(αR,βR)-α,β-Bis(4-hydroxy-3-methoxyphenyl)butyrolactone, also known as (-)-arctigenin, is a lignan compound isolated from the traditional medicinal plant *Arctium lappa* (greater burdock). It features a butyrolactone core substituted with two guaiacyl (4-hydroxy-3-methoxyphenyl) groups in a specific (αR,βR) stereochemical configuration. This compound is a key bioactive constituent and has been extensively studied for its diverse pharmacological properties. Research indicates significant anti-inflammatory, antiviral (e.g., against influenza A virus and HIV-1), and antitumor activities. Its mechanisms of action are complex and may involve modulation of signaling pathways such as NF-κB and STAT3, as well as induction of autophagy. Consequently, (-)-arctigenin serves as a valuable reference standard, a lead compound for drug discovery, and a tool for investigating biological mechanisms related to inflammation and cancer. As a natural product, it is primarily sourced from plant extracts or obtained via semi-synthesis. Its safety profile is generally favorable, but specific toxicological data should be consulted for research or potential therapeutic applications.