The experiment was carried out in the department of Veterinary Physiology and Biochemistry, College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram, India during March to November, 2022. The use of experimental animals and the experimental protocol has been duly approved by the institutional Animal Ethics Committee of the college vide No. CVSC/CAU/IAEC/21-22/P-8 dated, the 16th November, 2022. Internationally acceptable methods/techniques/protocols were followed during the present investigation and all the chemical/ drugs used were of high technical grades.
Plant collection and authentication
The plants of
Scurrula parasitica L. were collected from Mualvum, Kawnpui, Kolasib district of Mizoram, India.
Chemicals and reagents
Streptozotocin, Metformin, Chloroform and Tween 80 were purchased from HiMedia Laboratories Pvt. Ltd., Ethanol, Petroleum ether, Methanol, Ferric Chloride, Sodium Potassium Tartarate, Folin Ciocalteu reagent were purchased from Merck Limited. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,4,6-tri(2-pyridyl)-striazine (TPTZ), 6-hydroxy-2,5,7,8-tetramethyl chromane-2- carboxylic acid (Trolox) and Gallic acid from Sigma Chemicals Co. (St. Louis, USA). The kits for estimation of
in vivo antioxidant enzymes
viz. SOD, Catalase, GPx, MDA were from Wuhan Fine Biotech Co. Ltd. All the glassware used were of borosilicate quality.
Wistar rat
Adult Wistar rats were procured from M/s. Ruata Enterprise, Aizawl. Animals were housed in polypropylene cages in small groups of 6 rats per cage. Animals had free access to standard balanced ration and clean drinking water
ad-libitum and were maintained in standard laboratory conditions (12:12 hour light/dark cycle at ambient temperature ranging between 20-25
oC).
Processing of material
The
Scurrula parasitica L. leaves were washed in running tap water and finally rinsed with distilled water. The leaves were air dried in shade till completely dried and then ground to powder by a mechanical grinder and then soaked in solvents (1:5 w/v) with intermittent stirring for 5 days at room temperature. The filtrate was concentrated under reduced pressure as per the method described by
Zakaria et al., (2004) till the extract appears sufficiently dry and stored at -20
oC.
In-vitro antioxidant assay
The
in vitro antioxidant content of the extracts was estimated by three
in vitro assay methods
viz. DPPH free radical scavenging assay as described by
Leong and Shui (2001), Ferric reducing antioxidant potential (FRAP) assay according to the procedure of
Benzie and Strain (1999) and Total phenolic content (TPC) assay by the Folin-Ciocalteau method of
Singleton and Rossi (1965).
Preparation of oral suspension
The ethanol extract of the
Scurrula parasitica L. leaves was dissolved using 2% Tween 80. As per the requirement, 10% (100 mg.ml
-1) and 20% (200 mg.ml
-1) solutions were prepared for oral administration.
Dose rate for evaluation of in vivo antioxidant activity
The dose rate of (100 mg/bw kg
-1 and 200 mg/bw kg
-1) for evaluation of
in vivo antioxidant status were chosen as reported by
Laldingngheta et al., (2019).
Diabetes induction
Thirty healthy male Wistar rats were selected and divided into 5 groups of 6 animals each. The rats were kept off the feed for 24 hours and then the rats except from Group-I was administered streptozotocin at a dose of 40 mg.kg
-1 intraperitoneally as per the method of
Kalaivanan and Pugalendi (2011). The rats which have blood glucose level of 250 mg/dl or more after 72 hours of administration of streptozotocin were considered as diabetic rats. The Group-I rats served as normal control while Group II rats served as untreated diabetic control and received vehicle only. Rats in Group III received the standard drug, metformin at dose rate of 5 mg/kg body weight. Group IV and Group V rats received plant extracts at the dose rate of 100 mg/kg b.w. and 200 mg/kg b.w.
Assessment of in vivo antioxidant status
The blood samples of the rats in different groups were collected on 24
th day of treatment and the
in vivo antioxidant status of the rats were estimated. The levels of the Superoxide dismutase (SOD), Catalase, Glutathione peroxidise and Malondehyde (MDA) of the rats were estimated with kits manufactured by M/s. Wuhan Fine Biotech, Co. Ltd. The SOD, Catalase and GPX were estimated by Sandwich enzyme immunoassay. The microtiter plate was pre-coated with antibody specific to SOD, CAT and GPX respectively. Briefly, 100 µL each of working solution or samples were added into appropriate wells, covered with plate cover and incubated for 80 min at 37
oC. Pour out the liquids and washed three times with 200 µL wash solutions. Added 100 µL Biotinylated Antibody working solution in each well, covered with plate cover and incubated for 50 min at 37
oC. Aspirated and washed 3 times. Added 100 µL Streptavidin-HRP working solution in the wells, covered with plate sealer and incubated for 50 min at 37
oC followed by aspiration and 5 times washing. Added 90 µL of TMB substrate solution to the wells, covered with plate cover and incubate for 20 min at 37
oC. Added 50 µL stop reagent and took reading at 450 nm in ELISA plate reader. The MDA was estimated by competitive inhibition enzyme immunoassay technique. Briefly, added 50 µL of standard reagent or samples into the wells and 50 µL Biotinylated-conjugate in each well, mixed well, covered with plate cover and incubated for 60 min at 37
oC. Poured out the liquid, aspirated and washed with 200 µL wash solution. Added 100 µL Streptavidin- HRP working solution in the wells, covered with plate sealer and incubated for 60 min at 37
oC followed by aspiration and 5 times washing. Added 90 µL of TMB substrate solution to the wells, covered with plate cover and incubate for 20 min at 37
oC. Added 50 µL stop reagent and took reading at 450 nm in ELISA plate reader.