## Plants in medicine

The search for medicinal effects of plants has been a tradition since ancient times. The oldest records of using plants as medicine date back to the Mesopotamian period (2600 BC). Many of these natural substances (morphine, cocaine, tetrahydrocannabinol, and others) were used by folk healers, shamans and later by doctors. However, adverse effects of specific metabolites on human health, including frequent overdoses, mental disorders, and strong addiction, began to appear and were therefore more deeply studied. Ultimately, the use of many of these natural products was abandoned and replaced with synthetic alternatives. Secondary metabolites have evolved to interact with various molecular targets, thus affecting cells, tissues, and their physiological functions. In many cases, they can even resemble human metabolites, ligands, hormones, signalling molecules, or neurotransmitters, which can have a beneficial therapeutic effect on humans. Today, using plants and their metabolites or synthetic analogues is noteworthy in various areas of medicine.