Therapeutic potentials of metals in ancient India: A review through Charaka Samhita.

The Ayurvedic system of medicine has stood the test of time for four millennia or more. The ancient seers found that drugs of different origin (herbal, metal or animal) in addition to codes of conduct and dietary regulations are suitable tools to maintain health in healthy and eradicating diseases in diseased. Use of metallic preparations in healthcare is a unique feature in this system. Processed metals including Mercury, Gold, Silver, Lead, Zinc, Copper etc. were used very frequently by seers of the Indian tradition in different disease conditions with great authority. It is generally claimed, that these metals are detoxified during the highly complex manufacturing processes described in Ayurvedic, especially Rasashastra texts. Charaka Samhita, one of the scheduled books of Ayurveda also holds ample of references regarding the use of metals for different purposes, which are summarized in the current paper.

INTRODUCTION

The Ayurvedic system of medicine has great antiquity, dating back to about 5000 years B.C. Its Materia Medica contain resources in the form of drugs derived from plant, animal, metal and mineral sources,[1] the use of which have been advocated in various different pathological manifestations. These drugs have also been converted in to poly-herbal, herbo-mineral and metallic compound formulations by the seers, who have documented their clinical experiences and passed on the knowledge to further generations.

During the medieval period, with the advent of Rasashastra, use of certain heavy metals and minerals in Ayurvedic therapeutics increased. Rasashastra, an integral part of Ayurveda, deals with the drugs of mineral origin, and details their varieties, characteristics, processing techniques, properties, therapeutic uses, possibilities of developing adverse effects and their management etc. in a comprehensive way. Although the roots of this science (Rasa Shastra) exist in the ancient texts of Indian civilization, its development as an independent system of therapy started around the 8th century A.D.. Ayurvedic classics written before that time, like Charaka Samhita and Sushruta Samhita etc. contain descriptions of metals and minerals, their processing techniques and their utilization in therapeutics etc.

In due course of time, herbo mineral and metallic preparations came to occupy a significant seat in Ayurvedic pharmacopoeia and have routinely been used in practice in different parts of India for many centuries. Such preparations are held to be safe, efficacious even in minute doses, and, when manufactured and used following specified classical guidelines, not to lead to any significant untoward effects.[2] The past decade, however, has witnessed concerns by the western scientific community, regarding the safety of Ayurvedic Herbal, Herbo-mineral and metallic preparations, which is a major concern for the age-old Ayurvedic heritage.[3]

This paper attempts to screen Ayurvedic classics for references emphasizing the utilization of metals for medicinal and other purposes. Charaka Samhita was scrutinized and found to contain referred frequent references to metals used for different purposes including medicinal and non medicinal ones. Seer Charaka advocated converting the metals in to fine powders before their utilization and observing great caution during the period of administration in different disease manifestations.

OBJECTIVES

The present paper is a compilation holding references pertaining to metals during the period of Charaka Samhita along with some information on the metals explained in textbooks of Rasashastra and modern science.

The references found in the classic were grouped into different categories with an intension to give an insight about the frequency of usage of the metals . The categories are as under:

Utilization in therapeutics

Internal administration

External application

Utilization in the preparation of equipment/instruments

Other purposes etc.

Parada (Mercury)

Formulations containing mercury are only rarely mentioned in Charaka Samhita. The first reference pertaining to Parada and its utility in therapeutics mentioned in the classic is controversial,[4] only a few scholars interpret the term Rasa in the verse chikitsasthana 7/71 as Parada. The second reference is found in Dwivraniya Chikitsa, where the term Rasa is interpreted as Parada by the commentator Chakrapani.[5] It is interesting to note that, both these formulations are recommended for external application. Table 1

Table 1

Depicting the references of Parada

Though the term ‘Rasa’ has been rendered as ‘Parada’ by ‘Chakrapani’, it is very difficult to claim that mercury was in practice during the period of Charaka for the following reasons.

The term ‘Parada’ was not used by Charaka throughout the classic.

If the metal had been known to the physicians of those days, we might expect that it would have been discussed frequently, along with associated pharmaceutical procedures, and its combinations.

