S.L.J. Tea Sci. 72(2), 54-60, 2007, Printed in Sri Lanka 

Antipyretic activity of Sri Lankan black tea (Camellia sinensis) 

W D Ratnasoor iya, T S P Fernando and C D W Y Scncv i ra thna 

(Department of Zoology. University of Colombo, Colombo 03, Sri Lanka.) 

ABSTRACT 
This study examined the ant ipyret ic act iv i ty o f Sri Lankan black tea (Camellia sinensis 

L.) in yeast-induced rat pyrexia model using black tea brew ( B T B ) o f h igh grown Dust 

grade No : 1 tea. Di f ferent doses o f B T B (167 mg /m l , equivalent to 3 cups; 501 mg /m l , 

equivalent to 9 cups; and 1336 mg /m l , equivalent to 24 cups), water (control) or paracetomol 

(200 mg/kg , reference drug) were oral ly administered to yeast - induced pyretic rats ( N = 

6/group) and their rectal temperature monitored at hour ly intervals for 6 h. The results 

show that all doses o f B T B and paracetomol signif icantly (P < 0.05) suppressed the pyrexia-

induced by yeast ( low dose upto 2 h, m i d dose upto 5 h, high dose upto 4 h and paracetomol 

upto 4 h) . In addit ion, the m i d dose o f B T B signif icantly (P < 0.05) suppressed the intestinal 

secretion in enteropool ing assay o f mice suggesting an impai rment o f prostaglandin 

synthesis. It is concluded that Sri Lankan black tea possesses ant ipyret ic act iv i ty o f 

moderately long duration in rats and it could play a s imi lar role in humans. 

K e y w o r d s : Camellia sinensis; b lack tea; pyrexia; antipyretic 

INTRODUCTION 
Tea wh ich is manufactured f rom the topmost immature leaves and the bud o f Camellia 

sinensis (L ) O. Kuntze (Fami ly Theaceae) plant is one o f the most popular beverages 

consumed wor ldwide. Depending on the manufacturing process there are three main types 

o f teas; black ( fu l l y aerated or fermented) green (unaerated or unfermented) and oolong 

(part ial ly aerated or semifermented) (Modder and Amarakoon, 2002). I t is estimated that 

80% o f wor ld produced tea is consumed as black tea (Anonymous , 2004) predominant ly 

in Nor th Amer ica, Great Br i ta in and some Asian countries (Kunke l , 2003). 

Tea and health have always been inextr icably l inked. Several laboratory studies have 

demonstrated that tea, especially the green lea. exhibit distinct and diverse pharmacological 

p rope r t i es : a n t i o x i d a t i v e ; a n t i - i n f l a m m a t o r y ; a n t i c a r c i n o g e n i c ; a n t i m u t a g e n i c ; 

a n t i a n g i o g e n i c ; ant i a r t e r i o s e l e r o t i c ; an t i o b e s i t y ; a n t i d i a b e t i c ; an t i a g e i n g ; 

hypocholesterolaeimic; ant ibacterial ; ant iv i ra l ; impairment o f digestive enzyme act iv i ty; 

a l leviat ion o f l iver ai lments and neurological condit ions or reduct ion o f tooth decay and 

other gum ailments (Modder and Amarakoon, 2002; Koo and Cho, 2004). Furthermore, 

f indings from several epidemiological studies suggest that regular consumption o f moderate 

to high quanti ty o f tea lower the risk o f heart diseases, stroke and cancers (Modder and 

Amarakoon, 2002; Koo and Cho, 2004). 



Sadly, less attention has been focused on the bioactivity o f black tea which is heavily 

consumed by the tea drinkers in the world. In this regard, it has been suggested that more 

effort should be focused on black tea research in the future (Chi-Tang Ho et al, 2 0 0 5 ) . 

With respect to Sri Lankan unblend garden mark black tea (the second largest producer 

and exporter) published studies on its bioactivity are extremely limited (Abeywickrama, 

et al., 2 0 0 4 ; Abeywickrama, et ai, 2 0 0 5 ; O'Mahony, et al, 2 0 0 5 ; Ratnasooriya and 

Amarakoon, 2 0 0 7 ; Ratnasooriya, et al, 2 0 0 7 ) . 

