Plant materials and CPT preparation
The fresh fruits of T. chebula, T. bellerica and P. emblica were collected from Doisaket district, Chiang Mai, Thailand. T. arjuna fruit was purchased from Tong In drugstore, Maha Sarakham, Thailand. All plant materials were identified by Assist.Prof. Wanida Caichampoo, Pharmaceutical Chemistry and Natural Product Research Unit, Faculty of Pharmacy, Mahasarakham University, Maha Sarakham, Thailand. The voucher specimens were deposited at Faculty of Pharmacy, Mahasarakham University, Maha Sarakham, Thailand. The seed of each fruit was removed and the seedless fruits were dried in hot air oven at 60ºC for 48 h. Each seedless dried fruit was blended to fine powder and sieved through mesh no.18. CPT was prepared in form of dried powder. Each 15 g of powder of T. chebula, T. bellerica, T. arjuna and P. emblica were mixed and boiled with 1 L of distilled water for 1 h. The extracted solution was filtered through filter paper (WhatmanÒ Filter Paper No.1) and then converted to powder by freeze dryer (ScanVac, Denmark).
Total phenolic content determination
Total phenolic content assay was performed by using a rapid microplate Folin-Ciocalteu method [19]. CPT sample solution was prepared in the concentration of 1 mg/mL. Ten microliter of sample solution or gallic acid solution was mixed with 100 μL of Folin-Ciocalteu working solution. Added 1 M sodium carbonate in a volume of 80 μL and mixed thoroughly. The reaction mixture was allowed to stand for 20 min at room temperature and the total phenolic content was determined by UV spectrophotometry (SPECTROstar Nano, BMG LABTECH, Germany) at 630 nm. Linear correlation of gallic acid concentrations (x) and absorbance (y) was y=1.0322x+0.0588, R2 = 0.998. Total phenolic content of CPT was determined and represented as mg gallic acid equivalent (GAE) per g of extract.
HPLC quantitative analysis of CPT
Four phenolic compounds of the individual fruit constituent of chatuphalatika as gallic acid, ellagic acid, chebulinic acid and chebulagic acid were employed as chemical markers of CPT. Standard gallic acid, chebulinic acid and chebulagic acid (Sigma Aldrich Chemical Co., St. Louis, MO, USA) were dissolved in methanol (1 mg/mL). Stock solution of ellagic acid (Sigma Aldrich Chemical Co., St. Louis, MO, USA) was prepared in the concentration of 0.1 mg/mL. All standard solutions were freshly prepared prior to use. Desired concentrations of chemical marker were subsequently diluted with methanol from the stock solutions. CPT was dissolved in methanol at a concentration of 2 mg/mL and then filtered through 0.45 µm PTFE syringe filter (RaphiLe Bioscience, China).
In this study, the condition of HPLC analysis method was slightly modified from our previous study [8]. Chromatographic system consisted of Shimadzu SCL-10A VP equipped with LC-10 AD binary pumps and SPD-M20A photodiode array detector (Kyoto, Japan). Mobile phase was a mixture of solvents: 0.05% trifluoroacetic acid in water (Solvent A) and (Solvent B). The separation was carried out in a linear gradient elution mode on an Eclipse XDB-C18 column with 5 μm particle size, 4.6 mm internal diameter and 250 mm length as follows: 0-2 min, 5% B; 2-4 min, 5-10% B; 4-12 min, 10-15% B; 12-26 min, 15-30 % B;26-30 min, 30-100% B; 30-35 min, 100% B; 35-40 min, 100-5% B; 40-45 min, 5% B. Mobile phase flow rate was 1.0 mL/min. Injection volume was 20 µL and was introduced into the HPLC system in triplicate. The chromatographic runs were carried out at ambient temperature and the absorbance was detected at 270 nm. The corresponding peaks of phytochemical markers were confirmed by retention times and spectrum comparing with standards. Under chromatographic conditions, the contents of chemical marker were calculated from calibration curves.
Acute oral toxicity study of CPT
The acute toxicity study of CPT was performed in accordance with the Organisation for Economic Co-operation and Development (OECD) guidelines, test guideline 420.
- Animals
Wistar rats of both sex (n = 30, weighting 190-280 g, 8 weeks old) were obtained from the National Laboratory Animal Center (Mahidol University, Nakornpathom, Thailand). The animals were housed under standard conditions (ambient temperature 24 ± 2°C, humidity 55 ± 10%, 12-h light/dark cycle (lights on from 7:00 h to 19:00 h)) and allowed free access to the standard rodent laboratory chow (No. CP082, Perfect Companion Group Co. Ltd., Thailand) and drinking water. They were acclimatized to these housing conditions for 1 week before the experiments. The experimental protocol was approved by the Institutional Animal Care and Use Committee, Mahasarakham University, Thailand (Approval no.0002-2558).
- CPT preparation and administration
The CPT solution was freshly prepared before use. The extract was dissolved in the distilled water (DDW) and administered to the animals orally in the volume of 10 ml/kg body weight with the feeding needle.
- Experimental protocols
The animals were divided into 3 groups of 10 animals per group with each having equal numbers of male and female animals. Each group of animals received a single oral-dose of either DDW or CPT in DDW (2,000 or 5,000 mg/kg body weight). The animals were fasted overnight (12 hours) before administration of drug and 4 hours after dosing. After administration of drug, the animals were observed for mortality and clinical signs of toxicity within the first four hours, and daily for a period of 14 days. On day 15, the animals were subjected to blood collection for hematological analysis and necropsy. The body weight and food and water consumptions of the animals were recorded once daily throughout the experiment.
