ANTIDEPRESSANT ACTIVITY ON LEAVES OF POLYGONUM GLABRUM WILLD IN EXPERIMENTAL ANIMAL

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Behavioral despair test: (Willner, et, al. 1984)32
The rats were placed in cylinder (45×20cm) containing 38cm water (25±2?c), so that the rat could not touch the bottom of the cylinder with its hind limb or tail, or climb over the edge of the chamber. Two swim sessions were conducted, an initial 15min pretest, followed by a 5min test 24h leter.

Drugs were administered after pretest. The period of immobility (remained floating in water, without struggling and making only those movements necessary to keep its head above water) during 5 min test period noted.

Tail suspension test in mice: (Chermat, et, al.1986)33 (Steru et, al.1985)42
The male mice (20-25gm) were housed in plastic cage for at least 10 days prior to testing in a 12 h light cycle with food and water freely available. Animals were transported from the housing room to the testing area in their own cages and allowed to adapt to the new environment for 1h before testing. Groups of 10 animals were treated with test compound or the vehicle i.p. 30min prior to testing. For the test the mice  were suspended on the edge of shelf  58cm above the table top by adhesive tape placed approximately 1cm from the tip of the tail . The duration of immobility was recorded for a period of 5min. Mice was considered immobile when they hung passively and completely motionless for at least 1min

Learned helplessness test in rats : (Chabner, et.al.1996)34
Learned helplessness was produced in male Sprague-Dawley rats (300gm)by exposure to electric shock (0.7mA) for 1h on a schedule of  10s of shock/min.  The apparatus was a 30×45×30cm box with grid floor. At a height of 20cm above the floor ,a platform (7.5×7.5cm)can be inserted through one side wall to allow a jump-up escape response. The platform is not available during training. After the appropriate treatment, the animals were tested for acquisition of a jump-up escape in the same apparatus. At the beginning of trail the platform is pushed in to the box and a 0.4mA shock initiated. Shock was terminated in 10s if the animal has not escaped on to the platform by this time. If an escape response occurred, the animal is allowed to remain on the platform for the duration of 10s, then returned to the grid floor. Ten such trails with an inter-trail interval of 20s are given. In a naïve control group of rates, this training resulted in 80% acquiring helplessness behavior. Drugs were given before the training and test period.

LITERATURE AND TABLES :
The name Polygonum derived from the Greek word poly “many,” and gonu, “knee or joint,” hence “many joints” because of the thickened joints on the stem. The species name glabrum is based on the smooth or hairless appearance of the leaves. Polygonum glabrum is known as Denseflower knotweed due to its morphological appearance of the flower and stem.

Polygonum glabrumis the perennial plant belonging to the family Polygonacy. The genus Polygonum encompasses 150 species, of which 79 are known to occur in India (Hooker, 1985)15. Polygonum glabrum is distributed in Asia, Africa, and North America. Indian Polygonum glabrum  is perennial herb growing up to a height of 150cm distributed mainly in the eastern area at altitude of up to 1900m,  especially near liberal water source.

A good number of species of Polygonum have been used traditionally from a long time for a number of ailments in the indigenous system of medicine. The medicinal properties attributed to the species of Polygonum are demulcent and pectoral, astringent and tonic, diuretic, emetic, purgative, febrifuge, vesicant vulnerary, insecticide, and anthelmentic (Kirtikaret.al., 1975)6. Besidesit also possess antiviral (Bhakuniet.al., 1969)12 and antibacterial (Krishnamurthi, 1969)12 properties.

Ethno-medicinal investigation
Polygonum glabrumhas been studied for anti-inflammatory and anthelmintic activity. Recent interest has focus on its C.N.S. activity. Polygonum glabrum also has been investigated for hypotensive and spsmogenic activity (Singh et.al., 1985)11. Polygonum glabrum contains several compounds of  biological interest, including the sesquiterpenes and broad spectrum of flavonoids.

Anti-inflammatory activity
Anti-inflammatory studies were conducted on a hot water decoction and on an ethanol extract of the stem of Polygonum glabrum (Bhupinderet.al., 1987)4. It has been shown a significant anti-inflammatory activity against carrageenan-induced pedal edema in rats.

