Harmala alkaloids, also known as harmaline or harmalline, are a class of naturally occurring alkaloid compounds derived from various species of plants in the family Solanaceae. These alkaloids are primarily found in shrubs such as Peganum harmala (commonly called Syrian rue or shayeteh) and related species. Harmala alkaloids have been studied for their diverse biological activities, including effects on neurotransmitters and enzyme inhibition. Notably, they act as reversible inhibitors of the enzyme monoamine oxidase (MAO), particularly MAO-B. This property has led to research into potential therapeutic applications, such as in the treatment of Parkinson's disease and certain psychiatric disorders. In traditional medicine, harmala alkaloids have been used for various purposes, including as a remedy for digestive issues and as an anti-parasitic agent. However, their use is limited due to toxic side effects and legal restrictions in many countries. Research on these compounds continues, focusing on understanding their mechanisms of action and exploring potential therapeutic applications while ensuring safety and efficacy.