Isolation of xanthones from adventitious roots of St. John's Wort (Hypericum perforatum L.) and their antioxidant and cytotoxic activities

In this phytochemical study, 5 xanthones, 1,3,5,6-tetrahydroxyxanthone [1], 1,5,6-trihydroxy-3-methoxyxanthone [2], ferrxanthone [3], brasilixanthone B [4], and neolancerin [5] were isolated from adventitious roots of St. John's wort (Hypericum perforatum L.). Compound 1-5 were evaluated for antioxidant activities using the intracellular reactive oxygen species (ROS) radical scavenging 2′,7′-dichlorfluorescein-diacetate (DCFDA) assay and for cytotoxic activity against the HL-60 human promyelocytic leukemia cells. Among them, compound 1-4 exhibited scavenging activity with inhibition values of 27.4-33.2% at 10 μM; compound 1, 2, and 4 reduced the viability of HL-60 cells significantly, with IC₅₀ values of 31.5, 28.9, and 27.7 μM, respectively.