Chapter 14 The Chemistry of Drugs
Chapter 14 The Chemistry of Drugs
The medicinal use of plants has been discovered more than 2000 years ago. Greek physician Dioscorides described the use of opium, in which morphine is the main component In 1806, morphine was isolated from opium In 1820, quinine was isolated from the bark of the cinchona tree In 1860s, Pasteur discovered bacteria and phenol and related compounds started to be used to prevent bacteria infection In 1930s, sulfur-containing compounds known as surfa drugs were developed In 1939, penicillin(antibiotic) was found Today, there are more than 25,000 prescription (关8(处方药)and30000 escription drugs dru 方药)
• The medicinal use of plants has been discovered more than 2000 years ago. Greek physician Dioscorides described the use of opium, in which morphine is the main component. • In 1806, morphine was isolated from opium. • In 1820, quinine was isolated from the bark of the cinchona tree. • In 1860s, Pasteur discovered bacteria and phenol and related compounds started to be used to prevent bacteria infection. • In 1930s, sulfur-containing compounds known as surfa drugs were developed. • In 1939, penicillin (antibiotic) was found. • Today, there are more than 25,000 prescription drugs (处方药) and 300,000 nonprescription drugs (非处方药)
14.1 Drugs are classified by safety, social acceptability, origin, and biological activity Classified according to safety and social acceptability U.S. Drug Enforce me nt Agency Classification of Drugs Classification Description Examples Over-the-counter (OTC) Available to anyone Aspirin, cough me dicines Permitted nonmedical drugs Available in food beverage and tobacco products Alcohol caffeine. nicotine Prescribe drugs Requires physician authorization Antibiotics, birth control pills Control substance Schedule 1 No medical use, high abuse potential Heroine, LSD, mescaline, marijuana Schedule 2 Some medical use, high abuse potential Amphe tamine, cocaine, morphine, codeine Schedule 3 Prescription drugs, abuse potential Barbiturates. valium Most drugs exhibit a broad spectrum of activity. Aspirin relieves pain reduces fever and inflammation thins the blood, causes ringing in the ears
14.1 Drugs are classified by safety, social acceptability, origin, and biological activity • Classified according to safety and social acceptability Most drugs exhibit a broad spectrum of activity. Aspirin relieves pain, reduces fever and inflammation, thins the blood, causes ringing in the ears. U.S. Drug Enforcement Agency Classification of Drugs Classification Description Examples Over-the-counter (OTC) drugs Available to anyone Aspirin, cough medicines Permitted nonmedical drugs Available in food beverage and tobacco products Alcohol, caffeine, nicotine Prescribe drugs Requires physician authorization Antibiotics, birth control pills Control substance Schedule 1 No medical use, high abuse potential Heroine, LSD, mescaline, marijuana Schedule 2 Some medical use, high abuse potential Amphetamine, cocaine, morphine, codeine Schedule 3 Prescription drugs, abuse potential Barbiturates, valium
Classified according to origi Table 14.2 The Origin of Some Common Drug Origin Dr吗g Biological effect Natural product Caffeine Nerve stimulant Reserpine Hypertension reducer Vincristine Anticancer agent Penicilline Antibiotic Morphine analgesic Chemical derivative of natural Prednisone Antirheumatic product Ampicillin Antibiot LSD Hallucinogenic Chloroquinine Antimalarial Ethynodiol Contraceptive diacetate Synthetic Valium Antide pressant Benadryl Antihistamine Allo barbital Sedative-hypl Phencyclidine Veterinary anesthetic methadone analgesic
Classified according to origin Table 14.2 The Origin of Some Common Drug Origin Drug Biological Effect Natural product Caffeine Reserpine Vincristine Penicilline Morphine Nerve stimulant Hypertension reducer Anticancer agent Antibiotic analgesic Chemical derivative of natural product Prednisone Ampicillin LSD Chloroquinine Ethynodiol diacetate Antirheumatic Antibiotic Hallucinogenic Antimalarial Contraceptive Synthetic Valium Benadryl Allobarbital Phencyclidine methadone Antidepressant Antihistamine Sedative-hypnotic Veterinary anesthetic analgesic
14.2 The Lock-and-Key Model guides chemists in synthesizing new drugs HaC O—H T-shaped three dimensional structure found in all opioids morphine O-H N N HiC O-CH wo H3C CH O一C codeine O一CH3 heroine CHa all drugs that act like morphine have the same basic three-dimensional shape as morphine
