In addition, HMBC correlations [from the methyl at δH 1.98 (H3-14) to two quaternary carbons at δC 129.2 (C-8), 132.7 (C-7) and 133.6 (C-6); from two methine protons at H-2 and H-4 to C-6; and from the methine at H-5 to δC 131.0 (C-1), 132.7 (C-7), and 153.8 (C-3)] revealed the presence of the carboxylic group at C-1, instead of a hydroxyl group in compound 8.