Growing up in Tanzania, I knew that fruit trees were useful. Climbing a mango tree to pick a fruit was a common thing to do when I was hungry, even though at times there were unintended consequences. My failure to resist consuming unripened fruit, for example, caused my stomach to hurt. With such incidents becoming frequent, it was helpful to learn from my mother that consuming the leaves of a particular plant helped alleviate my stomach pain.
This lesson helped me appreciate the medicinal value of plants. However, I also witnessed my family and neighboring farmers clearing the land by slashing and burning unwanted trees and shrubs, seemingly unaware of their medicinal value, to create space for food crops.
But this lack of appreciation for the medicinal value of plants extends beyond my childhood community. As fires continue to burn in the Amazon and land is cleared for agriculture, most of the concerns have focused on the drop in global oxygen production if swaths of the forests disappear. But I’m also worried about the loss of potential medicines that are plentiful in forests and have not yet been discovered. Plants and humans also share many genes, so it may be possible to test various medicines in plants, providing a new strategy for drug testing.
As a plant physiologist, I am interested in plant biodiversity because of the potential to develop more resilient and nutritious crops. I am also interested in plant biodiversity because of its contribution to human health. About 80% of the world population relies on compounds derived from plants for medicines to treat various ailments, such as malaria and cancer, and to suppress pain.
Future medicines may come from plants
One of the greatest challenges in fighting diseases is the emergence of drug resistance that renders treatment ineffective. Physicians have observed drug resistance in the fight against malaria, cancer, tuberculosis and fungal infections. It is likely that drug resistance will emerge with other diseases, forcing researchers to find new medicines.
Plants are a rich source of new and diverse compounds that may prove to have medicinal properties or serve as building blocks for new drugs. And, as tropical rainforests are the largest reservoir of diverse species of plants, preserving biodiversity in tropical forests is important to ensure the supply of medicines of the future.
Plants and new cholesterol-lowering medicines
The goal of my own research is to understand how plants control the production of biochemical compounds called sterols. Humans produce one sterol, called cholesterol, which has functions including formation of testosterone and progesterone – hormones essential for normal body function. By contrast, plants produce a diverse array of sterols, including sitosterol, stigmasterol, campesterol, and cholesterol. These sterols are used for plant growth and defense against stress but also serve as precursors to medicinal compounds such as those found in the Indian Ayurvedic medicinal plant, ashwagandha.