CARDIOPROTECTIVE EFFECT OF TERMINALIA ARJUNA ON CAFFEINE INDUCED CORONARY HEART DISEASE

CARDIOPROTECTIVE EFFECT OF TERMINALIA ARJUNA ON CAFFEINE INDUCED CORONARY HEART DISEASE

S. Asha*¹ and G. Taju ²

Department of Biochemistry, D.K.M., College for Women ¹, (Autonomous), Vellore-632001, Tamil Nadu, India    

Department of Aquaculture, Biotechnology, C. Abdul Hakeem College ², Vellore-632001, Tamil Nadu, India

ABSTRACT:The  present study was aimed to investigate the effects of bark extract  of Terminalia arjuna  (6.75mg/kg of body weight) on caffeine (10 mg/kg body weight)  induced coronary heart disease. Male wistar  rats weighing  about 120 and 160g were used as the experimental animal for  the  study. Caffeine dissolved in physiological saline (Nacl) with a pH of 7.0 administered  orally  to wistar rats continuosly for about 14 days. Thereafter, all the animals at the end of experiment showed a significant elevation in level of total cholesterol, LDL cholesterol, VLDL cholesterol and triglycerides and also a decreased  level  of  HDL-cholesterol, (P< 0.01). When compared  to the control rats, co-treatment of rats  with caffeine and Terminalia arjuna resulted in an increase in HDL-cholesterol, decrease in serum total cholesterol, triglycerides, LDL cholesterol and VLDL cholesterol as compared to caffeine treated animals with a significant of p<0.05. These findings suggest that the bark extract of Terminalia arjuna has protective effects against caffeine  induced coronary  heart  disease and may have  potential as a cardioprotective agent.

INTRODUCTION: Caffeine is a trimethylxanthine, found in many everyday products like coffee, tea, kolanuts, chocolate, soda beverages, drugs etc. These are widely and immensely consumed. Its primary biological effect is the antagonism of the A1 and A2A subtypes of adenosine receptors ^{1, 2, 3} on the surface of heart muscle cells ⁴.  Caffeine has been found to have various pharmacological and cellular responses in biological systems ⁵.

These include stimulation of the central nervous system and cardiac muscle, increased urinary output, and relaxation of smooth muscles ⁶.

However, consumption of caffeine increases urinary calcium levels and also causes irregular heart beat in cartain people ⁷. It has also found to cross the placenta and blood brain barriers ⁸.

From other studies, high caffeine intake during pregnancy is associated with a risk factor for low birth weight ^{9, 10} and also doubles the risk and spontaneous abortion ^{11, 12}.

After ingestion of caffeine from coffee or other beverages, they are absorbed by the stomach and small intestine. Metabolism of caffeine takes place in the liver by the cytochrome P₄₅₀ oxidase enzyme system. It results in the formation of three metabolite products ¹³ like paraxanthine, Theobromine and Theophylline. These are further metabolized and then excreted in the urine.

Some reported that these active chemicals are responsible for the increase in serum cholesterol level after coffee consumption ¹⁴.

Gordon et al., ¹⁵ reported that increased total cholesterol concentration in blood increases the risk of coronary heart disease. It thus, implies that these chemicals (Caffeine) are responsible for the increased risk of coronary heart disease associated with consumption of caffeine products ¹⁶.

Several medicinal plants have been described to be beneficial for cardiac ailments. A few  of  them, for  example, Allium Sativum L. (garlic) , Cicer arietinum L. (Bengal gram),  Curcuma longa L. (turmeric ), Ocimum sanctum L. (tulsi), Terminalia arjuna (arjuna)  are identified  and researched  to  have  lipid  lowering  and cardioprotective activities ¹⁷. Among  these  plant, the  plant  which  has  shown  most promising  and  distinct  results  is  Terminalia arjuna, popularly  known  as arjuna ^{18, 19}.

Terminalia arjuna is a deciduous and evergreen tree found throughout India. It stands to about 20-30m above ground level, belongs to combretaceae family ^{20, 21}. Abundantly  found  throughout  Indo-sub Himalayan  tracts  of  Uttar Pradesh,  South Bihar, Madhya Pradesh  and Deccan  regions  near  ponds  and  rivers.  Also found in forests of Srilanka, Burma and Mauritius.

The  bark,  leaves  and  fruits  of  Terminalia arjuna  are  used  in  indigenous  system  of  medicine  for  different  ailments ²².The  bark powder  has  been  found  to  possess cardioprotective  properties, anti-ischaemic,  antioxidant action ²³, hypocholesterolaemic effect,  fungicidal ²⁴, antimicrobial ²⁵, antibacterial ²⁶,  antifertility, treatment  of  ulcers, skin disorders  and  as antidote to  poisons . It is also useful to cure obesity, hypertension and hyperglycemia ²⁷.

This study  was  therefore,  undertaken  to  study  the  cardioprotective effect  of  Terminalia  arjuna  on  the  risk  of  coronary  heart diseases associated  with  the  induction  of caffeine  in  experimental  animals.

