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Three citrus fruit extracts (orange, grapefruit and lemon), an olive leaf extract and a citrus–olive mixed extract (Citrolive), which was obtained from olive leaf and bitter orange fruits, were characterized by HPLC and investigated for their endothelium-dependent vascular relaxing ability. Subsequently, aorta rings from SHR were mounted in tissue baths. They were pre-contracted with methoxamine and exposed to the extracts. Intact, endothelium-denuded, L-NAME-, indomethacin- and sirtinol-treated preparations were used. All extracts exhibited endothelium-dependent relaxations that were totally reversed by L-NAME and partly blocked by sirtinol. Indomethacin also decreased the relaxing effect of high doses of lemon and olive extracts, but the arterial relaxations caused by low doses of the different extracts and those caused by high doses of Citrolive extract (a mixed extract) were potentiated by indomethacin. This study confirms Mediterranean plants as an excellent source of functional compounds, showing the relaxing effect of the assayed plant extracts in aorta rings from SHR. Moreover, the results obtained demonstrate the endothelium-dependent vascular relaxing effect of the studied extracts. Endothelial NO release seems implicated in the effect of all extracts and prostacyclin probably participates in the effect of lemon and olive extracts. Nevertheless, enhanced vasoconstrictor endoperoxides seem to be of special importance in the endothelial tissue of SHR, and the release of these products may impair, at least in part, the endothelium-dependent vascular relaxation caused in these animals by orange, grapefruit, lemon, olive, and in particular, Citrolive extracts.

This is an open access article distributed under the Creative Commons Attribution License., The effect of long-term intake of different doses (20, 40, and 60 mg/kg/day) of a Fraxinus excelsior L. seed extract (FESE) on spontaneously hypertensive rats (SHR) was evaluated. Water was used as control and captopril (50 mg/kg/day) was used as positive control. Systolic blood pressure, body weight, and food and liquid intake were registered weekly in SHR. The antioxidant and vascular relaxing properties of FESE were also studied in these animals. The development of hypertension was attenuated in the groups treated with captopril or FESE. The antihypertensive effect was more accentuated in the captopril group than in the FESE groups, and it was paradoxically more accentuated in the groups treated with 20 mg/kg/day or 40 mg/kg/day of FESE than in the group treated with the highest dose of this extract. Body weight gain and food intake increased in the FESE groups. After removing the corresponding antihypertensive treatment, the arterial blood pressure and the body weight of the FESE treated animals returned to control values. In addition, FESE increased plasma antioxidant capacity and decreased plasma and liver malondialdehyde levels. Moreover, acetylcholine relaxation improved in the aorta rings from the FESE treated rats. © 2014 Noemi López-Carreras et al.