Question

Give two examples of deadly, natural poisons which have been repurposed as therapeutic medicines. How do they work? What allowed these poisons to be used safely to help people?

Answer 1

1. Exenatide ( type II diabetes mellitus drug)- It is used to lower blood sugar and to increase the body’s production of insulin. The marketed drug is a synthetic version of exendin-4, a hormone found in the saliva of Gila monsters, large venomous lizards found in the southwestern U.S. and northwestern Mexico. It works as a functional analog of the human incretin Glucagon-Like Peptide-1 (GLP-1) (incretins enhance glucose-dependent insulin secretion and exhibit other antihyperglycemic actions). Also, GLP-1 system increases insulin secretion only in the presence of elevated plasma glucose levels, avoiding inappropriately high insulin levels during fasting.

2. Taxol or Paclitaxel from yew plant Taxus brevifolia- Also knnown as the Pacific yew, the bark of the plant contains a toxic ingredient that is harnessed on a cellular level to inhibit the progress of some cancers. A derived compound known as paclitaxel is effective in the treatment of breast, lung, and other cancers, as well as AIDS-related Kaposi’s sarcoma. It has also been found useful in preventing a re-narrowing of coronary arteries in stent recipients. The drug is a prime example of the use of poisons in the service of medicine and therapeutically. All species of yew contain highly poisonous alkaloids known as taxanes where all parts of the tree except the arils contain the alkaloid. The arils are edible and sweet, but the seed is dangerously poisonous. The human stomach can break down the seed coat and release these taxanes into the body which can have fatal results( 'berries' are eaten after removing the seeds).

Paclitaxel affects cytoskeleton and prevents microtubule disassembly and detachment of chromomsome centromeres from spindle. Resulting in defected cell division, it blocks the progression of mitosis and prolonged activation of the mitotic checkpoint triggers apoptosis or reversion to the G-phase of the cell cycle without cell division. It is therfore used to treat cancer cells.

These substances have poisonous properties in their natural environment ( body of respective organism as a defense mechanism) but are used in therapeutic causes by either altering their properties ( via synthetic analog production) or by using very small doses to treat the disease without reaching the lethal dose. Thus, when the have been apprved by the FDA after thorough research analysis, they are allowed and licensed to be sold for safe use to help people.