natural products as sources of drugs Flashcards
(23 cards)
what are some sources of lead compounds?
plant life / microorganisms / animal life, chemical synthesis
computer aided drugs
do synthetic drugs occur naturally?
no they are produced by the pharmaceutical industry
what are natural products / secondary metabolites?
organic compounds isolated from natural sources (cultures of microorganisms or plants)
proteins in the body, are they built from L or D amino acids?
L, d-amino acids are not natural
do natural products contain many chiral centres?
yeah
what are some characteristics of natural products?
chirality, stereoselectivity, and stereospecific production of chemicals
give some examples of plant extract drugs
from opium - morphine
from yew tree - taxol
from willow tree - salicylic acid
from coca bush - cocaine
give some examples of antibiotics produced by microorganisms
penicillin, cephalosporins, tetracyclines, streptomycin, chloramphenicol
are secondary metabolites required for growth and maintenance?
no they are not involved in essential life processes, they do not appear to provide a function that is required for growth and life maintenance
name some primary metabolites and give their function
sugars, peptides, proteins, fatty acids, and sterols, they are essential for growth and survival of the producing organiism
describe the appearance of secondary metabolites
rather large, complicated, organic molecules and may require as many as 30 separate enzymatic steps to synthesise.
Therefore, microorganisms devote significant energy and resources to the biogenesis of secondary metabolites that are not involved in essential life processes
This leads one to the conclusion that these molecules are important, if not essential, to the survival of these organisms
why do microorganisms produce secondary metabolites
not completely understood but one suggestion is that drugs give plants and microbes survival nutritional advantage by antagonism against the competition.
also, the toxicity of secondary metabolites to competing organisms is sufficient to make secondary metabolism valuable
what is the classification of secondary metabolites based on?
their structural properties
what what are the main classes of classification of secondary metabolites?
specialised amino acids and peptides, polyketides, terpenoids and steroids, alkaloids, specialised carbohydrates
which class do b-lactam antibiotics antibiotics fall in?
specialised amino acids and peptides
what is the mechanism of action of b-lactam antibiotics?
Penicillin inhibits a bacterial enzyme - transpeptidase which is involved in the synthesis of the bacterial wall.
penicillin becomes covalently linked to the enzyme’s active site leading to irreversible inhibition.
penicillin is an irreversible inhibitor of transpeptidase.
penicillin inhibits the final cross linking stage of cell wall synthesis, it reacts with transpeptidase to form an irreversible covalent bond which leads to a weakened cell wall. the cell swells due to water entering the cell, then bursts (lysis)
what does transpeptidase catalyse?
the final cross linking reaction of the bacterial cell walll biosynthesis
name some beta lactam antibiotics?
penicllin G, cephalosporin C, Tetracycline
what is erythromyocin
a non aromatic polyketide known as a macrlide
how does macrolide inhibit protein synthesis
inhibits bacterial protein synthesis by binding to the 50S ribosome subunit. these drugs are active against the majority of aerobic and anaerobic gram positive cocci and against gram negative anaerobes
where are alkanoids most commenly encounterd?
in the plant kingdom
the nitrogen containing part of an alkaloid, what is it a derivative of?
of amino acids
how do aminoglycosides inhibit protein synthesis & give an example of one
they bind to the 30S ribosome and inhibit bacterial protein synthesis by preventing the formation of an initiation complex with mRNA. They are active only against aerobic gram-negative bacilli and staphylococci
An example is Gentamicin.
