Bulbs of Allium cepa (onion) were collected from a local market in Dhaka city, Bangladesh during June 2013. The bulbs were taxonomically identified at the Bangladesh National Herbarium at Dhaka (Accession Number 38,358). The sliced and air-dried bulbs of Allium cepa (without skin) were grounded into a fine powder and 100g of the powder was extracted with 500 ml methanol for 48 hours. The extract was evaporated to dryness at 40oC. The final weight of the extract was 32.49g.
Cloves of Allium sativum (garlic) were collected from a local market in Dhaka city, Bangladesh during June 2013. The cloves were taxonomically identified at the Bangladesh National Herbarium at Dhaka (Accession Number 38,573). The sliced and air-dried cloves of Allium sativum (without skin) were grounded into a fine powder and 100g of the powder was extracted with 500 ml methanol for 48 hours. The extract was evaporated to dryness at 40oC. The final weight of the extract was 3.43g.
Rhizomes of Zingiber officinale (ginger) were collected from a local market in Dhaka city, Bangladesh during June 2013. The rhizomes were taxonomically identified at the Bangladesh National Herbarium at Dhaka (Accession Number 38,724). The sliced and air-dried rhizomes (without skin) of Zingiber officinale were grounded into a fine powder and 100g of the powder was extracted with 500 ml methanol for 48 hours. The extract was evaporated to dryness at 40oC. The final weight of the extract was 6.56g.
Chemicals: Glacial acetic acid was obtained from Sigma Chemicals, USA; aspirin was obtained from Square Pharmaceuticals Ltd., Bangladesh.
Animals: In the present study, Swiss albino mice (male), which weighed between 13-18g were used. The animals were obtained from International Centre for Diarrheal Disease Research, Bangladesh (ICDDR,B). All animals were kept under ambient temperature with 12h light followed by a 12h dark cycle. The animals were acclimatized for three days prior to actual experiments. The study was conducted following approval by the Institutional Animal Ethical Committee of University of Development Alternative, Dhaka, Bangladesh.
Antinociceptive activity: Antinociceptive activity of the methanol extracts of onion (MEAC), garlic (MEAS) and ginger (MEZO) was examined using previously described procedures. Briefly, mice were divided into seven groups of six mice each. Group 1 served as control and was administered vehicle only. Groups 2 and 3 were orally administered the standard antinociceptive drug aspirin at a dose of 200 and 400 mg per kg body weight, respectively. Groups 4-7 were administered methanolic bulb extract of onion (MEAC) at doses of 50, 100, 200 and 400 mg per kg body weight, respectively. Groups 8-11 were administered methanolic extract of garlic (MEAS) at doses of 50, 100, 200 and 400 mg per kg body weight, respectively. Groups 12-15 were administered methanolic extract of ginger (MEZO) at doses of 50, 100, 200 and 400 mg per kg body weight, respectively. Following a period of 60 minutes after oral administration of standard drug or extract, all mice were intraperitoneally injected with 1% acetic acid at a dose of 10 ml per kg body weight. A period of 15 minutes was given to each animal to ensure bio-availability of acetic acid, following which period, the number of abdominal constrictions (writhings) was counted for 10 min. The following formula was used for calculation of percent inhibition of the number of writhings in aspirin and MEAS administered animals compared to control mice,
Percent inhibition = (1 – We /Wc) X 100
Where We and Wc represents the number of writhings in aspirin or extract administered mice (Groups 2-15) and control mice (Group 1), respectively.
Statistical analysis: Experimental values are expressed as mean ± SEM. Independent Sample t-test was carried out for statistical comparison. Statistical significance was considered to be indicated by a p value < 0.05 in all cases.