Andrographis paniculata, a well known medicinal plant has been used since ancient times in Traditional Chinese medicine and Indian Ayurvedic medicine. It has been used as bitter tonic to treat digestive problems, snake bite, and infections ranging from Malaria to Dysentery. Recent research has thrown light on the anti-microbial activity of the plant. The most significant pharmacological activities of the plant that have been discovered are anti-allergic, anti-cancer and anti HIV effect. In the present study, the antimicrobial activity of the Andrographis paniculata plant extract has been tested against nine common human-affecting bacterial pathogens. Two different solvents - Methanol and Ethyl acetate have been used to prepare the Andrographis paniculata plant extract and the antimicrobial activity of the two extracts has been tested separately. The effectiveness of the extract against the pathogen is taken as the measure of the diameter of zones of inhibition, formed on the bacterial culture plates after a 24 hour Incubation period. The growth medium used is Mueller Hinton Agar.
Andrographis paniculata is traditionally known as Kalmegh. The plant belongs to family Acanthaceae and is widely used in Traditional Chinese, Ayurvedic and Homeopathic systems of medicine. The plant grows in waste grounds and prefers moist habitat. The herb is bitter in taste and has weak odour. The whole plant is used in medicine, with leaves and roots being the mostly used parts. It is widely cultivated in southern Asia, where it is used to treat infections and some diseases.
Description
It grows erect to a height of 30-110 cm in moist, shady places with glabrous leaves and white flowers with rose-purple spots on the petals. Stem dark green, 0.3 - 1.0 m in height, 2 - 6 mm in diameter, quadrangular with longitudinal furrows and wings on the angles of the younger parts, slightly enlarged at the nodes; leaves glabrous, up to 8.0 cm long and 2.5 cm broad, lanceolate, pinnate; flowers small, in lax spreading axillary and terminal racemes or panicles; capsules linear-oblong, acute at both ends, 1.9 cm x 0.3 cm; seeds numerous, sub quadrate, yellowish brown.
Characteristics
Since ancient times, A. paniculata is used as a wonderdrug in traditional Siddha and Ayurvedic systems of medicine as well as in tribal medicine in India and some other countries for multiple clinical applications. The therapeutic value of Kalmegh is due to its mechanism of action which is perhaps by enzyme induction. The plant extract exhibits antityphoid and antifungal activities. Kalmegh is also reported to possess antihepatotoxic, antibiotic, antimalarial, antihepatitic, antithrombogenic, antiinflammatory, antisnakevenom, and antipyretic properties to mention a few, besides its general use as an immunostimulant agent. A recent study conducted at Bastyr University, confirms anti-HIV activity of andrographolide.
Distribution
Andographis paniculata is distributed in tropical Asian countries, often in isolated patches. It can be found in a variety of habitats ie. plains, hill slopes, waste lands, farms, dry or wet lands, sea shore and even road sides. Native populations of A. paniculata are spread throughout south India and Sri Lanka which perhaps represent the centre of origin and diversity of the species. The herb is also available in northern stations of India, Java, Malaysia, Indonesia, West Indies and elsewhere in Americas where it is probably introduced. The species is also available in Hong Kong, Penang, Malacca, Pangkor Island (south of Penang), Malaya, Thailand, West Java, Borneo, Celebes, Brunei, West Indies, Jamaica, Barbados, Bahamas etc. However, precise data are lacking on the introduction and naturalization of the species in these countries. Unlike other species of the genus, A. paniculata is of common occurrence in most of the places in our country including the plains and hilly areas up to 500 m, which accounts for its wide use. Since time immemorial, village and ethnic communities in India have been using this herb for treating a variety of ailments.
Pharmacology
Andrographis paniculata plant extract is known to possess a variety of pharmacological activities. Andrographolide (Fig.1.0), the major constituent of the extract is implicated towards its pharmacological activity. A study has been conducted on the cellular processes and targets modulated by andrographolide treatment in human cancer and immune cells. Andrographolide treatment inhibited the in vitro proliferation of different tumor cell lines, representing various types of cancers. The compound exerts direct anticancer activity on cancer cells by cell cycle arrest at G0/G1 phase through induction of cell cycle inhibitory protein p27 and decreased expression of cyclin dependent kinase 4 (CDK4). Immunostimulatory activity of andrographolide is evidenced by increased proliferation of lymphocytes and production of interleukin 2. Andrographolide also enhanced the tumor necrosis factor α production and CD marker expression, resulting in increased cytotoxic activity of lymphocytes against cancer cells, which may contribute for its indirect anticancer activity. The in vivo anticancer activity of the compound is further substantiated against B16F0 melanoma syngenic and HT 29 xenograft models. These results suggest that andrographolide is an interesting pharmacophore with anticancer and immunomodulatory activities and hence has the potential for being developed as a cancer therapeutic agent
Objectives
The present study involves the test of the antimicrobial activity of Andrographis paniculata plant extract against nine common human-affecting bacterial pathogens with the following objectives:
1. To check the antimicrobial activity of the plant extract against human pathogens
2. To evaluate the activity of the plant extract in 2 different solvents - Methanol and Ethyl acetate being the solvents used respectively.
3. To perform HPLC of the extract and compare it with the authentic Andrographolide sample
Conclusion
Based on the results of the present study, it can be concluded that Andrographis paniculata plant extract shows significant antibacterial activity against most of the human- affecting pathogens. Extracts made from solvents that are more effective against the pathogens can be used to develop drugs that can be taken along with other Antibiotics. It is of common knowledge that the Andrographis paniculata plant can be used to treat a wide range of ailments. Hence, the advantage of such a combinatorial drug therapy would be the absence of side-effects and also increased effectiveness, in comparison with the present day anti-biotic based drug therapy.