Narciclasine is an isocarbostyril alkaloid, a natural product primarily isolated from plants of the Amaryllidaceae family, such as daffodils (*Narcissus* species). It is characterized by a phenanthridine core structure. Its most prominent and extensively researched application is in the field of oncology. Narciclasine exhibits potent and selective antitumor activity against a wide range of human cancer cell lines, including glioblastoma, colon, breast, and lung cancers. The mechanism of action involves the inhibition of protein synthesis by interfering with the peptidyl transferase center of the eukaryotic ribosome, leading to apoptosis in cancer cells. This has positioned it as a promising lead compound for the development of novel anticancer therapeutics. Beyond its direct antitumor effects, narciclasine has also been investigated for its anti-inflammatory and antiviral properties. Due to its natural origin and significant biological activity, it serves as a valuable reference standard and a key molecule in pharmacological and phytochemical research.