Anti-inflammatory activity of tea (Camellia sinensis) root extract
Introduction
Roots of medicinal plants are common ingredients of many folk and herbal medicines Kweifio-Okai, 1991a, Kweifio-Okai, 1991b, Hebtemariam, 2001 and root extracts of a number of medicinal plants have been reported to possess pharmacological activity, mainly anti-inflammatory activity Basu and Chaudhuri, 1991, Sen and Nag Chaudhuri., 1991, Sen et al., 1993, Cuellar et al., 1997, Njung'e et al., 2002. Tea (Camellia sinensis), which is the most consumed beverage all over the world, has been reported to contain a number of chemical constituents possessing medicinal and pharmacological properties Muramatsu et al., 1986, Toda et al., 1991, Blot et al., 1996, Arteel et al., 2002, Sartor et al., 2002 and it is expected that tea root might also be a storehouse of many chemicals of medicinal and pharmacological interest. However, when the tea plants are uprooted 30–100 years after plantation, the roots are used either for making ornamental furniture or as firewood. Earlier studies have reported that tea root extract (TRE) possesses antitumour effect in ascites (Sur and Ganguly, 1994) and solid tumour (Chaudhuri et al., 1998). Preliminary studies have also revealed the anti-inflammatory and antioxidant properties of the saponins (Lu et al., 2000) isolated from TRE (Sur et al., 2000). In the present investigation the methanol-water extract of the dried and ground tea root has been evaluated for anti-inflammatory, analgesic and antipyretic activities.
Section snippets
Plant materials
The roots of Camellia sinensis var assamica (clone TV-1, planted in 1964) were collected and supplied by Tocklai Experimental Station, Jorhat, Assam, India. A voucher specimen (TR-004) is deposited at the Tea Research Association, Kolkata, India.
Extraction and preparation of the sample
The tea root (1 kg) was cut into small pieces, dried, ground and soaked in 3 litres of 50% aqueous methanol for one week at room temperature (20–30 °C) with occasional shaking. The solvent was filtered and to the residue 1 litre of 50% aqueous methanol
Carrageenan-induced oedema
The rats were divided into three groups (n=6) and the first group served as negative control and received normal saline (0.1 ml/100 g i.p). The second group was administered acetyl salicylic acid (100 mg/kg i.p.) as the standard drug. Group 3 received 10 mg/kg i.p. TRE. Oedema was produced by the method described by Winter et al. (1962). Carrageenan (0.1 ml/100 g from a 10 mg/ml solution) was injected into the plantar aponeurosis of right hind paw of the rats of all three groups 30 min later.
Writhing in mice
The mice were randomly divided into 2 groups (6 mice/group). Mice of the first group received normal saline (0.1 ml/10 g) i.p. and the second group received 10 mg/kg i.p. TRE. Thirty minutes later, each mouse was given 0.1 ml/10 g i.p. of 1% acetic acid. Writhing response was observed by the method of Turner (1965). The time of onset of writhing and the number of writhings in 15 min were noted.
Tail clip method
It was done in mice by applying a metal artery clip at the base of the tail with its jaw sheathed with
Effect on body temperature
All experiments were conducted at a room temperature of 28 ± 1 °C. Rats (6 in a group) were injected with 10 mg/kg i.p. of TRE. Control group of rats received 0.1 ml/100 g i.p. normal saline. The rectal temperature of both the groups was recorded every 30 min for 4 hours.
2,4-Dinitrophenol (2,4-DNP)-induced pyrexia
Pyrexia was induced in rats by injecting DNP (15 mg/kg i.p.) with half of its weight of sodium bicarbonate according to the method of Anand et al. (1978). TRE (10 mg/kg, i.p.) and normal saline (0.1 ml/100 g i.p.) were injected
Acute toxicity studies
The LD50 of TRE was found to be 100 mg/kg i.p.
Carrageenan-induced oedema
TRE inhibited carrageenan-induced paw oedema by 41% in volume and 50% in weight which was slightly more than that produced by acetyl salicylic acid and highly significant as compared to control (Table 1).
Cotton pellet induced granuloma
The increase in the dry weight of cotton pellet granuloma was compared and it was found that TRE inhibited the increase in dry weight by 44% as compared to saline control and the inhibition was 29% higher than that produced by acetyl salicylic acid
Discussion
The present study revealed that TRE possesses significant anti-inflammatory, analgesic and antipyretic activities in experimental animals at a dose of 10 mg/kg i.p. which is one-tenth of its LD50 dose. The anti-inflammatory effect of TRE could be observed in acute (carrageenan and arachidonic acid induced paw oedema in rat and croton-oil induced ear inflammation in mice), sub-chronic (cotton pellet induced granuloma in rat) and chronic (Freund's complete adjuvant induced polyarthritis in rat)
Acknowledgements
The work was sponsored by National Tea Research Foundation (NTRF), Kolkata, India.
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