Effectiveness of an extraction

Based on the appropriate partition coefficient of an immiscible solvent pair it is possible to calculate the effectiveness of an extraction . 

Let us assume that V moles of solute present initially in a volume V2 of Solvent b Now, this particular sample undergoes extraction with a volume of Solvent a and subsequently y moles of compound are left in V2 at equilibrium. 

Substituting these values in Eq. (a) and using molarity instead of mole fraction, we have  

From Eqs. (d) it is quite evident that the fraction extracted is absolutely independent of the initial solute concentration. Hence, the fraction left unextracted after n extraction may be given by the following expression  

Form Eq. (e) it is distinctly obvious that a series of several extractions would definitely prove to be more efficacious than one single extraction using the same total volume of solvent. 

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Leptactina senegambica (Rubiaceas). The root-bark contains about 1 per cent, of alkaloids, including leptactinine, m.p. 264f-6°, which forms a picrate, m.p. 258° (dec.), picrolonate, m.p. 196°, and styphnate, m.p. 240-2°. The colour reactions with numerous alkaloidal reagents are recorded, some of which indicate that an indole nucleus is present. Pharmacological effects of an extract of the root bark are described (Paris and Bouquet, Ann. pharm. franc., 1946, 4, 233). 

Munavvar AS, Gan EK, Loke SE, Mah KF, Wong WH. Effect of an extract of Eri-oglossum edule on the central nervous system. J Ethnopharmacol 1989 25 217-220. 

This method is also used to measure ex vivo low-density lipoprotein (LDL) oxidation. LDL is isolated fresh from blood samples, oxidation is initiated by Cu(II) or AAPH, and peroxidation of the lipid components is followed at 234 nm for conjugated dienes (Prior and others 2005). In this specific case the procedure can be used to assess the interaction of certain antioxidant compounds, such as vitamin E, carotenoids, and retinyl stearate, exerting a protective effect on LDL (Esterbauer and others 1989). Hence, Viana and others (1996) studied the in vitro antioxidative effects of an extract rich in flavonoids. Similarly, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Wang and Goodman (1999) examined the antioxidant properties of 26 common dietary phenolic agents in an ex vivo LDL oxidation model. Salleh and others (2002) screened 12 edible plant extracts rich in polyphenols for their potential to inhibit oxidation of LDL in vitro. Gongalves and others (2004) observed that phenolic extracts from cherry inhibited LDL oxidation in vitro in a dose-dependent manner. Yildirin and others (2007) demonstrated that grapes inhibited oxidation of human LDL at a level comparable to wine. Coinu and others (2007) studied the antioxidant properties of extracts obtained from artichoke leaves and outer bracts measured on human oxidized LDL. Milde and others (2007) showed that many phenolics, as well as carotenoids, enhance resistance to LDL oxidation. 

Brunello N, Racagni G, Clostre F, Drieu K, Braquet P. (1985). Effects of an extract of Ginkgo biloba on noradrenergic systems of rat cerebral cortex. Pharmacol Res Common. 17(11) 1063-72. 

Macovschi 0, Prigent AF, Nemoz G, Pacheco FI. (1987). Effects of an extract of Ginkgo biloba on the 3, 5 -cyclic AMP phosphodiesterase activity of the brain of normal and triethyltin-intoxicated rats. J Neurochem. 49(1) 107-14. 

Porsolt RD, Martin P, Lenegre A, Fromage S, Drieu K. (1990). Effects of an extract of Ginkgo biloba (EGB 761) on "learned helplessness" and other models of stress in rodents. Pharmacol Blochem Behav. 36(4) 963-71. 

Ferri S, Cavicchini E, Romualdi P, Speroni E, Murari G. (1986). Possible mediation of catecholaminergic pathways in the antinociceptive effect of an extract of Cannabis sativa L. Psychopharmacology (Berlin). 89(2) 244-47. 

Groenewegen WA, Heptinstall S. (1990). A comparison of the effects of an extract of feverfew and parthenolide, a component of feverfew, on human platelet activity in-vitro. J Pharm Pharmacol. 

