Safety profile of plants and phytoconstituents used in traditional medicine worldwide

Abstract Herbal remedies have long been used to treat or alleviate symptoms in several pathologies or disorders. As stated by the World Health Organization, almost 80% of Asian and African populations use herbal products against various diseases. In addition, isolation of bioactive compounds/secondary metabolites has led to introduction of several novel candidates with interesting pharmacological properties. In this overview, acute and subchronic toxicities of medicinal plants and secondary metabolites are presented, based on the main chemical constituents of the examined extracts, namely flavonoids, polyphenols, and terpenes. A literature review showed that very few studies have investigated exposure periods longer than 90 days. Extract characterization was conducted in the vast majority of the reviewed studies and toxicological evaluations were performed in both sexes only in one species (mostly in rats). Toxic effects were mostly attributed to the presence of secondary metabolites. One of the main limitations of the present review is that in most cases, it was not clearly mentioned whether the examined part of the plant was the one used by the traditional medicines of the region, and the tested doses are not directly correlated with those of real-life exposure, while the solvents/methods of extracts preparation in the reviewed studies are not necessarily the same with those employed by the traditional medicine practitioners. It seems that, despite the general conception, herbal medicine should be practiced more cautiously. On the other hand, well-designed studies are required to assess the safety profiles of such herbal products in other species and with the appropriate animal protocols, for longer periods and in combination with chemicals to which humans are daily exposed as scarce data is available on chemical interactions of herbal products with other daily consumer products.