RESUMO
Calotropis procera (Aiton) Dryand (Apocynaceae), popularly known as milkweed, has been traditionally used to treat diseases particularly associated with gastric disorders, skin disease and inflammatory processes. The present study aimed to review the current scientific evidence regarding the pharmacological effects of C. procera extracted phytochemicals and possible research opportunities as complementary and alternative medicine. Scientific publications were searched in various electronic databases (PubMed, Scopus, Web of Science, Google Scholar, Springer, Wiley, and Mendeley) using the following search terms: Calotropis procera, medicinal plants, toxicity, phytochemical characterization, and biological effects. Collected data showed that cardenolides, steroid glycoside and flavonoids are the main classes of phytochemicals identified in C. procera latex and leaves. In addition, lignans, terpenes, coumarins, and phenolic acids have been reported. These metabolites have been correlated with their biological activities, including mainly antioxidant, anti-inflammatory, antitumoral, hypoglycemic, gastric protective, anti-microbial, insecticide, anti-fungal, anti-parasitic, among others. However, some of the studies were carried out with only a single dose or with a high dose not achievable under physiological conditions. Therefore, the validity of C. procera biological activity may be questionable. Not less important to highlight are the risks associated with its use and the possibility of accumulation of heavy metals that can be toxic. Furthermore, there are no clinical trials with C. procera to date. In conclusion, the need of bioassayguided isolation of bioactive compounds, bioavailability and efficacy, as well as pharmacological and toxicity studies, are needed using in vivo models and clinical trials in order to support the traditionally claimed health benefits.