Flavonoids from Rabdosia rubescens exert anti-inflammatory and growth inhibitory effect against human leukemia HL-60 cells

Eight flavonoids, 5,8,4′-trihydroxy-6,7,3′-trimethoxyflavone (1), 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone (2), nodifloretin (3), pedalitin, (4), penduletin (5), cirsiliol (6), luteolin (7), and quercetin (8), were isolated from the aerial parts of Rabdosia rubescens. Structures were established on the basis of 1D and 2D NMR and HRMS data. All flavonoids were tested for cytotoxicity in a small panel of cancer cell lines (Hep G2, COLO 205, MCF-7, and HL-60) and anti-inflammatory activity in LPS-treated RAW264.7 macrophage. Among them, compounds (1) and (4) were modestly active for inhibiting nitrite production in macrophage. Compound (2) was demonstrated to be selectively active against HL-60 cells with an IC₅₀ of 7.55 μM. This value is comparable to the IC₅₀ 4.64 μM of doxorubicin, the positive control used in this investigation.