Bark Drugs

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There is lot of adulteration and substitution of herbal raw materials, especially in case of bark drugs. Different plant materials are being sold in the market under the same vernacular, for example, 'Asoka'- Saraca asoca is the genuine plant species but bark of other plant taxa are being mixed up and sold or used under the name 'Asoka'. It is also apparent that after drying, it is very difficult to differentiate the bark of the same genus, as in case of 'Siris', instead of Albizia lebbek, barks of other Albizia species are being sold. Similarly, the bark of 'Arjuna' is also substituted with other Terminalia species. Therefore, in the present publication, attempt has been made to lay down quality parameters of 40 barks and their possible adulterants/substitutes.

This book is intended to present elements of both methods and indispensable techniques used for quality control and standardization of bark drugs. More emphasis has been made on classical pharmacognostical and phytochemical approaches in order to determine the correct botanical identity of the genuine source of the plant material required to be used in number of herbal formulations. Parameters selected are: botanical name with authority; family; synonyms, vernacular names; botanical description; distribution; macro and microscopic description with special emphasis on diagnostic characters supported by photographs; powder microscopy with camera lucida drawings. Apart from this, thin layer chromatographic profile has been developed and depicted by photographs of TLC plates and densitometeric scans of the chromatograms with a view to establish the diagnostic chemical profile of different bark drugs. In addition, all the stem barks were also screened for some terpenoids and polyphenols, as marker components, which are generally present in the bark drugs. The information presented in this book will have a considerable impact on the standardization and quality control of bark drugs and to check their possible adulterants and substitutes. Hence, it serves as a ready reckoner for pharmaceutical industries and academics particularly the researchers, teachers and students engaged in herbal drug research or study of indigenous systems of medicine.

Medicinal plants and herbal drugs can contribute substantially to affordable and safer healthcare. The large experience based information on the use of plants and natural drugs in receiving increasing support from experimental evidence. There is a rapidly growing appreciation of the opportunities in converting the observation of therapeutics into evidence supported therapeutics through reverse pharmacology, and the development of pharmacopoeial standards. As a result, the global market for traditional and alternative medicine has been increasing in recent years and is currently estimated between US $ 42-60 billion with growth rate of about 7% per annum. The global thrust areas for the products of medicinal plants include chronic disease conditions with multiple levels of complexity where allopathic drugs are unsatisfactory. Plant based products need more systematic attention for use as medicine, functional foods, food supplements and cosmaceuticals and as an excellent platform to catalyze innovation base drug discovery.

China, besides meeting its domestic requirements is estimated to earn five billion USS per year from the herbal trade. However, Indian share in world market is only 2%, because of inadequate documentation of systematic studies, limited investment in research and development, lack of linkage in the chain from production to quality evaluation, standardization, process development, controlled clinical data and marketing.

An important initial step in GMP for plant based drugs is quality control of the crude plant material. This necessitates characterization of the crude drug as well the common adulterants. This is comparatively easy in certain parts of the plant like the leaf, flower, fruit etc. due to their distinctive characters.. Bark of many plants is used not only in traditional systems (Ayurvedic, Chinese, Unani etc.) but also in modern medicine (e.g Cinchona bark for quinine). Macroscopic identification of barks is difficult due to lack of distinctive features and adulteration is a serious problem. It is necessary to rely on microscopic and chemical characteristics for proper identification and quality control of barks and such data are not available in many cases. The two volumes of WHO Monographs on Medicinal Plants contain no bark drug in the 60 monographs. Similarly the two volumes of IDMA's Herbal Pharmacopeia include only 2 barks among 40 crude drugs. The 136 monographs in four volumes of ICMR's Quality Control of Indian Medicinal Plants include only 21 barks.

The present book is perhaps the first publication devoted exclusively to standardization of bark drugs and fulfils a long felt need. It includes monographs on 40 commonly used barks or their adulterants. An unique feature of the book is the large number of original illustrations on microscopic features and TLC profile of selected barks. TLC profile ha used active constituents or easily available marker compounds. Adequate details have been provided for identifying the powdered bark also. This should be helpful in their detection in mixtures etc.

The book should be valuable to the industry and research workers by enabling them to standardize crude barks with simple equipment. The tests could also be incorporated by regulatory agencies in Formularies, Pharmacopeias etc. The authors need to be complemented for the painstaking studies to generate data included in this compendium. It is hoped that the next volume containing similar data on remaining barks of economic. importance to the pharmaceutical industry will see the light of the day soon.

Safety of phytopharmaceuticals is based on consistency in quality, especially of raw plant drugs. Therefore, if plant pharmaceuticals have to be recognized as rational drugs, they need to be standardized. The World Health Organization, in a number of its resolutions, emphasized the need for quality control of herbal drugs, as the world market for herbal medicines, including herbal products and raw materials, has been estimated to have an annual growth rate of 15% per annum. The global market is over US $ 60 billion per year which is estimated to increase to about 5 trillion by the year 2050. In spite of India being one of the eight important global centers for plant diversity, being immensely rich in medicinal plants occurring in diverse ecosystem, its contribution to global market is not very significant because of inadequate or lack of standards for raw material as well as finished products. The Indian pharmaceutical industry constantly faces the problem of the availability of genuine material. The adulteration and substitution of raw drugs is reported to be rampant. Although various attempts have been made by Government and non-Government organizations during the last few decades to produce official pharmacopoeial monographs and companion books for prescribing standards of identity, purity and safety, we still stand far away from achieving the desired goals due to many inherent problems and difficulties like number of plants being used by same vernacular and number of vernaculars being used for one plant species. Especially in case of bark drugs different plant material are being sold in the market in the name of one vernacular, for example, in case of Ashoka bark'-Saraca asoca should be sold or used in the name of Asoka bark but bark of other plant species of Saraca and other genera, viz Polyalthia longifolia and Bauhinia variegata, or even the bark of Shorea robusta is sold under the same vernacular. Similarly, the bark of 'Arjuna' is also substituted with other Terminalia species. In case of 'Siris' also, instead of Albizia lebbek, barks of other Albizia species are sold and used. Although a number of research publications and books are available in which plant drugs including the bark drugs are described but there is not any specific book available on the bark drugs except one book published by Prof Malti Chauhan on powder study of bark. Therefore, in the present publication attempt has been made to lay down quality parameters for some important bark drugs mainly used by the pharmaceutical industries manufacturing indigenous formulations of Ayurvedic, Unani and Siddha, System of Medicines. This book will serve as a ready reckoner for pharmaceutical industries for the authentication of raw bark drugs. Parameters taken for standardization and quality control of bark drugs in the present study are as per WHO guidelines. The vernacular names, taxonomical description, distribution and medicinal properties have been taken from already published records, thus cach bark has been described as follows:

Botanical name with authority; Family; Vernacular names; taxonomical description; Distribution; Macro and Microscopic description with special emphasis on diagnostic characters along with their photographs; Powder microscopy with camera lucida drawings; Phytochemical markers with TLC finger print profile and their chemical structure.