Past Tense

Two novel octapeptides, lyciumins A and B, have been isolated from Lycii Radicis Cortex (di gu pi) as anti-ACE and -renin substances and their structures have been established

YAHARA S. et al. Tetrahedron letters, 1989, vol. 30, no44, pp. 6041-6042

ACE inhibitors, or inhibitors of Angiotensin-Converting Enzyme, are a group of compounds that are used primarily in treatment of hypertension and congestive heart failure, in some cases as the drugs of first choice. Indications for ACE inhibitors include:

Prevention of cardiovascular disorders, Congestive heart failure (CHF), Hypertension, Left ventricular dysfunction, Prevention of nephropathy in diabetes mellitus.

In several of these indications, ACE inhibitors are used first-line as several agents in the class have been clinically shown to be superior to other classes of drugs in the reduction of morbidity and mortality.

ACE inhibitors lower arteriolar resistance and increase venous capacity; increase cardiac output and cardiac index, stroke work and volume, lower renovascular resistance, and lead to increased natriuresis (excretion of sodium in the urine).

Promising hypotensive effect of hawthorn extract: A randomized double-blind pilot study of mild, essential hypertension

Walker AF, Marakis G, Morris AP, Robinson PA. Phytother Res. 2002 Feb;16(1):48-54.

This pilot study was aimed at investigating the hypotensive potential of hawthorn extract and magnesium dietary supplements individually and in combination, compared with a placebo. Thirty-six mildly hypertensive subjects completed the study. At baseline, anthropometric and dietary assessment, as well as blood pressure measurements were taken at rest, after exercise and after a computer stress test. Volunteers were then randomly assigned to a daily supplement for 10 weeks of either: (a) 600 mg Mg, (b) 500 mg hawthorn extract, (c) a combination of (a) and (b), (d) placebo. Measurements were repeated at 5 and 10 weeks of intervention. There was a decline in both systolic and diastolic blood pressure in all treatment groups, including placebo, but ANOVA provided no evidence of difference between treatments. However, factorial contrast analysis in ANOVA showed a promising reduction (p = 0.081) in the resting diastolic blood pressure at week 10 in the 19 subjects who were assigned to the hawthorn extract, compared with the other groups. Furthermore, a trend towards a reduction in anxiety (p = 0.094) was also observed in those taking hawthorn compared with the other groups. These findings warrant further study, particularly in view of the low dose of hawthorn extract used.

Hawthorn: Pharmacology and therapeutic uses.

Rigelsky JM, Sweet BV. Am J Health Syst Pharm. 2002 Mar 1;59(5):417-22.

The uses, pharmacology, clinical efficacy, dosage and administration, adverse effects, and drug interactions of hawthorn are discussed. Hawthorn (Crataegus oxyacantha) is a fruit-bearing shrub with a long history as a medicinal substance. Uses have included the treatment of digestive ailments, dyspnoea, kidney stones, and cardiovascular disorders. Today, hawthorn is used primarily for various cardiovascular conditions. The cardiovascular effects are believed to be the result of positive inotropic activity, ability to increase the integrity of the blood vessel wall and improve coronary blood flow, and positive effects on oxygen utilization. Flavonoids are postulated to account for these effects. Hawthorn has shown promise in the treatment of New York Heart Association (NYHA) functional class II congestive heart failure (CHF) in both uncontrolled and controlled clinical trials. There are also suggestions of a beneficial effect on blood lipids. Trials to establish an antiarrhythmic effect in humans have not been conducted. The recommended daily dose of hawthorn is 160-900 mg of a native water-ethanol extract of the leaves or flowers (equivalent to 30-169 mg of epicatechin or 3.5-19.8 mg of flavonoids) administered in two or three doses. At therapeutic dosages, hawthorn may cause a mild rash, headache, sweating, dizziness, palpitations, sleepiness, agitation, and gastrointestinal symptoms. Hawthorn may interact with vasodilating medications and may potentiate or inhibit the actions of drugs used for heart failure, hypertension, angina, and arrhythmias.

Procyanidins in crataegus extract evoke endothelium-dependent vasorelaxation in rat aorta

Kim SH, Kanga KW, Kimb KW, Kim ND. Life Sci. 2000;67(2):121-31.

The extract of Crataegus, a mixture of flavonoids and procyanidins extracted from hawthorn, Crataegus oxyacantha, L. and C. monogyna Jacq., relaxed vascular tone or increased production of cyclic GMP in the rat aorta, but flavonoid components of Crataegus extract, hyperoside, rutin and vitexin, did not affect the vascular tone. The aim of the present study was to characterize the endothelium-dependent relaxation elicited by procyanidins fractionated from Crataegus extract in isolated rat aorta. Procyanidins caused endothelium-dependent relaxation which was associated with the production of cyclic GMP. Both responses to these procyanidins were inhibited by methylene blue or NG-nitro-L-arginine, but not by indomethacin. Relaxation in response to procyanidins was not affected by atropine, diphenhydramine, [D-Pro2,D-Trp7,9]substance P, propranolol, nifedipine, verapamil and glibenclamide, but were markedly reduced by tetraethylammonium. These findings showed that procyanidins in Crataegus extract may be responsible for the endothelium-dependent nitric oxide-mediated relaxation in isolated rat aorta, possibly via activation of tetraethylammonium-sensitive K+ channels.