14.2 The Lock-and-Key Model guides chemists in synthesizing new drugs all drugs that act like morphine have the same basic three-dimensional shape as morphine T-shaped three dimensional structure found in all opioids morphine codeine heroine
Drug molecule Fig 14.2 many (morphine) drugs act by fitting into receptor sites ey HiC O-H on molecules found in the bod Receptor site much as a key fits in a lock Lock O一H
Fig 14.2 many drugs act by fitting into receptor sites on molecules found in the body, much as a key fits in a lock Drug molecule (morphine) Receptor site Lock Key
Most new medicinal drugs are still discovered instead of designed Fig 14.3 ethnobotanists directed natural-products chemists to the yellow coating on the root of the African Bobqunnua tree Indigenous people have known for many generations that this coating has medicinal properties. From extracts of the coating, the chemists isolated a compound that is highly effective in treating fungal infections. This compound, produced by the tree to protect itself from root tot, shows much promise in the treatmentof the opportunistic fungal infections that plague those suffering from AIDS
Most new medicinal drugs are still discovered instead of designed. Fig 14.3 ethnobotanists directed natural-products chemists to the yellow coating on the root of the African Bobgunnua tree. Indigenous people have known for many generations that this coating has medicinal properties. From extracts of the coating, the chemists isolated a compound that is highly effective in treating fungal infections. This compound, produced by the tree to protect itself from root tot, shows much promise in the treatment of the opportunistic fungal infections that plague those suffering from AIDS
Another important method of drug discovery is the random screening of vast numbers of compounds O Taxol Taxol is a complex natural product useful in the treatmentor o Fig 14.4 originally isolated from the bark of the pacific yew tre various forms of cancer
Another important method of drug discovery is the random screening of vast numbers of compounds. N OH H O O O O O O O O OH O OH O Taxol Fig 14.4 originally isolated from the bark of the pacific yew tree, Taxol is a complex natural product useful in the treatment of various forms of cancer
Combinational Chemistry(组合化学) Tiny well or test tube in which reagents B and 4 are mixed Library" of products (a) Fig 14.5 (a)eight hy pothetical starting materials A through D and 1 through 4 can be combined in various ways to yield 16 products, each of which may have some biological activity not found in any of the starting materials. (b)A multitude of products are thus immediately available to be screened for medicinal activity
Combinational Chemistry (组合化学) Tiny well or test tube in which reagents B and 4 are mixed. Fig 14.5 (a) eight hypothetical starting materials A through D and 1 through 4 can be combined in various ways to yield 16 products, each of which may have some biological activity not found in any of the starting materials. (b) A multitude of products are thus immediately available to be screened for medicinal activity
14.3 Chemotherapy cures the host by killing the disease The use of drugs that destroy disease-causing agents without destroying the animal host is known as chemotherapy. It works by taking advantage of the ways a disease-causing agent, also known as a pathogen(病原体), is different from a host Sulfa drugs(磺胺类药物) and antibiotics(抗生素) treat bacteria infections Humans can use folic acid wf)from outside sources but bacteria have to synthesize from PABA H N C-OH H Several step PABA OH OH C-N-C--CH, CH -C N OH , NN H HH Bacterial enzyme Folic acid Fig 14.6 bacterial enzymes use para-aminobenzoic acid( PABa)to synthesize folic acid
14.3 Chemotherapy cures the host by killing the disease • The use of drugs that destroy disease-causing agents without destroying the animal host is known as chemotherapy. It works by taking advantage of the ways a disease-causing agent, also known as a pathogen (病原体), is different from a host. • Sulfa drugs （磺胺类药物） and antibiotics （抗生素）treat bacteria infections • Humans can use folic acid (叶酸) from outside sources, but bacteria have to synthesize from PABA. PABA Folic acid Several steps Bacterial enzyme Fig 14.6 bacterial enzymes use para-aminobenzoic acid (PABA) to synthesize folic acid