Il.Two Hundred Years of Drug Discoveries 15■ first ACE inhibito 12 Squibb's first billion dollar d from the synthesis of teprotide and tion of an increasing knowledge about ACE,another compound, major system that controls blood pressure and the targeted captopril,was synthesiz then followed by a number of synthesis of compounds that block the system.Since angi II is the effector molec appro Captopril hypothesis emerged at Du Pont Merck when it was possible to identify metabolically stable and orally effective angi TABLE 12 Actions of angiotensin Il coul stitute a ne nssue affected Action hype Artery Stimulates contraction growth zoles originally described by Takeda (Osaka.Japan)were Adrenal zona glomerulosa Stimulates secretion of in the"pipe-line"Potent and orally effective non-peptidic aldosterone were found.The first major brea Kidney Inhibits vli zoles,phthalamic acid derivatives,and the discovery of ulate Brain C.Fight against microbes and viruses 1.Identifying the role of germs Facilitates peripheral Among the scientific advances of 19th century.the emer- epeptrenalreea2eof gence of microbial theory of infectious diseases and the dis to prevent the ive to nil Heart Increases contractility and ens makers and oled with the ventricular hypertrophy of laboratory scientists who developed the technologies TABLE 1.3 lon Channels and Drugs that Affect Them Type of channel Drug family Drugs verapami Diltiazem,verapamil Na* zepine,phenytoin,valprolc acid Anticonvulsant drugs Antidiabetic drugs Glipizide.glyburide,tolazamide Class Il antian
II. Two Hundred Years of Drug Discoveries 15 fi rst ACE inhibitor, called teprotide, only active when given intravenously ( Table 1.2 ). Information learned from the synthesis of teprotide and an increasing knowledge about ACE, another compound, captopril, was synthesized 95 then followed by a number of other ACE inhibitors. US Food and Drug Administration (FDA) approval came in the early 1980s. Captopril was Squibb’s fi rst billion dollar drug and it opened a new approach for the treatment of hypertension. 96 ACE inhibitors discovery resulted from the systematic exploration of a major system that controls blood pressure and the targeted synthesis of compounds that block the system. Since angiotensin II is the effector molecule of the renin–angiotensin system, the most direct approach to block this system is to antagonize angiotensin II at the level of its receptor. A new hypothesis emerged at Du Pont Merck when it was possible to identify metabolically stable and orally effective angiotensin II-receptor antagonists. They could constitute a new and superior class of agents useful in treating hypertension and congestive heart failure: some simple N -benzylimidazoles originally described by Takeda (Osaka, Japan) were in the “ pipe-line. ” Potent and orally effective non-peptidic antagonists were found. The fi rst major breakthrough in order to increase the potency of the compounds (sartans) came with the development of a series of N -benzylimidazoles, phthalamic acid derivatives, and the discovery of losartan, a highly potent selective receptor antagonist with a long duration of action 97 ( Table 1.3 ). C . Fight against microbes and viruses 1 . Identifying the role of germs Among the scientifi c advances of 19th century, the emergence of microbial theory of infectious diseases and the discovery of fi rst vaccines to prevent those diseases have to be considered as main milestones. The brilliance of European lens makers and microscopists, coupled with the tinkering of laboratory scientists who developed the technologies TABLE 1.2 Actions of angiotensin II Tissue affected Action Artery Stimulates contraction growth Adrenal zona glomerulosa Stimulates secretion of aldosterone Kidney Inhibits release of renin Increases tubular reabsorption of sodium Stimulates vasoconstriction Releases prostaglandins Affects embryogenesis Brain Stimulates thirst and the release of vasopressin Sympathetic nervous system Increases central sympathetic outfl ow Facilitates peripheral sympathetic transmission Increases adrenal release of epinephrine Heart Increases contractility and ventricular hypertrophy TABLE 1.3 Ion Channels and Drugs that Affect Them Type of channel Drug family Drugs Ca Antiangina drugs Antihypertensive drugs Class IV antiarrhythmics Amlodipine, diltiazem, felodipine, nifedipine, verapamil