Novel hypotensive agents from Verbesina caracasana. 7. Further hypotensive metabolites from Verbesina caracasana - Delle Monache, G; Volpe, A R; Delle Monache, F; Vitali, A; Botta, B; Espinal, R; De Bonnevaux, S C; De Luca, C; Botta, M; Corelli, F; Carmignani, M (Bioorg Med Chem Lett, 1999)