Scientists unravel how nithyakalyani makes potent cancer drug
Business Line
TV JAYAN, May 15, 2018
Identify
‘missing link’ in biosynthesis of vinblastine
An ornamental plant commonly found in India and
elsewhere may emerge as the source of one of the largest-selling anti-cancer
drugs, vinblastine, with a team of researchers from the UK helping find missing
genes involved in the biosynthesis of the chemical.
Sixty years ago, two Canadian scientists studying
the anti-diabetic properties of the Madagascar periwinkle, known as nithyakalyani in Tamil and sadabahar in Hindi, stumbled
upon its anti-cancer properties. This led to the discovery of vinblastine and
vincristine, used to treat various cancers.
Six-decade mystery
Since then, many scientific groups have worked
tirelessly to unravel the cellular mechanisms involved in the production of
these valuable chemical compounds. They met with only partial success, as many
enzymes involved in their biosynthesis were still missing. The complex chemical
mechanisms that the plant uses to produce vinblastine remained a puzzle for
nearly six decades.
Now, a research team led by Sarah O’Connor,
biological chemist at John Innes Centre (JIC) in Norwich, UK, has identified
the missing steps in the biosynthesis of vinblastine, opening up a potential
avenue for rapid synthesis of the compound.
“Vinblastine is one of the of the most structurally
complex medicinally active natural products in plants...which is why so many
people in the past 60 years have been trying to get where we have got to in
this study. I cannot believe we are finally here,” said O’Connor in a
statement.
The JIC scientist, who has been working on the
periwinkle plant for over 15 years, is hopeful they can now try to increase the
amount of vinblastine produced — either in the plant itself, or by placing
synthetic genes in hosts such as yeast or other plants. Scientists from
François Rabelais University, Tours, France, also participated in the study.
Mass production
Producing 1 gram of vinblastine requires about 500
kg of dried periwinkle leaves, so the drug is currently synthesised chemically.
The reconstitution of vinblastine biosynthesis, following the discovery of the
‘missing steps’, could provide an additional source of this valuable drug. It
is currently used in the treatment of cancers of the lymphomas and bladder,
breast and lung.
The scientists, whose work appeared recently
in Science journal,
were able to identify the final missing genes in the vinblastine pathway.
Altogether, 31 steps are involved in the production of vinblastine in the
periwinkle plant, whose attractive white-and-pink flowers make it a garden
favourite worldwide.
O’Çonnor noted that over the decades, a number of
research groups around the world had contributed to the elucidation of the
pathway.
The scientists are now eyeing the production of
microgram quantities of the drug, establishing the viability of the
biosynthesis as a mode of producing commercial vinblastine.
Reference:-https://www.thehindubusinessline.com/news/scientists-unravel-how-nithyakalyani-makes-potent-cancer-drug/article23896299.ece
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