Amlodipine, diltiazem, felodipine, isradipine, nifedipine, verapamil Diltiazem, verapamil Na Anticonvulsant drugs Class I antiarrhythmics Diuretic drugs Local anesthetic drugs Carbamazepine, phenytoin, valproic acid IA IB IC Disopyramide, procainamide, quinidine Lidocaine, mexiletine, phenytoin, tocainide Encainide, fl ecainide, propafenone Amiloride Bupivacaine, cocaine, lidocaine, mepivacaine, tetracaine Cl Anticonvulsant drugs Hypnotic or anxiolytic drugs Muscle-relaxant drugs Clonazepam, phenobarbital Clonazepam, diazepam, lorazepam Diazepam K Antidiabetic drugs Antihypertensive drugs Class III antiarrhythmics Drugs opening K channels Glipizide, glyburide, tolazamide Diazoxide, minoxidil Amiodarone, clofi lium, dofetilide, N -acetylprocainamide, sotalol Adenosine, aprikalim, levcromakalim, nicorandil, pinacidil Ch01-P374194.indd 15 h01-P374194.indd 15 5/29/2008 5:42:07 PM /29/2008 5:42:07 PM
16 CHAPTER I A History of Drug Discovery in chlorinated water.Few decades later (1861).Ignaz Philip Semmelweis published his puepera fever. 1859 at the orign of the contamination of. 1867 Eventually.with the works of Robert Koch (Berlin Germany).Joseph Lister and Louis eur addi ing proof o reduces postoperative infections mic 1879 Louis Pasteur demonstrates value of vaccine to protect sheep against anthrax 182 Robert Ko e estab ished the purifying and disinfect During th 13 vely used for disinfection of open and infected wound Milon fluid (containing1%sodium hypochlorite and 6.5% sodium chloride) was marketed 1885 Louis Pasteur develops first rabies vaccine Kingdom,in 19 a general disinf nt anc 1890 ce)ir hore 1897 01a183 by William Sin wa. 1906 ge. 1 form the chlorine atom being substituted by an iodine one 1907 Clemens Von Pirquet introduces skin test for TB 829,Jean 1911 cal uses erve the He d his 1916 Polio epidemics break out in New York and homnoobt8aenespoata in Paris.The wer from th very until 1918-1919 oiamCkilnearty40-50 1928 Alexander Fleming discovers penicillin able form until 1940 in a tar (18. and Phenol s used by the F of sterilization and the media and methods for growing and 860.At that time,Joseph Lister not only reduced the inci dthe fou dence c infection by the int ld be ant fumi Carl Withelm Scheele.just came before"Guytonian's isolate bacteria in pure culture (Bacillus lactis)and so.can fumigations."based on chlorine activity (Table 1.4). be onsidered a co-founder of medical micro As soon as a so of chlo e gas who later isolated actena on olid 1789.n e empir 180.Antoine G.Labarague replaced pouash liquor by of diseases onstituted the hallmark of 19th century medi the cheaper caustic soda liquor and thus was bomn sodium cine.The idea that infectious diseases were caused by invis end of the 1820 s.Robert Colli ible agents,gave an opportur nity for many progresses. h ng of Its en
16 CHAPTER 1 A History of Drug Discovery of sterilization and the media and methods for growing and staining microbes, provided the foundation of the new medical science: microbiology that would explode in the 20th century. The practical use of disinfectant fumigations inaugurated by Carl Wilhelm Scheele, just came before “ Guytonian’s fumigations, ” based on chlorine activity ( Table 1.4 ). As soon as in 1785, a solution of chlorine gas in water was used to bleach textiles. Potassium hypochlorite (Eau de Javel) was prepared by Berthollet in 1789. In 1820, Antoine G. Labarraque replaced potash liquor by the cheaper caustic soda liquor and thus was born sodium hypochlorite. At the end of the 1820s, Robert Collins, then Oliver Wendell Holmes showed that puerperal (childbed) fever frequency decreased when midwives wash their hands in chlorinated water. 98 Few decades later (1861), Ignaz Philip Semmelweis published his research on the transmissible nature of puerperal fever. But he failed to convince physicians either in Vienna or in Budapest that they were at the origin of the contamination of pregnant women. 