Curcumin effect on Acanthamoeba triangularis encystation under nutrient starvation
Rachasak Boonhok,
Suthinee Sangkanu,
Suganya Phumjan,
Ramita Jongboonjua,
Nawarat Sangnopparat,
Pattamaporn Kwankaew,
Aman Tedasen,
Chooi Ling Lim,
Maria de Lourdes Pereira,
Mohammed Rahmatullah,
Polrat Wilairatana,
Christophe Wiart,
Karma G. Dolma,
Alok K. Paul,
Madhu Gupta,
Veeranoot Nissapatorn
Affiliations
Rachasak Boonhok
Department of Medical Technology, School of Allied Health Sciences, and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Suthinee Sangkanu
School of Allied Health Sciences, Southeast Asia Water Team (SEA Water Team) and World Union for Herbal Drug Discovery (WUHeDD), and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Suganya Phumjan
Department of Medical Technology, School of Allied Health Sciences, and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Ramita Jongboonjua
Department of Medical Technology, School of Allied Health Sciences, and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Nawarat Sangnopparat
Department of Medical Technology, School of Allied Health Sciences, and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Pattamaporn Kwankaew
Department of Medical Technology, School of Allied Health Sciences, and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Aman Tedasen
Department of Medical Technology, School of Allied Health Sciences, and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Chooi Ling Lim
Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
Maria de Lourdes Pereira
CICECO-Aveiro Institute of Materials and Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
Mohammed Rahmatullah
Department of Biotechnology and Genetic Engineering, University of Development Alternative, Dhaka, Bangladesh
Polrat Wilairatana
Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Rachathewee, Bangkok, Thailand
Christophe Wiart
The Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia
Karma G. Dolma
Department of Microbiology, Sikkim Manipal Institute of Medical Sciences, Sikkim, India
Alok K. Paul
School of Pharmacy and Pharmacology, University of Tasmania, Hobart, Tasmania, Australia
Madhu Gupta
Department of Pharmaceutics, Delhi Pharmaceutical Sciences and Research University, New Delhi, India
Veeranoot Nissapatorn
School of Allied Health Sciences, Southeast Asia Water Team (SEA Water Team) and World Union for Herbal Drug Discovery (WUHeDD), and Research Excellence Center for Innovation and Health Products (RECIHP), Walailak University, Thai Buri, Nakhon Si Thammarat, Thailand
Background Curcumin is an active compound derived from turmeric, Curcuma longa, and is known for its benefits to human health. The amoebicidal activity of curcumin against Acanthamoeba triangularis was recently discovered. However, a physiological change of intracellular pathways related to A. triangularis encystation mechanism, including autophagy in the surviving amoeba after curcumin treatment, has never been reported. This study aims to investigate the effect of curcumin on the survival of A. triangularis under nutrient starvation and nutrient-rich condition, as well as to evaluate the A. triangularis encystation and a physiological change of Acanthamoeba autophagy at the mRNA level. Methods In this study, A. triangularis amoebas were treated with a sublethal dose of curcumin under nutrient starvation and nutrient-rich condition and the surviving amoebas was investigated. Cysts formation and vacuolization were examined by microscopy and transcriptional expression of autophagy-related genes and other encystation-related genes were evaluated by real-time PCR. Results A. triangularis cysts were formed under nutrient starvation. However, in the presence of the autophagy inhibitor, 3-methyladenine (3-MA), the percentage of cysts was significantly reduced. Interestingly, in the presence of curcumin, most of the parasites remained in the trophozoite stage in both the starvation and nutrient-rich condition. In vacuolization analysis, the percentage of amoebas with enlarged vacuole was increased upon starvation. However, the percentage was significantly declined in the presence of curcumin and 3-MA. Molecular analysis of A. triangularis autophagy-related (ATG) genes showed that the mRNA expression of the ATG genes, ATG3, ATG8b, ATG12, ATG16, under the starvation with curcumin was at a basal level along the treatment. The results were similar to those of the curcumin-treated amoebas under a nutrient-rich condition, except AcATG16 which increased later. On the other hand, mRNA expression of encystation-related genes, cellulose synthase and serine proteinase, remained unchanged during the first 18 h, but significantly increased at 24 h post treatment. Conclusion Curcumin inhibits cyst formation in surviving trophozoites, which may result from its effect on mRNA expression of key Acanthamoeba ATG-related genes. However, further investigation into the mechanism of curcumin in A. triangularis trophozoites arrest and its association with autophagy or other encystation-related pathways is needed to support the future use of curcumin.
