Plant material
The fresh flowers of Woodfordia fruticosa were collected from Junagadh (Girnar region), Gujarat, India, in March 2008. The plant was compared with voucher specimen (voucher specimen No. PSN303) deposited by Dr. P.S. Nagar, at Department of Biosciences, Saurashtra University, Rajkot, Gujarat, India.
Preparation of the extract
The flowers were washed under tap water, air dried, homogenized to fine powder and stored in airtight bottles. Ten grams of dried powder was first defatted with petroleum ether and then extracted with methanol using Soxhlet apparatus (
14). The solvent was evaporated to dryness and the dried crude extract was stored in airtight bottle at 4°C. The percentage yield of methanol extract was 36%. For testing, the
Woodfordia fruticosa methanol (WFM) extract was dissolved in sterile distilled water and diluted to the desired concentrations.
Chemicals
All chemicals were of analytical-reagent 852
grade and obtained from the following sources: Carrageenan and dextran from Hi media (Mumbai, India); histamine, serotonin and diclofenac sodium from Sigma Aldrich (St. Louis, MO, USA); petroleum ether, methanol from Merck (Darmstadt, Germany) and biochemical kits were purchased from Span Diagnostics Ltd (Sachin, Surat, India).
Test sample preparation for Brine shrimp bioassay
Test sample was dissolved in DMSO (Dimethyl sulfoxide) to obtain stock solution of 1 mg/mL concentration. The final concentration of DMSO in the assay volume was kept at 2% to prevent possible false effects originating from DMSO toxicity. Pure DMSO and artificial seawater were used as negative control and potassium dichromate was used as the reference standard for the cytotoxicity assay.
Hatching of Brine shrimp cysts
Fresh cysts were produced from Fisheries Research Center, Okha, Gujarat, India. The cysts were hatched in a hatching tank containing artificial seawater made through dissolving a commercial marine salt (2%) in RO water (mineral water). The tank was well aerated with the aid of an air pump and the proper light source (1000-4000 lux) was also provided. The nauplii were hatched within 24-36 h at 30-35°C.
Brine shrimp lethality test
The toxicity of compound was tested at various concentrations viz. 10, 100, 250, 500, 750 and 1000 μg/mL in seawater containing 2% DMSO (v/v). Ten nauplii were used in each test. Three replications were used for each concentration. A parallel series of tests with the standard potassium dichromate solution (LC
50 = 20-40 μg) were tested and the blank control was always included. After 24 h, survivors were counted using a dissection microscope and the percentage of the mortality (%M) of each dose was calculated as compared with control. Cytotoxicity was considered significant if the LC
50-value was less than 20-30 μg/mL (
15).
Animals
Wistar albino rats of either sex (180-220 g) were used for the study. The animals were obtained from Sarabhai Research Center (SRC), Baroda. All the rats were kept in standard plastic rat cages with stainless steel coverlids and the wheat straw was used as a bedding material. The animals were kept at the animal house of Department of Biosciences, Saurashtra University, Rajkot. The animals were facilitated with standard environmental condition of photoperiod (12:12 h dark: light cycle) and temperature (25 ± 2°C). They were provided with commercial rat and mice feed (Pranav Agro Industries Ltd., Amruth Brand rat and mice pellet feed) and water was given ad libitum. The use of these animals and the study protocols were approved by CPCSEA recognized local ethical committee.
Anti-inflammatory studies
The animals were divided into four groups (six animals in each group) for anti-inflammatory studies. The dose of the Woodfordia fruticosa flowers was selected on the basis of therapeutic dose used in the traditional system of Ayurveda and the dose of Diclofenac was selected on the basis of literature survey as follows: Group I: Vehicle-treated control (distilled water), Group II: Methanol extract of Woodfordia fruticosa (400 mg/Kg body weight (WFM-400)), Group III: Methanol extract of Woodfordia fruticosa (600 mg/Kg body weight (WFM-600)), Group IV: Diclofenac sodium (- 10 mg/Kg body weight (diclofenac - 10)).