99 Eventually, with the works of Robert Koch (Berlin, Germany), Joseph Lister and Louis Pasteur adding proof of the existence and disease-causing abilities of microorganisms, a worldwide search for the microbial diseases began. Koch demonstrated, in 1881, the lethal effect of hypochlorites on pure cultures of bacteria. Few years after, in 1894, Isidor Traube established the purifying and disinfecting properties of hypochlorites in water treatment. During the World War I, Dakin’s hypochlorite solution has been extensively used for disinfection of open and infected wounds. Milton® fl uid (containing 1% sodium hypochlorite and 16.5% sodium chloride) was marketed in the United Kingdom, in 1916, as a general disinfectant and antiseptic in pediatrics and child care. Another halogen, iodine, had been discovered by Bernard Courtois (Dijon, France) in 1811, who extracted the element from wracks at seashore. Iodine “ tincture, ” proposed in 1835 by William Wallace (Dublin, Ireland) to disinfect wounds, was contested by iodoform, invented by Georges Simon Serullas (Paris, France). Structurally, it was very comparable to chloroform, the chlorine atom being substituted by an iodine one. In 1829, Jean Lugol, a French physician researching the medical uses of iodine in infectious diseases, observed that the presence of potassium iodide in water increases markedly the aqueous solubility of iodine. He used his preparation for dermatological treatments at Saint-Louis Hospital in Paris. The antiseptic properties of iodine were widely used from the discovery of iodine until today. In 1873, the French bacteriologist Davaine used tincture of iodine as an agent to treat anthrax. 100 The revolutionary change in hospital hygiene was introduced when Friedlieb Runge (Breslau, Germany) prepared carbolic acid (phenol) by distillation of coal tar (1834). 101 Joseph Lister (Glasgow, UK) proposed to use “ phenolic ” surgical ligatures and dressings. Phenol sprays were used by the French surgeon, Just Lucas-Championniere (Paris) in operating rooms around 1860. At that time, Joseph Lister not only reduced the incidence of wound infection by the introduction of antiseptic surgery, he also showed that urine could be kept sterile after boiling in swan-necked fl asks. He was the fi rst person to isolate bacteria in pure culture ( Bacillus lactis ) and so, can be considered a co-founder of medical microbiology with Koch, who later isolated bacteria on solid media. 102 More and more the experimental proof confi rmed the empirical behavior. In this environment, the microbial theory of a lot of diseases constituted the hallmark of 19th century medicine. The idea that infectious diseases were caused by invisible agents, gave an opportunity for many progresses. The laboratory took its entire place when microscopes, staining of preparations and sterilization were available. As an TABLE 1.4 Pre-antibiotic Era Discoveries in the Field of Infectious Diseases 1859 Louis Pasteur suggests that microorganisms may cause many human and animal diseases 1867 Joseph Lister publishes On the Antiseptic Principle in the Practice of Surgery showing that disinfection reduces postoperative infections 1879 Louis Pasteur demonstrates value of vaccine to protect sheep against anthrax 1882 Robert Koch isolates microorganism responsible for tuberculosis (TB), then leading cause of death 1883 Robert Koch isolates microorganism responsible for cholera, major epidemic disease in 19 th century 1885 Louis Pasteur develops fi rst rabies vaccine 1890 Emil von Behring and Shibasaburo Kitasato develop effective diphtheria antitoxin 1897 George Nuttall demonstrates that fl ies can spread plague bacilli 1906 August von Wasserman introduces diagnostic test for syphilis 1907 Clemens Von Pirquet introduces skin test for TB 1911 Paul Erhlich tests salvarsan, fi rst treatment effective against syphilis; regarded as birth of modern chemotherapy 1916 Polio epidemics break out in New York and Boston; polio outbreaks continue sporadically in summers for decades to come 1918–1919 An infl uenza pandemic kills nearly 40–50 million people worldwide 1928 Alexander Fleming discovers penicillin although it does not become available in a therapeutically usable form until 1940 Ch01-P374194.indd 16 h01-P374194.indd 16 5/29/2008 5:42:07 PM /29/2008 5:42:07 PM
