1. Department of Research and Development, Dr. Reddy's Laboratories Ltd., Integrated Product Development, Unit-III, Plot No. 116, S.V. Co-Op. Industrial Estate, Bollaram, Jinnaram, Medak District 502 325, A.P., India, and Institute of Science and Technology, Center for Environmental Science, J. N. T. University, Kukatpally, Hyderabad 500 072, India