Beta-Carboline Alkaloids: An Integrative Review of Chemistry, Structure–Activity Relationships and Pharmacological Significance

Abstract

Beta-Carbolines are a major class of indole-based alkaloids found in plants, marine organisms, insects, mammals, and various foods. Their tricyclic structure and variable saturation levels give rise to diverse biological activities, including anti-inflammatory, antimicrobial, antitumor, antioxidant, neuroactive, and cytotoxic effects. Key compounds such as harmine, harmaline, and harman have been widely studied for their therapeutic potential. The Pictet–Spengler reaction serves as the primary synthetic pathway, enabling structural modifications that enhance activity. This review highlights the structural types, synthesis, isolation methods, structure–activity relationships, and pharmacological significance of β-carbolines, emphasizing their growing importance in drug discovery.