Chakrapani is silent and doesn’t expressed an opinion on the term ‘Rasa’ at Chikitsa 7/71, but interprets the same term in the earlier verse (Chikitsa 7/70) as ‘expressed juice’, while, at Dwivraniya Chikitsa (25/116), he interprets ‘Rasa’ as Parada.

Later works like Sushruta Samhita (Chikitsa 25/39) and Astanga Hridaya (Uttara 13/36) preferred mercury as a component in topical applications. It was only later that the frequency of its internal utility increased. Probably, these developments might have been noticed by redactors and commentators like Dridhabala and Chakrapani, who expressed their opinions in their respective works.

Swarna (Gold)

Swarna, the Sara Lauha[6] is an important, noble metal known to Indians since antiquity. References can be traced back to Charaka and Sushruta Samhita where the noble metal has been attributed with a wide range of applications. The ‘Bhasma’ form of Gold is in metallic state. Quantitatively it is a combination of metallic Gold (96.76%), silica (1.14%), ferric oxide (0.14%), phosphates (0.78%), potash (0.16%), salt (0.078%), and traces of copper and magnesium.[7]

In its elemental form, Gold has been employed for centuries as an anti-pruritic agent to relieve itching palms. In 1980, Robert Koch observed that gold inhibits Mycobacterium tuberculosis in vitro. This led to trials on arthritis and lupus erythematosus. Also, previous studies carried out in 1973 on gold and its compounds observed beneficial activities at different levels. Gold compounds have the ability to decrease concentrations of rheumatic factors and influences the immunological responses.[53] It has also been established[54] that gold suppresses the anaphylactic release of histamine more effectively than gluco-corticoids. Sodium aurothio malate (water soluble preparation) was introduced around 25 years ago to treat arthritis, and is administered through IM injections. Its pharmacokinetics were not established but, its effects are probably due to its antimicrobial effects and stimulatIon of the Reticulo Endothelial system.[8]

Various formulations of ‘Swarna’ are useful: Vrishya, Balya, Rasayana, Medhya, Ayushya, Ojo Vardhaka, Vayah sthapaka etc.[9] and disease alleviators particularly in chronic debilitating diseases like Raja Yakshma, Swasa, Kasa, Pandu etc.[10] Normal dose levels given for ‘Swarna Bhasma’ is 15 mg. to 30 mg.[11] References pertaining to Swarna in Charaka Samhita have been depicted in Table 2.

Table 2

Depicting the references of Swarna for different purposes

Rajata (Silver)

Rajata (Silver), another noble metal like gold, also attracted the attention of the ancient Acharyas. The use of silver in therapeutics dates back to the period of Charaka and his contempories. Though, its therapeutic applications are not as extensive as other metals like Tamra or Loha, the ancient classics reveal that silver also enjoyed an important place in Ayurveda therapeutics.

Classics of alchemy say s that, samples of Rajata which are clear, lustrous (Swachha), heavy (Guru), and with metallic sheen (Snigdham), and which also become bright white on heating or cutting (Dahe Chede Samaprabham), without any ridges or furrows (Sphota rahitam), is genuine, and can be considered acceptable for therapeutic purposes.[11] Quantitatively ‘Rajata Bhasma’ is a combination of metallic silver (52 to 59%), free sulphur (0.675%), ferric oxide (14.33%), calcium (10.769%), silver chloride (0.479%), and traces of sodium, potassium and aluminium.[13] Various useful formulations of ‘Rajata’ are: Balya, Rasayana, Medhya, Ayushya, Ojo Vardhaka, Vayah sthapaka etc. The normal dosage range given for ‘Rajata Bhasma’ is 30 mg. to 120 mg.[14] The references of Rajata in Charaka Samhita as one of the components are listed in Table 3.

