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  • Stereochemistry

    If a question asked how would you describe the stereochemistry of the molecule, cytarabine, and its relationship to other significant biologically and pharmacologically active molecules, how would you go about answering it?

    I would describe the stereochemistry talking about the chiral centres and the asymetric centre and enantiomers etc, but for the second part of the question about relating it to biologically active molecules, I have no idea how to answer. Can someone help me please. Thanks!

  • #2
    Re: Stereochemistry

    Long time since I looked at chairs and tables. Stereochemistry is important because nature is generally left handed and therefore the laevo forms of molecules are usually most active. Companies produce laevo forms to extend the patent eg laevo cetirizine.

    However, dextromethorphinan and dexamphetamine are examples fo active dextro compds.


    • #3
      Re: Stereochemistry

      It all affects the bonding with the active site/receptor.
      Don't think of the molecules as stick diagrams, think of them as charged clouds with different local intensities, in three dimensions that are also affected by the molecules they come into contact with. The chirality and all that (forgotten all the terms now, such as 'z' isomers) affect this distribution.

      There's a good model of a molecule as it changes from formula-stick model-charge model on the internet somewhere.
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      • #4
        Re: Stereochemistry

        Yep, some enantiomers of a drug will fit and bind to the receptor (imagine lock and key mechanism) and cause a pharmacological action while other enantiomers will not, as will have a mirror image shape and will not bind to the receptor.

        Also some enantiomers will have different actions, for example one enantiomer of thailidomide is a sedative while the other is mutagenic.


        • #5
          Re: Stereochemistry

          Cytarabine is an antimetabolite which has a pyrimidine like structure. Thus it's pharmacology is similar (but not exactly the same) to that of other antimetabolites with a pyrimidine structure like 5 FU (5 fluorouracil) and others.

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