Therefore, we have initiated a research programme to investigate bioacti vities o f Sri Lankan 

black tea. In this study, we report antipyretic activity o f Sri Lankan black tea using high 

grown Dust grade No: 1 tea in rats. 

MATERIALS AND METHODS 
Animals 
Laboratory bred healthy adult male Wistar rats (weighing 2 0 0 - 2 2 5 g) and ICR strain male 

mice (weighing 3 0 - 4 0 g) purchased from Medical Research Institute, Borella, Sri Lanka 

were used. They were kept under standardized animal house conditions (temperature: 2 8 -

31 °C, photoperiod: approximately 12 hours o f light per day, relative humidity 5 0 - 5 5 % ) . 

They had free access to pelleted food (Ceylon Grain Elevators, Colombo, Sri Lanka) and 

tap water. All animrfexperiments were conducted in accordance with the internationally 

accepted laboratory animal use and care (based on Helsinki convention) and guidelines 

and rules ofthe Faculty o f Science, University o f Colombo, for animal experimentation. 

Sorce of tea 
Two or three topmost immature leaves and buds o f C. sinensis plants plucked from the 

plantation o f St. Coombs tea estate o f the Tea Research Institute, Talawakelle, Sri Lanka 

(1382 m above sea level: high grown) in August 2 0 0 5 was used to process Dust grade No: 

1 black tea by orthodox-rotovane technique at the estate factory. The tea sample was pure, 

unblend and typical to the grade as confirmed by sieve analysis, organoleptic profile, and 

physical and chemical analysis. Tea samples were packed in triple laminated aluminium 

foil bags (1 kg each) and stored at - 20 °C until use. 

Preparation of black tea brew (BTB) 
B T B was made according to ISO standards (Anonymous, 1980): adding 2 g of black tea to 

100 ml water and brewing for 5 min [yield (w/w) 4 3 . 7 % ] . For oral administration o f rats, 

3 concentrations o f B T B ( 1 6 7 mg/ml, equivalent to 3 cups; 501 mg/ml, equivalent to 9 

cups and 1336 mg/ml, equivalent to 24 cups) were made in 2 ml o f water. The volume of 1 

cup is considered as 170 ml. 

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Effects on rectal temperature 
Thirty rats were randomly assigned into 5 equal groups ( N = 6/group). The rectal temperature 

o f these rats were determined using a d ig i ta l thermometer (CT 461C, Cit izen systems 

Japan Co. , L T D , Tokyo , Japan). These rats were then subcutaneously injected w i th 10 m l / 

kg o f 1 5 % ( W / V ) aqueous suspension o f active dry yeast (General M i l l i n g Corporat ion, 

Lapu-Lapu Ci ty , Phi l ippines) to induce pyrexia. Nineteen hours after inject ion o f yeast, 

rectal temperature o f these rats was determined (Hul la t t i and Sharada, 2007). These rats 

were then oral ly treated w i t h B T B , water or paracetomol as fo l lows: group 1, 2 m l o f 

d ist i l led water, group 2 w i t h 167 mg /m l o f B T B , group 3 w i t h 501 mg/ml o f B T B , group 

4 w i t h 1336 m g / m l o f B T B and group 5 w i t h 200 mg /kg o f paracetomol (reference drug). 

Rectal temperature was then determined at 1, 2, 3 , 4 , and 5 h post treatment. 

Effect of B T B on small intestinal secretion 
Intestinal secretion was indirect ly evaluated by the enteropooling assay (Vital i el al., 2005). 

