Guided isolation

Li da W, Lee EB, Kang SS, Hyun JE, Whang WK. Activity-guided isolation of saponins from Kalopanax pictus with anti-inflammatory activity. Chem Pharm Bull (Tokyo) 2002 50 900-903. 

Table 1 Experiment 2. Guided isolation and identification of potential allelochemicals from Cladonia foliacea. O, fraction O P, fraction P UA, usnic acid ca, caulonema ch, chloronema sb, side branches. Protonemal system from shoots after 21 days in culture tested against three fractions from C. foliacea thallus and in control Mohr medium. The observations represent means calculated from about 300 protonemata for each species. P. squarrosa is the species least affected, while 7. flavovirens is the most affected by lichen fractions. 

Spore germination and protonemal growth and morphogenesis are therefore, useful systems to test in vitro, with good reproducibility, potential allelochemicals both through direct co-existence test in vitro or using the described bioassays to monitor/guide isolation, purification, characterization of chemical structure of bioactive compounds. 

Fig. 4 Experiment 2 Guided isolation and identification of potential allelochemicals from Cladonia foliacea. A, Regenerating protonema from Pleurochaete squarrosa leaves after 14 days in control sample B, regenerating protonema from P. squarrosa after 14 days in the inhibiting fraction P from lichen Cladonia foliacea . C, regenerating protonema from P. squarrosa after 14 days in the stimulating fraction O from lichen Cladonia foliacea. Light microscope (a and c x 25, b x 50).

Su, B.-N. et al. Activity-guided isolation of the chemical constituents of Muntingia calabura using a quinone reductase induction assay, Phytochemistry, 63, 335, 2003. 

Chang, L.C. et ah. Activity-guided isolation of constituents of Tephrosia purpurea with the potential to induce the phase II enzyme, quinone reductase, J. Nat. Prod., 60, 869, 1997. 

Other studies show the presence of a diversity of compounds other than limonoids as defenses in the tissues of Meliaceae. Woody tissues of Trichilia trifolia afforded three novel dolabellanes with flexible Curing structures. These substances were very active antifeedants in the Sitophilus bioassay (Ramirez et al., 2000). T. martiana seeds yielded large amounts of 2-((Z,Z)-6,9-heptadecadienyl)furan. T. hirta and T. americana bark have yielded novel steroids by insect bioassay-guided isolation and application of a nanoprobe nuclear magnetic resonance (NMR) technique for structure elucidation (Chaurest etal.,1996). Compounds isolated included hydroxyandrosta-l,4-diene-3,16-dione (Fig. 1.4) and derivatives. However, studies by Wheeler et al. (2001) suggest that other unidentified compounds may also be... 

Cremin P, Guiry PJ, Wolfender J-L, Hostettmann K, Donnelly DMX (2000) A Liquid Chromatography-Thermospray Ionisation-Mass Spectrometry Guided Isolation of a New Sesquiterpene Aryl Ester from Armillaria novae-zelandiae. J Chem Soc Perkin Trans 1 2325... 

Rimando, A.M., Olofsdotter, M., Dayan, F.E., Duke, S.O. Searching for rice allelochemicals An example of bioassay-guided isolation. Agron J 2001 93 16-20. 

Figure 1 Schematic of the behavior maze used to guide isolation and identification of the sea lamprey pheromone.19-27 28 Lake water mixed with a small amount of nonlamprey river water flows slowly from top to bottom at a depth of c.10cm in this two-choice maze, where preference of adult lamprey is assessed by measuring the ratio of time in the right channel to time in the left (fR/fiJ> while odor is into one side or the other.

Compounds chemically related with the triterpenoid group such as triterpene saponins were also isolated as antimicrobial constituents in the Anthemideae tribe. Seven saponins were bioassay-guided isolated from the flowers of Beilis perennis L. [215]. Compounds had an antimicrobial... 

Enniatins J2 and J3 were isolated by Pohanka et al. in 2004 from Fusarium sp. strain F31 by bioassay-guided isolation directed against Botrytis cinerea . ... 

The majority of the active constituents from the family Amaryllidaceae are alkaloids. These alkaloids have been isolated first and thereafter evaluated for their biological activities. A bioassay guided isolation of active extracts may lead to the isolation of interesting non-nitrogenons compounds that could be used as leads for the synthesis of nseful therapentic dmgs. 

B. Pezzuto, J. M. Kinghom, A. D., Activity-guided isolation of antioxidative constituents of Cotinus coggygria, J. Nat. Prod, 2000, 63, 1696-1698. 

Bioassay-guided Isolation and Anti-inflammatory Studies... 

Several examples of bioassay-guided isolation are given in the literature. Recio et al [47] used a topical irritant agent to track the activity during the isolation of the anti-inflammatory triterpenes from Diospyros leucomelas, whereas Cuellar et al. [48] employed a combined system of in vivo and in vitro experiments, consisting of the inhibition of an enzyme activity Fig. (1) . Other authors prefer in vitro models. Ammon and Safayhi [49] used the inhibition of leukotriene formation in rat peritoneal neutrophils to isolate the boswellic acids of gum resin exudate of Boswellia serrata, whereas Takaishi et al. [42] studied the inhibition of interleukin-1 secretion, and Jain et al. [50] studied the in vitro inhibition of phospholipase A2 activity. The main results of these studies are summarised in the pharmacological activity section of this chapter. 

Multiple chromatographies are needed to purify benzophenones, and a variety of normal and reversed-phase solvent systems and solid phases including column chromatography over silica gel, reversed-phase, and Sephadex LH-20, as well as preparative TLC and HPLC have been employed. Isolation methods for selected benzophenones are given, and our experiences with the activity-guided isolation of xanthochymol (138) from G. xanthochymus fruits are discussed. 

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