- Clinical observations
The animals were observed at cage-side for clinical signs of toxicity including changes in skin, fur, eyes, mucous membranes, respiratory system, circulatory system, autonomic and central nervous systems, somatomotor activity and behavior pattern. They were carefully observed for tremors, convulsion, salivation, diarrhea, lethargy, sleep and coma.
- Hematological analysis
The animals were anesthetized by an intraperitoneal injection of the thiopental sodium (50 mg/kg BW; Jagsonpal Pharmaceuticals Ltd., Faridabad, Haryana, India) and the blood samples were collected via cardiac puncture in the K2-EDTA tubes (BD Vacutainer blood collection tube; Becton Dickinson, Franklin Lakes, New Jersey, USA). The white blood cells (WBC) count, neutrophils, lymphocytes, monocytes, eosinophils, basophils, red blood cells (RBC) count, hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and platelet count were measured using V-53 reagent kit (Mindray, P.R. China) and BC-5300 Vet Auto Hematology Analyzer (Mindray, P.R. China).
- Necropsy
The animals were euthanized by an intraperitoneal injection of overdose thiopental sodium and the internal organs including brain, heart, lungs, liver, stomach, spleen, kidneys, adrenal glands, bladder, testes, uterus and ovaries were harvested. The organs were weighed and observed for the gross lesions. The organ weight was used to calculate the relative organ weight by the following formula: Relative organ weight = (organ weight (g)/body weight of the animal on sacrifice day (g)) x 100.
Lipid lowering study of CPT
- Animals
The thirty-six healthy male C57BL/6Mlac mice (weighting 20-25 g, 8 weeks old) were obtained from the National Laboratory Animal Center (Mahidol University, Nakornpathom, Thailand). The animals were housed under standard conditions as described in the acute oral toxicity study of the CPT. They were acclimatized to these housing conditions for 1 week before the experiments. The experimental protocol was approved by the Institutional Animal Care and Use Committee, Mahasarakham University, Thailand (Approval no.0002-2558).
- HFD
The standard rodent laboratory chow was used herein as the normal diet (ND) containing 59.82% of energy from carbohydrates, 28.95% of energy from proteins and 11.23% of energy from fats. The HFD was prepared by adding additional ingredients into the ND. The final composition of the HFD consisted of the ND (33%), casein (23%), lard (33%), cholesterol (1%), vitamin & mineral mixture (1%), DL-methionine (0.5%), butter (3%), sucrose (5%) and choline chloride (0.5%). The HFD contained 19.09% of the energy from carbohydrates, 19.31% of the energy from proteins and 61.60% of the energy from fats. The energy content per gram of the ND and HFD were 3.69 and 5.29 kcal, respectively.
- Drug preparation and administration
The CPT and atorvastatin (ATV) (Lipitor®; Pfizer Inc, New York, NY, USA) were dissolved in the DDW and being administered to the animals by oral gavage in the volume of 10 ml/kg body weight. The drug administration was performed at the same time (10:00 h to 11:00 h) every day.
- Experimental protocols
The animals were divided into two groups with the same average body weight. One group of animals was fed with the ND (ND group; n = 6) and the other group of animals was fed with the HFD (HFD group; n = 30) for 16 weeks. After 10 weeks of feeding, the blood samples were collected from the animals in both groups and used for the lipid profile investigation. Then, the animals fed with the HFD were further divided into five groups with the same average body weight and were assigned to receive DDW (HFD + DDW group; n = 6), 10 mg/kg of ATV (HFD + ATV 10 mg/kg group; n = 6), 250 mg/kg of CPT (HFD + CPT 250 mg/kg group; n = 6), 500 mg/kg of CPT (HFD + CPT 500 mg/kg group; n = 6) or 1,000 mg/kg of CPT (HFD + CPT 1,000 mg/kg group; n = 6) for 6 weeks (from week 11 to 16 of HFD feeding) while the animals fed with the ND received DDW (ND + DDW group; n = 6) for 6 weeks (from week 11 to 16 of ND feeding). At the end of the feeding, the blood samples were collected from all animals for the lipid profile investigation. The body weight and food intake of the animals were measured once daily throughout the experiment. The caloric intake was calculated by multiplying the food intake (g) by the energy content per gram of diet (kcal).
- Plasma lipid determination
The blood samples were collected from the tail vein of the overnight fasted animals into the heparinized tubes and centrifuged at 6,000 rpm for 10 minutes at 4°C. The plasma was obtained and processed for the determination of the TC levels by the CHOD-POD enzymatic colorimetric method, the HDL-C levels by the GPO-POD enzymatic colorimetric method and the triglyceride (TRIG) levels by the direct enzymatic colorimetric method using the commercial kits (Mindray Bio Medical Co., Ltd., P.R. China) and BS-380 Automatic Biochemistry Analyzer (Mindray, P.R. China). The LDL-C levels was calculated using Friedewald’s equation: LDL-C = TC – HDL-C – TRIG/5 [20].
Statistical analysis
The statistical analysis was performed with SigmaPlot version-11 computer software (Systat software, San Jose, CA, USA). The results were reported as mean ± SEM. The data was analyzed by Student’s t-test, one-way ANOVA followed by the Student-Newman-Keuls test or two-way repeated measures ANOVA followed by the Student-Newman-Keuls test.