A fluid extract of Passiftora incarnata L. was studied for its neuropharmacologieal properties. This extract, orally and intraperitoneally administered to rats, raised the nociceptive threshold in the tail-flick and hot-plate tests, but not in the vocalization test. On intraperitoneal injection, the extract significantly prolonged sleeping time, protected animals from the convulsive effect of pentylenetetrazole, and affected locomotor activity. The fluid extract was partitioned by solvents and chromatography and at least two products, one lipophilic (A) and one hydrophilic (B), were found to be active. They could not be ascribed to either alkaloids or the flavonoid structures present in the extract.
Four new diterpenoids, helioscopinolides F
(2), H (4), I (5), and L
(6), were isolated from three
different cultured cell lines of Euphorbia calyptrata var.
involucrata. Helioscopinolide B
(1)
and jolkinolide E (3), previously found in Euphorbia
helioscopia and Euphorbia jolkini,
respectively, were also isolated from the same cultures.
Structures were identified by
spectroscopic methods.
Inhibitory effects by addition of aqueous extracts of soy flour to an active Briggs-Rauscher mixture are reported. The effect consists of an immediate cessation of oscillations, but, after some time, the oscillatory behavior is regenerated with amplitude and frequency different from those observed in a reference mixture. The inhibition time depends linearly on the concentration of substances contained in the extract in a wide range of concentration. The inhibitory effects are due to the high free-radical scavenging activity of substances contained in the soy flour. Two preponderant products contained in the soy flour extract were identified and characterized as malonyldaidzin and malonylgenistin. The antioxidant activity of these isoflavones contained in the extracts was determined on the basis of the inhibition time. A qualitative mechanistic explanation of the inhibitory effects is given. Our findings are decisive indirect evidence of involvement and important role played by HOO . radicals in establishing oscillations in the Briggs-Rauscher (BR) system. The linear relationship between the inhibition time and the whole-mass concentration of antioxidant contained in soy extracts added to a BR mixture is an indication of the possibility to develop and implement an analytical procedure for monitoring the activity of antioxidant scavengers of free radicals based on the oscillating Briggs-Rauscher reaction.1. Introduction. ± As stated by Furrow and Noyes [1], the most dramatic oscillating reaction in solution is probably that discovered by Briggs and Rauscher [2], now referred to as the BR reaction. When appropriate amounts of H 2 O 2 , acidic iodate, manganous salt, malonic acid (MA), and starch indicator are mixed in aqueous solution, the system repeats the sequence colorless 3 yellow 3 blue several times.The mechanism of the BR reaction is quite complex; a skeleton mechanism, proposed in 1982 by Noyes and Furrow [3], reproduces some of the basic features of the oscillations in the system in closed reactors (batch conditions). At the same time, De Kepper and Epstein [4] developed a qualitatively similar mechanism that, taking into account flow terms, is able to model, besides oscillations, a variety of phenomena that appear in continuously stirred tank reactors (open conditions).The main intermediates in these mechanisms are: iodine, iodide ion, the oxyiodine species HOI, HOIO, and IO . 2 , and the hydroperoxyl radical HOO . . It is to be noted that IO .2 and HOO . radicals were not detected in BR mixtures: their presence and the important role they play in the onset of oscillations were proposed in analogy with the well-established mechanism for the Belousov-Zhabotinsky (BZ) reaction [5] and with a mechanism proposed for the Bray-Liebhafsky (BL) reaction [6].In a qualitative study, Franz [7] found that the addition of a crumbled superoxide dismutase pellet (health food, 2000 SOD units per pellet) to an actively reacting BR mixture caused an immediate cessation of oscillations (initial concentrations in the
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