Il.Two Hundred Years of Drug Discoveries 17■ most of diphtheria's 2.Sulfonamides and sanitization of drinkine water Pasteur's obiective to treat infectious diseases as cholera.tuberculosis,and diph theria,remained a dream although ome vaccines (small pox o rabie were already ava akthroug BASF (Mannheim.Germany)to produce coal tar dye and precursors.In 1871,the company marketed the red -dye alizar Othe y FIGURE1.14 Paul Ehrlich and Sahachiro Hata synthetic dyestuffs.Around the 1880s.German chemists following in Paul Ehrlich's wake,discovered the fact that took living cell ent way as dead production of the first large batch of Savaramos lace at Hoechst (H irt)on more thar and spurred Germany to become a leader in chemical and drug Ehrlich (Berlin,Germany)(looked for a cure or treatment production and it made syphilis a curable disease.The con or African trypanosomiasis and cept of the "magic bulle could be a "magic bullet"able to kill the microbe but not intravenously,which was very hazardous at that time.In e deae.In 1 Julius Morgenroth's laboratory (Berlin.Germany).the fol ounds on mic e,Ehrlich's Jap L14 the microorganism and the power of biliary salts to dis. It did not do much for the sleeping sickness microbe.but solve Trypanosome's or Pneumococcus external structures. it seemed to kill another (recently discovered)microbe Another concept concerning unspecific targets for drugs in the one which caused syphilis: Treponema pallidum vital prop ed s tious diseases.s Most clinicians thought the future woule conclusion could be drawn from thes informations abou be in immunotherapy rather than in chemotherapy.and it the viability of colored bacteria?Ehrlich refined the use of was not until the anti methylene blue in ba riological staining and used it to Bu Za pandem the tub 01g ing the nee to stand ur gainst disease.Forty to hypothesis.Ehrlich administrated Fifty million people worldwide were killed.Chemotherapy methylene blue to patients suffering from malaria. e earch had to be improved and continued.In the year At that time,syphilis was a disabling and prevalent dis ard Domagk (Figure go prom Ehrlich an ver on mic ed to dru ble to mi 、wihn3 weeks with no dead after oral administration.The experimental model he used
II. Two Hundred Years of Drug Discoveries 17 example, Escherichia coli , discovered in 1879, became the perfect example of easily grown, “ safe ” bacteria for laboratory practice. Working with pure cultures of the diphtheria bacillus in Pasteur’s laboratory in 1888, Emile Roux and Alexandre Yersin fi rst isolated the deadly toxin that causes most of diphtheria’s lethal effects. 103 One by one over the next several decades, various diseases revealed their microbial cause, including digestive ulcers. 2 . Sulfonamides Till the beginning of the 20th century, struggle against microbes remained devoted to the disinfection of wounds and sanitization of drinking water. Pasteur’s objective to treat infectious diseases as cholera, tuberculosis, and diphtheria, remained a dream although some vaccines (smallpox or rabies) were already available . The breakthrough would come from an unexpected side of the scientifi c fi eld: dyes industry. 104 In 1865, Friedrich Engelhorn founded BASF (Mannheim, Germany) to produce coal tar dyes and precursors. In 1871, the company marketed the red aniline-dye alizarin. Other new dyestuffs followed: eosin, auramine, and methylene blue, together with the azo dyes, which would eventually develop into the largest group of synthetic dyestuffs. Around the 1880s, German chemists, following in Paul Ehrlich’s wake, discovered the fact that living cells absorbed dyes in a different way as dead cells. He expected healing, probably more than he obtained. Nevertheless, he noticed some improvements. Thereafter, Ehrlich (Berlin, Germany) (looked for a cure or treatment for “ sleeping sickness ” or African trypanosomiasis and found that a chemical called Atoxyl® worked well but was a fairly strong arsenical compound and thus poisonous. Ehrlich began an exhaustive search for other arsenicals that could be a “ magic bullet ” able to kill the microbe but not the person when killing the disease. In 1909, after testing over 900 different compounds on mice, Ehrlich’s Japanese colleague Sahachiro Hata went back to no. 606 or dihydroxy-diamino-arsenobenzol-dihydrochlorid ( Figure 1.14 ). It did not do much for the sleeping sickness microbe, but it seemed to kill another (recently discovered) microbe, the one which caused syphilis: Treponema pallidum . If a microorganism could be colored, vital properties of the bacteria or the parasite could also be transformed. 