Scientists have discovered the natural drug precursors for a number of medicines by observing how indigenous cultures use plants to treat diseases. Many pharmaceuticals sold today, such as the anticancer drug Taxol and the analgesic Aspirin, had their chemistry derived from plant sources.
Spenser Reed ’14, a double major in food science and nutritional sciences, joined the search for natural pharmaceuticals this summer at the Cornell Biodiversity Laboratory in the Dominican Republic. In his research, Reed focused on evaluating the bioactive properties, or those that affect human cells, of plants used by indigenous groups to treat type 1 diabetes.
Type 1 diabetes is a chronic autoimmune disease caused by the body’s destruction of its own pancreatic beta cells, which are responsible for producing insulin. A type 1 diabetic’s impaired production of insulin, a hormone that is critical in regulating blood glucose levels, results in a reduced ability to maintain a normal blood glucose range of approximately 80-130 milligrams per deciliter.
Reed traveled to Punta Cana as a part of the Minority Health International Research and Training program, which aims to reduce health burdens on underserved populations, under the tutelage of Prof. Manuel Aregullin, plant biology, molecular biology and genetics. There he spent the summer doing fieldwork and learning about natural product synthesis in the classroom.
Reed described his work as “prospecting” for plants that could be used in drugs, and taking a closer look at the chemistry behind what makes these plant remedies effective.
“It never ceases to amaze me to read papers where the authors are able to find cytotoxic and antimutagenic properties in plants that the native people have been using for thousands of years,” he said. “We’re just validating it. These people have discovered it.”
After conducting a literature search regarding Dominican medicinal plant use and speaking with indigenous healers in Punta Cana, Reed selected five plants to survey for anti-diabetic properties. One of his choices –– the avocado leaf –– particularly stood out because it was rumored to be helpful in treating diabetes when brewed in a tea.
“As a type 1 diabetic myself for 15 years, my eyes just opened when I heard this,” Reed said. “After I searched the literature and found that nothing about [the] avocado leaf had been thoroughly investigated, I thought how interesting it could be to study [the] avocado. Perhaps we’re missing the chemistry behind it.”
To determine the bioactivity of his plant selections, Reed conducted a variety of in vitro tests after extracting compounds from the leaves. His trials included an antibiotic test; an allelopathy test that measures the ability of extracted compounds to influence growth and metabolism; and a toxicity test. The avocado leaf performed the best of any of the plants on these preliminary procedures, Reed said.
Reed even performed an oral glucose tolerance test on himself. His experiment involved drinking a sugar water solution and then a tea made from one of the plants of interest, prepared as the Dominican natives would. He monitored his postprandial, or after-eating, blood glucose levels every 30 minutes to determine the effects of the five plants.
The results for avocado leaf came in positive.
“None of the other plants had any effect except for the avocado leaf, which was able to keep my postprandial glucose range very tight, not above 150 milligrams per deciliter. I struggle with my blood glucose level going up to 300 milligrams per deciliter after eating, which can be disastrous for one’s health,” Reed said.
Currently, the only long-term treatment for type 1 diabetes is injection of insulin into the body to compensate for the body’s inability to produce the hormone on its own. The efficacy of the avocado leaf and other medicinal plants with anti-diabetic effects have only been hypothesized.
“They are potent antioxidants, and may be able, through a series of biochemical pathways, to influence blood sugar regulation,” Reed said.
Another possible explanation for their effectiveness, according to Reed, is that they act as insulin secretagogues, which are products that are able to stimulate the body’s damaged insulin-producing machinery.
Reed will continue studying the anti-diabetic properties of plants in Aregullin’s lab this semester, but this time he will be looking for bioactive properties of a Peruvian fern.
“Once we find out that a plant has some biological properties and we elucidate the chemistry, we can isolate individual chemicals and tie them to certain biological effects,” he said.
Reed hopes his work will eventually lead to an animal model or a cell-based assay.
Reed’s next step is to move from isolating and characterizing the bioactive chemicals in traditional plant remedies to testing their effects in live organisms.
“That would really be the pinnacle for me, both as a student and as a diabetic,” he said.
Original Author: Jacqueline Carozza