Bioactive alkenylphenols from Piper obliquum.

Various parts of Piper obliquum Ruíz & Pavon yielded the new alkenylphenols obliquol A (1) and obliquol B (2), the new 4-chromanone 3 together with the known compounds 4 and 5. A synthesis of obliquol B (2) was developed in order to confirm its structure and to provide sufficient amounts for biological testing. Compounds 1 and 2 have antibacterial activity comparable to that of ampicillin, 2 in addition possesses potent anti-NF-kappaB activity by targeting early events in the TNFalpha-induced NF-kappaB inflammatory pathway, which may explain the effects reported for the traditional use of the plant.