Table 3

Depicting the references of Rajata for different purposes

Tamra (Copper)

Tamra (Copper) is another ancient metal known to human civilization. During pre-Vedic times, the metal was part of day-today livelihood functions. Further, it is the earlier known metal for the preparation of the stronger alloy metals brass and bronze of which it is a component. Charaka uses the term Arka in a few places which Chakrapani clarifies as synonymous with Tamra.[15] According to the descriptions of Rasa in Vagbhata Ref. there are two forms of Tamra viz. Nepaliya and Mlechha, only the former being acceptable. Samples with characteristic metallic sheen (Snigdham), soft (Mridulam), bright reddish in color (Shonam), having high tensile strength (Ghanaghata Ksamam), heavy (Guru), and devoid of impurities (Nirvikaram) are identified as best used for medicinal purposes.[16]

Formulations of ‘Tamra’ are useful in a wide range of diseases like Krimi, Sthaulya, Arsha, Ksaya, Pandu, Kusta, Swasa, Kasa, Amlapitta, Sotha, Sula, Yakrit Roga and Grahani dosha etc.[17] In addition, Charaka advocates the use of Tamra Patra (copper vessels) in several pharmaceutical procedures.[18] Normal doses mentioned for ‘Tamra Bhasma’ is 15 mg to 60 mg.[19] The references mentioned in Charaka Samhita that hold Tamra as one of the active components are listed in Table 4.

Table 4

Depicting the references of Tamra for different purposes

Aayasa or Loha (Iron)

Next to Swarna, Rajata and Tamra, Loha or Ayasa is another metal known to ancient civilizations. During the period of Charaka, it was used in different dosage forms named Curna, Vati, Avaleha, Varti, Asavarishta etc. either for external or internal administration in a number of pathological manifestations. Iron compounds were particularly employed in diseases suchas anaemia and other debilitating conditions, where functions of hemopoitic systems are disturbed and the blood has consequently become deficient in iron. Rasa Shastra classics explain that Loha is par excellence a rejuvenator as it stimulates functional activity of all the organs, promotes life, strength, destroys a number of diseases, and acts as a restorative.[20] The utility of this metal in therapeutics was only identified modern medicine in the first half of the 17th century, when its salts were recognized as the best haematenics. According to descriptions in Rasa Vagbhata, there are three varieties of Loha viz. Munda, Teekshna and Kanta, the latter being the best variety to use.[21]

As preparations of Loha are of foremost importance in Ayurveda therapeutics, proper care should be taken during procedures for its purification and incineration. Chakrapani stresses the need to take care when administering it.[22] Charaka emphasizes a special Ayaskriti procedure, which converts thin leaves of metal into a fine absorbable form.[23] In addition to these uses, iron vessels were specifically recommended to be used in certain pharmaceutical procedures (Chikitsa 1-3/43, 15/187, 16/83, 26/250, 26/274 etc.) Quantitatively, it is a combination of ferric oxide (96.5%), ferrous oxide (2.5%), magnesium oxide (0.8%), calcium oxide (0.3%), together with traces of phosphorus and potassium. Different formulations of ‘Loha’ are useful in a wide range of diseases: Sula, Arsha, Gulma, Pliha Roga, Yakrit Roga, Ksaya, Pandu, Kamala etc.[24] Normal dose levels given for ‘Loha Bhasma’ are 30 mg. to 240 mg.[25] List of the formulations mentioned in Charaka Samhita that hold Loha as one of the active components are depicted in the Table 5.

Table 5

Depicting the references of Loha for different purposes

Mandura

Mandura, the second form of Iron, has been used for a wide range of therapeutic procedures in classical Ayurveda since antiquity. It is defined by Madhava Upadhyaya in the Ayurveda Prakasha as the debris collected after heating and beating processes of Iron around a blacksmith's anvil.[26] Generally, mandura is collected from sources like old anvils, and is considered to be very useful, if they are about 100 years old. Samples of ages 80 years and 60 years old are respectively considered moderately and least efficacious for therapeutic purposes.[27] According to the literature Mandura, which is smooth to touch (Snigdha / Masruna), heavy (Guru), strong (Dridham), without any fissures or furrows (Kotaravarjitam), and taken from age old constructions (Jirna nasta purastham) is genuine and can be used for therapeutic purposes.[28]

Purified mandura, when administered with proper justification is beneficial in inflammations, edematous conditions, jaundice etc. It is the drug of choice in cases of anaemia (Pandu), and Charaka refers to a number of its preparations. Chemically, Mandura is a combination of ferric oxide (59.14%), ferrous oxide (26.7%), chlorides (4.4%), magnesium (3.9%), sodium (1.7%) and a few other elements in trace quantities. Its unique constitution plays a pivotal role in therapeutics of anaemia and other associated disorders.[29] The normal dose given for ‘Mandura Bhasma’ is 30 mg. to 240 mg. 30 Few of the formulations mentioned in Charaka Samhita that hold Mandura as one of the active components are depicted in Table 6.

