Effects of the flavone luteolin, isolated from Colchicum richii, on guinea‐pig isolated smooth muscle and heart and on blood pressure and blood flow

Abstract

The effects of the flavone luteolin, extracted from Cokhkum richii, on guinea-pig isolated ileum, pulmonary artery, trachea, atrium, perfused heart, and on blood pressure and blood flow of anaesthetized guinea-pigs were studied. Luteolin (10-'-3 X M) caused concentration-dependent relaxation of the tone of ileum, epinephrineprecontracted pulmonary artery and only mild relaxation of acetylcholme-precontracted trachea. These effects were not affected by pretreatment with 1 m M theophylline except in the ileum where theophylline shifted to the left the luteolin concentration-effect curve. Luteolin (3 X 10-6-3 X M) caused an increase in the beating rate and the contractility of the spontaneously beating atrium and of the isolated perfused heart. Theophylline (1 mM) significantly inhibited the effects of luteolin on the atrium and the perfused heart. Luteolin, in doses of 0.3, 1.0, 1.5 and 5 mg/kg body weight had no effect on heart rate of anaesthetized guinea-pigs but caused depression of systolic and diastolic blood pressure except at the lowest dose used where there was a small increase in both parameters. Also, only the lowest dose (0.3 mg/kg) caused a small increase in blood flow. Larger doses of luteolin caused dose-related inhibition of blood flow. The effects of luteolin on blood pressure and blood flow were not affected by theophyllme pretreatment (5 mg/kg). These observations suggest that the effects of luteolin may be tissue-specific and in the isolated heart they may be attributed to inhibition of cyclic AMP phosphodiesterase. The data further demonstrate that luteolin has potential cardiovascular effects that merit further investigation.

The spasmolytic activity of extracts and some isolated compounds from the leaves of Morinda morindoides (Baker) Milne-Redh. (Rubiaceae)

“…In some cases, mechanisms underling the antispasmodic activity of tested extracts are also reported (Gilani et al, 2005(Gilani et al, , 2006(Gilani et al, , 2007(Gilani et al, , 2008. Extensive investigations of active antispasmodic extracts have led to the isolation of active compounds belonging to different phytochemical groups (Abdalla et al, 1994;Bergendorff and Sterner, 1995;Rojas et al, 1995Rojas et al, , 1996Trute et al, 1997;Barile et al, 2005).…”

Inhibitory effects of Taraxacum mongolicum with phreatic water on melanin synthesis

“…Currently, it is known that luteolin is effective in terms of antioxidant activation, whitening effect, 44 and repercussive and analgesic actions 45 . In the recent study by Hur, 46 luteolin did not inhibit tyrosinase activation directly, but it concentration-dependently inhibited tyrosinase activation and melanin generation increase by a-MSH in the B16 melanoma cell as well as cAMP generation by MSH and forskolin, which identified the action mechanism of its whitening action generation.…”

Cardiovascular effects ofArbutus unedo L. in spontaneously hypertensive rats

“…Recently, Fitzpatrick and his collegues (1993) have reported that quercitin (a flavonoid) and tannic acid (tannins) produced endothelium-dependent relaxation in precontracted smooth muscle of intact rat aortic rings. In other respects, flavonoids are also reported for their hypotensive action in anaesthetized guinea-pigs (Abdalla et al, 1994). Regarding the renal effects apparent in 9 week-old rats, Arbutus (250 mg/kg/24 h) induced an important increase of diuresis and natriuresis.…”