The Sanskrit word-Dhatu comes from a verb-dha- meaning-to Support. There are 7 basic tissues or dhatus which support and sustain. The living body in context with Rasa Shastra, the word dhatu denotes a metal. The Sanskrit word -loha derived from a root-luh, meaning to pull. The ores, from which the metals are extracted, were known as loha. The ancient texts of Ayurveda have mentioned the classification of metals as follows:

• Sara Loha: Includes Swarna and Rajata

• Shuddha Loha: Comprises Swarna, Rajata, Tamra and Loha

• Sadharana Loha: Contains Tikshna Loha and Tamra.

• Putiloha: Naga, Vanga and Yashad

• Mishra Loha: Consists of alloys like Kansya, Pittala, Varta

It is apparent from this classification that Vanga is classified as puti loha. Here, the word Puti means bad smell, obnoxious or dirty. All three metals mentioned in this group emit obnoxious smell while they are melting. Vanga has been widely described in our texts and several therapeutic properties have been started. Much importance has been given to its efficacy as Vrishya and as a therapy for Meha Roga [1] (Table 1-3).

Types of Vanga

There are two varieties of Vanga [3]:

• Khuraka

• Misraka

The Khuraka type of Vanga has better qualities than Misraka (which is unfit for therapeutic use).

Properties of Two Varieties of Vanga

As described in texts (R.R.S 5/154-155& R.T18/3-4) Khuraka and Mishraka Vanga possesses the following properties (Table 4):

Shodhan of Vanga [4]

As we know, metals and minerals should be made free from impurities, toxic qualities and adulterants before they are subjected to therapeutic administration in the body.

Table 1: Synonyms of Vanga

Table 2: Historical Review of Vanga in Different Classical Literature

Table 3: Synonyms of Vanga According to Different Texts [2]

Table 4: Properties of Varieties of Vanga

Table 5: Materials and Method used for Shodhana according to Different Classical Literature [7]

For achieving this, metals and minerals have to undergo Shodhana process which is the initial step for Bhasma preparation. Dhalana process brings brittleness, softness and reduces its particle size to some extent.

Reason for Vanga Shodhana

Improperly prepared Vanga Bhasma on oral administration will produce following types of disorders:

Ashmari                Kilasa                            Gulma                                    Hradroga

Kusta                       Apachi                          Meha                                       Kasa

Shwitra                  Kshaya                         Pandu                                     Swasa

Daha                        Bhagandra                 Vidradi                                  Vami

Swayathu             Shoola                           iJwara                                    Rakta vikara

                                                                              Agnimandya

Hence proper Shodhan and Maran are essential to be performed before its oral administration [5].

Shodhana Process for Vanga

A number of shodhana processes have been described for Vanga Shodhana by various Acharyas: They are as follows [6] (Table 5-10):

• Dhalana

• Swedana

• Seka

• Sechana

• Nirvap

Table 6: Herbal Drugs used in Jarana/ Marana of Vanga

Table 7: The Mineral Drugs used in Jarans/ Marana of Vanga

Table 8: The Animal Origin Drugs Used In Jarana/Marana of Vanga [8]

Table 9: Puta used for Preparation of Vanga Bhasma

Table 10: Pharmacological Actions According to Various Classical References

Modern Review of Tin [9]

History: The early Greek alchemist called tin as the metal Hermes, while during 6th A.D. it was known as Zensor Jupitor and designated by the symbol R. this element is found as a component of Pre-historic Bronzes, which evidences the use of this metal by mankind thousands of years before the dawn of history. In Latin, Tin was Plumbum candidum, -white lead‖. Plumbum was the generic name for soft white metals with low melting points.

General Introduction

Tin is a soft, silvery white metal with a highly crystalline structure that is malleable and ductile occurring in Block p, Group 14 and period 5 of the Periodic Table. It is the 49^th most abundant element in earth‘s crust and has, 10 stable isotopes, which is the largest number of stable isotopes for an elements in the periodic table. Tin is obtained chiefly from the mineral Cassiterite where it occurs as tin dioxide, SnO2. Of the various tin bearing minerals, states, +2 and the slightly more stable +4, tin forms two series of compounds- namely, those of bivalent tin (tin(ii)) and quadrivalent tin (tin(iv)). The most important inorganic compounds of tin are the oxides, chlorides, fluorides and halogenated stannates and stannites. Tin can form 1-4 covalent bounds with carbon.

