Introduction

         Tuberculosis is a highly infectious disease with about one third of the world’s population including 40% from India estimated to be infected¹. However, this problem has become serious as MTB developed resistance against both the first line as also the second line of drugs. Due to this, there is an emergence of multi-drug resistant (MDR) and extensively-drug resistant (XDR) strains of MTB all over the world including India². The WHO intends to integrate traditional medicine into National Health systems (NHS) globally. This is an opportunity for building safe, affordable and effective NHS especially for Third world countries, rich in both medicinal plant resources and traditional medicine knowledge. It is the time for Governments to found research into holistic health models as an alternative of squandering more billions on ‘health genomics’, which will increase intervention and iatrogenic damages to health. The recent increase of TB is associated with the emergence of the human immunodeficiency virus (HIV) and the rapid spreads of MDR-TB strains degenerate the situation. Second-line drugs have many more adverse effects than the first-line anti-TB drugs. Medicinal plants offer a great hope to fulfill these needs and have been used for curing diseases for many centuries. These have been used extensively as pure compounds or as a crude material. Only a few plant species have been thoroughly investigated for their medicinal properties³. India is one of the few countries in the world which has unique wealth of medicinal plants and vast traditional knowledge of use of herbal medicine for cure of various diseases. Most healthy individuals are able to control the infection with a strong immune response, halting the progression of the disease, but not necessarily eradicating the organism⁴.

Conventional anti MTB drugs

          Drugs such as Isoniazid (INH or H), Rifampicin (RMP or R), Streptomycin (STM or S), Ethambutol (EMB or E) and Pyrazinamide (PZA or Z) are all considered first line of drugs to control MTB. Besides that second line and third line of drugs are being administered when drug resistance surfaced. Multi drug resistant tuberculosis (MDR-TB) or Vank’s disease show resistance to isoniazid and rifampicin⁵ and Extensively drug-resistant TB (XDR-TB) is a rare type of multidrug-resistant tuberculosis (MDR-TB) that is resistant to isoniazid, rifampin, plus any fluoroquinolones and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin)⁶. Though these drugs are in clinical use they are known for their adverse side-effects.        

Side-effects caused by conventional anti MTB drugs

          Besides developing drug resistance long term administering of isoniazid can cause side effects such as nausea, vomiting, epi-gastric pain and in some cases cutaneous pruritus⁷. Similarly administering of rifampicin can cause fatigue, dizziness, headache, dyspnea, and ataxia in patient’s treated. Pyrazinamide administration for longer period can develop dermatitis. Another effective anti MTB drugs is ethambutol and chronic administering can lead to Retrobulbar neuritis, nausea, vomiting, abdominal pain and hepatotoxicity, hematological symptoms (eosinophilia, neutropenia, and thrombocytopenia), cardiovascular symptoms (myocarditis and pericarditis), neurological symptoms (headache, dizziness, and mental confusion), hyperuricemia/ gout (due to a reduction in the excretion of uric acid by the kidney), hypersensitivity (skin rash, arthralgia, and fever) and (occasionally) pulmonary infiltrates.Treatment with streptomycin reported to cause vestibular and auditory nerve damage and occasionally renal damage⁸.        

Use of medicinal plants

          The use of plants as the source of remedies for the treatment of many diseases dates back to prehistory period and people of all continents have practiced this old tradition. Plants contribute to be the major source of medicines throughout the human history. The World Health Organization (WHO) estimated that about 80% of world’s population rely on traditional medicinal plants for their primary health care. The uses of herbs and herbal products have also been broadly accepted in our modern way of life⁹. Plant species serve as a rich source of many novel biologically active compounds; although very few have been thoroughly investigated for their medicinal properties. About 30-40% of plants are used in today’s conventional drugs and rest are used as herbal supplements, botanicals and beverages¹⁰.     

          Herbal medicine is a major component in all indigenous people traditional medicine and is a common element in ayurvedic, homeopathic, naturopathic, traditional, oriental and Native American Indian medicines. WHO notes that of the 119 plant-derived pharmaceutical medicines, about 74% are used in modern medicine in ways that correlated directly with their traditional uses as plant medicines by native’s culture¹¹. The uses of some medicinal plants vary a lot according to regional and cultural aspects. Their use is often associated with witchcraft and superstition because the practitioners do not have the scientific insight to explain or predict the curative action of the plants. One example of such an irrational concept is the Doctrine of Signatures (elements of which are found in many of the healing cultures of the world) based on the assumption that the appearance of plants may give clues to their medicinal properties¹².        

