (metabolicamente ativa) e cística (de resistência), durante seu ciclo de vida. O protozoário constitui um agente etiológico da Ceratite Amebiana, uma doença que pode causar inflamação ocular severa e cegueira. Novos fármacos podem ser desenvolvidos a partir de moléculas encontradas em plantas e assim ajudar em seu difícil tratamento. Aqui, Acanthospermum australe (Asteraceae), uma planta utilizada na medicina popular, teve seu efeito sobre trofozoítos de Acanthamoeba polyphaga testado. O extrato aquoso e etanólico de A. australe foram obtidos das partes aéreas por infusão e maceração estática, respectivamente. As concentrações 10, 5, 2,5, 1,25 e 0,625 mg/ml dos extratos foram testadas contra trofozoítos do protozoário. O efeito citotóxico dos extratos foi testado em células de mamífero utilizando o ensaio de brometo de 3-[4,5-dimetiltiazol-2-il]-2,5-difeniltetrazólio (MTT). A concentração de 10 mg/ml do extrato etanólico foi letal a 100% dos trofozoítos de A. polyphaga em 24 h e ambos os extratos apresentaram efeito citotóxico contra as células de mamífero. Estes resultados sugerem que o extrato etanólico de A. australe pode ter componentes com relevância para o desenvolvimento de novos fármacos amebicidas.
Subject(s)
Xanthium/adverse effects , Mimiviridae/classification , Plant Components, Aerial , Amebicides/analysisABSTRACT
PURPOSE: To evaluate the cysticidal effect of 5 kinds of commercially available contact lens disinfectants against 2 clinical isolates of Acanthamoeba. METHODS: Five kinds of commercially available contact lens disinfectants were soaked with cysts of Acanthamoeba ludgdunesis and castellanii at the concentration of 10(3), 10(4), and 10(5) cells/ml for 1 and 4 or 6 hours. Cysts which were not excysted in 7 days after treatment were recognized to be killed. Morphologic changes were evaluated by electron microscopic observation. RESULTS: Contact lens disinfectants which contain myristamidopropyl dimethylamine (MAPD) showed the best cysticidal effect. These disinfectants demonstrated a cysticidal effect on both Acanthamoeba species of all concentrations in 6-hour treatment. Contact lens disinfectants which contain polyhexamethylene biguanide (PHMB) did not demonstrate cysticidal effect, except for Acanthamoeba castellanii at the concentration of 10(3) cells/ml, in either 4- or 6-hour treatment. Separation of plasma membrane from endocyst and damage of organelles were prominent in cases showing a cysticidal effect. CONCLUSIONS: Contact lens disinfectant which contains MAPD may be helpful in preventing the Acanthamoeba keratitis. A higher concentration of PHMB is required to be effective in preventing Acanthamoeba keratitis.