MATERIALS AND METHODS:

Plant Material: The bark  of  Terminalia  arjuna (TA)  obtained  from  the  southern  part  of  India. The  dried  bark  powder  was  extracted  with  ethyl alcohol ( 90 % )  by hot  continuous percolation  over  72  hours  by  using  Soxhlet  apparatus. The  alcoholic  extract  was  filtered and concentrated  to  a  dry  mass  by using  Vacuum  distillation  and  evaporation. A dark brownish red shiny crystal like residue was obtained. The chemical constituents of the extract were identified by quantitative analysis for the presence of flavonoids, alkaloids, glycosides, carbohydrates, amino acids, proteins and tannins. The extracts were  stored  in  a vacuum  dessicator  and  the weighed  dose  was  used  for  the experiment  by  dissolving  in the distilled  water.

Chemical: Caffeine was obtained from Sigma Chemical Company. U.S.A and diluted in physiological saline (Nacl) with a pH of 7.0.

Animals: Twelve  male  Wistar  rats  weighing  between  120  and  160g  were  used. The rats were housed for atleast one week before the start of the experiment. They were maintained in a 12-h light /dark cycle and fed with regular laboratory diet and water ad libitum. The twelve male rats used for this study were randomly divided into three experimental groups (A, B and C). Group A served as the control while groups B and C where administered caffeine (dissolved in saline) orally at dosage of 10mg/kg body weight respectively for fourteen days. In addition Group C animals  were  treated  with  bark  powder of Terminalia arjuna  at  the dosage of 6.75 mg/kg of body weight after  induction of caffeine. This treatment was carried out once a day for 4 weeks [6days/week]. The animals were used as per Ethical Committee No.- 1282/ac/09/CPCSEA.

Sample Collection and Preparation: Twenty four hours after the last administration, the animals were sacrificed and blood from each animal collected by cardiac puncture into clean sample bottles. This was allowed to clot and then centrifuged at 3000 rpm for five minutes. The serum was separated and stored away for further analysis.

Determination of Serum Lipid Parameters: Serum Total Cholesterol concentration was estimated according to Chod-Pap method reported by Fredrickson et al., ²⁸ and Allain et al. ²⁹.

The determination of the serum triacylglycerol concentration was carried out using the glycerol-phosphate oxidase method described by Trinder ³⁰.  HDL  cholesterol  was  determined  by  the phosphotungstate  precipitation  method  adopted  by  Richmond ³¹.

The VLDL cholesterol content  of  serum  was  estimated,  by  dividing  the  serum  triglyceride value  by  the  factor 5 ³². The concentration  of  LDL  cholesterol  was derived  from  the  difference  between total  cholesterol  and  sum  of  HDL and  VLDL   cholesterol  according  to  Friedwald et al., relationship ³³.

Statistical Analysis: Statistical Analysis was performed using the Turkey Multiple comparison test, all values were expressed as mean ± S.E (n=4 in each group). A value of p<0.05 was considered statistically significant.

RESULTS AND DISCUSSION: Terminalia  arjuna  is  a  plant, well  known  for  its  cardioprotective  properties  in  the ancient  Indian system of medicine. In  the  present study  cardioprotective effects of oral administration of  Terminalia arjuna  against  caffeine  induced  coronary  heart  disease  were evaluated in  male  Wistar  rats. Experimental values of Terminalia arjuna suggests its benefits in the treatment of coronary artery diseases, heart failure, and hypercholesterolemia ³⁴. Reported work obtained from ³⁵ on Terminalia arjuna shows that its cardioprotective activity was due to its free radical scavenging activity. The effect of caffeine and bark powder of Terminalia arjuna on the serum lipid profile in male Wistar rats was presented in table 1.

TABLE 1: EFFECT OF CAFFEINE AND BARK EXTRACT ON SERUM LIPID    PROFILE IN RATS

Results are mean ± S.E. * Significantly different from control (p<0.05). ** Significantly different from control (p<0.001).

The  results  indicate  that  oral administration  of  caffeine  in induced animals produced  an increase in total   serum  cholesterol, Triglyceride, LDL-cholesterol  and  VLDL cholesterol  with  a  decrease  in  HDL  cholesterol  level  relative  to  the  control (Group I) Animals. It shows the significance of (p<0.001) when compared to control.

Since the level of HDL cholesterol concentration has decreased and LDL cholesterol concentration has increased, these have been associated with increased risk of coronary heart disease ^{36, 37}.

This hypercholestrolemic and hyper triglyceridemic effects in rats, following the oral administration of caffeine may be due to the presence of some constituents like theobromine and theophylline as the metabolite ³⁸.

It was also  found  that  the  rats  receiving Terminalia arjuna (Treated animals)  had a marked reduction  in  total  cholesterol ^{39, 40}, triglycerides, LDL  cholesterol ³⁶, and VLDL cholesterol. However, it also showed an increased HDL cholesterol with a significance of p<0.05 when compared to the induced animals.

Hence, treated rats showed a significant prevention to the risk of coronary heart disease ⁴¹.  Thus, Terminalia arjuna was observed to be the most potent  hypolipidemic, hypotriglycemic  agent  and  also  raised  high  density lipo-cholesterol. All  these observations  from  our  present  study  clearly  indicated  the cardioprotective effect of  Terminalia arjuna  against  the  damage  caused  by  caffeine administration.

ACKNOWLEDGEMENT: The author would like to thank Miss A. Kavitha, Department of Biochemistry, D.K.M. College for Women, Vellore, India, for her technical assistance.

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