Website: http://www.msinp.com/herbs/product/processed_shilajit/e-zine_issue_No_3_Mar_1997_Unearthing_the_evidence.htm(This article is from e-zine issue No 3 Mar 1997)

Unearthing the evidenceThe claims that surround folk medicines may not all be down to superstition, says Paul Phillips; researchers are shedding light on the healing properties of naturally-occurring substances such as shilajitUniversal remedies, or panaceas, are used in folk medicine all over the world. Millions of people - some highly educated - will pay large sums of money for panaceas and in certain cultures people will turn to these before conventional medicine. This is strange to the majority of western scientists, who often see panaceas as a barrier to rational and effective medical provision. Most panaceas have little medicinal value and, although in most cases acquiring them does not harm the environment and is ethically acceptable, the high value of such products sometimes encourages criminal and cruel practices.Nevertheless, there are plenty of recorded case studies where sceptics have been proved wrong. Aspirin, for example, originally obtained from willow bark, is an often quoted example within western tradition. But it is to the East that we have to look for many of today's exciting case studies. Here, another folk medicine that has recently captured the attention of scientists is shilajit - a blackishbrown exudation found in the romantic surroundings of the Himalayas, from Arunachal Pradesh in the east to Kashmir in the west. It is also found in Afghanistan, Bhutan, China, Nepal, Pakistan, Tibet and some regions of the former USSR (Caucasus, Ural), as well as in Norway, where it is gathered in small quantities from steep rock faces at altitudes between 1000 and 5000 m.1

In regional folk medicine, shilajit is a reputed rasayana (a rejuvenator and immunomodulator), claimed to arrest the process of ageing and prolong life.2 It is also used to treat a range of conditions ranging from ulcers and asthma, to diabetes and rheumatism. Considering the claims made for shilajit, it is surprising that detailed analytical work on this product took so long to get going.Researchers first began to investigate the chemical composition and bioactivity of shilajit in the early 1970s. Before then, it was not clear whether shilajit was a bitumen - a plant fossil - that had been exposed due to rock weathering at high altitude, or a material formed from modern plant remains. If the substance is a fossil, then its future supply is limited, but if formed recently then it may be possible to produce future supplies relatively cheaply.

Active ingredientsEarly work on shilajit showed that it is mainly composed of humus - the characteristic organic constituent of soils - together with other organic components. Humus consists of organic residues that have lost their original structure following rapid decomposition in the environment. It is not a clearly defined substance - its composition changes constantly and it can disappear by slow decomposition unless new residual matter is

incorporated. Humus contains two components of interest: fulvic acid and humic acid. The former has the lowest molecular weight components, containing uronic acids, phenolic glucosides and amino acids, while the latter is composed of high molecular weight compounds and contains a high proportion of phenolics.The humus extracts from shilajit were shown to possess a lattice-like structure, perforated by voids of varying dimensions (0.010.05 mm). These are filled with organic molecules or metal complexes, which may be responsible for the therapeutic effects. However, shilajit humus is not special; degrading humus samples and analysing the products spectroscopically shows that it is structurally similar to ordinary soil.Chemical research in the 1970s indicated that shilajit is quite recent in origin. In 1976, components of the plant Euphorbia royleana were discovered in shilajit, making the ancient fossil route unlikely.3 The plant is named after Euphorbias, who was the court physician of Juba II - the Romanised ruler of a North African kingdom - in the first century AD. There are ca 100 species of this plant growing wild in most temperate regions of the world. When damaged, they exude a milky latex that irritates the skin and eyes. Could this latex be transformed into the components of shilajit? Some of the organic compounds in Euphorbia royleana and shilajit are also found in animals such as beavers, who frequently eat the buds and bark of trees, and this is thought to be responsible for the deposits in these animals.

Fig 1. Some of the compounds that may be present in samples of shilajit

However, the controversy about the origin of shilajit raged on until the mid-1980s, when clear evidence emerged, indicating that the substance was of recent plant origin.4 Chemical analysis of shilajit by researchers at Banaras Hindu University in India revealed that, among other compounds, it contains biphenyl metabolites, (Fig 1). Interestingly, the group also identified some of the same biphenyls (13) in Trifolium repens, a plant that grows abundantly in regions where shilajit is found.5 This led to the conclusion that humification of some resin/latex bearing plants is the most likely source of shilajit.When Banaras researchers subjected compounds (2) and (3) to column chromatography, they discovered that they were partially transformed to a benzocoumarin (4). This compound (4) has also been detected in shilajit, possibly arising via an intermediate compound (5). The results were quite exciting because biphenyls are a rare group of natural products in higher plants,6 and no biphenyl with a carboxy function at C6 had been encountered before. Interestingly, compounds (2), (3) and (4) have significant anti-allergic activity - a property claimed for shilajit.By the late 1980s it was known that humification of resin-bearing plants was responsible for the major organic mass of shilajit - about 80 per cent of the humus component. The amount and composition of the remaining organic mass, which is a mixture of low Mw

compounds, varies depending on where the shilajit comes from (Table 1). The most common low Mw compounds present are oxygenated dibenzo-a-pyrones (6), (7) and (8). They are probably produced from the naturally-occurringmacrocycle (9), via an intermediate such as (10), (Scheme 1). Solvent extraction of shilajit results in a compound similar to (10), which can be autoxidised to (6) and (8) when exposed to light.Researchers propose that the physiological properties of shilajit are due to compounds such as the dibenzo-a-pyrones, along with triterpenes and phenolic lipids. Fulvic acids may also have a physiological role, acting as carrier molecules for the more bioactive smaller compounds.

