Collection and purification of parasite
The experiment was conducted in summer, monsoon, pre-monsoon and winter seasons of Jammu region from the starting session of January 2018 till the end of December 2018.
Cryptosporidium oocysts were collected from an eighteen day old cow calf suffering from clinical cryptosporidiosis, in an organized cattle farm of Jammu region. Further, the experiments were carried out in the Department of Veterinary Parasitology, Sher-e-Kashmir University of Agricultural Sciences and Technology, R.S Pura, Jammu. Infection was confirmed by modified Ziehl Neelsen staining technique (
Henricksen and Pohlenz, 1981). Confirmation of
C. parvum was done through amplification of gp 60 gene using a nested PCR (
Alves et al. 2003). Oocysts were purified from the faeces by primary and secondary purification methods. Primary purification of the oocysts from faeces was done by modified Sheather’s sucrose floatation techniques
(Current et al., 1983) and secondary purification of the oocysts was done by a discontinuous step-gradient centrifugation technique (
Arrowood and Sterling, 1987). The final concentration of purified
C. parvum oocysts was adjusted to 10
8/ml using a Neubauer Chamber. It was fortified with streptopenicillin (streptomycin @ 100 µg/ml and penicillin @ 100 IU/ ml) and was stored at 4°C for further use.
Preparation of ethanolic extract of C. longa
C. longa tuber was purchased from the local market, completely dried, powdered and then ethanolic extract was prepared. Ethanolic extract of
C. longa was prepared as per the method of
Harborne (1998). The per cent extractability of ethanolic extract was determined as per the formula:
Different working concentrations of
C. longa extract were prepared in HPLC grade methanol and stored in a refrigerator at 4°C.
Preparation of the stock solutions and calibration of standard compound curcumin stock solution of the pure reference compound, curcumin (sigma-Aldrich, USA) @ 1.0 mg/ml was prepared in HPLC grade methanol and stored in a refrigerator at 4°C. From the stock solution, working solutions for each reference compound were prepared by dilution with HPLC grade methanol. Two microliters of each dilution was injected for the preparation of a calibration curve.
HPLC analysis
Curcumin was separated and quantified by a Shimadzu HPLC system (Kyoto, Japan) consisting of an LC-10 ATvp pump, SIL-10 ADvp automatic sampling unit (auto sampler), CTO-10 and SCL-10 Avp as the system controller. Class VP software (version 6.10) (Company, City and Country) was used for data analysis and data processing. The samples were analyzed at 30°C on RP-18.5 μm, 250x 4 mm i.d. Merck (Darmstadt, Germany) column. Photo Diode Array (PDA) detection was performed at 423 nm. The analysis was carried out using a mobile phase of methanol: water (2:3) which was delivered at a flow rate of 0.7 ml/min.
The animals
The study was conducted on 200 female Swiss albino mice. These mice aged two weeks, were procured from Indian Institute of Integrative Medicine (IIIM), Jammu. Mice were maintained in separate cages, provided with pelleted food, water
adlibitum and were initially acclimatized for one week. Prepatent and patent periods were observed and mean oocysts shedding were calculated. They were all free from any parasitic infection on three consecutive days, as determined by examining their stools using a formol-ether concentration method and modified Ziehl-Neelsen technique (
Henricksen and Pohlenz, 1981).
Immunosuppression and infection
Immunosuppression in groups II to X animals was carried at age of 3 weeks (seven days prior to the inoculation of the infection) by administering dexamethasone @ 30 µg/ml in drinking water and continued till the end of the experiment. Mice of groups III to X were infected orally with 10
4 oocysts/animal (
Tarazona, 1998) at 4 weeks of age.
Experimental design
All the female Swiss albino mice were randomly divided into ten groups
i.e., group I to group X, with 20 animals each which were housed in separate cages. Group I mice served as healthy control and received distilled water. Group II mice served as control for immunocompromised and were administered dexamethasone @ 30 µg/ml in drinking water. Group III mice were given dexamethasone and also were given
C. parvum oocysts @ 10
4 oocysts/animal
(Tarazona et al., 1998) orally. Group IV animals were immunocompromised, infected and treated orally with nitazoxanide @ 150 mg/kg/day (
Blagburn, 1998). Group V, VI and VII animals were immunocompromised, infected and treated with ethanolic extract of
C. longa @ 4, 6 and 8 mg/kg/day/os, respectively. Group VIII, IX and X animals were immunocompromised, infected and treated orally with pure salt of curcumin (Sigma-Aldrich, USA) and given @ 4, 6 and 8 mg/kg/day/os, respectively. In the present study, initial dose (4 mg/kg/day/os) of curcumin was used as per the findings of
Cervantes-Valencia et al., 2016 against
Eimeria spp. (coccidian protozoa). Treatment with all the therapeutic drugs was started simultaneously at 5
th DPI and continued for 5 successive days
i.e. upto 11
th DPI. Eight mice were euthanized humanly using ether inhalation on 7
th DPI and the remaining 12 mice were sacrificed on 11
th DPI.
Parameters for therapeutic evaluation
Therapeutic evaluation of ethanolic extract of
C. longa and curcumin against experimental cryptosporidiosis in mice was assessed based on oocysts per gram of faeces voided, average body weight of the animals and pathological alterations recorded in necropsy animals. In order to monitor oocysts count throughout the experiment, pooled faecal sample of the animals of each group were collected. Initially the oocysts count was measured on day of treatment (0 DPT) followed by 3
rd, 5
th and 7
th DPT. Per cent efficacy was monitored on 7
th day post treatment.
The number of oocysts per gram of faeces was calculated using the method of
Grinberg et al., (2002). The percent mean oocysts reduction was calculated as per the formula:
Average body weight of the experimental animals was recorded on 0, 5, 7, 9 and 11 DPI.
Statistical analysis of data was done using a two way ANOVA (
Snedecor and Cocharan, 1994) and the means having significant difference were ranked as per Duncan’s multiple range test (
Duncan, 1955).
Further, for histopathological observations, intestines were collected in 10% neutral buffered formalin. Paraffin blocks were prepared, 4-6 µ sections were cut and stained with haematoxylin and eosin stain (
Luna, 1968).
Ethical aspects
The institutional animal Ethical Committee of Sher-e- Kashmir University of Agricultural Sciences and Technology, Jammu granted an approval for the conduct of present work vide letter number-3/IAEC-17/2017.