Penicillin semisynthetic penicillins

Other Reactions. The reaction of Thydioxybenzaldehyde with sodium cyanide and ammonium chloride, Strecker synthesis, yields /J-hydroxyphenylglycine [938-97-6] a key intermediate in the manufacture of semisynthetic penicillins and cephalosporins (see Antibiotics, p-LACTAMs). 

Pharmaceuticals. -Hydroxybenzaldehyde is often a convenient intermediate in the manufacture of pharmaceuticals (qv). For example, 2-(p-hydroxyphenyl)glycine can be prepared in a two-step synthesis starting with -hydroxybenzaldehyde (86). This amino acid is an important commercial intermediate in the preparation of the semisynthetic penicillin, amoxicillin (see ANTIBIOTICS, P-LACTAMs). Many cephalosporin-type antibiotics can be made by this route as well (87). The antiemetic trimethobenzamide [138-56-7] is convenientiy prepared from -hydroxybenzaldehyde (88) (see Gastrointestinal agents). 

Worldwide retail antibiotic sales in 1986 were approximately 11 biUion of which penicillins comprised approximately 2.5 biUion (66). Preparations containing ampicillin are estimated at 800 million whereas those containing amoxicillin are estimated at 1,020 million. Total sales include sales of ampicillin esters and the iireidopenicillins derived from ampicillin. Total sales of penicillins, including semisynthetic penicillins in the United States in 1987, were 25 million (67). Sales of amoxicillin, the largest single selling penicillin, were approximately 350 million. 

The cost of 6-APA, ampicillin, and amoxicillin is invariably linked to that of penicillin G. 6-APA remains one of the cheapest raw starting materials available for the preparation of semisynthetic penicillins and other related P-lactam antibiotics. 

The second most important group of immobilized enzymes is stiU the penicillin G and V acylases. These are used in the pharmaceutical industry to make the intermediate 6-aminopenici11anic acid [551-16-6] (6-APA), which in turn is used to manufacture semisynthetic penicillins, in particular ampicilHn [69-53-4] and amoxicillin [26787-78-0]. This is a remarkable example of how a complex chemical synthesis can be replaced with a simple enzymatic one ... 

Pharmacologically useful isoxazoles (B-82MI41600) include antibacterial sulfonamides (614), (615) and (616), semisynthetic penicillins (617), (618), (619) and (620), semisynthetic cephalosporin (621), anabolic steroid (622), the monoamine oxidase inhibitor (623) (used in psychotherapy), antiinflammatory agent (624) and antitumor agent (625). 

Although the last step in the preparation of a semisynthetic penicillin may appear to be a straightforward acylation of 6-APA, the wealth of functionality and reactivity of the 3-lactam requires highly specialized conditions for achieving this transformation. 

Amino acid separations represent another specific application of the technology. Amino acids are important synthesis precursors - in particular for pharmaceuticals -such as, for example, D-phenylglycine or D-parahydroxyphenylglycine in the preparation of semisynthetic penicillins. They are also used for other chiral fine chemicals and for incorporation into modified biologically active peptides. Since the unnatural amino acids cannot be obtained by fermentation or from natural sources, they must be prepared by conventional synthesis followed by racemate resolution, by asymmetric synthesis, or by biotransformation of chiral or prochiral precursors. Thus, amino acids represent an important class of compounds that can benefit from more efficient separations technology. 

Like benzylpenieillin, penicillin V is still widely used in its own right but can also be used as a starting material for the manufacture of the semisynthetic penicillins, none of which can be made by direct fermentation. 

Hydrolysis of penicillin mediated by penicillinase that has motivated attempts to alter its strnctnre (e.g., in semisynthetic penicillins). 

Fig. 2.2 illustrates the three types of chemicals by reference to the production of the semisynthetic penicillin antibiotic, ampicillin. 

Kanegafuchi Chemical Industries produce D-p-hydroxyphenyl glycine, which is a key raw material for the semisynthetic penicillins ampicillin and amoxycillin. Here, an enantioselective hydantoinase is applied to convert the hydantoin to the D-p-hydroxyphenyl glycine. The quantitative conversion of the amide hydrolysis is achieved because of the in situ racemization of the unreacted hydantoins. Under the conditions of enzymatic hydrolysis, the starting material readily racemizes. Therefore, this process enables the stereospecific preparation of various amino acids at a conversion of 100% [38]. 

The answer is b. (Hardman, pp 1077—1086.) Piperacillin is a broad-spectrum, semisynthetic penicillin for parenteral use. Its spectrum of activity includes various Gram-positive and Gram-negative organisms including Pseudomonas. The indications for piperacillin are similar to those for car-benicillin, ticarcillin, and mezlocillin, with the primary use being sus-... 

As streptococcal cellulitis is indistinguishable clinically from staphylococcal cellulitis, administration of a semisynthetic penicillin (nafrillin or oxacillin) or first-generation cephalosporin (cefazolin) is recommended until a definitive diagnosis, by skin or blood cultures, can be made (Table 47-4). If documented to be a mild cellulitis secondary to streptococci, oral penicillin VK, or intramuscular procaine penicillin may be administered. More severe streptococcal infections should be treated with IV antibiotics (such as ceftriaxone 50 to 100 mg/kg as a single dose). 

