Plant metabolites – that is, substances generated by the metabolic processes of plants – are a true mine for medicine : it is estimated that about half of modern drugs are derived from these compounds. For example, one of the most widely used anticancer drugs is placlitaxel, which comes from the bark of the Pacific yew.
The different species of plants produce about 200,000 specialized metabolites, but it is not easy to identify them and obtain the amount necessary for them to produce therapeutic effects. And that is the challenge of the scientists. They discovered a promising substance against type 2 diabetes, a disease suffered by more than five million Spaniards and 320 million people around the world. It is a metabolite produced by a well-known garden plant, of the genus Crocosmia , characterized by its fan-shaped leaves and bright orange flowers .
Lower glucose without side effects
But what is special about this plant compound? One of the drugs most used to treat diabetes, both type 1 and type 2, are alpha-glucosidase inhibitors , which decrease the absorption of carbohydrates in the digestive system (and, consequently, the levels of blood glucose) after meals. The problem is that the inhibition of alpha-glucosidases – a type of enzymes – also produces unpleasant side effects: diarrhea, flatulence and abdominal pain.
Ten years ago, and after analyzing 30,000 extracts of plants and other organisms, scientists finally came up with a compound that had the same inhibitory effects without causing intestinal discomfort , and they found it in the bulbs of the species Crocosmia × crocosmiiflora .
However, there was still a long way to go before it could be dispensed in pharmacies. Baptized as montbretin A (MbA) –in the Anglo-Saxon world, crocosmia is known as montbretia- , the metabolite of the ornamental plant cannot be produced in large quantities without knowing the highly complex biochemical mechanisms and the genes involved in its biosynthesis.
Now, scientists from the University of British Columbia and the Canadian Glycomics Network research center have just announced in the journal The Plant Cell that they have found the first three intermediate metabolites in the biosynthesis of MbA, including a product called mini- MbA, which they have in turn associated with the activity of four enzymes. As the Canadian experts have verified, mini-MbA also has the desired inhibitory effect on the intestinal absorption of carbohydrates . In addition, and this is very important in view of their future industrial production, scientists have cloned the genes of these enzymes so that a wild tobacco plant makes mini-MbA itself.
Más información: Montbretin A Biosynthesis. Sandra Irmisch, Seohyun Jo, Christopher R Roach, Sharon Jancsik, Macaire M.S. Yuen, Lina Madilao, Mark Mark O’Neil-Johnson, Russell Williams, Stephen G Withers, Joerg Bohlmann. Plant Cell, jul. 2018, DOI: https://doi.org/10.1105/tpc.18.00406
