Figure 8.

Isolated compounds (A) quercetin, (B) catechin and (C) kaempferol of Peak-1, -2 and -3 samples obtained from RP-HPLC of hot-water extract of A. arabica bark via LC-MS analysis. Proton-decoupled natural abundance ¹H-NMR and C¹³-NMR of the Peak-1 sample of A. arabica bark (obtained from a chromatograph over the period of 70% acetonitrile from 10 to 40 min with a retention time of 9.7 min) at 40 °C. The spectrum values were obtained at 600 MHz after 119,044 transients (14 h) by the pulsed Fourier-transform method on a Varian XL-100 A spectrometer. The representative structures of flavonoids, corresponding to the molecular formula of quercetin, catechin and kaempferol, are C₁₅H₁₀O_7, C₁₅H₁₄O₆ and C₁₅H₁₀O₆.