Study of Antihypertensive effects of Ocimum sanctum

Background: Ocimum sanctum is a well reputed medicinal herb being used in the treatment of various ailments in this Indo Pak Subcontinents since ancient time. Methods: In this study the Antihypertensive effects of water extract of Ocimum sanctum and Water soluble fraction of methanol extract of Ocimum sanctum were tried for its antihypertensive effects on albino rats. Extracts were administered via vein and BP was recorded in the carotid artery by direct invasive method. Result: Normal blood pressure was 81/71 mm of Hg (mean blood pressure was 75 mm of Hg. Water extract of Ocimum sanctum has got significant antihypertensive effect(19-30 %). Water soluble fraction of methanol extract of Ocimum sanctum has also got significant antihypertensive effect(15-27 %)


Introduction:
Ocimum sanctum commonly known as Tulsi (Bengali) widely popular among the Hindu as sacred basil; has a wide distribution throughout the whole Indo-Pak-Bangladesh Sub-Continent, Arabia, Chaina, Burma, Ceylon, Malay archipelago, Australia, Islands of Pacific and western Asia 1 .The herb Ocimum sanctum Line (Family-Labiatae) are annual 30 to 60 cm in height and are much branched.It has got a wide use since ancient time in Ayrveda system of medicine.It is used as stomachic, anthelmentic , alexiteric , antipyretic and is also useful in diseases of heart and blood, leucoderma, strangury, asthma , bronchitis , vomiting, foul smells, lumbago pains, hiccough, painful eye , purulent discharge of the ear and in earache.It is also useful in cutaneous diseases like ringworm and for dislodging maggots.In Ceylon, the herb used in decoction for cough and catarrh , sometimes chewed as a substitute for betel.Fresh roots are ground with water and are applied to the bites of wasps , bees ,worms and leeches.Fixed oil of Ocimum sanctum was found to have anti inflammatory effect 2,3 along with its analgesic activity.The crushed fresh roots, leaves and stems are applied to the bites of mosquitoes 4 .The leaves of Ocimum sanctum are rubbed with lime juice over the ring worm to cure it .Ocimum sanctum has got its preventive role on measles.The leaves of Ocimum sanctum are expectorant in chronic cough specially in children and given sweetened with honey.Juice of leaves along with honey and juices of ginger & onion relieve asthma .The leaf juice is antispasmodic and antiemetic.Again the same is aphrodisiac and is useful in dysentery , indigestion , hemorrhoids.Dried leaf dust is used as snuff in gastro-intestinal tract.Decoction of roots are helpful in malaria fever & causes sweating .Volatile oils from the leaves got anti-microbial 5,6 and mosquito repellent action 7 .The leaves have been reported to have antifertility effect 8 .Till today the Hindues use to lay their dead bodies or moribund patient under Ocimum sanctum plants .It is a sacred basil to them .So a lot of scientific exploration , and efforts were made in the past to establish the ancient use of Ocimum sanctum in the modern science.It has got anti diabetic effects also 9,10 .Dhar et al screened some Indian plants for biological activity.Ethanol extract(50%) of Ocimum sanctum was found to possess antihypertensive effect along with other effects 11 .Hypertension is a main noncommunicable disease of our country.In one of our study we found 22.22% of a rural population of 60-64 years suffers from hypertension 12 .

Materials and Methods:
The leaves of ' Ocimum sanctum were collected from the medicinal plant garden of pharmacy Dept. of Rajshahi University, Rajshahi and dried.Voucher specimen was identified by Bangladesh National Herberium and deposited there too (DACB Accession No .28100 dated 21/10/2000).Leaves were collected in the month of October and dried in shade with fan.Then grinned to powder and extracted with menthol (ME) .The residue is then extracted with distilled water and freeze dried(WE).The menthol (ME) extract is sparingly soluble in distilled water(11.84%).This water soluble fragment (WF) was also tried with different doses.Aqueous solutions were prepared from this water extract.Water extract(WE) dissolved in distilled water in various concentrations and was administered intravenously The experiment was carried out on Swiss-albino rats, 2-3 months old, weighing between 200-300 gms of either sex.The animals were obtained from the animal house of BCSIR Laboratories, Chittagong. 25% aqueous solution of Urethane was administered in a dose 0.7ml/100g of rat; 50% of which was administered intraperitonially and rest half subcutaneously to anaesthetize the rats.After anaesthesia the animal was placed in a supine position on a dissecting table with arms ligated.Carotid artery was cannulated and connected to the transducer properly filled with heparinized saline.Heparin was procured from local market and diluted with normal saline such that one ml contains 100units.Special precaution was taken about the air bubble.No bubble was The transdiucer is again connected to a recorder.Two channel Recorder(Gemini model no.7070) was used.Pressure transducer preamplifier Model no.7082 UGO Basile, Bilogical Research Apparatus Comerio-(va)-Itali was used to convert pressor response to electrical responses which is being recorded.Jugular vein was cannulated by cannulae filled with normal saline to administer drugs of various concentrations in volume of .05-0.2 ml.Tracings were recorded and studied.Treatment with distilled water served the negative control whereas prazocin as positive control.Statistical analysis was done by students'-'t' -test.Ethical approval was taken before the study

Results:
The normal blood pressure of rat was 83/71 mm of Hg (displayed in table 1).Treatment with Ocimum sanctum(WE) reduced the pressure by 66/50mm of Hg with 1mg dose which is highly significant in comparison to normal.Higher doses also produced significant fall.Smaller dose(0.05mg)does not produce any significant change in blood pressure.Prazocin 2µg produced similar hypotension(63/51 mm of Hg) for more prolonged period( table 1).Mean blood pressures were responded similarly.

*
= Just significant (p<.05) n= number of experiments ** = significant (p<.01)SE = standard error *** = Highly significant (p<.001)Plate-B1: Blood Pressure tracings of rats after treatment with different doses of Ocimum sanctum Plate-B2: Blood Pressure tracings of rats after treatment with different extracts of Ocimum sanctum Plate-B3: Blood Pressure tracings of rats after treatment with prazosin and Ocimum sanctum

Table 1 :
Effects of Ocimum sanctum(WE) on normal rats.

Table 2 :
Effects of Ocimum sanctum methanol extract water soluble fraction(WF) on normal rats.

Table 3 :
Comparision between the potency of Ocimum sanctum(WE) and methanol extract water soluble fraction(WF) on normal rats.