Properties of Tin

• Symbol                                    Sn
• Atomic number                     50
• Atomic mass                           118.70 g.mol^-1

• Position in periodic table   P block, group 14, Period 5

• Density                                     5.77g cm^-3 (alpha tin) and 

                                                   7.3 g cm^-3 at 20 c (Beta tin)

• Melting point                          232 C
• Boiling point                           2603 C
• Isotopes                                   10
• State of matter                        Solid at 298 K
• Specific gravity                       7.31

Physical Properties

Tin is malleable, ductile and highly crystalline metal. When a bar of tin is bent, a crackling sound known as tin cry can be heard due to the twisting/twinning of the crystals. The most common allotrope of tin is a silver white metallic looking solid known as the B-form (or ‗beta-form‘). Allotropes are forms of an element with different physical and chemical properties. B-tin is both malleable and ductile. At temperature greater than 200 C, tin becomes very brittle. A second form of tin is α- tin (or alpha tin), also known as ‗gray tin‘. grey tin forms when white tin is cooled to temperature less than about 13 C. Gray tin is gray amorphous (lacking a crystalline shape) powder. The change from white tin to gray tin takes place rather slowly. This change is responsible for some peculiar and amazing changes in objects made from.

Chemical Properties

Inorganic compounds (A compound is considered inorganic when there is no direct covalent tin-carbon bond in molecule, even though it may contain an organic anion), it can appear in two oxidation states: +2 (stannous form) and +4 (stannic form). Tin is soluble in dil. mineral acid and in hot potassium hydroxide but not attacked by food acids and alkalis .An Acid solution tends to preserve the stannous state in which tin is powerful reducing agent. Tin reacts with dilute acids yielding stannous salts and hydrogen, concentrated nitric acid converts it into β-stannic acid. The metal resists weak alkalis but dissolves in hot concentrated alkalis to form Meta stannate and hydrogen.

­­

Oxides of Tin

Stannous oxide-it is generally prepared by precipitation of stannous oxide hydrate form a solution of stannous chloride and chloride and caustic soda. Heating at 100 C in the absence of air converts the hydrate into oxide.

Properties and Uses

It is stable, usually blue black, crystalline product, insoluble in water. It decomposes at 385 C to form stannic oxide and tin. It is a less stable form varying in color from brown to red to dark green and violet.

Stannic oxide-it is prepared by blowing hot air over molten tin by atomizing tin by means of high pressure steam and burning the finely divided metal or by the calcinations of hydrated stannic oxide obtained from sodium stannates. It occurs in nature in form of Casseterite as a principal ore of tin.

Properties and Uses

It forms white tetragonal crystals, which are insoluble in water, but soluble in conc. Sulphuric acid.

Sources

The important tin producing countries are Malaysia, Bolivia, Thailand, Republic of Congo, Nigeria and China which accounts for 99% of world production. Small tonnage is produced in Australia U.K., Burma, Japan, Canada, Spain and Portugal. In India though occurrences of tin ore have been reported from some of the localities in Bihar, Rajasthan, Gujarat and Karnataka.

Important ores of tin:

• Cassiterite: SnO2 (tin stone)

• Cylindrite: Pb3Sn4FeSb2Si4

• Stannite: Cu2SFeSnS2

• Tealite: PbSnS2

• Canfieldite: Ag8SnS6

Extraction of Tin

Tin is extracted by mixing carbon in reverberatory furnace. The metallurgy of tin is simple but its extraction from the ore is complicated due to presence of reduced iron that forms-hard head‖ with the tin.

Biological Significance

Tin as an essential trace element to life was included in the 8^th decade of the previous century. This elements was discovered as essential for normal growth, without 1or 2 ppm (parts per million) in their diet rats gain weight only 2/3rds of their normal rate.