105 Which conclusion could be drawn from these informations about the viability of colored bacteria? Ehrlich refi ned the use of methylene blue in bacteriological staining and used it to stain the tubercle bacillus, showing the dye bound to the bacterium and resisted discoloration with an acid alcohol wash. 106 Following this hypothesis, Ehrlich administrated methylene blue to patients suffering from malaria. At that time, syphilis was a disabling and prevalent disease. Ehrlich and Hata tested 606 over and over on mice, guinea pigs, and then rabbits with syphilis. They achieved complete cures within 3 weeks, with no dead animals 107 . A production of the fi rst large batch of Salvarsan® took place at Hoechst (Frankfurt) on July 1910. It was an almost immediate success and was sold all over the world. It spurred Germany to become a leader in chemical and drug production and it made syphilis a curable disease. The concept of the “ magic bullet ” was born simultaneously to the concept of chemotherapy. Arsenicals, unlike vaccines, were not tightly controlled and were far more subject to misprescription and misuse as far as they had to be administered intravenously, which was very hazardous at that time. In Julius Morgenroth’s laboratory (Berlin, Germany), the following year, other works were performed on Pneumococcus and particularly on the nature of the external capsule of the microorganism and the power of biliary salts to dissolve Trypanosome’s or Pneumococcus external structures. Another concept concerning unspecifi c targets for drugs in infectious diseases was built, also explaining the activity of various isoquinoline derivatives for treating different infectious diseases. 108 Most clinicians thought the future would be in immunotherapy rather than in chemotherapy, and it was not until the antibiotic revolution of the 1940s that the balance would shift. But the infl uenza pandemic (so-called Spanish Flu) of 1918–1920 clearly demonstrated the inability of medical science to stand up against disease. Forty to Fifty million people worldwide were killed. Chemotherapy research had to be improved and continued. In the year 1927, Gerhardt Domagk ( Figure 1.15 ), who got a promotion in Bayer’s research department (Wuppertal, Germany), aimed to fi nd a drug capable to destroy microorganisms after oral administration. The experimental model he used FIGURE 1.14 Paul Ehrlich and Sahachiro Hata . Ch01-P374194.indd 17 h01-P374194.indd 17 5/29/2008 5:42:07 PM /29/2008 5:42:07 PM
■18 CHAPTER I A History of Drug Discovery FIGURE 1.16 Rene Dubos FIGURE 1.15 Gerhardt Domagk. due to the nazi veto received his medal after world wa II.in 1947.Even if Domagk discovered sulfonamides.he was the streptococcal infection of mice.allowing experi- did not discover the way they were active.The work was eur I S D) magk t ion to dyes the last the Nob in Physiology or Medicine in 1957).Prontosil was inac attach strongly to protein in wool fibers or leather,so that tve on bacteria cultures because it needed presence of a they hold fast against fading or cleaning.Domagk reasc ned .The ac part was the that they if not ein in b ng m in wholel 11936had d dve.had to b sulfonylurea derivative (sulfamidochrysoidine)to be active Sulfanilamide was brought to the United States by Perrin Fritz Mietzsch and Jose I r larer tested the new dye in 1932 H.Long and Eleanor A.Bliss. who used itinclinicalapp str United s but not toxic and named the 936 when it was used to treat president franklin deland changed to Prontosil giving birth to the new era of anti- Roosevelt's son Franklin,Jr.,who was severely ill from a chemherapy.Them cre treptococcic infe ection.More than 5.000 sulfa drugs were the late and cary r ong th At least two ersions ame story are coe Churchill hen he came down ith pneumo nia during World War II);sulfathiazole was used agains of staphylococcal septicemia;the baby made an unex oth pneumonia and staphylococcal infections: covery. A her accoun that Domagk and stapny wh rick Domask did not immediatel publish his results His landmark paper (February 1935)published shortly 3.Antibiotics after that it took a the Nobel zerphvyoloy n recru Avery. to the
