Tilia americana and Annona diversifolia are plants widely distributed in Mexico and sold in markets for their medicinal properties on the central nervous system (CNS) including possible neuroprotection. Pharmacological studies have corroborated CNS activities due to
flavonoid constituents, but evidence of their neuroprotector effects are lacking. This study was conducted to test aqueous and organic extracts of these two plants for
neuroprotective effects in a novel experimental model of intestinal
ischemia in situ. T. americana and A. diversifolia aqueous and organic extracts were administrated to guinea pigs at an oral dose of 100 and 300 mg/kg for 15 days. Twenty four hours after the last administration, the animals were anesthetized and intestinal
ischemia in situ was induced by clamping for 80 min selected branches of the superior mesenteric artery. Ischemic segments placed in an in vitro organ bath were stimulated electrically (0.3 Hz frequency, 3.0 ms duration, 14 V intensity) and chemically (ACh; 1 × 10(-9) to 1×10(-5) M). Neuroprotection was considered present when the depressed contractile response of the ischemic tissue to electrical stimulation was normalized in the treated animals. Results showed that pretreatment with the T. americana
hexane and aqueous extracts, but not with those from A. diversifolia, significantly improved responses of the ischemic tissue. These results suggest that T. americana possesses
neuroprotective effects against neuronal damage induced by
ischemia, and that
flavonoids as well as non-polar constituents are involved. Our study supports the use of this plant in
folk medicine and suggests its possible effectiveness for
stroke prevention.