Preliminary studies have shown a way to reduce cell damage and blunt the effect of one of the factors responsible for the onset of several diseases such as cancer, diabetes, cardiovascular diseases and ageing.
Reactive oxygen species, which are produced continuously in the body during cellular metabolism and responsible for cellular damage, are removed by naturally occurring antioxidants. However, the scavenging system fails when the amount of ROS produced is elevated. The most prevalent reactive oxygen species is hydrogen peroxide; excess amount of hydrogen peroxide can damage the cells the most.
By using vanadia nanowires, a team of researchers at the Indian Institute of Science (IISc), Bangalore was able to successfully remove any excess reactive oxygen species produced. The vanadia nanowires functionally mimic an antioxidant enzyme (glutathione peroxidase) produced by the body to scavenge hydrogen peroxide. Glutathione peroxidase is one of the two enzymes that control the level of hydrogen peroxide inside a cell.
The results of the study were published recently in the journal Nature Communications .
Unlike the nano form, the bulk, foam and complex forms of vanadium do the exact opposite. They produce more reactive oxygen species thereby negatively affecting the viability of cells.
In a nano form, vanadium is able to reduce hydrogen peroxide without changing the oxidation state of the metal, which is unusual for a metal ion.
“If the metal changes its oxidation state then vanadium can produce reactive oxygen species, which is what happens when vanadium is in a bulk and foam form,” said Prof. Govindasamy Mugesh from the Department of Inorganic and Physical Chemistry, IISc. He is one of the corresponding authors of the paper.
The nanowires proved successful as an ROS scavenger as they reacted with hydrogen peroxide to produce water. “Hydrogen peroxide reacts with vanadia on the surface of the nanowires, and once water is produced, the next molecule of hydrogen peroxide binds to the nanowire surface. So vanadia is able to continuously scavenge hydrogen peroxide without getting deactivated,” Prof. Mugesh said.
The efficiency of the nanowires as a scavenger was tested using hydrogen peroxide in a test tube and inside cells; cell lines were used for in vitro studies. “The scavenging is 100 per cent when hydrogen peroxide is used. But inside a cell, vanadia maintains optimum levels of reactive oxygen species,” Prof. Mugesh said.
The scavenging capacity inside a cell was significant even after 24 hours.
Apparently, the inability to completely remove hydrogen peroxide turns out to be beneficial.
“Optimum removal ensures that other biological functions remain unaffected by vanadia. If it scavenges all the hydrogen peroxide then it may block certain functions of the cell,” he explained.
According to Prof. Patrick D’Silva, Department of Biochemistry, IISc, the vanadia nanowires work in parallel to and in conjunction with the normal cellular antioxidant system. Prof. D’Silva is the other corresponding author of the paper.
Though the number of nanowires that get into a cell cannot be controlled, the amount of vanadia nanowires used is very small — in parts per million.
As vanadium is found in trace quantity in human body, its antioxidant potential inside cells was investigated. Since its harmful effects when in bulk and foam form were already known, the researchers studied its properties at nanoscale. “We tested a few other metal oxide nanoparticles but they did not show such antioxidant effect,” Prof. Mugesh said.
They have not studied how the nanowires get into a cell but know that they cannot stay inside a cell for over a day or two.
Its potential as an antioxidant will be known only when animal and human clinical trials are carried out.