Polygonum glabrumwas also studied in another models representing acute, sub-acute and chronic inflammation. It was observed to be consistently effective in suppressing the exudates and granuloma formation in the granuloma pouch test, the formaldehyde-induces chronic arthritic reaction and immunologically-meted adjuvant- induces poly arthritis syndrome. The latter is accepted as a models having chronicity and immunological basis, two important feature of human rheumatoid arthritis (Billingham and Davies,1979)16, there this procedure is probably the most important and valid screening method. Significantly, 18h data on the primary reaction in the injected limbs also been reported to be a more specific and reliable model of acute inflammation than the commonly employed carrageenan paw edema test (Sofia et al., 1975)17. The effects of Polygonum glabrum were approximately similar in the models after i.p as well as  p.o  administration, lending greater validity to the anti-inflammatory activity of Polygonum glabrum .In addition Polygonum glabrum was equally active against the acute 4h reaction to formaldehyde.

Polygonum glabrum  has been observed to be an effective anti-inflammatory agent against three models of acute inflammatory reaction and three models of sub acute or chronic inflammation. It was observed that PG was relatively less potent than  phenylbutazone in most acute models while it was usually more potent in the sub acute or chronic models. This pattern was observed both after oral and i.p. administration although, dose for dose, Polygonumglabrum was less effective orally indicating  poorer bioavailability of the active principle due to either to partial absorption or to a first pass metabolism by the liver. (Prado et al, 1990)26

Anthelmintic Property:-
A pure anthelmintic substance (PGA) has been isolated from the leaf of Polygonum glabrum willd. (Muddathiret al.,1987)13. The antiparasitic in-vitro activity of several fractions isolated from the plant has been examined comparatively with that of PGA. PGA also showed molluscicidal activity against Biomphalaria glabrata and Limneatruncatula Mull.

 PGA had highly significant taenicidal activity in-vitro, whereas it had weaker trematodicidal and amoebicidal activities. The anthelmintic activity was mainly studied against Hymenolepis nana var. fraternal of the white mouse.

The in-vitro screening for anti-parasitic activity of divers fraction isolated from the leaf of, Polygonum glabrum confirmed the properties of PGA the anthelmintic activity against Hmenolepis nana var. fraternal being observed at LD=2×10-3 mg/ml which is ten times lower then that of crude extract.

The trematodicidal activity of PGA against fasciola was observed at LD= 6×10?1  mg/ml while the crude extract was inactive.

The amoebicidal activity of PGA against Entamoeba histolytica was observed at MID =5×10-1 mg/ml.

The in-vivo anthelmintic activity of PGA was assayed against Hymenolepis nana ver.fraternal at 200-600 mg/kg and gave no positively significant results; however it has been observed that a good tolerance of PGA in white mice at dose=400mg/kg.

PGA and crude extract of PG were molluscicidal against Biomphalaria glabrata and Limnea truncatula Mull, while El-Tohami (1979)21found aqueous extract  from the leaves of same plant not to be molluscicidal against Biomphalaria pfeifferi and Bulinus truncatus (from Sudanese breeding), when assayed at 250ppm. Crude fraction gave 100% mortality of B.glabrata  40% mortality of  Limnea truncatula, after 24h exposure at 100ppm. PGA gave 100% mortality of P.glabrata at 1-0.5ppm and 100% mortality of  Limnea truncatula at 2-1ppm, after 24h exposure.

Other effects
P.glabrumhas been reported to have number of additional effects. In one study the crude aqueous extract has been produced hypotention  and reduce respiration rate. These effects could not be modified by atropinisation (Singh et.al., 1985)11. Whereas leaves extract has shown falling effect in b.p. and caused increase in the rate and volume of respiration.

Both stem and leaves portion individually produced a spasmogenic response in albino rat’s and rabbit’s intestine. The spasmogenic activity of aqueous leaves extract inhibited completely by pheniramine and atropine which shows that this response is mediated through cholinergic and histaminergic system (Singh et.al., 1985)11.

