Figure 1

Structure of β-sitosterol isolated from A. curassavica. The compound was identified based on the following evidence: IR spectrum showed hydroxyl (3430 cm^-1) and tris-substituted double-bond (1642 and 80.1 cm^-1). The EI/MS mass spectrum showed m+ at m/z 414, corresponding to the molecular formula (C₂₉H₅₀O) for β-sitosterol. The other characteristic peaks were at m/z 273 [m-sidechain]⁺ 255 [m-side chain - H₂O]⁺ 231 [m-side + +1chain-ring D], 213 [231-H₂O] and 300. The H-NMR spectrum showed 2 tertiary methyl groups at δ 0.68 and 1.02, corresponding to H-18 and H-19. Three secondary methyls appeared at δ 0.92, 0.82 and 0.84, corresponding to H-21, H-26 and H-27, respectively. (J = 6.5 Hz). H-29 appeared as triplet at δ 0.85 (J = 7.0 Hz). The C-NMR spectrum indicated 29 carbon atoms, 10 primary, 10 secondary and 3 tertiary carbon; 6 methyl groups being present. C-5 and C-6 were olefinic carbon atoms appearing at δ 121.70 and 140.74.