Table 6

Depicting the references of Mandura

Naga/Sisaka (Lead)

Naga is an important Puti Loha known since ancient times, also identified by other terms like Sisaka or Sisa. Charak emphasizes that medicinal uses of this metal should be external, partiicular in cases of Mandala Kusta. The Brihad Rasa Raja Sundara describes two varieties of Naga viz. Kumara and Samala the former being the acceptable variety for therapeutic applications. Samples which melt easily (Drutadravam), and are heavy (Mahabharam), externally black in color (Bahihkrishnam), and when incised shine with bright black luster (Chede Krishna Samujwalam) should be considered genuine and preferred for therapeutic purposes.[31] Quantitatively Naga Bhasma is a combination of lead oxide (75.6%), ferric oxide (7.5%), together with traces of calcium and magnesium chlorides and carbonates.

Different formulations of ‘Naga’ are beneficial in diseases like Prameha, Gulma, Arsha, Sweta Pradara, Grahani roga, Antra sotha etc.[32] Therapeutic dosages given for ‘Naga Bhasma’ range from 30 mg. to 120 mg.[33] References mentioned in Charaka Samhita, that hold Naga as one of the components are depicted in Table 7.

Table 7

Depicting the references of Naga for different purposes

Vanga/Trapu (Tin)

Vanga, one of the Puti Lohas was known to ancient Indian physicians by the name of Trapu. In Charaka Samhita, the metal is categorized under Parthiva Dravyas. According to descriptions in Rasa Vagbhata, there are two varieties of Vanga viz. Khuraka and Mishraka, the former being acceptable for therapeutic applications. Samples with the characteristics, bright white in color (Dhavalam), soft (Mridulam), shiny, smooth (Snigdham), easily melts (Drutadravam), and heavy (Guru) are identified as Khura Vanga and should be preferred for therapeutic purposes.34 Quantitatively Vanga Bhasma is a combination of stannic oxide (i.e. of tin) (91.4%), ferric oxide (2.9%), potassium (2.9%), calcium oxide (2%), aluminium (2%) and magnesium (0.6%) oxides.

Formulations of ‘Vanga’ are variously beneficial in diseases such as: Prameha, Kasa, Shwasa, Krimi, Ksaya, Pandu, Pradara, Garbhashaya Chyuti etc.[35] Singly or in combination with other puti lohas, it is beneficial in disorders of the Genito Urinary Tract. It has also been said that, Vanga Bhasma is the drug of choice in the case of Prameha.[36] Therapeutic doses given for ‘Vanga Bhasma’ range from 120 mg. to 240 mg.[37] The references mentioned in Charaka Samhita, which hold Vanga as one of the components are depicted in Table 8.

Table 8

Depicting the references of Vanga for different purposes

Pittala (Brass)

Pittala is an important Misra Loha, an alloy of Copper and Zinc, known since the period of Samhita Kala. Charaka used this metal to prepare Vasti netra. It is known as Brass. As per the descriptions available in Rasa Ratna Samuchaya, there are two varieties of Pittala viz. Ritika and Kakatundi.

Formulations of ‘Pittala’ are beneficial in diseases like Krimi, Kusta, Pandu etc.[38] The therapeutic doses given for ‘Pittala Bhasma’ range from 60 mg. to 120 mg.[39] Very few references mentioned in Charaka Samhita that hold Pittala as one of the components are depicted in Table 9.

