Effect of oregano essential oil and carvacrol on Cryptosporidium parvum infectivity in HCT-8 cells

• Published in: Parasitology international Vol. 67; no. 2; pp. 170 - 175
• Main Authors: Gaur, Shashank, Kuhlenschmidt, Theresa B., Kuhlenschmidt, Mark S., Andrade, Juan E.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2018
• Subjects: Carvacrol; Cell Line; Cell Survival - drug effects; Child; Cryptosporidiosis - drug therapy; Cryptosporidiosis - parasitology; Cryptosporidium; Cryptosporidium parvum - drug effects; HCT-8; Humans; In vitro; Microbial Sensitivity Tests; Monoterpenes - pharmacology; Oils, Volatile - chemistry; Oils, Volatile - pharmacology; Oocysts - drug effects; Oregano; Origanum - chemistry; Parasite; Sporozoites - drug effects; PP1; Cryptosporidium; HCT-8; CV; C. parvum; IC50; OEO; Parasite; Oregano; Carvacrol; In vitro
• ISSN: 1383-5769; 1873-0329
• DOI: 10.1016/j.parint.2017.11.001

Cryptosporidium parvum is the second leading cause of persistent diarrhea among children in low-resource settings. This study examined the effect of oregano essential oil (OEO) and carvacrol (CV) on inhibition of C. parvum infectivity in vitro. HCT-8 cells were seeded (1×106) in 96-well microtiter plates until confluency. Cell viability and infectivity were assessed by seeding HCT-8 cell monolayers with C. parvum oocysts (1×104) in two modalities: 1) 4h co-culture with bioactive (0–250μg/mL) followed by washing and incubation (48h, 37°C, 5% CO2) in bioactive-free media; and 2) 4h co-culture of C. parvum oocysts followed by washing and treatment with bioactive (0–250μg/mL) during 48-h incubation. Cell viability was tested using Live/Dead™ assay whereas infectivity was measured using C. parvum-specific antibody staining via immunofluorescence detection. Loss of cell viability was observed starting at 125μg/mL and 60μg/mL for OEO and CV, respectively. Neither OEO nor CV modulated the invasion of C. parvum sporozoites in HCT-8 cells. Treatment with bioactive after invasion reduced relative C. parvum infectivity in a dose-dependent manner to 55.6±10.4% and 45.8±4.1% at 60 and 30μg/mL of OEO and CV, respectively. OEO and CV are potential bioactives to counteract C. parvum infection in children. Schematic of in vitro assessment of C. parvum growth and invasion. In modality 1, oocysts and excysting sporozoites are exposed to different dosages of OEO or CV for 4h. Then, 2-day incubation with untreated media. In modality 2, sporozoites (trophozoites) attached or permeated in HCT-8 cell monolayers in the first 4h and undergoing asexual division into merozoites are exposed to different dosages of bioactive for 2days. [Display omitted] •Oregano Essential Oil (OEO) and Carvacrol (CV) have anti-cryptosporidium activity.•OEO and CV inhibit relative C. parvum infectivity of HCT-8 cells in a dose dependent manner.•OEO and CV have no effect on invasion of C. parvum sporozoites of HCT-8 cells.