Cancer is a leading cause of death worldwide, and though treatments for the disease are available, they can damage healthy cells or have severe side-effects on the patients. Around 19 million new cases of cancer were reported in 2020. In the same year, the disease claimed 10 million lives. Since current cancer treatments can harm patients in different ways, scientists are searching for new, more targeted cancer drugs, and traditional medicines. A team of Polish researchers have analysed some compounds present in potatoes and tomatoes to demonstrate their potential to be used in cancer drugs.
The study, led by Magdalena Winkiel at Adam Mickiewicz University in Poland, was published on December 7 in the journal Frontiers in Pharmacology. The compounds reviewed by the researchers are bioactive compounds known as glycoalkaloids.
What is a bioactive compound?
A bioactive compound is a type of chemical found in small amounts in plants and certain foods such as fruits, vegetables, whole grains, nuts and oils, and performs actions in the body that may promote good health.
What are glycoalkaloids?
Glycoalkaloids are nitrogen-containing bioactive compounds found in the Solanaceae family of plants, which includes tomatoes, potatoes, peppers and aubergines.
In a statement released by Frontiers, Winkiel said scientists around the world are still searching for the drugs which will be lethal to cancer cells but at the same time safe for healthy cells. She added that it is not easy despite the advances in medicine and powerful development of modern treatment techniques.
Winkiel explained that this is why it might be worth going back to medicinal plants that were used years ago with success in the treatment of various ailments. She said she believes it is worth re-examining the properties of these medicinal plants and perhaps rediscovering their potential.
What are the five glycoalkaloids studied as part of the research?
The researchers studied five glycoalkaloids, namely solanine, solasonine, tomatine, chaconine and solamargine. These compounds are found in crude extracts of the Solanaceae family of plants, also known as nightshades. Many plants belonging to this family are toxic because of the alkaloids they produce as a defence against animals who attempt to eat the plants.
How can poison be changed into medicine?
However, if the poison is used in the correct dose, it can be changed into a medicine. The study states that once scientists find a safe therapeutic dose for alkaloids, they can be used as powerful clinical tools.
How do glycoalkaloids have potential for cancer treatments?
Since glycoalkaloids inhibit cancer cell growth, they may promote cancer cell death. Inhibition of cancer cell growth and promotion of cancer cell death are the key target areas for controlling the disease and improving patient prognosis. Therefore, glycoalkaloids have huge potential for future treatments.
In silico studies, which refer to experimentation performed by computers, suggest that glycoalkaloids are not toxic and do not risk damaging DNA or causing future tumours. However, glycoalkaloids may affect the reproductive system.
Winkiel said even if the anticancer drugs used nowadays cannot be replaced, combined therapy might increase the effectiveness of this treatment.
Potential functions of different glycoalkaloids in treating cancer
In order to determine which glycoalkaloids are safe and promising enough to test in humans, in-vitro and model animal studies must be conducted. Solanine and chaconine are glycoalkaloids derived from potatoes, their levels inside the vegetable depending on the cultivar of the potato and the light and temperature conditions the potatoes are exposed to.
According to the study, solanine prevents some potentially carcinogenic chemicals from transforming into carcinogens in the body, and inhibits metastasis, a biological process in which cancer cells break away from where they first formed, travel through the blood or lymph system, and form a new tumour in other tissues or organs of the body. When used at therapeutic doses, solanine can kill leukaemia cells, studies on a particular type of leukaemia cells showed.
Solamargine is mostly found in aubergines, and is one of several glycoalkaloids that could be used as complementary treatment. This is because it targets cancer stem cells which are believed to play a significant role in cancer drug resistance. Solamargine also prevents liver cancer cells from reproducing.
Solasonine is found in several plants from the nightshade family, and is believed to attack cancer stem cells. Tomatine, found in tomatoes, supports the body’s regulation of the cell cycle so that it can kill cancer cells. Therefore, tomatoes also offer potential for future medicine.
Nanotechnology can be used to develop cancer drugs with glycoalkaloids
In order to determine how this in-vitro potential can be turned into practical medicine, further research will be needed. High temperature processing improves glycoalkaloid properties, and nanoparticles have recently been found to improve transmission of glycoalkaloids to cancer cells, boosting drug delivery, suggesting that nanotechnology and high temperature processing can be incorporated in the cancer drug development process using glycoalkaloids.
However, before cancer drugs straight out of the vegetable patch are used on patients, scientists need to better understand the mechanisms of action of glycoalkaloids, and scrutinise the potential safety concerns.