Chandrasekaran CV, Gupta A, Agarwal A. (2010) Effect of an extract of Andrographis paniculata leaves on inflammatory and allergic mediators in vitro. J Ethnopharmacol 129 203-207. 

Mahaffey, et al. Effects of an extract of Serenoa repens on dogs with hyperplasia of the prostate gland. Amer J Vet Res 2000 61(8) 880-885. 

A reference for this method is P. S. Venkateswaran, 1. Millman, and B. S. Blumberg, Effect of an extract from Phyllanthus niruri on hepatitis B and woodchuck hepatitis viruses in vitro and in vivo studies, Proc. Natl. Acad. Sci., USA, 1987, 84, 274-278, which is incorporated herein by reference. 

It was previously shown that the effectiveness of an extraction, using a given volume of solvent, could be increased by increasing the number of times the extraction was performed. The effectiveness of the extraction may be further increased by a modification of the procedure which gives the effect of countercurrent extraction. To effect this modification, one proceeds as follows The solution is divided equally between several separatory funnels which are numbered in sequence. An arbirran, volume of a solvent which is immiscible whrh and more dense than the solution is added to the first funnel, and the liquids are equilibrated by shaking. The lower layer (the extract) is transferred to the second funnel, and an amount of solvent equal to that used in the first extraction is added to the first funnel. Both mixtures are equilibrated by shaking, and the extract from the second funnel is added to the third, that from the first is added to the second, and fresh solvent is added to the first. The procedure is then repeated. 

Rocha FA, Leite AK, Pompeu MM, Cunha TM, Verri WA Jr, Soares FM, Castro RR, Cunha FQ (2008) Protective effect of an extract from Ascaris suum in experimental arthritis models. Infect Immun 76(6) 2736-2745... 

Dubos, R.J. (1939) Bactericidal effect of an extract of a soil bacillus on gram-positive cocci. Proc. Soc. Exp. Biol. (NY) 40 311-312. 

Olas, B., J. Saluk-Juszczak, I. Pawlaczyk, et al. 2006. Antioxidant and antiaggregatory effects of an extract from Conyza canadensis on blood platelets in vitro. Platelets 17(6) 354-360. 

Moore, M. 2003. Medicinal plants of the Mountain West. Revised and expanded edition. Santa Fe Museum of New Mexico Press. RoUand, A., J. Fleurentin, M.C. Lanhers, R. Misslin, and F. Mortier. 2001. Neurophysiological effects of an extract of Eschscholzia californica Cham. (Papaveraceae). Phytother. Res. 15(5) 377-381. 

Noguchi, M., T. Kakuma, K. Tomiyasu, et al. 2008. Effect of an extract of Ganoderma lucidum in men with lower urinary tract s)Tnptoms A double-blind, placebo-controlled randomized and dose-ranging study. Asian J. Androl. 10(4) 651-658. 

Loesche, W., W.A. Groenewegen, S. Krause, P. Spangenberg, and S. Heptinstall. 1988. Effects of an extract of feverfew (Tanacetum parthenium) on arachidonic acid metabolism in human blood platelets. Biomed. Biochim. Acta 47(10-11) S241-S243. 

Compare the effectiveness of an extraction with favorable and unfavorable distribution coefficients by repeating the calculations of Illustrations 3 and 5, substituting the system water (A)-n-heptane (J5)-acetone (C), equilibrium data for which are available in Ind, Eng, Chem, 41, 1761 (1949). 

Stough C, Lloyd J, Clarke J, Downey LA, Hutchison CW, Rodgers T, Nathan PJ (2001) The chronic effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy human subjects. Psychopharmacology (BctI) 156 481-484... 

Karcher L, Zagermann P, Krieglstein J (1984) Effect of an extract of Ginkgo biloba on rat brain energy metabolism in hypoxia. Naunyn Schmiedebergs Arch Pharmacol 327(l) 31-35... 

Shen M, Lu Z, Ye Q (2000) Effects of an extract of Ginkgo biloba on the blood flow of brains and back legs of dogs. Zhong Yao Cai 23(12) 764-766... 

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