From the information available from animal experiments, it is possible that fluoride and tin have essential role in human nutrition and metabolism. Tin is considered as one of the essential trace elements for human body. Tin and Vanadium appear to influence lipid metabolism, possibly as oxidation-reduction catalysts. 

Nowadays, administration of metals is in ionic form in Bhasma. This is similar to effects produced by the injection of colloidal metals, except that the action is slow in beginning, feeble in degree and prolonged in time. The observation indicates that the pharmacological action is being due to conversation of these microns into ionic condition.

Metabolism of Tin

Absorption: Various experimental evidences from human as well as several animal species revealed that ingested inorganic tin poorly absorbed. Most studies indicate that less than 3% of tin is absorbed from G.I.T., although values as high as 20% have been reported. It has been observed that following a singly oral dose of 20mg of tin (II) or tin (IV) per kg body weight in rats, 2.85% and 0.64% was absorbed respectively.

In a study, absorption of tin with the anion pyrophosphate was significantly lower than when the anion was either citrate or fluoride, this difference in absorption is attributable to greater tendency of pyrophosphate to form insoluble complexes with tin than either fluoride or citrate. Gastrointestinal absorption from food or water is the principal source of internally deposited tin in the general population. Gastrointestinal absorption is generally quit low, with only about 2% of the amount ingested being transferred to the bloodstream. 35% of tin that reaches the blood is deposited in mineral bone, 15% is distributed throughout all other organs and tissue of the body and remaining 50% is excreted. Of the tin deposited in any organ or tissue, 20% is retained with a biological half-life of 4 days, 20% is retained with a biological half-life of 25 days and 60% is retained with a biological half-life of 400 days. Typical daily human dietary intake: -4mg. 

Distribution

In animal experiments, it was observed that following both oral and parenteral administration of tin, there was highest accumulation of the element in the liver, kidney and bone. The tissue distribution of tin observed by Hiles et al. in a study expressed as percentage of the administered tin (II) and tin (IV) respectively, are as follows:

• Skeleton = 1.02 and 0.24

• Liver = 0.08 and 0.02

• Kidney = 0.09 and 0.002

Extremely low level of tin in blood has been noted two days after oral or intravenous administration of tin in rats and was detectable only in RBCs. In a study conducted in human beings, most of the tin (80%) present in the blood was found in the cells.

Claimed Deficiency of Tin

Early studies of tin deficiency were flawed and thus did not conclusively establish the essentiality of tin, however, a recent study by Yokoi et al. on rats presents reasonable evidence in support of the view that tin is essential. When compared with those fed 2mg of tin/ of diet, rats fed 17 ng of tin/g of diet exhibited poor growth, decreased efficiency of food utilization, alopecia, depressed responses to sound and changes in mineral concentrations in various organs.

Levels in human (paper by Argonne, National lan, Eus, human health fact sheet. Aug., 2005):

• Blood/mg dL-0.38         Muscle/p.p.m: 0.33-2.4

• Bone/p.p.m: 1.4             Daily Dietary intake: 0.2-3.5mg

• Liver/p.p.m: 0.23-2.4   Total Mass in Avg. human: 20mg

It may contribute to the tertiary structure if some proteins. The human in take varies from 1.5 to 3.5 mg per day in normal food.

Cellular/Intracellular Attributes and Interactions

• Tin synergists: Nickel, iodine, Vitamin B1, Vitamin C,

• Tin Antagonists/Inhibitors: Iron, calcium, copper, chloride, vitamin B2, Vitamin E, bismuth, zinc

Low Levels/Deficiency-Symptoms

• Fatigue, depression, low cardiac output (left), low adrenals, shortness of breath, asthma, headaches, insomnia

• In animals, low tin results in poor growth, alopecia/bilateral, hair loss, hearing loss and reduced feeding efficiency

• Tetravalent tin has strong tendency to form coordination complexes with 4,5,6 or possibly 8 ligands. Thus, it has been suggested that tin may contribute to tertiary structure of protein or other components of biological importance

• It has also been postulated that tin may participate in Oxidation Reduction reactions in biological system because the Sn2+ Sn4+ potential of 0.13 volt is within the physiological range. In fact it is very neat the Oxidation- reduction potential of Flavin enzyme. (American Journal of Clinical Nutrition)

• Oral Vanga Bhasma has shown Testicular Regeneration activity and prevention of degenerative effects of cadmium induced testicular degeneration

High Levels/Overdose of Tin

Skin rashes, GIT upset, Palpitation.