Carrageenan-induced rat paw edema
Carrageenan-induced rat paw edema was done through the method of Winter
et al. (
16). The inflammation was induced through injecting 0.1 mL of freshly prepared carrageenan (1%) aqueous suspension in normal saline underneath the plantar tissue of the right hind paw of the rats. The different groups of rats were administered with WFM (400 and 600 mg/Kg, p.o.) and diclofenac (10 mg/Kg, p.o.). The control group received vehicle (distilled water, 10 mL/Kg, p.o.). 1 h after the drug treatment and the paw edema was induced through the injection of carrageenan (an edematogenic agent). The paw volume was measured using a Plethysmometer. The measures were determined at 0 h (Vo: before the edematogenic agent injection) and 1, 2, 3, 4 and 5 h later (Vt). The difference between Vt and Vo was taken as the edema value. The percentage of inhibition was calculated according to the following formula:
Histamine, dextran and serotonin-induced rat paw edema
The animals were treated in a manner similar to that of carrageenan-induced paw edema model. A volume of 0.1 mL freshly prepared of 1% histamine, dextran and serotonin (
17-
19) were injected in the paw of rats. The paw volume was measured as mentioned in the carrageenan-induced paw edema model.
Formaldehyde-induced rat paw edema
The inflammation was induced through the injection of 0.1 mL of freshly prepared Formaldehyde (3%) underneath the plantar tissue of the right hind paw of rats (
20). The test drug was administered consecutively for seven days to all the groups. On seventh day, after 1 h of drug administration, the paw edema of the rat was induced by subplantar injection of formaldehyde solution. The paw volume was determined at 0 h and at 3, 24 and 48 h after the formaldehyde injection as described in the carrageenan model.
Cotton pellet-induced granuloma in rats
The effect of WFM on the chronic phases of inflammation was assessed in the cotton pellet-induced granuloma rat model, as described by Swingle and Shideman (
21). Autoclaved cotton pellets weighing 100 mg each, were implanted subcutaneously, one on each side of the abdomen of the animal, through a small ventral incision of rats anesthetized with ether. The different groups of rats were administered with WFM (400 and 600 mg/Kg, p.o.) and diclofenac (10 mg/Kg. p.o.) once daily for 7 consecutive days from the day of cotton pellet insertion. The control group received vehicle (distilled water, 10 mL/Kg, p.o.). On the 8
th day, the animals were sacrificed and the cotton pellets were removed, dried at 60°C for 24 h and their mass was determined. The results are expressed as mg granulation tissue formed per 100 g body weight.
Biochemical analysis
On the 8
th day, the animals were sacrificed under mild ether anesthesia and the blood was collected in clean centrifuge tubes for biochemical estimations. The serum was obtained by centrifugation and various serum biochemical parameters, viz. total protein (
22), albumin (
23), acid phosphatase (
24) and alkaline phosphatase (
25) were estimated using Span Diagnostics test kits. The absorbance of all the biochemical parameters was measured in a UV-VIS Spectrophotometer (Shimadzu, Tokyo, Japan).
Analgesic study
Formaldehyde-induced paw licking response in rats
The effect of WFM on formaldehyde-induced paw licking response was evaluated through the procedure of Magali
et al. (
26). The test drug was administered once daily for seven consecutive days to all the groups. On seventh day, after 1 h of drug administration, the subplantar injection of 0.1 mL of 3% formaldehyde solution in normal saline was injected. After the injection of formaldehyde, the animals were kept under observation for 30 min. The amount of time spent licking the injected paw was noted and considered to be indicative of pain. The time taken for the onset of paw licking was initially measured. The first nociceptive responses normally peaked 5 min after the formaldehyde injection and the second phase was 15-30 min after the formaldehyde injection, representing the neurogenic and inflammatory pain. Therefore, the frequency of paw licking was measured in five intervals at 0-5 min., 6-10 min., 11-15 min., 16-20 min., and 21-30 min.
Statistical analysis
In this study, recorded values are expressed as mean ± standard error of mean (SEM). Statistical significance was determined using one-way ANOVA followed by Student’s t-test. Values are considered statistically significant at p < 0.05 for t-test and f < 0.05 for ANOVA. In cytotoxicity study, LC50-values and 95% of confidence intervals were determined.