REVIEW ON PLANTS MAINLY USED FOR THE PREPARATION OF KSHAR SUTRA

Many herbal remedies individually or in combination have been recommended in various medical treatises for the cure of different diseases. Ksharsutraan Ayurvedic para-surgical measure is used the treatment of Nadi Vrana (sinus), Bhagandara (fistulain ano), arbuda (excision of small benign tumour) etc. by using different medicinal plants. The standard kshar sutra is prepared by using snuhi ksheera (latex of Euphorbia nerrifolia Linn), apamarg kshar (water extract of ashes of Achyranthus aspera Linn plant) and haridra powder (powder of Curcuma longa L). This review mainly focuses on the plants that are used in preparation of Ksharsutra so that more research work is carried out in the direction of standardization, therapeutic level determination of Ksharsutra plants.


Introduction
Ayurveda is the most ancient health care system and is practiced widely in India, Sri Lanka and other countries. According to the WHO survey 80% of the populations living in the developing countries rely almost exclusively on traditional medicine for their primary health care needs. Exploration of the chemical constituents of the plants and pharmacological screening may provide us the basis for developing the leads for development of novel agents. In addition, herbs have provided us some of the very important life saving drugs used in the armamentarium of modern medicine. However, among the estimated 250,000-400,000 plant species, only 6% have been studied for biological activity, and about 15% have been investigated phytochemically(1). Kshar Sutra is a Sanskrit phrase in which Kshar refers to anything that is corrosive or caustic; while Sutra means a yarn or thread (The origin of the English word "Sew"). It is described in one of the most ancient medicine known to mankind that is -Ayurved, which originated and flourished in India. Ayurveda is still at its peak in India and gaining a great popularity worldwide. The Ksharsutra was first mentioned by the "Father of Surgery" Sushruta in his text named SUSHRUT -SAMHITA for the treatment of Nadi Vrana (sinus), Bhagandara (fistula-in -ano), arbuda (excision of small benign tumour) etc. Although Brihattrayithe chief three texts of Ayurveda mention the use of kshara sutra, there is no description of their preparation. It was Chakrapani Dutta in late eleventh century who has mentioned in his book Chakradatta, the method of preparation with a clear-cut indication of its use in bhagandara and arsha (haemorrhoid) for the first time. He explains the method that by smearing a sutra (thread) repeatedly in the latex of snuhi and haridra (turmeric) powder makes the kshara sutra. Later authors like Bhavamishra, Bhaisajyaratnavali etc. also mention the same method. But because of brevity of preparation and inadequate explanation of procedure of application, it lost its popularity among Ayurvedic surgeons (2-4).

Types of Kshar Sutra
In the textual reference of Chakradatta and Rasatarangini we get only indication of the thread made up of Snuhi, apamarga and Turmeric. Susruta describes about many kind of Kshars like Karaveera, Palasa, Kadali etc. in Susruta Samhita. So many studies have already carried out with variations in the Kshara and the latex. The most remarkable are Guggulu Ksharasutra, Udumbara Ksharasutra, Gomutra Ksharasutra, Papaya Ksharasutra, Ksharasutra prepared with Ficus carica latex etc (4-5).

Method of Preparation
The standard kshar sutra is prepared by repeated coatings of snuhi ksheera (latex of Euphorbia Nerrifolia Linn), apamarg kshar (water extract of ashes of Achyranthus aspera Linn plant) and haridra powder over a surgical linen thread no. 20. This thread is spread throughout lengthwise in hangers. Each thread on the hanger is then smeared with snuhi latex with the help of gauze piece soaked in the latex.
Kshara sutra cabinet has a source of hot air with regulated temperature to dry the thread and an Ultra Violet light that is used for sterilization. This wet hanger is transferred in kshar sutra cabinet for drying and sterilization. Same process is repeated next day. Eleven such coatings with snuhi ksheera alone should be accomplished. The twelfth coating is done by first smearing the thread with ksheera and in wet condition thread is passed through the apamarg kshar. It is again transfer into the cabinet for drying and sterilization. This process is repeated till seven coatings of snuhi ksheer and apamarg kshar is achieved. Final three coating are completed with snuhi ksheera and fine powder of turmeric in the same fashion. Thus twenty-one coatings over the thread are completed (6).

Mode of Action
Kshar Sutra is now a popular treatment modality in India for the management of fistula in ano. Many Clinical trials have been carried out in different institutes to evaluate the action of Kshara sutra in various disease conditions. The countries like Srilanka and Japan have also conducted many clinical trials and established the action of this thread. According to Ayurveda the action of Kshar sutra is thought to be due to its healing and cleansing effect in the local area where it is applied. It can be suggested that due to the anti microbial action and as a saton it allows the proper drainage of pus from the fistula that leads to a proper healing. On the other hand the cutting effect of thread incises the skin gradually without a surgical incision. Many studies confirm that it is more effective in the way of reducing hospital stay and less infection than the conventional saton therapy. Researchers suggest that it is having the action of Excision, Scrapping, Draining, Penetrating, Debridement, Sclerosing, Healing, Bactericidal and Bacteriostatic (6).