Aminoglycosidee + penicillin G 100,000-200,000 unit kg/day IV in four divided doses or a semisynthetic penicillin (nafcillin 150-200 mg/kg/day [not to exceed 12 g/24 hours] IV in four to six equally divided doses) depending on isolation of staphylococci or streptococa ... 

Penicillinacylase is used industrially to catalyze the hydrolytic removal of the side chain in naturally occurring penicillins such as benzylpenicillin (4.49) and phenoxymethylpenicillin (4.50). The nucleus 6-aminopenicillic acid (4.48) is then used as the starting material for the preparation of semisynthetic penicillins. Appropriate acylation of the 6-NH2 group leads to )3-lactamase-stable and broad-spectrum penicillins. 

The bacterium Staphylococcus aureus, which is a major cause of infection in the developed countries, is now resistant to most antibiotics. It is usually present on the skin, where it causes no problems, but it can invade the body through cuts and wounds, including those caused by surgery. These bacteria are now prevalent in many hospitals, so that infection is a major problem for the medical staff in hospitals. The resistant bacterium is known as methicillin-resistant Staphylococcus aureus (MRSA). It is also known in the mass media as the super bug . Penicillin kiUs bacteria because the P-lactam group in the antibiotic inhibits a reaction that is essential for bacterial ceU wall production. Consequently, the bacteria cannot proliferate. Resistance to penicillin in many bacteria is due to production of an enzyme, p-lactamase, that degrades P-lactams. The antibiotic methicillin is one of a group of semisynthetic penicillins in which the P-lactam group is not... 

Scheme 6.7). Penicillin G amidase from Mcaligenes faecalis, which is used in the manufacture of semisynthetic penicillins and cephalosporins, was used in both steps to afford a one-pot cascade process [21]. The acylation was performed in an aqueous medium at pH 10-11 and, after separation of the remaining amine enantiomer, the acylated amine was hydrolyzed with the same enzyme by lowering the pH to 7. 

Subequent acylation of 6-APA by various acid derivatives led to the formation of a large number of semisynthetic penicillins. 

From the chemical point of view, the first type of semisynthetic penicillins, undoubtedly, are considered relatively simple derivatives of 6-APA and aromatic or aryloxycar-boxylic acids (benzylpenicillin, phenoxymethylpenicillin, meticillin, naphicillin). 

Another type of semisynthetic penicillins that are considered heteroylcarboxylic acid derivatives, in which the acyl group is represented as an aromatic heterocyclic acid derivative (oxacillin, cloxacillin, dicoxacillin). 

The next type of semisynthetic penicillins are those in which the acyl group is represented by an amino acid, mainly a-aminophenylacetic acid (phenylglycine) or p-oxy-a-aminophenylacetic acid, and correspondingly, ampicillin and amoxicillin. 

Like other semisynthetic penicillins, methicillin exhibits an antibacterial effect similar to that of benzylpenicillin. The main difference between methicillin and benzylpenicillin is that it is not inactivated by the enzyme penicillinase, and therefore it is effective with respect to agents producing this enzyme (staphylococci). It is used for infections caused by benzylpenicillin-resistant staphylococci (septicemia, pneumonia, empyemia, osteomyelitis, abscesses, infected wounds, and others). Synonyms of this drug are cinopenil, celbenin, staphcillin, and others. 

Another type of semisynthetic penicillin that should undoubtedly be considered is penicillin derivatives of heteroylcarboxylic acids (as a rule an isoxazol) in the third position of which is present a substituted or nonsubstituted phenyl radical (oxacillin, cloxacilhn, dicloxaciUin), which plays the role of the radical in the acyl side group. These penicillins (oxacilhn, cloxacilhn, dicloxacilhn), which are resistant to penicillinase, are active with respect to peniciUin-G-resistant staphylococci. Their antimicrobial spectrum is restricted to Gram-positive microorganisms. 

The following type of semisynthetic penicillins that should be considered are those in which amino acids, mainly a-aminophenylacetic or p-oxy-a-amino-phenylacetic acids, act as the acyl radical (ampicillin, amoxacilUn). 

Chemical or enzymatic hydrolysis of this compound allows to obtain large quantities of 7-aminocephalosporanic acid. A number of semisynthetic beta-lactam cephalosporin antibiotics were created by acylating the amino group of the last with various acid derivatives (analogous to the semisynthetic penicillin series) and currently there are about 25,000 of them, of which about 100 are used in medicine. Unlike penicillins, semisynthetic cephalosporins are synthesized not only by expanding the spectrum of various acids by which 7-aminocephalosporanic acid is acylated, but also by internal modifications of aminocephalosporanic nucleus (Rj and Rj). 

Lab test abnormalities Elevations of AST, ALT, bilirubin, and LDH have been noted in patients receiving semisynthetic penicillins (particularly oxacillin) such reactions are more common in infants. Elevations of serum alkaline phosphatase and hypernatremia and reduction in serum potassium, albumin, total proteins, and uric acid may occur. 

Figure 1.15. Structure of 6-aminopenicillanic acid (a) generalized penicillin structure (b) and side-groups present in two natural penicillins and two semisynthetic penicillins (c)...

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