30 March 2011
By Dipannita Das
A rare and endemic herb found in the Western Ghats and containing camptothecin (CPT), an alkaloid used in the treatment of cancer, is being grown and multiplied through the tissue culture method.
The project, taken up by MSc students Nilesh Rokade and Priyanka Kadam of the Abasaheb Garware College’s Biodiversity department, has shown encouraging results. The camptothecin content in the herb ‘Ophiorrhiza rugosa var. prostrata,’ has been found comparable to the CPT in ‘Mappia foetida’, a tree known for its anti–cancer properties.
According to Ankur Patwardhan, head of the biodiversity department, "We need to look at our medicinal farming systems in a different way. ‘Theme farming’ has become the need of the hour as medicinal plants are cultivated mainly for their secondary metabolites (active components).
"The pressure on the wild population of Mappia foetida has endangered the plant," he says. "Since there is a huge demand for CPT from pharmaceutical industries, we thought we should explore ‘Camptothecin farming’ where we grow tree species like the Mappia foetida’ as well as herbaceous crops that yield CPT. But, while the Mappia foetida takes seven to eight years to mature, the Ophiorrhiza rugosa var. prostrata, has the advantage of being harvested annually."
Patwardhan pointed out that the herb has the potential to be integrated in the farming system through intercropping and can be cultivated along with Mappia foetida. Two years ago he and his students had taken up experimental plantation on the crestline of the Western Ghats and now they intend to use intercropping with Ophiorrhiza to explore the possibility of commercial cultivation. Since natural regeneration of Ophiorrhiza is poor, tissue culture was opted for in the production of plantlets.
Gauri Abhyankar, a lecturer in the biotechnology department, said that through micropropagation, this herb can be multiplied, making it possible to raise them in a short time. Already, thousands of plants have been multiplied from around 20 to 25 plants, she said.
"CPT in this herb has been found in the leaves, flowers and seeds too. The students are now trained and can work to cultivate other endangered medicinal plants using the tissue culture method," she said.
Nilesh Rokade, one of the students working on the project, said that tissue culture helps the herb remain disease–free and have uniform yield. Explaining the process they followed, he said that first the herbs are collected from the Western Ghats and packed. A micro–habitat is then created with the required humidity and shade. The plant is placed in a test tube or bottle and allowed to grow in the laboratory.
Another student, Priyanka Kadam, said that this practice of micropropagation can be used to multiply stock plant material and meet the demand for CPT. "We are working in the lab to see how CPT can be extracted efficiently from these herbs. Developing mass multiplication protocols and standardising cultivation strategy of this species should be the focus of future studies," she added.
Demand for Camptothecin
- CPT is a plant–based alkaloid that has clinical applications mainly against cancer. It is also found useful against HIV–I, falciparim malaria and also exhibits anti–bacterial properties
- Drug manufacturers are dependant on the natural source of CPT as it is difficult to synthesize artificially
- The supply of woodchips (the main source of CPT is the bark and roots) of ‘Mappia foetida’ is 50% less than the current demand. There is also an urgent need to find alternative sources of CPT that can cater to the demands of the pharma industry