18 CHAPTER 1 A History of Drug Discovery was the streptococcal infection of mice, allowing experiments on the effect of the intake of a large amount of drugs. Domagk turned his attention to azo dyes, so-called because the two major parts of the molecule are linked by a double bond between two nitrogen atoms. Some of these dyes attach strongly to protein in wool fi bers or leather, so that they hold fast against fading or cleaning. Domagk reasoned that they might also attach themselves to the protein in bacteria, inhibiting if not killing microorganisms. Chrysoidine, which was a marvelous deep-red dye, had to be grafted to a sulfonylurea derivative (sulfamidochrysoidine) to be active. Fritz Mietzsch and Josef Klarer tested the new dye in 1932 on laboratory rats and rabbits infected with streptococci bacteria. Domagk found that it was highly antibacterial but not toxic and named the substance Streptozan®, soon changed to Prontosil® giving birth to the new era of antimicrobial chemotherapy. The fi rst human cure occurred in 1932. At least two versions of the same story are coexisting. It is not still clear whether it was administered in an act of desperation, in a 10-month-old boy who was dying of staphylococcal septicemia; the baby made an unexpectedly rapid recovery. Another account is that Domagk used Prontosil® to treat his own daughter, who was deadly ill from a streptococcal infection following a pin prick. Domagk did not immediately publish his results. His landmark paper (February 1935) published shortly after that it took a patent, attracted the curiosity of a great number of researchers in Europe. Domagk was awarded the Nobel Prize in Physiology or Medicine in 1939, but due to the Nazi veto, received his medal after World War II, in 1947. Even if Domagk discovered sulfonamides, he did not discover the way they were active. The work was done by a French team at the Pasteur Institute in Paris by Ernest Fourneau, Jacques and Thérèse Trefouël, Federico Nitti and Daniel Bovet (the last received the Nobel Prize in Physiology or Medicine in 1957). Prontosil® was inactive on bacteria cultures because it needed presence of a reductase to split the molecule. The active part was the sulfonamide (amino-4-benzene sulfonamide) itself and not the dye! Doctors in whole Europe in 1936 had stunning results using the new drug to treat childbed fever and meningitis. Sulfanilamide was brought to the United States by Perrin H. Long and Eleanor A. Bliss, who used it in clinical applications at Johns Hopkins University (Baltimore) in 1936. Prontosil® won wide publicity in the United States in 1936 when it was used to treat President Franklin Delano Roosevelt’s son Franklin, Jr., who was severely ill from a streptococcic infection. More than 5,000 sulfa drugs were prepared in the late 1930s and early 1940s. Among them, sulfapyridine was used against pneumonia (it was used to treat Winston Churchill when he came down with pneumonia during World War II); sulfathiazole was used against both pneumonia and staphylococcal infections; sulfadiazine was used against pneumococcal, streptococcal, and staphylococcal bacteria; and sulfaguanadine against dysentery. 3 . Antibiotics The 1930s were also the period for a new era, the birth of antibiotic treatments. 109 René Dubos ( Figure 1.16 ) had been recruited by Oswald Avery, to the Rockefeller Institute FIGURE 1.15 Gerhardt Domagk . FIGURE 1.16 René Dubos . Ch01-P374194.indd 18 h01-P374194.indd 18 5/29/2008 5:42:08 PM /29/2008 5:42:08 PM
lI.Two Hundred Years of Drug Discoveries 19 FIGURE 118 Boris Ernest Chain Howard florey Florey and Boris Ernst chain (Figure 118).to look at re urrecting Fleming's work with penicillin.The erimen FIGURE 1.17 Alexander Flming tal job was performed and published in July 1940,without buman was successfully treated.Before long enicillin extracted from a soil bacillus.Tyrothricin (later showed d e Nobet Prie ror Medicine 1945 As early interview th The New ria.able toarest the growth of staphylococcus.but proved between discovery of penicillin (in 1928)and its full-scale highly toxic. e for sucn a (a)Penicillins identifving the chemical makeup of penicillin.search for It was the desire to find an internal antiseptic that drove other penicillin-producing organisms to enhance production Alexander Fleming (Figure 1.17)in his pioneering work in of the drug.it ation ar crystallization,experments London in the ama ang ob that the deter and at an alar ate Ho the effective dosage for humans,and search for equipment and financial resources to enhance full-scale production.The which Fleming called lysozyme-was effective at dissolv- adjunctive role of serendipity in overcoming these obsta in c give to the The industry contributed.through its fer In his laboratory (Saint Mary's Hospital,London) mentation facilities and comn steep liquor used for the Fleming was in the medium of culture,to penicillin deve lopment.The produc cci.Remo om one hes by mo an 10-fold hattle nds incurred on D-day at Normar lin)produced by the mould was dissolving the bacteria Also.diseases like syphilis and gonorrhea could suddenly be treated more easily than with ,Hodgki eariertreatnments. as then that e name penicilli Dorothy n was seen by the med y.in the early 1940s.enabling the World War I led two medical researchers.Howard
