Ph.D. (Chemistry) University of Karachi, 1996
Postdoc. H.E.J. Research Institute of Chemistry, University of Karachi, 1996-1998
Postdoc. Florida Atlantic University, Florida 1998-2001
Isolation of new pharmaceutical agents from marine organisms, microorganisms and traditional medicinal plants, biosynthesis of natural products and microbial transformations of bioactive natural products.Natural products are organic compounds, which are isolated from natural sources such as marine organism, microorganisms and plants. These organisms rely mainly on their chemical defense by producing these compounds also termed as secondary metabolites. Natural products are source of new pharmaceutical agents. Recent survey indicate that ca.60% of anti-tumor and anti-infective agents that commercially available or in the late stages of clinical trails are of natural product origin. Our lab is involved in the isolation of bioactive natural products using by various chromatographic techniques like column chromatography (CC), high performance liquid chromatography (HPLC), and thin layer chromatography (TLC). The structure of the pure secondary metabolites is established with the aid of extensive spectroscopic studies such as one-dimensional (1
C-NMR, DEPT, NOE), two-dimensional (COSY, NOESY, TOCSY, HMQC, HMBC) NMR experiments, mass spectrometry (EI, CI, FAB, FD, GC-MS, and linked scan), UV and IR spectrophotometery. After complete chracterization of pure natural product, we study detailed anti-microbial, anti-viral and anti-inflammatory activities of these compounds to find out their potential biomedical applications. For most bioactive natural products, we broaden our scope of investigations to biosynthetic and biotransformation aspects using cell free (crude enzyme preparation of marine organisms) and whole cell cultures of bacteria and fungi, respectively. The latter produce unnatural analogues, which help to study structure-activity relationship of bioactive natural product. The biosynthesis of bioactive compound is studied by incubation of stable isotopes or radioactively labeled precursors in cell free extract of plant or marine organism. Incorporation of these precursors helps to establish biosynthetic origin of these compounds in nature.
Recent Selected Publications:
1. A. Ata, L. J. Conci, J. Bettriidge, I. Orhan and B. Sener, Novel Microbial Transformations of Sclareolide, Chem. and Pharm. Bull , 55, 118, 2007.
2. K. S. Kosmulalage, S. Zahid, C. C. Udenigwe, S.Akhtar, A. Ata and R. Samarasekera, Glutathione S-Transferase, Acetylcholinesterase Inhibitory and Antibacterial Activities of Chemical Constituents of Barleria Prionitis, Z. Naturforsch B, 62b, 580, 2007.
3. S. Zahid, A. Ata and R. Samarasekera, New Triterpenoids from Artocaprus nobilis, Z. Naturforsch B, 62b, 280, 2007.
4. C.C. Udenigwe, A. Ata and R. Samarasekera, Glutathione S-Transferase Inhibiting Chemical Constituents ofCaesalpinia bonduc, Chem. Pharm. Bull., 55, 442, 2007.
5. S. Zahid, C. C. Udenigwe, A. Ata, M. O. Eze, E. P. Segstro and P. Holloway, New Bioactive Chemical Constituents ofCoprnus micaceus, Nat. Prod. Res., 20, 1283, 2006.
6. M. H. Meshkatalsadat, A. Mollataghi and A. Ata, New Triterpenoidal Alkaloids from Buxus hyrcana, Z. Naturforsch,61b, 201, 2006.