Nature is the best source of anticancer drugs: Indexing natural products for their anticancer bioactivity

A Review on Onychine and its Analogs: Synthesis and Biological Activity

BACKGROUND

Onychine is a 4-azafluorenone alkaloid isolated from the Annonaceae family, in low concentrations. Onychine and its analogs exhibit a wide range of pharmacological activities such as antifungal, antibacterial, anticancer, and antimalarial. Because of the high bioactivity of some 4-azafluorenone derivatives, several synthetic methods have been developed for their procurement.

OBJECTIVE

Considering the importance of these alkaloids, we aim to present the main synthetic approaches to onychines and its derivatives and the biological activity of some 4-azafluorenones.

METHODS

The most prominent methodologies for the synthesis of onychines were reviewed.

RESULTS

In this work, we cover many synthetic approaches for the synthesis of onychine and 4-azafluorenone derivatives including intramolecular cyclizations, multicomponent reactions, microwave-assisted multicomponent reactions, Diels-alder reactions, among others. Moreover, we also review the biological activity of 4-azafluorenones.

CONCLUSION

4-azafluorenones have risen as prominent structures in medicinal chemistry; however, most of the time, access to new derivatives involves toxic catalysts, harsh reaction conditions, and long-step procedures. Therefore, the development of new synthetic routes with more operational simplicity, simple purification procedure, good yields, and low environmental impact, is desirable.