Penicillin - its discovery, properties and uses.

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Introduction

Penicillin is a familiar word to everyone. The first idea that comes to people’s mind is Penicillin is a group of antibiotics, as Penicillin is a very common antibiotic that kills bacteria. Apart from killing bacteria, what else do people know? Probably is nothing. In this project, I would like to find out what do Penicillin is and how people discovery Penicillin.

First of all, go with the basic thing, what antibiotic is. Antibiotics are molecules that stop microbes, both bacteria and fungi, from growing or kill them outright. Antibiotics can be classified as either bactericidal or bacteriostatic. Antibiotics that stop bacteria from growing are bacteriostatic. Antibiotics that cause bacterial cell death are bactericidal. They lower the bacterial count, penicillin, is bactericidal. Some antibiotics can display bacteriostatic activity in some circumstances and bactericidal activity in other, where sufficient damage to one or more cell pathways or structures occurs such that a net bactericidal response is triggered. Many antibiotics are bacteriostatic at low concentrations and bactericidal at higher concentrations. This distinction is often not important clinically.

Antibiotic can either be natural products or man-made synthetic chemicals. Most of the antibiotic introduced into human clinical use to treat infections disease in the past 60 years have been natural products, elaborated by the one microorganism in a particular habitat and set of environmental condition to affect neighboring microbes, either to regulate their growth or to rigger their elimination. Antibiotic natural products are produced by the both bacteria and fungi, with the major group of antibiotic-producing bacteria being the actinomycetes.

When a new antibiotic molecule was detected in a microbial culture broth or a screen in a synthetic medicinal chemistry program, it will compare against benchmark antibiotics with known mechanisms of action. A novel mechanism suggested a new target could be delineated through biochemical analysis. In turn, knowledge of the targets and mechanism of action of major antibacterial drug classes also gave a range of assays that would allow categorization of newly discovered antibacterial by mechanism of action. For example, against cell wall biosynthesis or as inhibitors of protein biosynthesis. The evaluation of new antibacterial molecules typically follows a hierarchical procedure. First, a new compound is tested against a panel of bacterial strains, many of them pathogens arising from clinical isolates, and many of those possessing resistance to prior generations of antibiotics. If a new antibiotic candidate show that sufficient potency against marker strains, then the molecule may be evaluated in animals inoculated to have high levels of infections with specific strains of bacteria in particular tissues, such as bacterial infections of blood and bacteremia, to see if the candidate molecule is protective and curative. The new antibiotic may then be compared against standard antibiotics use against such bacterial infections, with both of the antibiotic -sensitive and antibiotic-resistant strains of pathogens. If the new molecule passes those test, it may well be on its way as a development candidates.

Penicillin was first used in the 1940s, afterwards, they remain the most important group of antibiotics even though many other antibiotics produced and new penicillin derivative continues to be developed. Penicillin binds to the cell wall of bacteria. Bacteria are single cell organisms, which can be rod-shaped or spherical. Spherical bacteria are known as cocci, and they can be single or double, in clumps or in strings. Bacteria have a cell wall, DNA and the means to synthesize protein, but no nucleus. Bacteria have many biochemical differences compared with human cells, and some antibiotics are apparently non-toxic to humans. Other, however, can cause harmful effects as a result of their effects on normal healthy cells. Most antibiotics are effective against rapidly dividing cells.

Discovery and history of penicillin

Most of the people think the discovery of penicillin is attributed to Scottish scientist Alexander Fleming in 1928. He showed that, if Penicillium notatum was grown in the appropriate substrate, it would exude a substance with antibiotic properties, which he dubbed penicillin. This accidental observation began the modern era of antibiotic discovery. However, several people reported the bacteriostatic effects of Penicillium earlier than Fleming. Such as since the middle ages, the use of bread with a blue mould (presumably penicillium) as a means of treating suppurating wounds was a principal of folk medicine in Europe.

Actually, early in the ancient times, many different cultures such as the Greek, India, already used mould and also other plants to deal with infection. However, due to poor knowledge about medicine, they couldn't distinguish or distill the efficacious component in the moulds. The moulds involved in many old treatments. Around 1550 BC in Egypt, an Egyptian physician, stated that if a “wound rots…then bind on it spoiled barley bread”. In fact, the Egyptian used all types of moulds to treat surface infections. It showed that early in 1550 BC in the historical records, were already records describing the use of fermented materials in and moulds in the treatment of disease. Because those treatments were carried out without any understanding of cellular and biochemical processes of the human body or any understanding on the nature of cure, there was a chance of the patient dying from the treatment as well as being remedy.

In China, the Chinese also put mouldy soybean curd on boils, used mould for carbuncles and other kinds of skin infection. In Russia, the Russian farmer used warm soil as treatment for infected wounds. In Greece, mouldy bread was a traditional treatment for infection and wounds. About 161-137 BC, soldiers in the army of Sri Lankan in order to make plaster of the oil cakes (a traditional Sri Lankan sweetmeat) to treat wounds, they stored oil cakes for long periods in their hearth lofts before their campaign start. It shows that they assumed that the oil cakes can work for desiccant and antibacterial. In Babylonia, Babylonian doctors use a mixture of frog bile and sour milk to remedy the eyes. Also, the Sumerian doctors gave patients beer soup mixed with turtle shells and snake skins. At that time, from the techniques they used, it could be said that they cannot define what component in those food that can remedy illness and did not fully understand the nature of the medicine.

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Till 1640, John Parkington, who is a Pharmacist, wrote a book which is about using mould as an antibiotic for treatment. Afterwards, there was more knowledge about moulds. Also on pharmacology, mould became respected as a treatment and more pharmacists started to study mould to extend the knowledge. In 1871, John Burdon-Sanderson, who graduated in Edinburgh University with a degree of Medicinal Doctor and started to work at St. Mary’s Hospital as a lecturer after graduate, found out by covering mould and drying the air current, bacteria will be easily killed. This inspired Joseph Lister, the father of antisepsis, ...

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