About Authors:
R.C. Gedar1*, Rakesh Sharma2, Sanjeev Sharma2
1Seth G. L. Bihani S. D. college of technical education, IPSDR, Sriganganagar (Raj.)
2J. C. D. M. Pharmacy College, Sirsa (Hry.)
*rcgedar@gmail.com
Abstract
This review highlights the current advances in knowledge about the safety, efficacy and quality control of botanical medicines. Phytotherapeutic agents are standardized herbal preparations consisting of complex mixtures of one or more plants which contain as active ingredients plant parts or plant material in the crude or processed state. A marked growth in the worldwide phytotherapeutic market has occurred over the last 15 years. For the European and USA markets alone, this will reach about $7 billion and $5 billion per annum, respectively, in 1999, and hasthus attracted the interest of most large pharmaceutical companies. Insufficient data exist for most plants to guarantee their quality, efficacy and safety. The idea that herbal drugs are safe and free from side effects is false.
Reference Id: PHARMATUTOR-ART-1551
INTRODUCTION
Since ancient times, mankind has used plants to cure disease and relive physical sufferings. His understanding of herbal drugs was very innovative and critical from earliest times and usually was restricted to the medicine men of the tribe. Knowledge regarding sources and uses of different parts of medicinal plants was inherited through generations. Several developing countries have at present well organised and deep rooted traditional systems of medicine, namely, Ayurveda, Sidha, and Unani, have been in existence here for several centuries. In traditional medicine, more than one thousand plants are regularly used which are mostly collected in their wild form. Traditional herbal medicine plays an important role side by side with modern medicine in health care of people, particularly in poorer sections, as western medicine is unavailable to many for economic and other reasons. (Wyk B. V. 2004, Bhattacharjee S.K. 2005)
Quality control of herbal drugs
Quality control for efficacy and safety of herbal products is of paramount importance. Quality can be defined as the status of a drug that is determined by identity, purity, content and other chemical, physical, or biological properties or by the manufacturing processes. Quality control is a term that refers to processes involved in maintains the quality and validity of manufactured products. (Mukherjee P. K. 2002)
In general, quality control is based on three important pharmacopoeial terminology:
· Identity: Is the herb the one it should be?
· Purity: Are there contaminants, e.g., in the form of other herbs which should not be there?
· Content or assay: Is the content of active constituents within the defined limits? It is obvious that the content is the most difficult one to assess, since in most herbal drugs the active constituents are unknown. Sometimes markers can be used which are, by definition, chemically defined constituents that are of interest for control purposes, independent of whether they have any therapeutic activity or not.
· Quality control and the standardization of herbal medicines involve several steps. The source and quality of raw materials, good agricultural practices and manufacturing processes are certainly essential steps for the quality control of herbal medicines and play a pivotal role in guaranteeing the quality and stability of herbal preparations. The quality of a plant product is determined by the prevailing conditions during growth, and accepted Good Agricultural Practices (GAP) can control this. These include seed selection, growth conditions, use of fertilizers, harvesting, drying and storage. In fact, GAP procedures are, and will be, an integral part of quality control. Factors such as the use of fresh plants, age and part of plant collected, period, time and method of collection, temperature of processing, exposure to light, availability of water, nutrients, drying, packing, transportation of raw material and storage, can greatly affect the quality, and hence the therapeutic value of herbal medicines. Apart from these criteria, factors such as the method of extraction, contamination with microorganisms, heavy metals, and pesticides can alter the quality, safety, and efficacy of herbal drugs. Thus proper standardization and quality control of both the raw material and the herbal preparations should be conducted. Standardization involves adjusting the herbal drug preparation to a defined content of a constituent or a group of substances with known therapeutic activity by adding excipients or by mixing herbal drugs or herbal drug preparations. Botanical extracts made directly from crude plant material show substantial variation in composition, quality, and therapeutic effects. Standardized extracts are highquality extracts containing consistent levels of specified compounds, and they are subjected to rigorous quality controls during all phases of the growing, harvesting, and manufacturing processes. (Bhattacharjee S. K. 2005, Bandaranayake W.M, 2006)
