Ruth Segal

The antimicrobial activity of the essential oil from Achillea fragrantissima

Essential oil from Achillea fragrantissima exerted a bactericidic effect on several gram positive and gram negative bacterial strains, as well as on Candida albicans. The oil was fractionated on sillica gel columns by a gradient of ether in petrol ether (30 degrees C-40 degrees C). Two fractions which contained less polar compounds were active against C. albicans only. The fractions which contained more polar compounds inhibited the growth of all the microorganisms tested. One of these compounds was identified as terpinen-4-ol. Commercial terpinen-4-ol had a similar antimicrobial activity.

Trichothecene-induced hemolysis: I. The hemolytic activity of T-2 toxin

In the present investigation, the hemolytic properties of T-2 toxin were examined. Tests with different concentrations of T-2 toxin showed that essentially complete hemolysis of rat erythrocytes commenced after a lag period, the length of which depended on the concentration of toxin. Comparison of the characteristics of hemolysis caused by T-2 toxin, saponins, H2O2, and polyoxyethylene surfactants showed great similarity between T-2 toxin and the latter two which proceed by a free radical mechanism. The same mechanism was suggested for hemolysis caused by T-2 toxin on the basis of the additional following observations: (1) darkness inhibited hemolysis; (2) specific free radical scavengers, i.e., vitamin E, mannitol, and histidine, inhibited hemolysis caused by T-2 toxin.

On the mechanism of saponin hemolysis—I: Hydrolysis of the glycosidic bond

Abstract The mechanism of saponin induced hemolysis was investigated by extracting the active hemolysing factor from ghost cells of saponin hemolysed blood. The fact that only the corresponding aglycones could be extracted, shows that hydrolysis of the glycosidic bond precedes hemolysis. It is suggested that lack of hemolytic activity in a saponin is due either to its non adsorbability to the red cell or to the lack of a proper membrane glycosidase necessary for hydrolysing the glycosidic bond.

The constitution of essential oils from Artemisia herba alba populations of Israel and Sinai

Abstract The essential oils of Artemisia herba alba populations, four from Israel and one from Sinai, were analysed. Identification of components was achieved either by isolation of pure components or by GC and GC/MS. The composition of the oils differed in the various populations. All the oils contained 1,8-cineole in varying concentrations. Irregular monoterpenes were found in two populations, in one of them at high concentration. Two main types of oils were discerned, the cineole-thujane-bornane type and the pinane type. The differences in the composition of the essential oils in the A . herba alba populations investigated are in line with the variations of their sesquiterpene lactones.

The Antibacterial and Antispasmodic Activity of Artemisia herba alba Asso. II. Examination of Essential Oils from Various Chemotypes

AbstractThe essential oils from four Artemisia herba alba populations collected in Israel were investigated for their antibacterial and antispasmodic activities. All the oils had slight antibacterial activities in the concentration range of 1-2 mg/ml. Some correlations between the chemical composition of the oils and their antibacterial activity was observed. All the essential oils tested showed marked antispasmodic effects on rabbit jejunum at about 1 × 10−5%. The antibacterial together with the antispasmodic effects may explain the extensive use of A. herba alba in folk medicine.

Constitution of the essential oil from an Artemisia herba-alba population of Spain

Abstract The composition of the essential oil from a Spanish population of Artemisia herba-alba has been compared with that of Israeli populations of the same plant. The chemotaxonomic affinity of the two populations was not reflected in the compositions of the oils.

The susceptibility of cholesterol-depleted erythrocytes to saponin and sapogenin hemolysis.

The assumption that complex formation between erythrocyte membrane cholesterol and saponins or sapogenins is the cause for their hemolytic activity, was tested by measuring the susceptibility of cholesterol-depleted erythrocytes towards these hemolysins. For some of the hemolysins cholesterol depletion caused inhibition of hemolysis, for others an augmentation. The results suggest that cholesterol does not serve as a specific binding site for these hemolysins.

Effect of ester groups on the haemolytic action of some saponins and sapogenins

Abstract The saponin and sapogenin of Styrax officinalis L. both being benzoic acid esters, were found to be highly haemolytic, producing haemolysis at equal molar concentrations. No haemolytic activity was detectable after saponification. Methylation of the carboxylate group in the glycosidic part of the saponin, only slightly enhances activity. The haemolytic activity of some sapogenins was investigated and compared with that of their acetic and benzoic acid esters. All sapogenins were found to be highly haemolytic, esterification enhancing this property. It is proposed that the aglyconic part of the saponin molecule is the main factor in determining the haemolytic properties of saponins.

Chemotypes of Artemisia herba-alba in Israel based on their sesquiterpene lactone and essential oil constitution

Abstract Analysis of sesquiterpene lactones and essential oils of various Artemisia herba-alba populations growing in Israel revealed the existence of five different chemotypes. These vary in their chemical profile from populations of the Sinai Desert, Egypt, Morocco and Spain. On the basis of the substitution patterns of the sesquiterpene lactones isolated from the Israeli populations which bear a hydroxyl or acetoxy function at C-9 it is suggested that these constitute a chemotaxonomic subspecies in the A. herba-alba complex.

New sesquiterpene lactones from Artemisia herba alba

Abstract The structures of herbolides A, B and C, new sesquiterpene lactones isolated from Artermisia herba alba , were determined by chemical and spectroscopic methods.