Phytotoxins from Hofmeisteria schaffneri: Isolation and synthesis of 2′-(2″-hydroxy-4″-methylphenyl)-2′-oxoethyl acetate

Article abstract of DOI:10.1021/np0501278

Activity-directed fractionation of a CH₂Cl₂-MeOH (1:1) extract of Hofmeisteria schaffneri led to the isolation of a new phytotoxin characterized as 2′-(2″-hydroxy-4″-methylphenyl)- 2′-oxoethyl acetate and designated the trivial name of hofmeisterin (1). In addition, the known compounds β-carotene, euparin, and 3′,4′,4a′,9a′-tetrahydro-6,7′- dimethylspiro[benzofuran-3(2H),2′-pyrano[2,3-b]benzofuran]-2, 4a′-diol (2) were obtained. The identification of the isolates was accomplished by spectroscopic methods. The structure of 1 was unequivocally confirmed by synthesis. The methyl derivative 1a was also synthesized following the same strategy. Compounds 1 and 2 inhibited radicle growth of Amaranthus hypochondriacus (IC₅₀ = 3.2 × 10^-4 and 1.2 × 10^-5 M, respectively) and significantly inhibited activation of the calmodulin (CaM)-dependent enzyme cAMP phosphodiesterase (PDE) with IC ₅₀ values of 4.4 and 4.22 μM, respectively.