Euphorbia neriifolia L.
Euphorbia neriifolia Linn (Euphorbiaceae) is found throughout the Deccan Peninsula of India and commonly occurs in the dry hilly rocky grounds of north, central and south India. It is an herb full of spine, and is popularly known as sehund or thohar in Hindi. Ayurveda describes the plant as bitter, pungent, laxative, carminative, improves appetite, as well as useful in abdominal problems, bronchitis, tumours, loss of onsciousness, delirium, leucoderma, piles, inflammation, enlargement of spleen, anaemia, ulcers and fever. Its leaves, in the Indian traditional system, are used as aphrodisiac, diuretic, and also in cough and cold, bleeding piles and ano-rectal fistula (7). Plants of euphorbia species show anticarcinogenic activity due to the presence of several terpenes, anthocyanins, alcohols and steroids; diterpenoid ingenol 3,20dibenzoate and phorbol 12-tiglate 13decanoate isolated from Euphorbiaceae plants show antileukaemic activity against the P-388 lymphocytic leukaemia in mice (8). Euphol, a triterpene alcohol from the roots of Euphorbia kansui, has inhibitory activity against mice skin tumour (9). E. neriifolia, being widely available in large quantities, is potentially a low-cost source of active therapeutic substances. We have previously reported on the mild CNS depressant, wound healing and immunomodulatory activities of the hydroalcohol leaf extract (10-12). Little phytopharmacological work, however, has been done on the medicinal application of the leaf. Saponin isolated from the leaf possesses good haemolytic and in-vitro antioxidant activity but it is devoid of antibacterial activity up to 10 mg/ml concentration (13). Euphorbia neriifolia leaves are used as aphrodisiac, diuretic and also used in the treatment of bronchitis, bleeding piles and in ano-rectal fistula. The tribal population of Chattishgarh region uses the milky latex as an ingredient of aphrodisiac mixture (7, 14). The aqueous extract of the latex of Euphorbia neriifolia facilitated the wound healing process as evidenced by increase in tensile strength, DNA content, epithelization and angiogenesis (15). E. neriifolia Leaf is rich in crude sapogenin, and euphol (0.023 %) was identified as a major constituent. The sapogenin fraction showed antioxidant, radioprotective and cytotoxic activity against malignant melanoma cells (16). Natives of Chhattisgarh use externally boiled 'thohar' milk in castor oil with salt to cure the deep cracks in soles of legs. The milk of 'thohar' is also used commonly like aloe gel in case of burns. 'thohar' milk can be used successfully for healing of wounds. Application of lukewarm 'thohar' leaves reduces itching pain and swelling in piles (17). E. neriifolia hydroalcoholic extract was found to contain sugar, tannins, flavonoids, alkaloids triterpenoidal saponin on preliminary phytochemical analysis. Several triterpenoids like Glut-5en-3$-ol, Glut 5(10)-en-1-one, taraxerol and $-amyrin has been isolated from powdered plant, stem and leaves of E. neriifolia (18-19). Antiquorin have been isolated from ethanol extract of fresh root of E. neriifolia (20). Neriifolione, a triterpene and a new tetracyclic triterpene named as nerifoliene along with euphol were isolated from the latex of E. neriifolia (21). Achyranthes aspera L.
Achyranthes aspera Linn. (Amaranthaceae,) is commonly found as a weed on way side and at waste places throughout India. The plant is reported to yield a water-soluble base and a chloroform soluble base. The former was earlier designated as achyranthine (22). It was characterized as a betaine derivative of N-methylpyrrolidine-3-carboxylic acid (22). Later studies showed that the watersoluble base was betaine and not achyranthine (23). The chloroform soluble basic fraction was shown to be a mixer of two uncharacterized alkaloid entities (24). The ethanol extract of the plant contained alkaloids and saponins while flavonoids and tannin were found absent (25). The shoot yielded a new aliphatic dihydroxyketone, characterized as 36, 47dihydroxyhenpentacontan-4 one together with tritriacontanol (26). An essential oil; a new long chain alcohol characterized as 17-pentatriacontanol four new compounds characterized as 27cyclohexylheptacosan-7-ol, 16-hydroxy-26 methylheptacosan-2-one, 4methylheptatriacont-1-en-10-ol and tetracontanol-2 (27-28). The chloroform extract of the stem led to the isolation of n pentatriacontan, 6-pentatriacontanone, hexatriacontane and triacontane (29). The inflorescence is reported to contain flavonoids and alkaloids (30). The defatted seeds are reported to yield a saponin in a yield of 2%, which was identified as oleanolic acid-oligosaccharide. The sugar moiety of the saponin was composed of glucose, galactose, xylose and rhamnose (31-33). Isolated a crude sapogenin fraction from the seeds yielded oleanolic acid (34). Later, investigation led to the isolation of two oleanolic acid based saponins, saponin A and saponin B which were characterized as α-Lrhamnopyranosyl (1→4)-β'-Dglucopyranosyl (1→4)-β'-D glucuronopyranosyl ( 1→3)-oleanolic acid and β-D-galactopyranosyl (1→28) ester of saponin A, respectively (35). In another study, the total saponins were hydrolysed with acid and the genin was identified as oleanolic acid (35). A rapid procedure for the separation of triterpenoid saponin based on partition chromatography from the plant has been described (36). The seeds are reported to contain hexatriacontane, 10-octacosanone, 10triacosanone and 4-triacontanone (29). The root of the plant was found to contain alkaloids but indicated absence of saponin and tannins (37-38).

CONCLUSION
Major thrust by whole of the pharmaceutical industry is focused towards design and development of new innovative/indigenous plant based drugs through investigation of leads from traditional system of medicine. In recent years, ethno-botanical and traditional uses of natural compounds, especially of plant origin received much attention as they are well tested for their efficacy and generally believed to be safe for human use.