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Thursday 8 February 2018

Cells & Oxidative stress

Cells & Oxidative Stress

A tale of degeneration

The effect of free radicals on animal cells


A cell is a living being, a machine made up of millions upon millions of proteins though it has no ability to express feelings, Yet it still considered to be an individual in our body. Despite that, We have trillions of cells that exceed the number of stars in a milky way!

Effect of heavy metals - click on the image to see the big picture
Our cells are attacked daily by many foreign objects even if they were not to be seen or touched like U.V light, X rays, or any type of electromagnetic waves, Cosmic rays, heavy metals (e.g., Copper, Iron, Lead, Mercury), free radicals (Reactive oxygen species or ROS) and much more..., Still! God has given our body a great immune system and repair mechanisms that can make up any damaged parts back like.


Electromagnetic waves from weakest to the strongest

All biological polymers ( long-chain molecules formed of repeating units such as starch (glucose), proteins and nucleic acids) are subject to damage from the body's own heat and from the aqueous environment inside the cell, and DNA is no exception. It was estimated that 5000 purine bases (A) and (G) are lost each day from the DNA of each human cell because heat breaks the bonds linking them to deoxyribose. Therefore, any damage to our DNA that remains stable may or may not lead to the production of infecting-causing proteins.

One of the recent and up-to-date issues the world is facing right now that is the causal-agent of many degenerative diseases are the presence of Free radicals in our body or Reactive oxygen species as a synonym.


Free radicals are compounds resulted from a homogenous cleavage meaning that the products of the reaction have an equally distributed electrons.   (refer to the following example explaining free radicals formation)
Source: https://archives.library.illinois.edu/erec/University%20Archives/1505050/Organic/Alkanes/AlkaneText/sec1-18/1-18.htm

Mode of action of Free Radicals (Oxidants)

Free radicals target mainly the cell's DNA or main proteins so that's why we are giving free radicals a number one priority and attention. They work on reacting with the DNA content disrupting it, leading to mutation and damage eventually to the production of unknown function proteins that could be lethal to our body OR it can induce cancer, degenerative disease which is yet none knows their exact origin, free radicals could be the reason for that besides other factors.

Having the cell's main proteins disrupted will alter the cell's metabolism, delaying its function and growth ultimately death.

This is what we call a state of Oxidative Stress to the cell, where it becomes prone to become cancerous, become harmful to the human body, or be the reason of a disorder considering the tissue it falls in.

Factors inducing the production of free radicals:


  • Environmental
    • Stress
    • Radiation
    • Exercise (heavy exercising)
    • Smoke ( even passive smoking )
    • Pollution
  • Inside the human body 
    • Mitochondria


Stress, most of us get stressed out from time to time but that is a normal thing in our daily lives, But chronic stress like people who continuously having arguments or overly working can affect the brain size, structure and function right down to your DNA.

Stress begins with something called the Hypothalamus Pituitary Adrenal axis (HPAA), a series of interactions between endocrine glands on the brain (pituitary gland) and the kidney (adrenaline glands) when your brain face a stressful situation, this axis is activated and secretes a hormone called cortisol which ready you for taking an action. However, high levels of cortisol in chronic stress situations is dangerous; because it increases the number and activity level of neuro-connections in the Amygdala ( a part of the brain responsible for/control fear) which leads to a deterioration in the electrical signals present in the Hippocampus ( a part of the brain that controls learning, short memory and stress control)  negatively affecting the activity of the HPA axis weakening it making it hard to control stress.

Eventually, your brain starts to shrink losing many synaptic connections altering the brain's cells and neurons which can lead to even more serious disorders like Alzheimer's or Depression.


Smoking and pollution are related to each other in the fact of cigarette's composition it has heavy metals in it like cadmium and lead, carbon mono-oxide that comes from incomplete combustions in some vehicle's exhaust polluting the air and thereby affecting our lungs and the cells inside which can lead to oxidative stress.

