547.972The Chinese plant Rosa rugosa Thunb. is known to be an antioxidant and a good natural source of antioxidants [1]. Therefore, we investigated the chemical composition of flowers of R. rugosa Thunb. collected in Xinjiang Autonomous region (PRC).Dry raw material (5 kg) was extracted with ethanol (70%). The alcohol extract was concentrated in vacuo and fractionated over a column packed with large-pore ion-exchange resin with elution by water and aqueous alcohol (25 and 50%). The alcohol fractions were rechromatographed over polyamide, silica gel, and Sephadex LH-20 to afford 1-9, of which four were kaempferol flavonoids, four were quercetin flavonoids, and one was a phenylethylglycoside. The aqueous fraction was extracted with ethylacetate and chromatographed over silica gel to isolate two acidic phenolic compounds 10 and 11.Kaempferol (1), yellow powder (acetone), mp 278-279°C. UV spectrum (λ max , MeOH, nm): 266, 322sh, 366; +AlCl 3 : 270, 305sh, 350sh, 424; +AlCl 3 /HCl: 270, 305sh, 347sh, 424. PMR spectrum (400 MHz, acetone-d 6 , δ, ppm, J/Hz): 8.16 (2H, d, J = 8.8, H-2′,6′), 7.03 (2H, d, J = 8.8, H-3′,5′), 6.54 (1H, d, J = 2.0, H-8), 6.27 (1H, d, J = 2.0, H-6).