Potential Health Effect:

• Inhalation: No adverse effects expected but dust may cause mechanical irritation

• Ingestion: Large doses may cause nausea, vomiting and diarrhea

• Skin Contact: no adverse effects expected, may cause mild irritation and redness

• Eye Contact: No adverse effect expected but dust may cause mechanical irritation

Chronic Exposure

Prolonged inhalation of the dust or fume may result in a benign pneumoconiosis, producing distinctive changes in the lungs with no apparent disability or complications.

The tin can be taken into the body by eating food, drinking water, or breathing air. Gastrointestinal absorption from food or water or water is the principal source of internally deposited tin in the general population. Gastrointestinal absorption is generally quite low, with only about 2% of the amount ingested being transferred to the bloodstream. Thirty-five percent of tin that reaches the blood is  deposited  in  mineral  bone  15%  is  distributed throughout all other organs and tissues of the body and the remaining 50% are excreted. If the tin deposited in any organ or tissue, 20% is retained with a biological half- life of 4 days, 20% is retained with a biological half- life of 25 days and 60% is retained with a biological half- life of 400days. In humans, absorption of inorganic tin from the gastrointestinal tract is low (generally less than 5%), but is influenced by dose, anion (compound solubility) and the presence of other substances. Unabsorbed ingested tin is, mostly (95-99%) excreted in the faeces within 48 h. absorbed tin distributed mainly to bone, but also to the lungs, liver and kidneys. Limited evidence suggest that inorganic tin does not readily cross the blood- brain barrier. Absorbed tin is mainly excreted in the urine, with some additional biliary excretion occurring. In mice, the biological half-life of absorbed inorganic tin was approximately 30 days.

Vanga is one among the metal mixed with many impurities and vanga Bhasma is indicated in disease like pandu, prameha, rakta pradara, kasa, kashay and etc. Vanga has different pharmaceutical procedure for shodhana as well as Marana and its Bhasma usually gets prepared with total 9-10 putas approximately.

1. Sharma, Sadanand. Ras Tarangini. Edited by Kashinath Shastry, Hindi commentary by Dharmanananda Shastri, 11th Edn., Motilal Banarsidass, 2009, 18th Taranga, p. 434, verse 1.

2. Vagbhatacharya. Rasa Ratna Samuccaya. Edited with Hindi commentary by Siddhiprada, Chaukhambha Orientalia, 1st Edn., 2011, chap. 5, pp. 171–173.

3. Somdev, Acharya. Rasendra Chudamani. Edited with Hindi commentary by Siddhinandan Mishra, 2009, pp. 264–268, shloka 137.

4. Vagbhatacharya. Rasa Ratna Samuccaya. Hindi commentary by Dattatreya Anant Kulkarni, Meherchand Lachhmandas Publications, 1st Edn., 2007, chap. 5.

5. Agnivesa, Acharya. Charaka Samhita. Edited with Hindi commentary by Tripathi, Chaukambha Surbharati Prakashan, 3rd Edn., Varanasi, verse SU. Stha. 5/74.

6. Govindapadacharya, Srimad Bhagvat. Rasa Hridaya Tantra. Edited by Chaturbhuja Mishra, 2nd Edn., 2002, verses 5/5, 18/15, 18/69.

7. Somdev, Acharya. Rasendra Chudamani. Hindi translation, Orientation, Varanasi, 2004, verse 14/134, pp. 264–265.

8. Yoga Ratnakara. Vidyotini Hindi commentary by Lakshmipati Shastri, edited by Bramhasanker Shastri, Chaukhambha Prakashan, Varanasi, 2009.

9. Dutta, P.K. General and Inorganic Chemistry. Vol. 1, Sarat Book House, 1996, p. 189.