Ever heard of bitter melon? Well, if you’ve never, now you have. It also goes by other names such as bitter gourd, bitter apple, karela and many more names depending on your native language. It is the fruit of Momordica charantia, but all that basic knowledge you can find on Wikipedia.
What is more interesting however and harder to decode is the ability of this precious fruit to fight HIV-1 against infecting eukaryotic cells or replicating in infected tissues. This ability is due to a protein it contains known as MAP30 (Momordica anti-HIV protein of 30 kDa).
Many are already aware of its moderate hypoglycemic effects. This means that it can lower blood sugar. It is also active against various tumors. However, in this article, the focus is on HIV-1.
HIV-1, the most common viral strain, had been notoriously hard to treat for a few decades. However, as of 2019, a number of drugs are in place to fight against this virus at different stages of invasion. Moreover, these drugs can now be used in combination therapies against the virus. As such the progression of HIV to AIDS is now rare. However, what is common and really scary, are the side effects of the drugs.
Once infected by the HIV-1 virus, the virus is able to enter the cell by interacting with various proteins on the host’s cell surface. Once inside the host cell, the virus uses an enzyme known as reverse transcriptase to convert the viral RNA into DNA which is the primary genetic material in a eukaryotic cell. Once the viral DNA is complete, the enzyme integrase is then used to fix it into the chromosomal DNA of the host cell.
Antiretroviral drugs work by targeting various proteins that assist the virus to invade the host cell. During the phase at which the virus is seeking to enter the host cell, a retroviral drug can block the receptor found at the surface of the cell. Examples of such target receptors is the CCR5 and CXCR4 found on the surface of white blood cells.
These receptors are normally the main means of communication between signaling molecules and white blood cells. The CCR5 receptor, for example, has chemokines as ligands. This means that various chemokines interact with this receptor and informs it of an ongoing infection anywhere in the body. This deploys the particular white blood cell to the area of invasion.
Now, remember the HIV-1 also makes use of this receptor to gain entry into the host cell. That is why some antiretroviral drugs block these receptors. But blocking this receptor also blocks it from interacting with signaling molecules that tell it to go to a site of infection. As such, the drug becomes a double-edged sword. While it keeps the virus from entering the cell, it also renders the white blood cells in question unable to keep up with infections. And this becomes a side effect of the drug; a weakened immune system.
Other drugs produce side effects because they also interfere one way or another with essential cellular processes that the virus takes advantage of. Some drugs also inhibit the enzymes reverse transcriptase or integrase.
Now, given that you have a rough idea of how antiretroviral drugs work, and why they bring about severe side effects, let’s look at how MAP30 in the bitter melons function.
Back in the 1990s, the scientist Lee-Huang reported that a plant protein known as MAP30 isolated from Mormodica charantia (bitter melon) is able to fight the HIV-1 virus at multiple stages of its life cycle. This was after an experiment against the HIV-1 virus.
Is the mechanism of action that MAP30 uses any different from other HIV-1 drugs combatants? Well, yes. And that is the most exciting part.
The experiment showed that while MAP30 also inhibits the enzyme integrase, it cannot enter a cell that is not infected with HIV-1. This unique phenomenon might be due to the fact that viral infections change the cell membrane properties of the infected cell. Only infected cells are therefore vulnerable to MAP30.
Once inside an infected cell, MAP30 also inactivates the cellular ribosomes. This inhibits the synthesis of proteins and renders the cell unable to function. In a mitotic tissue, this cell will eventually die due to its inability to replicate and sustain itself.
Another fatal blow that MAP30 happily delivers to HIV-1 is to make its DNA useless. It does this by relaxing the supercoiled strands of DNA. This renders the genetic material of the virus that was integrated into chromosomal DNA of the host cell topologically inactive. This means that the viral genetic code cannot be transcribed. MAP30, however, cannot damage human DNA.
So, yes MAP30, contained in bitter lemon, has a significant effect against HIV-1 virus and can prevent acute infection as well as replication in chronically infected cells.
There are some important precautions however while consuming bitter lemon:
- The seeds of bitter lemon should not be taken during pregnancy due to the presence of momorcharins which can induce abortions or cause morphological abnormalities.
- Due to its hypoglycaemic effects, it should not be consumed if one has low blood sugar.
- Avoid giving children the crude extracts.
For best results, the adult daily dosage should be 10-15 ml of fresh juice.