Screening Of Medicinal Plants Used In Rural Indian Folk Medicine For Treatment Of Diarrhoea
By - 05/01/2005
Since ancient days, Man has been suffering from various ailments. To our rescue, Nature has provided a rich store house of herbal products to cure all ailments of Mankind. Such products are widely used as therapeutic agents for different ailments such as hypertension, mental illness, cancer, leprosy and skin disorders.
The ever increasing threat to human life by both neoplastic diseases and AIDS makes the pursuit of antihuman, antiviral and antimicrobial compounds take an compelling urgency.
The wealth of India is stored in the enormous natural flora which has been gifted to her. Endowed with a wide diversity of agro-climatic conditions, India is virtually herbarium of the world.
It is felt by experts that the drugs of natural origin with their wide range of action shall play an important role in health care particularly in the rural areas of India. India is the home for a number of commercially important medicinal and aromatic crops; its geographical location with salubrious climate is congenial for cultivation of a majority of important medicinal and aromatic crops. Studies involving traditional medicines frequently contribute new ideas. Numerous encouraging leads have come up with the convergence of empirical uses of various species in various parts of the globe showing potential antimicrobial property. 1, 2, 3
The use of medicinal plants in the world and especially in India, contributes significantly to primary health care. It is interesting to determine whether their traditional uses are supported by actual pharmacological effects or merely based on folklore.4, 5
Diarrhoea is a major public health problem in developing countries and is said to be endemic in many regions of Asia and is the leading cause of high degree of morbidity and mortality which contributes to the death of 3.3 to 6 million children annually. Enteric bacteria comprise the major etiologic agents of sporadic and epidemic diarrhoea both in children and adults.6, 7 Enteric bacteria such as Salmonella, Shigella, Proteus, Klebsiella, E.coli, Pseudomonas, Vibrio cholerae and Staphylococcus aureus are commonly associated with diarrhoea.
Multiple drug resistance among Enteropathogens in various geographic regions presents a major threat in the control of diarrhoea. Therefore indigenous medicinal plants as an alternative to antibiotic are said to play a significant role here. This particular aspect of using medicinal plants as a remedy or home cure for diarrhoea is applied in our study.
In the present study, we chose some plants currently used in the folk medicine in our region , small rural place in Coastal Karnataka- Southern India surrounded by western ghats, a rich fauna and a good source of medicinal plants. All of these plants selected for the study have been used as traditional folklore medicine for the treatment of diarrhoeal diseases in this region.
Ethanol and aqueous extracts of different parts of the commonly available plants of the coastal Karnataka region of South India were evaluated for antidiarrhoeal activity against the enteric pathogens.
Brief introduction of the local traditional Medicinal plants used during the study:
1.Centella asiatica [Indian Pennywort; gotukola, hydrocotyle asiatica, Jal Brahmi]
A slender herbaceous creeping perennial plant with rooted nodes and long internodes. It is distributed throughout India on moist soil along the canals and coconut plantations. It is commonly found as a weed in crop fields and the waste places throughout India upto 600 metres. It is found in marshy areas all over India, Srilanka and Madagscar. It is mainly used to treat mental and neurological disturbances. Apart from its role as a brain tonic, its efficacy in treating tuberculosis, Syphilis, Amoebic dysentery and common cold is well documented in Literature. It is being grown on black plastic in the upper piedmont of North Carolina.
Considerable work has been carried out on the phytochemical properties of the plant which has been reviewed and it is reported to consist of triterpenoid glycosides, free acids, volatile oils and flavonoids. It has been found that the activity of this plant extract against the microorganisms is mainly concentrated on the triterpene asiaticoside. The asiaticoside has given encouraging results in treatment of leprosy. Brahmi represents the creative energy of this universe. It is the main revitalizing herb for the nerves and brain cells. It is rich in minerals such as calcium, magnesium, potassium, phosphorus and Aluminium.8, 9, 10
2. Holorrhena antidysentrica [kurchii, Tellicherry bark]
Holorrhena is a genus of trees or shrubs distributed throughout the tropical and subtropical regions of the world. It is a small deciduous tree with white flowers and found throughout the dry forests of India as far as Travancore. A small laticiferous deciduous tree with woody branches that grows upto the height of 900 meters. It grows upto an attitude of 4000sq feet.