Fig. 1 Steps for Quality Control of Herbal Drugs
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Microscopic Evaluation
Quality control of herbal drugs has traditionally been based on appearance and to- day microscopic evaluation is indispensable in the initial identification of herbs, as well as in identifying small fragments of crude or powdered herbs, and detection of foreign matter and adulterants. A primary visual evaluation, which seldom needs more than a simple magnifying lens, can be used to ensure that the plant is of the required species, and that the right part of the plant is being used. At other times, microscopic analysis is needed to determine the correct species and/or that the correct part of the species is present. For instance, pollen morphology may be used in the case of flowers to identify the species, and the presence of certain microscopic structures such as leaf stomata can be used to identify the plant part used. (http://www.pharmatutor.org)
Determination of Foreign Matter
Herbal drugs should be made from the stated part of the plant and be devoid of other parts of the same plant or other plants. They should be entirely free from moulds or insects, including excreta and visible contaminant such as sand and stones, poisonous and harmful foreign matter and chemical residues. Animal matters such as insects and “invisible” microbial contaminants, which can produce toxins, are also among the potential contaminants of herbal medicines. Macroscopic examination can easily be employed to determine the presence of foreign matter. Furthermore, when foreign matter consists, for example, of a chemical residue, TLC is often needed to detect the contaminants. (Bandaranayke W. M. 2006)
Determination of Ash
To determine ash content the plant material is burnt and the residual ash is measured as total and acid-insoluble ash. Total ash is the measure of the total amount of material left after burning and includes ash derived from the part of the plant itself and acid-insoluble ash. The latter is the residue obtained after boiling the total ash with dilute hydrochloric acid, and burning the remaining insoluble matter. The second procedure measures the amount of silica present, especially in the form of sand and siliceous earth.(WHO guildline, 2007)
Determination of Heavy Metals
Contamination by toxic metals can either be accidental or intentional. Contamination by heavy metals such as mercury, lead, copper, cadmium, and arsenic in her- bal remedies can be attributed to many causes, including environmental pollution, and can pose clinically relevant dangers for the health of the user and should therefore be limited. The potential intake of the toxic metal can be estimated on the basis of the level of its presence in the product and the recommended or estimated dosage of the product. This potential exposure can then be put into a toxicological perspective by comparison with the so called Provisional Tolerable Weekly Intake values (PTWI) for toxic metals, which have been established by the Food and Agriculture Organization of the World Health Organization (FAO-WHO). A simple, straightforward determination of heavy metals can be found in many pharmacopoeias and is based on colour reactions with special reagents such as thioacetamide or di-ethyl dithiocarbamate, and the amount present is estimated by comparison with a standard. (WHO guildline 2007, Kunle et.al. 2012)
Determination of Microbial Contaminants and Aflatoxins
Medicinal plants may be associated with a broad variety of microbial contaminants, represented by bacteria, fungi, and viruses. Inevitably, this microbiological back- ground depends on several environmental factors and exerts an important impact on the overall quality of herbal products and preparations. Risk assessment of the microbial load of medicinal plants has therefore become an important subject in the establishment of modern Hazard Analysis and Critical Control Point (HACCP) schemes.
Herbal drugs normally carry a number of bacteria and moulds, often originating in the soil. Poor methods of harvesting, cleaning, drying, handling, and storage may also cause additional contamination, as may be the case with Escherichia coli or Salmonella spp. While a large range of bacteria and fungi are from naturally occurring micro flora, aerobic spore-forming bacteria frequently predominate. The European Pharmacopoeia also specifies that E. coli and Salmonella spp. should be absent from herbal preparations.
