Differential allelopathic expression of different plant parts of Achillea biebersteinii.

Achillea biebersteinii (Asteraceae) is a perennial medicinal plant and has a wide distributional range in the Mediterranean region. The present study investigated the inhibitory effects of different plant parts of A. biebersteinii on germination characteristics and seedling growth of wild barley (Hordeum spontaneum). Water extracts were prepared by incubating separately five grams of dried powder of roots, stems, leaves and flowers of A. biebersteinii in 100 ml of distilled water for 24 h and distilled water was used as the control. The water extracts from different plant parts of A. biebersteinii differed in their effects on the germination and seedling growth of wild barley. Water extracts prepared from leaves and flowers were more suppressive to germination of wild barley than root and stem extracts. The maximum inhibition in radical and plumule growth of germinating caryopses and in root and shoot growth of greenhouse-grown wild barley was recorded for leaf extract followed by flower extract. The lowest Chl a, Chl b and total chlorophyll and protein contents were resulted after exposure to leaf extracts. According to these results, the inhibitory effects of different A. biebersteinii plant parts can be arranged in the order: leaf > flower > stem > root.

Acute toxicity and antispasmodic activities of Achillea wilhelmsii C. Koch.

Since Achillea wilhelmsii is used as antispasmodic in traditional medicine, we conducted our current work to investigate its rationale on scientific grounds. Acute toxicity studies of crude methanol extract of Achillea wilhelmsii (Aw. CMeOH) is also performed. Effect of Aw. CMeOH and its fractions were tested on isolated sections of rabbits' jejunum at test concentrations 0.01, 0.03, 1.0, 3.0, 5.0 and 10mg/ml. The test extracts, in similar concentrations, were also tested on KCl-induced contractions. Calcium chloride curves were constructed for those fractions which relaxed KCl induced contractions in the absence and presence of the test samples to investigate its possible mode of action through calcium channels. Aw. CMeOH tested positive for flavonoids, saponins, tannins, glycosides, terpenoids, sterols, phenols, carbohydrates and proteins. LD(50) for acute toxicity studies is 2707±12.6 mg/kg. Mean EC(50) values for Aw. CMeOH on spontaneous and KCl-induced contractions are 3.41±0.18 (2.56-3.8, n=6) and 0.68±0.05 (0.6-0.85, n=6) mg/ml, respectively. Respective EC(50) values for n-hexane fraction on spontaneous and KCl-induced contractions are 3.06±0.08 (2.8-3.3, n=6) and 1.68±0.8 (1.4-1.9, n=6) mg/ml, respectively. Corresponding EC(50) (mg/ml) values for chloroformic, ethylacetate and aqueous fractions of Achillea wilhelmsii on spontaneous rabbits' jejunum preparations are 4.8±0.2 (4.41-5.63, n=6), 5.07±0.15 (4.7-5.58, n=6) and 5.2±0.13 (4.91-5.64, n=4), respectively. Constructing calcium chloride curves, in the presence of 0.1 mg/ml of Aw. CMeOH, mean EC(50) value (log molar [Ca(++)]) is-1.98±0.03 (-1.89-2.05, n=6) vs. control EC(50) (log molar [Ca(++)])-2.41±0.02 (-2.32-2.44, n=6). Mean EC(50) value (log molar [Ca(++)]) for 0.3 mg/ml n-hexane fraction is-1.76±0.05 (-1.70 -1.93, n=6) vs. control EC(50) (log molar [Ca(++)]) value-2.18±0.07 (-2.0-2.46, n=6). While in the presence of chloroformic fraction (3 mg/ml), mean EC(50) (log molar [Ca(++)]) value is -2.4±0.1 (-2.78 -2.9, n=6) vs. control EC(50) (log molar [Ca(++)]) value-2.70±0.05 (-2.5-2.8, n=6). Mean EC(50) value (log molar [Ca(++)]) for ethyl acetate fraction (1 mg/ml) is-1.94±0.07 (-1.75-2.05, n=6) vs. control EC(50) (log molar [Ca(++)]) value-2.69±0.04 (-2.57-2.79, n=6). Mean EC(50) (log molar [Ca(++)]) value for residual aqueous fraction (3 mg/ml) is-1.8±0.3 (-1.71-1.84, n=6) vs. control EC(50) (log molar [Ca(++)]) -2.6±0.04 (-2.59-2.76, n=6). Whereas, the verapamil (0.1µM) EC(50) value (log molar [Ca(++)]) is-1.7±0.1 (-1.6-1.8, n=6) vs. control EC(50) value (log molar [Ca(++)])- 2.4±0.09 (-2.3-2.47, n=6). The present research work confirms that the intestinal relaxation effect of Achillea wilhelmsii is supporting its traditional use as antispasmodic. The plant species can be a source for calcium antagonist(s), which can preferably be isolated from n-hexane fraction.