The waste products of mitochondria after carrying out metabolism leads to the production of free radicals ( it is not really that worrying) since our cells have its own defense systems But in our case here we are talking about a worst case scenario like having an individual who isn't taking care of his health and unfortunately the environment around him isn't clean, therefore the accumulation or the continuous production of these free radicals from the mitochondria exceeding the rate of the cells defense system will lead to mutations and serious damage.

How can our cells defend itself?

Our cells have few defense mechanism systems that use it to protect itself from free radicals, some of which are made inside the cell and the only one which is needed to be supplied by the diet we eat:

  • GSH = Glutathione 
  • SD = Superoxide Dismutase
  • CA = Catalase
  • AN = Antioxidants (Food)


Catalase is an enzyme secreted by our cells which catalyzes the breakdown of hydrogen peroxide         (free radical) to water and oxygen.
Check out the following link about the qualitative determination of catalase - https://allaboutbiologyworld.blogspot.com/2017/07/detection-of-catalase-in-potatoes.html

Superoxide Dismutase is an important antioxidant defense in nearly all living cells exposed to oxygen, it protects cells from damage induced by free radicals and has powerful anti-inflammatory activity.

It protects us from lethal free radicals like the fearsome superoxide a very active free radical, in a redox. the reaction it converts it to hydrogen peroxide which is the later converted to oxygen and water by Catalase enzyme.



On the other hand, our own phagocytic cells have the ability to secrete superoxide anion in combat against bacterial cells which is a very great methodology our body can do to fight hazards indicating that not every bad thing is bad.

Antioxidants

Antioxidants are more likely to be life guardians just like probiotics, antioxidants work on preventing any further damage to a cell by any oxidants (free radicals in our case), they can be natural or synthetic. Furthermore, antioxidants exhibit synergism, being more potent as mixtures than when used individually.

Natural antioxidants: polyphenols, carotenes, Tocopherols ( alpha, beta, gamma, and delta) and Tocotrienols (alpha, beta, gamma, and delta)

Artifical antioxidants: Butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), pyrogallol and tertiary butyl hydroxyquinone (TBHQ)

Antioxidants can be acquired from your diet means that you need to start putting colored fruits and vegetables in your diets such as Tomatoes, colored pepper, berries ( especially blueberries), honey, tea, strawberries, and wine.

Antioxidants work on by blocking the free radicals coming out from the environment or from the result of mitochondria waste-products so they are essential to every individual's body and are to be taken into consideration when you are preparing your meal or having a snack.

Glutathione

Is an amazing antioxidant that can bind to free radicals, heavy metals and any toxic compounds like cyanides due to the presence of sulfur-containing compounds ( it is composed of glutamic, cysteine and glycine amino acids) sulphur element distinct the compound in its ability to stick to many compounds that is why it is very important in our body and luckily our body can synthesize it ( there are supplements you can buy as well)


Acknowledgements

Check out the following animation on power point presentation by Doctor Dalal Askar, supervised by Professor Mohamed Mahmoud Youssef ( Food science and technology professor ) in Faculty of Agriculture, Alexandria University, Egypt.
Link - https://drive.google.com/file/d/18l0aOs6GkQEikzYGc-3ryb4vcVWmsZ4L/view

I do not own it, copyrights go to its maker - it was only used for explanatory purposes

References


  • https://www.nature.com/articles/ncomms16087
  • https://www.youtube.com/watch?v=Eh2PYQBICWs
  • https://archives.library.illinois.edu/erec/University%20Archives/1505050/Organic/Alkanes/AlkaneText/sec1-18/1-18.htm
  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1876613/
  • https://www.youtube.com/watch?v=KLrzfwCY3uY
  • Pennington Nutrition Series Healthier lives through education in nutrition and preventive medicine 2009 No. 1
  • Food Chemistry 15306
  • https://www.youtube.com/watch?v=WuyPuH9ojCE
  • https://www.youtube.com/watch?v=zrwhSkeZceg&t=563s