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level: Tetracycline SAR

Questions and Answers List

level questions: Tetracycline SAR

Question	Answer
All derivatives containing less than __ rings are inactive	four
The simplest tetracycline derivative that retains the characteristic broad-spectrum activity associated with this antibiotic class is __	6-demethyl-6-deoxytetracycline
The enolized tricarbonylmethane system at C_ to C_ must be intact for good activity	C1 and C3
Replacement of the __ at C2 with other functions reduces or abolishes activity	amide
Mono alkylation of the __ reduces activity proportionately to the size of the alkyl group	amide nitrogen
The dimethyl amino group at position __ must have alpha form: __ are very much less active than the natural isomers	4, 4 epitetracyclines
Removal of 4-dimethylamino group __ activity	reduces
Activity is largely retained in the __ amines but rapidly diminishes at __	primary & N-methyl secondary, higher alkylamines
A cis-A/B-ring fusion with a a-hydroxyl group at __ is essential	C-12a
esters at the C12a hydroxyl group are inactive, with the exception of __, which readily oxidizes in aqueous solutions	formyl ester
__ at C-11a leads to inactive compounds	Alkylation
__ at C-5a and C-11a markedly decreases activity __ at ring C also decrease activity	Dehydrogenation, Aromatization
Subtituents at positions __ representing the largely hydrophobic "northern and western" faces of the molecule, can be modified with varying degrees of success, resulting in retention and sometimes improvement of antibiotic activity	5, 5a, 6, 7, 8 and 9
__ group in oxytetracycline and doxycycline may influence pharmacokinetic properties but does not change antimicrobial activity	5-hydroxyl group
Acid stable __ have been used to prepare various mono substituted and di substituted derivatives by electrophilic substitution reactions at C__ and C__ of the D ring	6-deoxytetracyclines and 6-demethyl-6-deoxytetracyclines, C7 and C9
The more useful results have been achieved with the introduction of substituents at C oddly, strongly, __ groups and strongly __ groups enhance activity.	electron withdrawing, electron donating
The most fruitful site for semisynthetic modification of the tetracyclines has been at position __. Neither __ nor the __ group are essential for antibacterial activity	6, 6a-methyl, 6a-hydroxyl
Polar substituents at C__and C__ decrease lipid versus water solubility of the tetracyclines this position is more sensitive __	C5, C6 C6 (most sensitive)