Table 9

Depicting the references of Riti for different purposes

Kamsya (Bronze)

Kamsya is another important Misra Loha, an alloy of Copper and Tin known since the period of Samhita Kala. Charaka used this metal to prepare Vasti netra. It is known as Bell Metal or Bronze. According to the descriptions given in Ayurveda Prakasha, there are two varieties of Kamsya viz. Pushpa and Tailika, only the former being acceptable for therapeutic applications. Samples giving a sharp sound (Teekshna Shabdam), soft (Mridu), smooth to touch (Snigdha), slightly grayish (Eshat Shyamalam), clear from impurities (Shubhram/Nirmalam) and turning red on heating (Dahe Raktam) possess the characteristic features of the material preferred for therapeutic purposes.[40]

Formulations of ‘Kamsya’ are beneficial in diseases like Krimi, Kusta etc.[41] Therapeutic doses iven for ‘Kamsya Bhasma’ range from 60 mg. to 120 mg.[42] Very few references mentioned in Charaka Samhita that hold Kamsya as one of the active components are depicted in Table 10.

Table 10

Depicting the references of Kamsya for different purposes

DISCUSSION

It becomes clear from screening the classic Charaka Samhita that metals like Gold, Silver, Iron, Copper, Lead, Tin etc. as well as some alloys were used to treat a wide range of diseases. Fine powders of these metals were prescribed for both internal and external applications. References also can be traced where the metallic powders were applied to the eyes.[43] Emphasis is given to purification of metals and their conversion to micro-fine powders by following specified guidelines, processes which were termed ‘Ayaskriti′. Charaka suggest using these metallic preparations with great authority, stating them to be safe and efficacious if used judiciously. He also emphasizes that great caution is needed when using such metallic powders in therapeutics.

In addition to the therapeutic utilization; different metals ranging from gold to iron were also used in preparing equipments like Jihva Nirlekhana Yantra (tongue scrappers),[44] Nabhi Kartana Yantra (sharp instruments to cut umbilical cord),[45] Vasti Netra (nozzle of enema pot),[46] different Anjana Shalakas (metallic applicator for application of medicaments into eyes)[47] etc. Besides this, Charak recommends preparing containers and vessels with different metals like gold[48], silver[49], copper[50], iron[51] and some alloys[52] etc. where instructions for pharmaceutical procedures like boiling etc. are given.

Close scrutiny makes it clear that such metallic preparations have held a significant place in Ayurvedic pharmacopoeia since antiquity. In the recent past, western scientists have begun to focus on the toxic nature of metals like mercury, lead etc. Reviewing the Ayurvedic literature reveals that ancient scholars had considered the possibility of toxicity of metallic preparations, and emphasized the necessity of taking great care over this point. They evolved specific methods using various pharmaceutical techniques like shodhana, jarana, marana etc. which have their own significance in detoxifying and increasing the therapeutic potential of metals.

CONCLUSIONS

Reviewing Charaka Samhita reveals thatAyurveda utilized metals for various therapeutic and non-therapeutic purposes. The text emphasizes the need to observe great caution while using metals, and directs that they should be reduced to micro-fine powders through the specially designed process ‘Ayaskriti′. The reduced metals may contain associated compounds together with major elements, which have their own significance in the process of disease pacification. In addition, a few of the metallic powders also may provide nourishment, as they are a combination of many trace elements and electrolytes. In the recent past, some researchers have suggested that these metallic/mineral preparations are anti-oxidants which fight free radicals, anddisease causing organisms and also help in developing immunity.[55] Studies carried-out in different parts of India have indicated that, when metals and minerals are converted into medicines strictly adhering to the classical guidelines specified in ancient texts, they are devoid of any toxicity even at the level of 100 TEDs. Histo-pathological studies of visceral organs in these studies revealed no apparent changes. For example, a study on Rasa Karpura, established safety of the compound even at 40 TED.[56]

Furthermore, the effectiveness of Ayurvedic medicines is not usually due to single active ingredients, but, usually to complex mixtures of compounds which target the pathological manifestation in several different ways. Therefore, Ayurveda differs from systems of medicine using single ingredients.

Keeping all these in mind, it can be said that the damning reports such as those of unacceptable levels of heavy metals etc. in Ayurvedic preparations should not be considered cause for alarm. The concepts, practices and products of the Ayurvedic system of medicine are unique, and its therapeutic values are needed to be explored by utilizing and adopting sophisticated technology, Only then can ailing humanity benefit from its age-old remedies.