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Our essential elements

The United Nations declared 2019 the Year of the Periodic Table to commemorate the 150th anniversary of the establishment of the periodic table by Dmitry Ivanovich Mendeleev. At the time, only 63 elements had been discovered and based on the periodicity of their physical and chemical properties, they were arranged in the form of a table.

Today, there are 118 elements and while many of us learnt about (and have likely forgotten) the basic chemistry of the table at school, the hidden stories and uses for chemical elements are less known and unexplored.

Professor Wolfgang Maret is the only professor of Metallomics (the interdisciplinary field of integrating metal chemistry and biology) in the world. We spoke with Professor Maret about his favourite element zinc to research and why a focus on the elements is a wide-open field with significant impact on human health.

“The perception that there are a select few ‘elements of life’ is wrong and that the majority of the 118 elements (and counting) have a role to play in giving us the complex world we live in and that it includes even synthetic elements such as technetium, which is used in nuclear medicine to image the heart and other organs.”– Professor Maret

We need zinc to think

In biology, zinc (Zn), specifically the Zn2+ ion, is hugely important although people generally know very little about it. It exists in the same quantity as iron in the human body. Zn plays an important role in all our cells and affects growth, hormone action, the immune system, the brain and the development and progression of chronic diseases such as diabetes and cancer.

It is estimated that over one billion people are at risk, or are, Zn-deficient, commonly caused by reduced dietary intake. A Zn deficiency slows down wound healing and causes appetite loss, hair loss, fertility problems, and susceptibility to infection, to name a few. Infants who are Zn-deficient are at particular risk of infections and can have stunted growth. 

“King’s has a place in the history of using Zinc in Medicine. In the 1970’s Guy’s Alumni, Dr E.J. Moynahan, discovered that the lives of patients suffering from the specific dermatitis disorder, Acrodermatitis enteropathica, can be saved by a life-long treatment with Zn supplementation.”

Chromium Pandemonium

Chromium (Cr) has a wide range of biological properties. It is sometimes considered an essential micronutrient in one form (Cr(III)) but highly toxic in another (Cr(VI)).

“Chromium (as Cr(III)) is an essential micronutrient that increases the function of insulin. Chromium picolinate is sold as a nutritional supplement but its benefits and safety are controversial”.

Cr(VI) is a known carcinogen as it is taken up in cells and causes the DNA strands to break and is widely accepted as a cause for lung cancer. The most notable exposure to Cr(VI) is the Hinkley groundwater contamination where Cr(VI)-tainted water was pumped into wastewater ponds in the town of Hinkley, California causing several health implications for the residents. This contamination event is depicted in the film Erin Brockovich. 

Lithium for Longevity

Lithium was in the headlines in 2019 as The Nobel Prize for Chemistry was awarded to Goodenough, Whittingham and Yoshino for the development of lithium-ion batteries. This lightweight, rechargeable and powerful battery is now used in everything from mobile phones to laptops and electric vehicles. It can also store significant amounts of energy from solar and wind power, making possible a fossil fuel-free society.

“Lithium is also significant in biological chemistry. Lithium salts are used to treat some mood disorders and is suggested to increase longevity. In a recent article in the Proceedings of the National Academy of Sciences USA, it was one of three experimental drugs that increased the life span of the fruit fly, with epidemiological evidence for humans existing as well.”

All elements are ‘elements of life’

There is a common idea that there are around 20 chemical elements that are nutritionally essential for humans. However, many additional ones have beneficial or pharmacological effects, and virtually all-natural elements can be measured in our bodies. 

“It is most remarkable that some apparently non-essential elements are present at higher concentrations than some essential ones. The consequences are largely unknown. And then there are toxic elements such as lead, cadmium and mercury.  There is a fine line between essential and toxic as the essential elements also become toxic at higher concentrations.”– Professor Maret

Too much of one element is disastrous, for example, mercury poisoning affects the entire central nervous system and leads to personality changes and memory loss. Occupational exposure to mercury such as old English felt-hatmakers gave rise to the expression ‘mad as a hatter’. However, some elements have medicinal applications, for example, platinum compounds are the most widely used drugs in chemotherapy to treat some cancer patients. 

Elements in the future

Additional elements are used in everyday life and cause new problems. For example, smartphones contain 66 chemical elements. In 2016, 44.7 million tons of electronic waste were produced worldwide posing yet unmet challenges for environmental toxicology of soil, water and air.

Metallomics overcomes the traditional view of relating biochemistry only to organic chemistry.  It discusses the functions of metal ions in the biological context of their environments in organisms.  A less well-established term “elementomics” includes non-metals.  Among those, bromine was discovered as an essential element for humans only in 2014, foreshadowing that even in 2020 we may not know all the essential elements.

Over the last couple of years, a unique core facility has been developed at King’s. In the London Metallomics Facility, elements can be analysed and imaged in tissues by mass spectrometry and other techniques.  The Facility is being supported by the Wellcome Trust and King’s and a King’s Together Strategic Award.  A special 1-day symposium “Metal fingerprints in normal cell states and disease” will be held at King’s on the 6th of May to highlight recent achievements from the Facility.

Professor Wolfgang Maret is a Professor of Metallomics in the Department of Nutritional Sciences at King’s and teaches Biochemistry. He obtained his MSc in chemistry and his PhD in Natural Sciences in Germany and then received most of his scientific training (25+ years) in the US.  For his contributions to zinc biology, Professor Maret was awarded the Christopher J. Frederickson prize of the International Society for Zinc in Biology in Kyoto, Japan, in September.

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