Purification of Gastroprotective Triterpenoids from the Stem Bark of Amphipterygium adstringens; Role of Prostaglandins, Sulfhydryls, Nitric Oxide and Capsaicin-Sensitive Neurons - Arrieta, Jesús; Benitez, Javier; Flores, Edith; Castillo, Carlos; Navarrete, Andrés (Planta Medica, 2003)