The presence of fungi should be carefully investigated and/or monitored, since some common species produce toxins, especially aflotoxins. Aflatoxins in herbal drugs can be dangerous to health even if they are absorbed in minute amounts. Procedures for the determination of aflatoxin contamination in herbal drugs are published by the WHO. After a thorough clean-up procedure, TLC is used for confirmation. (Nanda khurana et.al. 2011)
Determination of Pesticide Residues
Even though there are no serious reports of toxicity due to the presence of pesticides and fumigants, it is important that herbs and herbal products are free of these chemicals or at least are controlled for the absence of unsafe levels. Herbal drugs are liable to contain pesticide residues, which accumulate from agricultural practices, such as spraying, treatment of soils during cultivation, and administering of fumigants during storage. (Archana Gautam 2010)
Determination of Radioactive Contamination
There are many sources of ionization radiation, including radionuclide, occurring in the environment. Hence a certain degree of exposure is inevitable. Dangerous contamination, however, may be the consequence of a nuclear accident. The WHO, in close cooperation with several other international organizations, has developed guidelines in the event of a widespread contamination by radionuclides resulting from major nuclear accidents.(Archana Gautam 2010, WHO guildline 2007))
Analytical Methods
Additional information, especially on chromatographic and/or spectroscopic methods can be found in the general scientific literature. The plant or plant extract can be evaluated by various biological methods to determine pharmacological activity, potency, and toxicity. A simple chromatographic technique such as TLC may provide valuable additional information to establish the identity of the plant material. This is especially important for those species that contain different active constituents. Qualitative and quantitative information can be gathered concerning the presence or absence of metabolites or breakdown products. TLC fingerprinting is of key importance for herbal drugs made up of essential oils, resins, and gums, which are complex mixtures of constituents that no longer have any organic structure. It is a powerful and relatively rapid solution to distinguish between chemical classes, where macroscopy and microscopy will fail. Chromatograms of essential oils, for example, are widely published in the scientific literature, and can be of valuable help in identification. The instruments for UV-VIS determinations are easy to operate, and validation procedures are straight forward but at the same time precise. Although measurements are made rapidly, sample preparation can be time consuming and works well only for less complex samples, and those compounds with absorbance in the UV-VIS region. HPLC is the preferred method for quantitative analysis of more complex mixtures. Though the separation of volatile components such as essential and fatty oils can be achieved with HPLC, it is best performed by GC or GC/MS. The quantitative determination of constituents has been made easy by recent developments in analytical instrumentation. Recent advances in the isolation, purification, and structure elucidation of naturally occurring metabolites have made it possible to establish appropriate strategies for the determination and analysis of quality and the process of standardization of herbal preparations. Classification of plants and organisms by their chemical constituents is referred to as chemotaxonomy. TLC, HPLC, GC, quantitative TLC (QTLC), and high-performance TLC (HPTLC) can determine the homogeneity of a plant extract. Over-pressured layer chromatography (OPLC), infrared and UV-VIS spectrometry, MS, GC, liquid chromatography (LC) used alone, or in combinations such as GC/MS, LC/MS, and MS/MS, and nuclear magnetic resonance (NMR), electrophoretic techniques, especially by hyphenated chromatographies, are powerful tools, often used for standardization and to control the quality of both the raw material and the finished product. The results from these sophisticated techniques provide a chemical fingerprint as to the nature of chemicals or impurities present in the plant or extract. Based on the concept of photoequivalence, the chromatographic fingerprints of herbal medicines can be used to address the issue of quality control. Methods based on information theory, similarity estimation, chemical pattern recognition, spectral correlative chromatograms (SCC), multivariate resolution, the combination of chromatographic fingerprints and chemometric evaluation for evaluating fingerprints are all powerful tools for quality control of herbal products. (Bandaranayake W. M, Kunle et.al. 2012).
References
• Archana Gautam et.al., “identification, evaluation & standardization of herbal drugs: a review”, Pub in scholars research library, 2010, Vol 2(6), Page no. 302-315
• Bandaranayake Wickramasingh M., ‘Quality control, screening, toxicity, and regulation of herbal drugs’ Online available on- faculty.ksu.edu.sa
• Bhattacharjee Supriya Kumar, Dr. De L.C, “Medicinal Herbs and Flowers” 1st published in 2005, Published by Aavishkar Publishing and Distributers, Jaipur, Page no. 1,8
• Calixto J.B, ‘Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines’ Online available on - scielo.br/scielo.php?pid=S0100-879X2000000200004&script=sci_arttext
• http://www.pharmatutor.org/pharmacognosy/quality-control-of-phytomedicines.html
• Kunle et.al., “Standardization of herbal medicines- A review”, Pun in International journal of biodiversity & conservation, 2012, Vol 4(3), Page no. 101-112
• Mukherjee Pulok K., “Quality control of herbal drugs” First edition 2002, Published by Business horizons, New Delhi, Page no. 21, 57-59,70-82.
• Nandna Khurana et.al., “Microbiological quality control assessment of some commercial herbal drugs”, Pub in International journal of pharmaceutical quality assurance, 2011, Vol 3(4), Page no. 15-17
• WHO guidelines for assessing quality of herbal medicines with reference to contaminants and residues, 2007
• Wyk Ben-Erik Van, Wink Michael, “Medicinal Plants of The World” 1st Published in 2004, Published by Times Editions, Singapore, Page no. 24-26.
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