II. Two Hundred Years of Drug Discoveries 19 (New York) and challenged to fi nd a soil microbe that could destroy a bacteria. 110 In 1939, he discovered a substance extracted from a soil bacillus. Tyrothricin (later showed composition of two substances, gramicidin (20%) and tyrocidine (80%), cured mice infected with pneumococci. It was the fi rst natural antibiotic extracted from soil bacteria, able to arrest the growth of staphylococcus, but proved highly toxic. (a) Penicillins It was the desire to fi nd an internal antiseptic that drove Alexander Fleming ( Figure 1.17 ) in his pioneering work in London in the 1920s after the amazing observation that the human teardrop contained a chemical capable of destroying bacteria – and at an alarming rate. However, the excitement at this discovery was soon dashed. While the new discovery – which Fleming called lysozyme – was effective at dissolving harmless microbes, it proved ineffective at negating those that caused disease. Fleming, however, did not give up. In 1928, his diligence was rewarded. In his laboratory (Saint Mary’s Hospital, London) Fleming was in the process of developing staphylococci . Removing the lid from one of these cultures, Fleming was surprised to see that around the mould, the colonies of staphylococci had been dissolved. Something (penicillin) produced by the mould was dissolving the bacteria. After further testing, Fleming was able to isolate the juice of the mould and it was then that he named it penicillin. 111 Penicillin was seen by the medical community as a nonevent. The overwhelming casualties on the battlefi eld during the World War II led two medical researchers, Howard FIGURE 1.17 Alexander Fleming . Florey and Boris Ernst Chain ( Figure 1.18 ), to look at resurrecting Fleming’s work with penicillin. The experimental job was performed and published in July 1940, without raising any (positive or negative) reaction among pharmaceutical world. 112 After much refi nement they were able to develop a powdered form of penicillin. In 1941, the fi rst human was successfully treated. Before long, penicillin was in full production. Fleming, Florey and Chain were awarded the Nobel Prize for Medicine in 1945. 113 As early as 1945, in an interview with The New York Times , Fleming warned that the misuse of penicillin could lead to selection of resistant forms of bacteria. 114 Fourteen years elapsed between discovery of penicillin (in 1928) and its full-scale production for therapeutic use (in 1942). A great number of factors were responsible for such a delay: initial diffi culty of other bacteriologists in reproducing Fleming’s discovery, identifying the chemical makeup of penicillin, search for other penicillin-producing organisms to enhance production of the drug, its purifi cation and crystallization, experiments on animals (chiefl y mice) to determine toxicity, hesitancy to administer the drug to humans, standardization of an effective dosage for humans, and search for equipment and fi nancial resources to enhance full-scale production. The adjunctive role of serendipity in overcoming these obstacles and in contributing to the successful conclusion of the penicillin project constituted an amazing story. 115 The agricultural industry contributed, through its fermentation facilities and corn steep liquor used for the medium of culture, to penicillin development. The production of penicillin increased by more than 10-fold. In fact, by 1944, there was suffi cient penicillin to treat all of the severe battle wounds incurred on D-day at Normandy. Also, diseases like syphilis and gonorrhea could suddenly be treated more easily than with earlier treatments. Dorothy Crowfoot Hodgkin (Oxford), Nobel Prize in Chemistry in 1964, determined the chemical structure of penicillin by crystallography, in the early 1940s, enabling synthetic production of derivatives. John Sheehan at MIT FIGURE 1.18 Boris Ernest Chain Howard Florey . Ch01-P374194.indd 19 h01-P374194.indd 19 5/29/2008 5:42:08 PM /29/2008 5:42:08 PM