It is especially abundant in the sub Himalayan tract. Considerable work has been carried out on the chemistry and biological activity of Kurchii has been reviewed by several workers and is reported to have 29 different alkaloids in it. It is been used in Indian tribals for anaemia, epilepsy, stomach pain and cholera. In Ayurveda, it is used as antihelminthic, for diarrhoea and skin diseases. Portuguese had used it as a hot decoction in bowel infection.11,12, 13
3. Myristica fragrans [nutmeg][Mace tree]
It is cultivated in hotter parts of India upto 750 metres with a rainfall of 150-300 cm per annum. It’s a aromatic evergreen tree with greyish black bark having lenticular spots on the outside and red juice on the inner side. The tree is a native of the Mouccan islands and cultivated widely in Indonesia, Malay Peninsula, Penang, Srilanka, India and West Indies. It has been successfully cultivated in Chennai and many parts of South India. The burnt seed kernel powdered and mixed with buttermilk forms a very specific remedy for diarrhoea and vomiting in children.
The principle constituents of M fragrans are nutmeg which is said to be the source of 2 types of oils-one is the essential oil [5-15% is volatile oil] and the other is the fixed oil of nutmeg [24-40%]. Of the different components present in the essential oil, Mystrican and its chlorderivatives are said to have strong antibacterial, antifungal and insecticidal properties.14,15
4. Ocimum sanctum [tenuflorum][holy or sacred basil]
Ocimum sanctum the sacred Tulsi finds diverse uses in the indigenous system of Medicine. It is found throughout India ascending upto 800metres in the Himalayas and in the Andaman and Nicobar Islands. An erect much branched softly pubescent under shrub 30-60cm high with red or purple sub quadrangular branches. At least two types of Ocimum sanctum are encountered within cultivation, the green type [Sri Tulasi] is the most common, and the second type [Krishna tulasi] bears purple leaves. The plant is an erect, herbaceous, much branched, softly hairy annual.
It has a bright yellow volatile oil and also contains alkaloids and tannins. It has been traditionally used for skin diseases, Hepatitis and viral influenza.
The essential oil of Ocimum sanctum is said to have antibacterial as well as antifungal activity. The leaves of the plant has been used as an expectorant ,diaphoretic, anticancer, antihelminthic, antiseptic, analgesic and tonic rejuvinator.16,17
5. Camellia sinensis and Coffee Arabica
Medicinal properties of Tea were known to mankind since antiquity. A therapeutic procedure often blindly followed by village folk in certain parts of India is to give orally a strong decoction of Tea or coffee to patients with diarrhoea. This part of the country has Tea and Coffee plantations which require damp conditions.
The coffee plant s a woody perennial evergreen dicotyledon of genus coffee and is a member of the Rubiaceae family. It is grown in Central and South America, India, Africa and Indonesia. It is a native to Ethopia and Sudan. It prefers cool mountain sides rather than lowland rain forest. There are more than 600 species of coffee plant with at least 25 major types. The two most commercially important types are Arabica [coffee Arabica] and Robusta [coffee canephora].
The plant is a large bush growing at 600-2000m above sea level. Arabica coffee plants can grow up to heights of 10-12 feet but need to be in a warm temperature.
Tannins, component present in tea [15-20%] and Coffee [5%] are responsible for astringent activity. These tannins are polyphenyl group of compounds. The tannins primarily act on and damage bacterial membranes. These tannins in pure form or as gallotannic acid denature or precipitate proteins thereby altering their surface structures. Chelating properties of tannins coupled with the ability for denaturing bacterial proteins contribute towards the antibacterial activity. It has been shown that catechins, the precursors of tannins also have antibacterial activity.18, 19
These tannins apart from their antibacterial activity are also found to show some antiviral properties. Caffeine, another important component of Tea [1-4%] and coffee [1-2%] apart from its role as a smooth muscle relaxant and diuretic, causes irritation in the stomach and increases the production of acid.