Toxicology
The toxicological studies showed that P.glabrum appears to be possess a reasonable margin of safety (Bhupinderet.al., 1987)13.P.glabrum up to 2g/kg p.o. did not cause any death in the mice.

The LD50 after a series of i.p. doses was 10mg/kg approximately by Karber’s method (1931)18 and 760mg/kg (±125mg/kg S.E.) by the graphic method of Miller and Tainter (1944)19.    Polygonum glabrum  administration in dose up to   50mg/kg i.p. and 200mg/kg p.o. once did not cause any death in the rats up to 30days.

Phytochemical investigation

Phytochemistry:
Phytochemistry is in the strict sense of the word the study of phytochemicals. These are chemicals derived from plants. In a narrower sense the terms are often used to describe the large number of secondary metabolic compounds found in plants. Many of these are known to provide protection against insect attacks and plant diseases. They also exhibit a number of protective functions for human consumers Techniques commonly using in the field of Phytochemistry are extraction, isolation and structural elucidation (MS,1Dand 2D NMR) of natural products, as well as various chromatography techniques (MPLC, HPLC, LC-MS).

The title of a book on hallucinogens by Efronet al.‚ namely, "Ethnopharmacologic Search for Drugs", where it was defined. (Wada et al, 1989)20

Terms and concept: The term “Ethnopharmacology” was first used in 1967 as “The inter diexploration of biologically active agents traditionally employed or observed by man”.

Shortly before the start of the 20th century American botanist William Hershberger coined another frequently used term “Ethnobotany”. Ethnobotany is a multidisciplinary science defined as the interaction between plants and people.

In order to highlight the role pharmacy as a profession can play in the development of traditional ethnophamacopoeias, recently the concept of "Ethnopharmacy” was proposed by Heinrich, it has been defined as the interdisciplinary science that deals with the study of the pharmaceutical means, considered in relation to the cultural determinants that characterizes the uses of these means in a given human group. It involves studies of the identification, classification and cognitive categorization of the natural material from which the remedy will be produced, which encompasses not only botanical and pharmacological but also phytochemicals, galenicals, drug delivery, toxicological, clinical, pharmacy practice/anthropological, historical and other aspects of research on medicinal plants in popular and traditional medical systems.4

Phytochemistry is widely used in the field of Chinese medicine especially in the field of herbal medicine5.

Phytochemical technique mainly applies to the quality control of Chinese medicine or herbal medicine of various chemical components, such as saponins, alkaloids, volatile oils, flavonoids and anthraquinones. In the development of rapid and reproducible analytical techniques, the combination of HPLC with different detectors, such as diode array detector (DAD), refractive index detector (RID), evaporative light scattering detector (ELSD) and mass spectrometric detector(MSD), has been widely developed 5.

In most cases, biologically active compounds in Chinese medicine or herbal medicine have not been determined. Therefore, it is important to use the phytochemicals methods to screen and analyze bioactive components, not only for the quality control of crude drugs, but also for the elucidation of their therapeutic mechanisms. Modern pharmacological studies indicate that binding to receptors or ion channels on cell membrane is the first step of some drug actions. A new method in Phytochemistry; biochromatography, has been developed. This method combines human red celll membrane extraction and high performance liquid chromatography to screen potential active components in Chinese medicine. Phytochemicals is plant or fruit derived chemical compounds. "Phytonutrients" refer to phytochemicals or compounds that come from edible plant5.

Polygonumcontains various compounds with documented biological activity2.

Constituents that have stimulated the most interest includes sesquiterpenes , 2,3-dihydroxyisodrimeninol and their diesters, a broad range of flavonoids  including  quercetin, rhamnetin, quercitrin, avicularin, and rutin, the polyphenols like vanillic, syringic, p-hydroxybenzoic, protocatecheuic, gallic and cis-and trans p-coumaric acids and essential oils.

The following major groups of bioactive constituents will summaries the constituents of Polygonumglabrum.

Sesquiterpenes: The sesquiterpenes present in Polygonumglabrum include,3-dihydroxyisodrimeninol and their diesters  (Wada et al, 1989)201 are  given below.

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