          The forest in India is the principal repository of large number of medicinal and aromatic plants, which are largely collected as raw materials for manufacture of drugs and perfumery products. About 8,000 herbal remedies have been codified in AYUSH systems in INDIA. Ayurveda, Unani, Siddha and Folk (tribal) medicines are the major systems of indigenous medicines. Among these systems, Ayurveda and Unani Medicines are most developed and widely practiced in India¹³. According to WHO, around 21,000 plant species have the potential for being used as medicinal plants¹⁴.        

          It has been estimated, that in developed countries such as United States, plant drugs constitute as much as 25% of the total drugs, while in fast developing countries such as India and China, the contribution is as much as 80%. These countries provide two third of the plants used in modern system of medicine and the health care system of rural population depend on indigenous systems of medicine¹⁵.        

          Treatment with medicinal plants is considered very safe as there is no or only minimal side effects. These remedies are in sync with nature which is the biggest advantage. The golden fact is that use of herbal treatments is independent of any age groups and the sexes. Medicinal plants such as Aloe, Tulsi, Neem, Turmeric and Ginger cure several common ailments. These are considered as home remedies in many parts of the country. It is a known fact that lots of consumers are using Basil (Tulsi) for making medicines, black tea, in pooja and other activities in their day to day life¹⁶. Now, after finding the role of herbs in medicine, lots of consumers started the plantation of tulsi and other medicinal plants in their home gardens.        

          Medicinal plants are considered as rich resources of ingredients which can be used in drug development pharmacopoeial, non- pharmacopoeial or synthetic drugs and play a critical role in the development of human cultures around the whole world. Moreover, some plants are considered as important source of nutrition and as a result of that they are recommended for their therapeutic values. Some of these plants include ginger, green tea, walnuts, aloe, pepper and turmeric etc. Some plants and their derivatives are considered as important source for active ingredients which are used in aspirin and toothpaste etc.¹⁷. Apart from the medicinal uses, herbs are also used in natural dye, pest control, food, perfume, tea and so on. In many countries different kinds of medicinal plants/ herbs are used to keep ants, flies, mice and flee away from homes and offices. Now a day’s medicinal herbs are important sources for pharmaceutical manufacturing¹⁸.        

          Over the past two decades, there has been a tremendous increase in the use of herbal medicine; however, there is still a significant lack of research data in this field. Medicinal plants are also important for pharmacological research and drug development, not only when plant constituents are used directlypeutic agents, but also as starting materials for the synthesis of drugs or as models for pharmacologically active compounds¹⁹. Major pharmaceutical companies are currently conducting extensive research on plant materials, gathered from forests and other habitats, for their potential medicinal value²⁰.        

Anti MTB agents derived from the ayurvedic literature

          Ayurveda, means the science of life (Ayur = Life, Veda = Science), is an ancient medical knowledge which was developed in India thousands of years ago and describes numerous plants to treat several diseases. When we particularly talk about TB, more than 250 medicinal plants from India have been reported17. The comprehensive safety, toxicity and clinical studies are needed for these plants before using them effectively as curative and/or preventive medications against TB. List of plants in India used in Ayurvedic treatment has been discussed in Table 1.

Anti-tubercular plants from foreign origin

          Anti-tubercular plants are not only in India but are found in places all over the world such as South Africa, New Zealand, Malaysia, Nigeria, Tibet etc. A list of anti-tubercular plants from foreign origin are shown in Table 2.

Conclusion

          Natural products as crude materials with efficacy against various diseases have been selected by humans over many generations of practical experience. However many effective medicines such as morphine, aspirin, atropine, ephedrine, reserpine and digitoxin were developed from natural products. Medicinal plants, since times immemorial have been used in virtually all cultures as a source of medicine. The widespread use of herbal remedies and health care preparations described in ancient texts such as the Vedas and the Bible are obtained from commonly used traditional herbs and medicinal plants, traced to the occurrence of natural products with medicinal properties.

          Conventional (allopathic) medicines are indeed effective until the emergence of MDR and XDR isolates but are known to cause side-effects. In contrast ayurvedic and other traditional medicines appear to be promising by inhibition of MTB and XDR isolates but are known to cause side-effects. In contrast ayurvedic and other traditional medicine appear to be promising by inhibition of MTB and XDR strains in-vitro. However their overall in-vivo efficacy, toxicity and Maximum tolerated dose reveal to be extensively studied before it enters in to human usage.

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