Materials and Methods:
The aqueous and alcoholic extracts of the above plants was prepared according to the method of Nair et al with certain modifications.1 The following Enteric pathogens like Vibrio cholerae 01[El Tor]; Vibrio cholerae 0139, species of Shigella, Salmonella typhimurium, S.enteritidis, Enteropathogenic E coli, Enteroinvasive E coli, Coagulase Positive Staphylococcus aureus, Aeromonas hydrophila, E coli ATCC 25922, Staphylococcus aureus ATCC 25923 and fungus Candida were used.
The working concentrations of the extracts used were 100, 200, 300 and 400 mg/ml respectively. Different methods viz. punch well method, agar dilution method and a newly introduced method by us Trench method was used.
Viable cell count method: It was used to study whether the observed inhibition of growth was bactericidal or bacteriostatic in activity.
Bacterial suspensions were diluted 1:105 with nutrient broth. One ml of the dilution and extracts were mixed and incubated at 37C and at intervals 0.1ml of the mixture was spread onto two separate nutrient agar plates which were incubated overnight at 37C. The mean number of colonies were enumerated and compared with those of a control Phosphate buffered saline.20, 21, 22
Results:
The present study showed that all the extracts possess antidiarrhoeal activity against all the tested enteric pathogens depending upon the nature of active ingredients present in the extracts.
Broad spectrum activity of the extracts was observed at concentrations of 200,300 and 400 mg/ml against a battery of enteric pathogens but the inhibitory effect was best demonstrated at a concentration of 300mg/ml of the agar. Zones of growth inhibition were measured using vernier calipers. Viable cell count method was used to study whether the observed inhibition of growth was bactericidal or bacteriostatic in activity. In case of Vibrio cholerae 01. Vibrio cholerae 0139 and Staphylococcus aureus, the extract was found to be bactericidal in activity.
The antibacterial activity of the plant and its extracts against different test organisms as assessed by measuring the diameter of the growth inhibition zone in ethanol showed high degree of inhibition against the enteric pathogens used.
The results of preliminary screening have shown that the extracts are active against gram positive and gram negative bacteria thus supporting the ethnopharmacological use of the plants in the treatment of diarrhoeal diseases in this part of the country. These active crude alcoholic extracts were also assayed for cellular toxicity to fresh sheep erythrocytes and found to have no cellular toxicity.
Recurrent diarrhoea is prevalent in developing countries particularly in tropical regions. A natural based antidiarrhoeal home remedy can serve as an ideal tool to limit diarrhoea related morbidity and mortality.
In the present study, extracts of Tea[leaves] and coffee [beans], Ocimum sanctum[leaves], H antidysentrica [bark] , Centella asiatica [leaves] Mystrica fragrans[ seeds] showed significant inhibitory activity against the Enteric pathogens.
Discussion:
The western ghats of South India are rich in culture and ecology. The biodiversity contained in this mosaic of tropical forest types, from wet evergreen forests to mangrove swamp is considered worthy of global protection efforts.
The rarity of the most deciduous forest type, high degree of species endemism, unique variety of forest types, uniqueness of lowland evergreen forest in a monsoonal climate and the biogeographically significances of this isolated area between the African and the Indo-Malaysian forest blocks combine to make the Western ghats a very important biological resource.
