Aims: Piper sarmentosum or locally known as Kaduk, is a tropical herb plant that was investigated for its phenolic content by previous researchers. The present study aimed at the analysis of crude methanolic extract of P. sarmentosum leaves for phenolic compounds identification and its anti-amoebic properties against pathogenic Acanthamoeba castellanii. Methodology and results: Folin-Ciocalteu assay was used to determine P. sarmentosum leaves methanolic extract (PSLME)’s total phenolic content (TPC). The extract was further characterized by using gas chromatography-mass spectrometry (GC-MS), reverse phase-high performance liquid chromatography (RP-HPLC) and liquid chromatography-mass spectrometry (LC-MS) analyses to determine the chemical constituents in methanolic PSLME extract. The cytotoxicity of the extract was evaluated through the determination of inhibition concentration for half of cell population (IC50) of pathogenic A. castellanii followed by cell morphological analysis using inverted light and scanning electron microscopies. Acridine-orange/Propidium iodide (AOPI) staining was also conducted to determine the integrity of cell membrane for quantitative analysis. The results demonstrated that the TPC from PSLME was 142.72 mg [GAE]/g with a total of 33 phenolic compounds identified. The IC50 value obtained for A. castellanii was low (74.64 μg/mL) which indicates promising anti-acanthamoebic activity. Microscopy analyses showed that the plant extract caused cells encystment, in which exhibited by distinctive morphological changes on the cells shape and organelle, as well as shortening of acanthopodia. The dual staining and its quantitative analysis prove compromised membrane integrity in the treated amoeba. Conclusion, significance and impact of study This finding provides the evidence that PSLME contains active phenolic compounds contributing to the anti-acanthamoebic activity on pathogenic Acanthamoeba species.
Piperaceae ; Acanthamoeba castellanii--pathogenicity

The existence of symbiotic relationships between Acanthamoeba and a variety of bacteria is well-documented. However, the ability of Acanthamoeba interacting with host bacterial pathogens has gained particular attention. Here, to understand the interactions of Escherichia coli K1 and E. coli K5 strains with Acanthamoeba castellanii trophozoites and cysts, association assay, invasion assay, survival assay, and the measurement of bacterial numbers from cysts were performed, and nonpathogenic E. coli K12 was also applied. The association ratio of E. coli K1 with A. castellanii was 4.3 cfu per amoeba for 1 hr but E. coli K5 with A. castellanii was 1 cfu per amoeba for 1 hr. By invasion and survival assays, E. coli K5 was recovered less than E. coli K1 but still alive inside A. castellanii. E. coli K1 and K5 survived and multiplied intracellularly in A. castellanii. The survival assay was performed under a favourable condition for 22 hr and 43 hr with the encystment of A. castellanii. Under the favourable condition for the transformation of trophozoites into cysts, E. coli K5 multiplied significantly. Moreover, the pathogenic potential of E. coli K1 from A. castellanii cysts exhibited no changes as compared with E. coli K1 from A. castellanii trophozoites. E. coli K5 was multiplied in A. castellanii trophozoites and survived in A. castellanii cysts. Therefore, this study suggests that E. coli K5 can use A. castellanii as a reservoir host or a vector for the bacterial transmission.
Acanthamoeba castellanii/*microbiology ; Animals ; Disease Reservoirs/*microbiology ; Disease Vectors ; Escherichia coli/growth & development/pathogenicity/*physiology ; Oocysts/microbiology ; Symbiosis/*physiology ; Trophozoites/microbiology

The pathogenic mechanism of granulomatous amebic encephalitis (GAE) and amebic keratitis (AK) by Acanthamoeba has yet to be clarified. Protease has been recognized to play an important role in the pathogenesis of GAE and AK. In the present study, we have compared specific activity and cytopathic effects (CPE) of purified 33 kDa serine proteinases from Acanthamoeba strains with different degree of virulence (A. healyi OC-3A, A. lugdunensis KA/E2, and A. castellanii Neff). Trophozoites of the 3 strains revealed different degrees of CPE on human corneal epithelial (HCE) cells. The effect was remarkably reduced by adding phenylmethylsulfonylfluoride (PMSF), a serine proteinase inhibitor. This result indicated that PMSF-susceptible proteinase is the main component causing cytopathy to HCE cells by Acanthamoeba. The purified 33 kDa serine proteinase showed strong activity toward HCE cells and extracellular matrix proteins. The purified proteinase from OC-3A, the most virulent strain, demonstrated the highest enzyme activity compared to KA/E2, an ocular isolate, and Neff, a soil isolate. Polyclonal antibodies against the purified 33 kDa serine proteinase inhibit almost completely the proteolytic activity of culture supernatant of Acanthamoeba. In line with these results, the 33 kDa serine proteinase is suggested to play an important role in pathogenesis and to be the main component of virulence factor of Acanthamoeba.
Virulence Factors/isolation & purification/*metabolism ; Virulence ; Trophozoites/physiology ; Substrate Specificity ; Soil/parasitology ; Serine Endopeptidases/isolation & purification/*metabolism ; Humans ; Epithelial Cells/parasitology/*pathology ; Encephalitis ; Cornea/cytology/parasitology/*pathology ; Cells, Cultured ; Animals ; Acanthamoeba castellanii/enzymology/growth & development/pathogenicity ; Acanthamoeba Keratitis/parasitology ; Acanthamoeba/classification/*enzymology/growth & development/*pathogenicity

Acanthamoeba spp. are single-celled protozoan organisms that are widely distributed in the environment. In this study, to understand functional roles of a mannose-binding protein (MBP), Acanthamoeba castellanii was treated with methyl-alpha-D-mannopyranoside (mannose), and adhesion and cytotoxicity of the amoeba were analyzed. In addition, to understand the association of MBP for amoeba phagocytosis, phagocytosis assay was analyzed using non-pathogenic bacterium, Escherichia coli K12. Amoebae treated with mannose for 20 cycles exhibited larger vacuoles occupying the most area of the amoebic cytoplasm in comparison with the control group amoebae and glucose-treated amoebae. Mannose-selected amoebae exhibited lower levels of binding to Chinese hamster ovary (CHO) cells. Exogenous mannose inhibited >50% inhibition of amoebae (control group) binding to CHO cells. Moreover, exogenous mannose inhibited amoebae (i.e., man-treated) binding to CHO cells by <15%. Mannose-selected amoebae exhibited significantly decreased cytotoxicity to CHO cells compared with the control group amoebae, 25.1% vs 92.1%. In phagocytic assay, mannose-selected amoebae exhibited significant decreases in bacterial uptake in comparison with the control group, 0.019% vs 0.03% (P<0.05). Taken together, it is suggested that mannose-selected A. castellanii trophozoites should be severely damaged and do not well interact with a target cell via a lectin of MBP.
Acanthamoeba castellanii/drug effects/metabolism/*pathogenicity ; Amebiasis/*parasitology ; Animals ; CHO Cells ; Cell Adhesion/drug effects ; Cell Survival ; Cricetinae ; Cricetulus ; Escherichia coli K12/metabolism ; Female ; Mannose/*pharmacology ; Mannose-Binding Lectin/*metabolism ; Phagocytosis ; Protozoan Proteins/metabolism