Toxic essential oils: anxiolytic, antinociceptive and antimicrobial properties of the yarrow Achillea umbellata Sibth. et Sm. (Asteraceae) volatiles.

Many plant species are used for medicinal purposes without the knowledge of their possible toxic effect. The ethnopharmacologically renowned genus Achillea L. (Asteraceae) is even more troublesome in this respect since different taxa are believed to have the same beneficial properties as A. millefolium. According to the median lethal i.p. dose (LD(50)=853 mg/kg, mice), the volatiles of Achillea umbellata Sibth. et Sm. are more toxic than the thujone-containing essential oils (LD(50)>960 mg/kg). A GC-MS analysis of A. umbellata oil revealed the presence of a series of fragranyl esters (six new natural products). The major constituents of this oil, the rare monoterpene alcohol fragranol and fragranyl acetate, and one more ester (benzoate), as well as the oil itself, showed antianxiety, analgesic and, in some instances, paralyzing properties at 50-150 mg/kg but these are very likely sign of intoxication and not of possible beneficial effects of the plant volatiles. Testing of antimicrobial activity demonstrated that the oil possesses moderate activity against pathogenic microorganisms, but the effect of the oil differs in pro- and eukaryotic cells. According to the results obtained, fragranol may be considered as the main active principle responsible for the observed activity/toxicity.

Reproductive evaluation of aqueous crude extract of Achillea millefolium L. (Asteraceae) in Wistar rats.

The present study was conducted to evaluate the toxicity of the exposure to the aqueous extract from leaves (AE) of Achillea millefolium L. on reproductive endpoints in Wistar rats. Adult male rats were treated daily with yarrow extract (0.3, 0.6 and 1.2 g/kg/day) during 90 days by oral gavage. Endpoints including reproductive organ weights, sperm and spermatid numbers as well as sperm morphology were evaluated. No clinical signs of toxicity were detected over the treatment period, and body weight gain was similar in all groups. A significant increase in the percentage of abnormal sperm in the group treated with the highest dose of yarrow extract was detected with no other important changes in the other reproductive endpoints studied in the male rats. Furthermore, a possible estrogenic/antiestrogenic activity of the yarrow extract screened after a 3-day treatment of immature female rats which did not show any uterotrophic effects.

Preliminary screening study of reproductive outcomes after exposure to yarrow in the pregnant rat.

BACKGROUND: Yarrow (Achillea millefolium) is used for the treatment of diarrhea, as a urinary antiseptic, hypotensive, and diuretic. Yarrow also has traditionally been used as an abortifacient, emmenagogue, contraceptive, and for stimulating uterine contractions. For this reason, it is contra-indicated for use in pregnancy. There has, however, been little scientific research carried out to either confirm or refute this recommendation. METHODS: Female rats were dosed, orally by gavage using 56 times the human dose of yarrow daily on either gestation days (GD) 1-8 or GD 8-15. Two groups of controls were included; the first received water and the second received an equivalent dose of ethanol to that found in the yarrow preparation over the two gestation periods. On GD 20, rats were sacrificed, placentae were weighed, and corpora lutea counted. The fetuses were weighed and examined for signs of external, internal or skeletal malformations. RESULTS: The dose used was not materno-toxic. There was no increase in pre- or post-implantation losses suggesting that yarrow was neither an abortifacient nor a contraceptive. Placental weights were increased in rats treated with yarrow on GD 8-15 compared to water and ethanol controls and on GD 1-8 compared to water control fetuses. Body weight was reduced in fetuses exposed to yarrow on GD 8-15 compared to water control fetuses. There was no difference in incidence of external or internal malformations. CONCLUSIONS: In the present study it was found that yarrow, when administered to rats at 56 times the human dose, was associated with reduced fetal weight and increased placental weight. In the absence of a no observable effect level for these variables it must be concluded that the consumption of yarrow is contraindicated during pregnancy until further investigations have been carried out.