Two new anthraquinones with antiviral activities from the barks of Morinda citrifolia (Noni)

Abstract Two new anthraquinones, 1,3-dihydroxy-5-methoxy-6-methoxymethyl-2-methyl-9,10-anthraquinone ( 1 ) and 1,3-dihydroxy-5-methoxy-2,6-bismethoxymethyl-9,10-anthraquinone ( 2 ), together with ten known anthraquinone derivatives ( 3 – 12 ), three coumarin derivatives ( 13 – 15 ), and 6-gingerol ( 16 ) were isolated from the barks of Morinda citrifolia (Noni) collected in the Yongxing island of Xisha. The structures of compounds ( 1–16 ) were determined on the basis of extensive spectroscopic analyses, as well as by comparison with literature reports. The new compounds 1 and 2 were tested for their antiviral, cytotoxic, and antibacterial activities. In the primary bioassays, compounds 1 and 2 displayed weak anti-H1N1 activity with IC 50 values of 66.1 and 10.5 μM, respectively. In addition, compound 2 showed weak anti-H3N2 activity with IC 50 value of 11.5 μM, and had weak antimicrobial activity against Staphylococcus aureus with MIC value of 24.5 μM.