Structural revision of sesbagrandiflorains A and B, and synthesis and biological evaluation of 6-methoxy-2-arylbenzofuran derivatives

AbstractSesbagrandiflorains A (1) and B (2), isolated from the stem bark of the Indonesian fabaceous plantSesbania grandiflora, were reported to be 6-methoxy-2-(2 ´,3´-dihydroxy-5´-methoxyphenyl)-1-benzofuran-3-carbaldehyde and 6-hydroxy-2-(2´,3´-dihydroxy-5´-methoxyphenyl)-1-benzofuran-3-carbaldehyde, respectively. However, based on reevaluation of their 1D and 2D NMR data, the chemical structures of 1 and 2 have been revised to 4-hydroxy-2-(4´-hydrox y-2´-methoxyphenyl)-6-methoxybenzofuran-3-carbaldehyde and 4-hydroxy-2-(4´-hydroxy-2´-hydroxyphenyl)-6-methoxybenzofuran-3-carbaldehyde, respectively. In addition, seven new derivatives of1 have been synthesized from the natural product in good yields (65  − 93%). The chemical structures of the synthetic compounds—one diester (6), four ethers (7–10), one secondary amine (11), and one oxime (12)—were confirmed by MS and NMR analysis. Compound 6 exhibited moderate antibacterial activity against the plant pathogenRhodococcus fascians with a MIC of 0.1  mg/mL. Compounds 8 and 12 demonstrated respectable cytotoxicity against A375 melanoma cancer cells line with the relative IC50 values of 22.8 and 32.7  μM, respectively.
Source: Journal of Natural Medicines - Category: Drugs & Pharmacology Source Type: research