A possible general mechanism for ultrasound-assisted extraction (UAE) suggested from the results of UAE of chlorogenic acid from Cynara scolymus L. (artichoke) leaves.

The use of ultrasound-assisted extraction (UAE) for the extraction of chlorogenic acid (CA) from Cynara scolymus L., (artichoke) leaves using 80% methanol at room temperature over 15 min gave a significant increase in yield (up to a 50%) compared with maceration at room temperature and close to that obtained by boiling over the same time period. A note of caution is introduced when comparing UAE with Soxhlet extraction because, in the latter case, the liquid entering the Soxhlet extractor is more concentrated in methanol (nearly 100%) that the solvent in the reservoir (80% methanol) due to fractionation during distillation. The mechanism of UAE is discussed in terms of the effects of cavitation on the swelling index, solvent diffusion and the removal of a stagnant layer of solvent surrounding the plant material.

Anti-HIV activity of flavonoids and proanthocyanidins from Crataegus sinaica.

In addition to quercetin, hyperoside, rutin, vitexin, 2″-O-rhamnosylvitexin, (4″'-O-acetyl)-2″-O-rhamno-sylvitexin, epicatechin, procyanidin B-5, proanthocyanidin A-2, procyanidin B-2 and procyanidin C-1, which were reported before in Crataegus sinaica (Rosaceae), three more flavonoids were isolated from the same plant, i.e. (+)-taxifolin, 3-O-ß-arabinopyranosyl-(+)-taxifolin and 3-0-ß-xylopyranosyl-(+)-taxifolin. The in vitro anti-HIV activity of some selected flavonoids and proanthocyanidins was evaluated. The dimeric procyanidin B2 and proanthocyanidin A2, and especially the trimeric procyanidin C1 showed some in vitro anti-HIV activity.

Poisonous plants contaminating edible ones and toxic substances in plant foods. Part 3. Pyrrolizidine alkaloids from Heliotropium digynum Forssk. (= H. luteum, Poir.).

Investigation of the alkaloidal constituents of Heliotropium digynum resulted in the isolation of four alkaloids viz. heliotrine, europine, lasiocarpine and 7-angelylheliotrine. Moreover, HPLC and GLC showed the probable presence of heliotridine and some other unidentified minor constituents. A summary of the pharmacotoxicity and biological activity of the ethanolic extract, total alkaloids with special reference to heliotrine is presented.

Constituents of Egyptian Euphorbiaceae. IX. Irritant and cytotoxic ingenane esters from Euphorbia paralias L.

The irritant and cytotoxic constituents of the latex of Euphorbia paralias L. were separated from the hydrocarbon fraction by means of solvent partition. 3 new ingenane esters were identified from the toxic ether fraction. The major compound was 3-angelyl-20-deoxyingenol and the 2 minor compounds were 3-hexanoyl-20-deoxyingenol and 3-angelyl-ingenol. These compounds were of a similar potency to podophyllin in the inhibition of 3H-thymidine uptake by TLX/5 mouse lymphoma cells. In addition the compounds produced a persistent erythema of the mouse ear in sub-microgram doses.