Bøger af C. K. Chu

Due to the worldwide epidemic of acquired immunodeficiency syndrome (AIDS), the past ten years have witnessed a flurry of activity in the chemotherapy of viral diseases. Unprecedented scientific efforts have been made by scientists and clinicians to combat infections of human immunodeficiency virus (HIY), the causative agent. Looking back over the past ten years, we have made remarkable progress toward the treatment of the viral disease: isolation of HIV only two years after the identification of the disease, plus major strides in the areas of the molecular biology and virology of the retrovirus, etc. More remarkably, the discovery of the chemotherapeutic agent AZT (Retrovir) was made within two years after the isolation and identification of the virus, followed by unprecedented drug development efforts to culminate in the FDA approval of AZT in twenty-three months, which was a record-breaking time for approval of any drug for a major disease. The last six to seven years have particularly been an exciting and productive period for nucleoside chemists. Since the activity of AZI' was established in 1985, nucleoside chemists have had golden opportunities to discover additional anti-HIV nucleosipes, which are hoped to be less toxic and more effective than AZT, and the opportunity continues. As we all are aware, AZT possesses extremely potent anti-HIY activity, and no other nucleoside or non­ nucleoside has surpassed the potency of AZT in vitro.

During the past fifty years, thousands of natural products have been isolated from plants, fungi, and bacteria. Apart from intense searches by pharmaceutical companies for medicinals and the concentrated effort mounted by the National Cancer Institute, many of these have not been tested in biological systems. The major reasons for this appear to be, at least, twofold. First, individual researchers looking for biologically active natural products will often isolate only small amounts of material sufficient to determine a structure and calculate the specific activity for their particular bioassay systems: insufficient funds preclude re-isolating the compound unless industrial potential is foreseen. Second, the difficulty with which original structures were proved prior to 1972. This required the isolation of relatively large quantities of a natural product and there followed extensive degradation, elemental analyses of the parent and its fragments, then synthesis, piece by piece, of the molecule. All this took time and energy. No wonder that when the structure was proved the chemist was enervated. And coupled to this was the fact that many chemists were not trained to test their materials in biological systems. In contrast, today a natural product can be isolated, its mass and molecular formula determined and, if there is some serendipity, crystals may be obtained for single crystal x-ray analysis. If conditions are near perfect, it is possible to isolate and identify a novel compound in a month.