Scheme 1. A possible route to making dibenzo-a-pyrones (6) and (8)

It is now known that the composition of shilajit is influenced by factors such as the plant species involved, the geological nature of the rock, local temperature profiles, humidity and altitude. Although the composition varies from place to place, the general consistency of samples from various sources points to a common production process that results from biological and chemical action on plant remains.

Shilajit and healthBy the late 1980s, several research groups had begun to take the claims for the remarkable medicinal powers of shilajit seriously, and to investigate whether they might have some basis in fact. Banaras Hindu University researchers collected shilajit from Badakstan, Afghanistan, at an altitude of 2800 m, and prepared aqueous solutions, to investigate its pharmacological action on the central nervous and cardiovascular systems, skeletal muscles, gastric secretions and inflammation in albino rats.7

These simple aqueous solutions were shown to be biologically active. For example, the anti-inflammatory activity of shilajit is comparable to that of betamethasone - a glucocorticoid given orally at doses of 0.55 mg. These findings suggest that shilajit may have a role in treating rheumatism, as proposed in folk medicine. Shilajit was also found to be an analgesic and a possible anti-ulcer agent, and doses of up to 1 g per kg caused no apparent problems - a promising start.Research continued to investigate other claims made for shilajit. In 1989, the Banaras group published a paper on the role of shilajit in treating allergic disorders.8 By now researchers realised that crude aqueous solutions of shilajit had limited value and that using combinations of the main constituents would be the best way to pinpoint the bioactive agents. They studied the effect of shilajit and the combined effects of its main constituents: fulvic acids, 4¢-methoxy-6-carbomethoxybiphenyl (2) and 3, 8-dihydroxy-dibenzo-a-pyrone (8). The results were promising; shilajit and different combinations of its main constituents seemed to offer a potential treatment for allergic disorders - just as folk medicine suggests.

Too good to be true?

But are there any risks in using crude shilajit? By the early 1990s, potential problems with crude shilajit were emerging, highlighted in a paper by the Banaras researchers.2 This focused on the fact that very little information about the geographical origin of the shilajit is available to purchasers. The place of origin is an important factor that determines its composition and likely medicinal value.Shilajit samples from different regions of the world can have markedly different physiological properties. In a controlled experiment on rats with stress-induced gastric ulcers, shilajit from India and Nepal decreased the volume of gastric secretion and acid output, whereas samples from Pakistan and Russia did not. Therefore, for treating human ulcers, the geographical origin of the shilajit is probably important. Sufferers buying shilajit from the wrong region would gain no benefit, yet they would continue to use the panacea because of their commitment to this type of treatment.What about the possible toxins that may be present? Some samples of shilajit have been found to be heavily contaminated with fungal organisms such as A. niger, A. ochraceous and T. roseum. These are capable of producing lethal mycotoxins, and it is not clear how many people have been adversely affected.Another potential problem of using the raw material is that native, unprocessed shilajit contains significant amounts of stable free radicals. Humic constituents from soils contain high levels of such radicals. Two types of free radicals have been detected using electron spin resonance: long lifetime stable radicals, which are stabilised by metal ions present within the sample, and short lifetime radicals. Free radicals can cause irreparable cell damage. The concentration of free radicals in humic material increases as the pH is raised; above pH 8.0 such radicals are stabilised due to the formation of semiquinone species. Table 1 indicates that Russian shilajit has a pH in this range and, for this reason, Russian doctors do not give shilajit to ulcer patients who have a greater risk of developing cancer.

Table 1. How the composition of shilajit varies with geographical region

 

Country and region of origin

pH of 1% aqueous solution

Relative % composition of low Mw extracts

Fulvic acid % composition

Relative % composition of

humic constituents

India, Kumaon 6.2 17.9 21.4 19.8

Nepal, Dolpa 7.5 20.0 15.4 11.4

Pakistan, Peshawar 6.8 4.3 15.5 5.6

Russia, Tien-Shan 8.2 29.7 19.0 11.5

Although it is now widely accepted that shilajit can be valuable in conventional medicine, the best way forward is to formulate drugs using the active constituents, rather than use crude shilajit. Those trained in classical science may well smile at this stage and feel satisfied at the triumph of the structurereactivity concept of drug action over a more traditional folk-based approach. But we need to be careful and humble at all times. Yes, a small band of dedicated scientists worked away for many years to

demonstrate the real value in such a panacea. But what if they had dismissed the many claims made for shilajit as being due to mere superstition? How many other aids to healing are we overlooking because they do not fit into our conceptual framework?Dr Paul Phillips is a senior lecturer in the school of environmental science at Nene College of Higher Education, Park Campus, Northampton NN2 7AL.

References1. S.Ghosal et al, Phytotherapy Res., 1991, 5, 211. 2. S. Bhaumik, S. Chattopadhyay and S. Ghosal, Phytotherapy Res., 1993, 7, 425. 3. S. Ghosal et al, J Pharm. Sci., 1976, 65, 772. 4. Y. C. Kong et al, Int. J. Crude Drug Res., 1987, 25, 179. 5. S. Ghosal, S. K. Singh and R.S. Srivastava, J. Chem. Res., 1988, 196. 6. M. V. S. Sultanbawa, Tetrahedron, 1980, 36, 1465. 7. S. B. Acharya et al, Indian J. Exp. Biol., 1988, 26, 775. 8. S. Ghosal et al, Phytotherapy Res., 1989, 6, 249.