You will be shown biomedical passages and your task is to the answer the provided question. Provide a concise and accurate response and do not include any additional text in the response other than the answer.

Question: Which one was the first chromone in clinical use?

Context: The first chromone in clinical use, khellin, was extracted from the seeds of the plant Ammi visnaga, and had been used for centuries as a diuretic and as a smooth muscle relaxant.
Khellin