Historically, the Western Ghats were well-covered in dense forests. In the South, they contain the only rain forests of Southern India. These forests are home to an interesting and diverse fauna and flora, many of them showing a affinity to South east Asia but increasingly threatened by human activity. 23, 24
Detection of etiological agents of diarrhoea is important for therapeutic aspects and for implementing appropriate control strategies. In developing countries, the bacterial pathogens most commonly associated with endemic forms of diarrhoea are diarrheagenic Escherichia coli, Salmonella spp, Shigella, Vibrio cholerae, Aeromonas, and Plesiomonas spp. The emergence and widespread distribution of drug resistant enteric bacteria have imposed serious limitations on successful antibiotic treatment. Spontaneous acquisition of drug resistance among the enteric pathogens is due to selective pressure of antibiotic therapy and R plasmids.
The problem of antimicrobial resistance in microorganisms causing diarrhoeal diseases in both developed and developing countries continues to be alarming. These multiple drug resistant strains have caused major disease outbreaks with high mortality and morbidity in developing countries. The emergence of infections caused by multiple drug resistant enteric pathogens has now necessitated the search for alternative parenteral agents and the introduction of natural plant products have served as a very important replacement for the resistant strains.25, 26, 27
Medicinal plants have been used for centuries as remedies for human diseases because they contain components of therapeutic value. Recently the acceptance of traditional medicine as an alternative form of health care and the development of microbial resistance to the available antibiotics has led us, the authors to investigate the antimicrobial activity of medicinal plants. 28, 29
Moreover, the increasing use of plant extracts in the food, cosmetic and pharmaceutical industries suggests that, in order to find active compounds, a systemic study of medicinal plants is very important.
The aim of our study was to investigate the antimicrobial activity of extracts from medicinal plants used in folk medicine.
Centella asiatica is a medicinal plant that has been in use since prehistoric times. Its active constituents include pentacyclic triterpine derivatives. Studies have been conducted in particular to investigate the madecassosides and asiaticosides. In common with most traditional phytotherapeutic agents, Centella asiatica is used in folk medicine to treat a wide range of indications. In contrast to other medicinal plants, however, Centella asiatica has been subjected to quite extensive experimental and clinical investigation.30, 31, 32
Considerable work has been carried out on the chemistry and biological activity of Holarrhena antidysentrica which has been reviewed by several workers and is reported to have 29 different alkaloids in it. Amoebicidal, antituberculous and other antiprotozoal activity of individual alkaloids especially conessine have been extensively investigated.
Jain and Tarafder have mentioned the use of this plant by the various Indian tribals in cases of number of ailments like anemia, epilepsy, stomach pain and cholera. In Ayurveda, kurchi is used as antihelminthic, for diarrhoea and skin diseases. Portuguese had used it as a hot decoction in bowel infection.11, 12, 33, 34
It is a practice more among the villagers of Kerala, that the dried kernels of Mystrica fragrans being used commonly as a remedy to diarrhoea especially in infantile diarrhoea. Historically, nutmeg has been used as a form of medicine to treat many illnesses ranging from those affecting the nervous system to the digestive system like acute or chronic diarrhoea, dysentery, releaving cramps in cholera, insomnia, carminative during convalescence, sedative and also antispasmodic in asthma.
The nutmeg seed is one of the four components of the fruit obtained from the nutmeg tree. There are 2 types of oils obtained from the nutmeg seed - one is the essential oil [5-15% is volatile oil] and the other is the fixed oil of nutmeg [24-40%]. Clinical research shows that oils may even help create a environment in which disease, bacteria, virus, fungus etc cannot live. Of the different components present in the essential oil, Mystrican and its chloroderivatives are said to have strong antibacterial, antifungal and insecticidal properties. 35-39
Ocimum sanctum the sacred Tulsi finds diverse uses in the indigenous system of Medicine. The leaves of the plant have been used as an expectorant, diaphoretic, anticancer, antihelminthic, antiseptic, analgesic and tonic rejuvinator. Dry leaves are used in fungal infections, the fresh juice of the leaves are used in the treatment of bronchitis, otitis media and skin diseases. Antibacterial activity of ether extract of the leaves against Escherichia coli, Staphylococcus aureus and Mycobacterium tuberculosis have been reported elsewhere. Essential oil of Ocimum sanctum have also showed antifungal activity against Aspergillus niger, Rhizopus stolinifera and Pencillum digitatum. Alcoholic and aqueous extract of Ocimum sanctum have also shown adaptogenic action against antigenic challenge of Salmonella typhi and sheep erythrocytes.40, 41, 42
Tannins, component present in Tea [15-20 %] and coffee [5%] are responsible for astringent activity. These tannins are polyphenyl group of compounds. Ikigai et al have reported that bactericidal catechins which are nothing but tannins primarily act on and damage bacterial membranes. These tannins in pure form or as gallotannic acid denature or precipitate proteins thereby altering their surface structures. The observations that gram negative bacteria are more resistant to bactericidal catechins than gram positive bacteria can be explained to some extent by the presence of negatively charged lipopolysaccharides. Tannins are also found to exhibit some antiviral properties.