Br ie f ly , 18 mice were randomly div ided into three groups ( N = 6/group). M ice in group 1 

were ora l ly treated w i t h 0.2 m l o f water, group 2 w i t h 0.2 m l water and group 3 w i t h 501 

mg /m l o f B T B . Forty minui ts later, mice in groups 2 and 3 were oral ly administed w i t h 0.2 

m l o f castor o i l . A f te r 30 m i n all the mice were sacri f iced using ether and their smal l 

intestines were removed and weighed. The weights were then expressed as mg/20g body 

weight . The difference in the intestinal weight between the normal control and caster o i l 

treated control was considered as the caster o i l - induced accumulat ion o f intestinal fluid. 

Statistical analysis 
Data are given as means ± S E M . Statistical comparisons were made using the Mann-

Whi tney U-test. P < 0.05 was considered as signif icant. 

RESULTS 
The results obtained w i t h rectal temperature measurements are summarized in Table 1. As 

shown, subcutaneous administrat ion o f yeast induced pyrexia in rats (> 100 °F). B T B 167 

mg /m l dose s igni f icant ly (P < 0.05) suppressed the pyrexia only at l ' 1 and 2 n i 1 h post-

treatment. On the other hand, 501 mg/ml and 1336 m g / m l doses o f B T B signi f icant ly (P < 

0.05) reduced pyrexia up to 5 h and 6 h respectively. The reference drug paracetomol also 

s igni f icant ly (P < 0.05) reduced pyrexia up to 4 h. The antipyretic potential o f black tea 

brew was essentially comparable to that o f paracetomol (200 mg/kg ) . 

The results in the enteropool ing assay are summar ized in Table 2. As shown, oral 

administrat ion o f castor o i l s igni f icant ly (P < 0.05) increased the intestinal f lu id secretion, 

compared w i th the normal control. B T B on the other hand, signif icant ly (P < 0 .05) inhibited 

the castor o i l - induced intestinal secretion. 

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T a b l e 1 . E f fec ts o f ora l adminis t ra t ion o f black tea brew ( B T B ) o f Dust grade N o : 1 tea (167, 5 0 1 , and 1336 m g / m l ) and paracetomol on 

yeast - induced pyrex ia in rats (mean ± S E M ) 

T r e a t m e n t T e m p e r a t u r e °F 

B e f o r e yeast A f t e r yeast Post t r e a t m e n t 

1" h o u r 2°° h o u r 3 r d h o u r 4 t h h o u r 5 l h h o u r 

C o n t r o l (Water ) 98.5 ± 0 . 3 0 101.15 ± 0 . 2 9 101.13 ± 0 . 2 4 101.32 ± 0.16 101.00 ± 0.34 101.02 ± 0 . 2 8 100.58 ± 0 . 2 5 

B T B 

167 m g / m l (eq. 3 cups) 98.3 ± 0.32 101.02 dz 0.15 99.55 ± 0 . 2 3 * 99.76 ± 0 .02* 100.07 ± 0 . 0 7 100.17 ± 0 . 0 9 100.07 ± 0.04 

501 m g / m l (eq. 9 cups) 98.9 ± 0 . 3 8 100.20 ± 0 . 0 3 99.54 ± 0 . 1 5 * 99.13 ± 0 . 1 5 * 99.56 ± 0 . 1 4 * 99.67 ± 0 .18* 99.16 ± 0 . 2 5 * 

1336 m g / m l (eq. 24 cups) 98.3 ± 0.40 101.70 ± 0 . 1 2 99.63 ± 0 . 1 6 * 99.46 ± 0 . 1 5 * 99.40 ± 0 . 1 9 * 99.45 ± 0 . 1 4 * 99.56 ± 0 . 1 2 

Paracetomol (200 m g / k g ) 98.9 ± 0 . 4 3 100.98 ± 0 . 2 3 98.66 ± 0.09* 98.73 ± 0 . 0 6 * 98.83 ± 0.03* 99.08 ± 0 . 0 3 * 99.18 ± 0 . 0 7 

* = P < 0.05 compared to control ( M a n n - W h i t n e y U-Test); eq = equivalent 



Tabic 2. Effect o f oral administrat ion o f 501 mg/ml black tea brew (BTB) o f Dust grade 

N o : 1 tea on castor o i l - induced enteropool ing in mice ( m c a n ± S E M ) 

