Structural Elucidation of Some Flavonoids Isolated from <i>Litsea costalis</i> and Their Biological Evaluation

Litsea costalis is a well-known medicinal plant in tropical and subtropical areas. Four significant flavonoids were extracted and characterized from the plant leaf extract. One component was discovered for the first time in flavonoid chemistry, flavan-4-ol, (3′, 4′-methylenedioxy-5,7-dimethoxy chroman-4-ol). Three flavonoids were discovered for the first time in this plant. The detected products are (+)-pinostrobin, (+)-onysilin, and (+)-pinocembrin. The fourth component was characterized for the first time in this plant and introduced in flavonoid chemistry. The extracted component antioxidant activity against DPPH indicated an IC50 value of around 30 µg/mL.