In the year 1988, during the preliminary phase of a formulation of foods to aid the prevention of Cholera and other diarrhoeal diseases in Japan, it was found that green tea agglutinated Cholera and their diarrhoeal diseases in Japan , it was found that green tea agglutinated Cholera vibrios and rendered them non-mobile.43,44,45
As far as our knowledge on literature review goes, the antibacterial activity of Centella asiatica leaves, Holorrhena antidysentrica stem bark and nutmeg of Mystrica fragrans against the enteric pathogens has not been documented so far in Indian literature. Although the antibacterial property of Tea was first reported from Japan by using Japanese tea against the diarrhoeal pathogens; our work mainly concentrated on antibacterial activity of tea ad coffee extracts against Salmonella serotypes causing diarrhoea as well as Enteric fever. The different brands of Tea [black tea, Japanese green tea, China tea] and Coffee inhibited the growth of both Gram positive and Gram negative bacteria.19, 20, 21.
Since our work was focused only on the crude extracts and their antibacterial activity, we are now on the process of separating the active components responsible for the antibacterial activity.
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14. Grover JK, Khandkar S, Vats V, Dhunnoo Y, Das. Pharmacological studies on Mystrica fragrans-antidiarrheal, hypnotic, analgesic and hemodynamic parameters. Exp Clin Pharmacol 2002; 24[10]: 675-80.
15. Nadhkarni KM. Indian Materia Medica. Bombay: Popular Prakashan, 1976.
16. Gupta S, Yadava JNS. Antidiarrhoeal profile of an extract and some fractions from Mystrica fragrans [nutmeg]. Int J Pharmacognosy 1992; 30:179-83.
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18. Mamatha Shetty, Subbannayya K, Shivananda P G. Antibacterial activity of Tea [ camellia sinensus] and Coffee [coffee Arabica] with special reference to Salmonella typhimurium. J Com Dis 1994; 26: 147-50.
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About the Author
Dr.Mamatha Ballal MSc PhD is the Associate Professor of Microbiology
at Kasturba Medical College-
Manipal (MAHE - Deemed University) for the past 19 yrs. She teaches Microbiology
for MSc., MD, MBBS, BDS, BPT, BOT, Nursing, BMLT, DMLT, MSc MLT and Dietitics
in Hotel Management students. She was awarded National Academy of Medical Sciences
fellowship in 1999 to be trained for Molecular techniques in enteric infections.
She is the peer reviewer for the Indian
Journal of Pharmacology, Indian
Journal of Biotechnology and
Indian Journal of Medical Microbiology. Member of board of studies for Microbiology
(MBBS, BDS, MD, MSc, Nursing). She has published 46 scientific articles in various
National and International Journals. She is life member of various associations
like Indian Association of Medical Microbiologists, Indian Association of Pathologists,
and Microbiologists and Association of Microbiologists of India. Authored and
co-authored book for Medical Laboratory technology, information technology and
Medical documentation courses. Participation in content writing for e- learning
programme as a subject expert for MBBS curriculum. Her interest on Medicinal
plants and their activity against Enteric pathogens have been acclaimed recognition
allover.