Well, dear Reader! Looks like you’ve found your way to our issue of Anti-Cancer drugs in this month’s theme of Medicinal Chemistry. Now, cancer is defined as a disease caused by the uncontrolled division of abnormal cells in the body, but it’s a lot more terrifying than that to lots of people. In this article, we want to talk about the kinds of drugs used in the treatment of cancer and chemotherapy.
Antimetabolites
Do you think cancer can be treated? Well, yes but how? A drug called antimetabolite can interfere with one or more enzymes which are necessary for DNA synthesis. Antimetabolites have structures that are very similar to pyrimidines, purines or other molecules that cancer cells need in order to build their DNA. By mimicking these molecules, the antimetabolites interfere with the cancer cells’ ability to replicate properly. As a result, the cancer cells die. Now let’s focus on the chemistry aspect of this. There are different types of antimetabolites, each of which are chemically different. One of them is fludarabine that works by stopping the abnormal blood cells from multiplying. It is a white solid which inhibits DNA synthesis and is generally used as its 5 -O phosphorylated form known as fludarabine phosphate. The molecular structure of this compound looks something like this-
Antibiotics
We’re sure you’ve heard about these, even learnt about them in biology at school. Antibiotics work against bacteria by preventing the formation of the bacterial cell wall, as you probably know- but we’re here to bring this process to you in greater detail and its relevance to treating cancer. There are many antibiotics that work by binding to the DNA and preventing its activation, therefore controlling the making of RNA. These drugs generally interact with DNA and squeeze between the bases, strand breakage and other means of damaging DNA. Many antibiotic drugs are found and made usable from nature, but aren’t as specific to microbes as are others, and are therefore more toxic to the body. Among antibiotics are the anthracyclines, which are crucial antitumour drugs. The chemical structure of one commonly used antibiotic is shown opposite: (daunorubicin)
Enzyme L-Asparaginase
This enzyme helps specifically with the treatment of Leukemia, which is the cancer of the body’s blood-forming tissues, including the bone marrow. Asparagine is a chemical found in the body which is made by normal cells. When these cancer cells are denied asparagine, they ultimately die. The enzyme L-Asparaginase breaks down asparagine, without which the cancer cells do not have the ample energy to keep up their rapid growth.
It’s got a pretty cool origin story- it was discovered that blood serum from guinea pigs and other rodents in South America worked against leukaemia, and the enzyme was pinpointed as the anti-cancer agent!
Methotrexate
Like others, methotrexate is an immunosuppressive drug that interferes with some actively growing cells within the body in order to treat diseases, especially cancer. Methotrexate increases the release of adenosine, a highly anti-inflammatory chemical that is found in human cells. Adenosine will in turn, inhibit the accumulation of cancer cells in inflamed areas of the body.
Ever wondered why the consumption of folic acid is recommended with methotrexate? To answer this question, let’s understand the chemistry of this too. Folic acid is a synthetic form of folate, also known as vitamin B9. Folate is required for the body to make DNA and RNA. Chemically, folate consists of three distinct chemical bonds linked together. The compound is also bonded through an amide linkage. Folic acid would simply work by reducing the harmful side effects of methotrexate.
Readers, by now you must have discovered that a lot of chemistry is involved even in curing diseases such as cancer. So can we claim chemistry can indirectly save lives too? Wow! Let’s look forward to the next article with the same level of fascination!
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Written by:
Mythri Subash and Malaya Parwani
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