Protective Effect of Struthanthus marginatus on Ethanol‑induced Gastric Damage in Mice

Background: Our research group previously characterized the antioxidant and gastroprotective effects of Struthanthus marginatus (Loranthaceae), a medicinal herb used in Brazil as a healing agent. Objective: The aim of this study is to evaluate the chemical composition of aqueous extract of S. marginatus (AESm), as well as the mechanisms underlying its gastroprotective and ulcer healing properties using different protocols in mice. Materials and Methods: Gas chromatography‑mass spectrometry and liquid chromatography/electrospray ionization‑mass spectrometry‑mass spectrometry/diode array detection analyses to evaluate the chemical composition of AESm were conducted. The antisecretory activity (basal or stimulated) was determined using the pyloric ligature method. The gastroprotective action of nitric oxide and sulfydryl groups (–SH groups) were evaluated using ethanol‑induced gastric ulcer model. The healing ability was evaluated using an acetic acid‑induced chronic ulcer. Results: Chromatographic analyses of AESm permitted to identify several compounds, including 3‑trans‑caffeoylquinic acid (3‑trans‑CGA), quercetin, and kaempferol as the major constituents. Oral treatment of animals with AESm (500 mg/kg/day) reduced the severity of ethanol‑induced gastric damage similar to omeprazole and in a more pronounced manner than 3‑trans‑CGA. Such effect was significantly reduced in animals pretreated with Nω‑nitro‑L‑arginine methyl ester. In addition, AESm inhibited gastric acid secretion in pylorus‑ligated mice stimulated with histamine or pilocarpine similar to atropine or cimetidine, respectively. A decrease in acetic acid‑induced gastric ulcers similar to that promoted by cimetidine was also observed. Conclusion: The results show that S. marginatus is rich in flavonoids and that these compounds contribute directly to the gastroprotective and ulcer healing effects of this herb. The inhibition of gastric secretion is the possible gastroprotective mechanism.