Treatment Small intestine Castor oil-induced intestinal 
weight (mg/20g) f luid accumulation (mg) 

N o r m a l control (water) 

Castor o i l control 

(0.2 m l castor o i l + water) 

501 m g / m l o f B T B 

(0.2 m l castor o i l + 501 mg / m l B T B ) 1029.3 ± 3 . 5 a b 

1337.2 ± 2 . 8 a 

829.4 ± 2.3 

507.8 

199.9 

a P < 0.05 compared to normal c o n t r o l , b P < 0.05 compared to castor o i l control ( M a n n -

Whi tney U-Test) 

DISCUSSION 
The ancients be l ieved that green tea is benef ic ia l fo r regula t ing body temperature 

(Anonymous , 2005) and might be useful in malar ia (Stagg and M i l l i n , 1975). O n the other 

hand, antipyretic effects o f black tea is not mentioned either in Ayurvedha or fo lk lore. This 

study shows, for the first t ime, that black tea made f rom Sri Lankan h igh g rown Dust grade 

N o : 1 tea possesses signif icant ant ipyret ic act iv i ty when tested in yeast- induced pyrexia 

model o f rats. This model is val idated, reproducible, rel iable and w ide ly used to test 

ant ipyret ic effects o f potential drugs (Gupta et ai, 2005; Hu l la t t i and Sharada, 2007). 

Therefore, the results obtained are genuine and reassuring. This is and important f ind ing 

w i t h c l in ical signif icance. 

The antipyretic effect o f B T B was prompt (appeared wi th in 1 h) and moderately long (lasted 

up to 4-5h) l ike the reference drug paracetomol wh ich is frequently used therapeutical ly to 

alHveviate pyrexia (Rang el al., 1995). Further, in the rat model B T B had a fever suppressing 

effect s imi lar to paracetomol (w i th respect to magnitude and durat ion). 

Sweat ing reduces body temperature (Carola et al., 1990). But this antipyretic effect is not 

mediated via sweating as rats do not have sweat glands (Mat thews, 1970). Tea contains 

appreciable amount o f caffeine (Modder and Amarakoon, 2002). Caffeine is a known 

vasoconstrictor (Benowi lz , 1990). Hence, constr ict ion o f skin b lood vessels w o u l d be 

expected. Thus , reduct ion o f body temperature due lo rad ia t ion is un l i ke l y . The 

thermoregulatory center in the hypothalamus controls the set body temperature o f mammals 

(Carola et ai. 1990). Prostaglandins are known to elevate the thermoregulatory set point 

and thereby produce pyrexia (Carola et al., 1990). Prostaglandin synthesis blockers cyc lo-

oxygenase inhibi tors (cox) l ike aspir in, paracetomol, ibuprofen (Rang et of., 1995) reduce 

elevated temperature in pyrexia. Therefore, it is passible that B T B may also suppress 

58 



yeast-induced pyrexia by a similar mechanism. Indeed, inh ib i t ion o f expression o f cox- 2 

has been reported in black tea extracts (Luceri et ai, 2002). Furthermore, reduction o f 

intestinal weight in the caster o i l experiment suggests an inh ib i t ion o f prostaglandin 

biosynthesis (Gunakkanru et al, 2005). There are other mediators such as cytokines, tumor 

necrosis factor (Rang et ai, 1995) underly ing pathogenesis o f fever. Possibil ity exists that 

B T B could also inh ib i t these mediators in br inging about antipyrasis. Further studies are 

obviously needed to c la r i fy this point. 

In conclusion, this study, shows for the first t ime, that Sri Lanka black tea possesses marked 

antipyretic act iv i ty in rats. Further, research are necessary to demonstrate similar effects 

in human. 

ACKNOWLEDGEMENTS 
This investigation received financial support f r o m the Nat ional Science Foundation under 

grant number NSF/Fe l low/2005 /01 . Thanks are also due to Dr. Z iyad Mohamed, former 

Director, Tea Research Insti tute, Talawakelle, for p rov id ing the tea sample. 

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