Chromatography Lichen substances

Asahina and Shibata published another classic, Chemistry of Lichen Substances, in 1954. Both scientists and their coworkers not only elucidated the structure of numerous compounds, but also described their synthesis and introduced the determination of lichen substances by microcrystallization, a remarkable progress in times without thin layer chromatography and high performance liquid chromatography. Other important work on the chemistry of lichen substances was done by Roller, Pfau,... [Pg.3]

Extraction has to be continued until all lichen substances are dissolved (6-60 h). Often heavily soluble compounds precipitate in the extract and can be removed by filtration. One way to work up the extract is separation in an acid, a phenolic and a neutral part, by shaking successively with a solution of NaHCOj (10% in H2O) and NaOH (2% in HjO). Some compounds, e.g. chlorinated phenolics, are soluble in a solution of Na2C03 (5% in H2O). Shaking should be continued for 10-15 min. Another way is chromatography of the extract over silica gel. The ratio of product to adsorbent is about 1 30 to 1 50, and an approved sequence of eluents is n-hex-ane-diethyl ether-methanol. Many extracts are heavily soluble in n-hexane to overcome this difficulty, the mixture is dissolved in a proper... [Pg.11]

Thin layer chromatography (TLC) is now the method of choice for the rapid determination and identification of lichen substances, and nu-merous papers have been published on this subject. Santesson (1967) reported the Rf values of about 80 lichen substances, and Yoshimura and Kurokawa (1977) investigated the sensitivity of TLC for several lichen substances lecanoric... [Pg.47]

Gas liquid chromatography (GLC) has found only limited application in lichen chemistry because most lichen substances are very polar and have low volatility. To overcome this problem, more volatile derivatives are used. Nishikawa et al. (1973) analyzed the low molecular weight carbohydrates of eight lichen species as their acetyl, trifluoroacetyl and trimethylsilyl derivatives by GLC under the following conditions Hj,... [Pg.107]

Santesson J (1967) Chemical studies on lichens. 4. Thin layer chromatography of lichen substances. Acta Chem Scand 21 1162-1172... [Pg.469]

Shibata S, litaka Y (1984) Renewed studies on the structure of didymic acid. Chem Pharm Bull 32 366-368 Shibata S, Furuya T, lizuka H (1965) Gas liquid chromatography of lichen substances. 1. Studies on zeorin. Chem Pharm Bull 13 1254-1257... [Pg.470]

Strack D, Feige GB, Kroll R (1979) Screening of aromatic lichen substances by high performance liquid chromatography. Z Naturforsch 34c 695-698... [Pg.471]

Chemical methods As with many areas of natural product chemistry, new impetus in the chemistry of lichen substances is provided by the more rapid and improved methods for detecting, isolating and purifying these compounds and in determining their structure. The techniques of preparative TLC, radial chromatography and preparative HPLC provide rapid and efficient methods for the purification of lichen substances and developments in mass spectrometry, proton and carbon-13 nuclear magnetic resonance (NMR) spectroscopy and X-ray analysis greatly aid structural smdies. [Pg.17]

Fahselt, D. Gas-Liquid Chromatography of the Lichen Substance Usnic Acid. Bryologist 78, 452 (1975). [Pg.224]

A number of methods are available for visualizing the spots after chromatography. If the adsorbent is impregnated with a fluorescence indicator, most aromatic compounds will be visible in UV light. Even on ordinary adsorbents (e.g., silica gel G) many aromatic compounds will exhibit a characteristic fluorescence in UV light. Nearly all lichen substances can be made visible by spraying the chromatographed plates with a 10% solution of sulfuric acid... [Pg.640]

Publications on Thin Layer Chromatography of Lichen Substances... [Pg.641]

High performance liquid chromatography is an ideal supplement of or replacement for identification of lichen substances because it is more sensitive and can be interpreted quantitatively. Applications of HPLC in lichen chemistry are summarized in Table 1. [Pg.6]

L Arup U, Ekman S, Lindblom L, Mattson J-E (1993) High Performance Thin Layer Chromatography (HPTLC), an Improved Technique for Screening Lichen Substances. Lichenologist 25 61... [Pg.240]

High-performance liquid chromatography (HPLC) This method was applied to identify and quantify characteristic substances in commercially available oakmoss products. This technique provides a powerful complement to the established TLC method. The bonded reverse phase columns are used here, and all the aromatic lichen products are suitable for analysis with this method. Samples are dissolved in methanol and injected in to the appropriate portion column, through which an... [Pg.16]

Preparative-layer chromatography has been used in some cases, especially when small quantities of substance are involved. Culberson and Kristinsson (1969) separated some depsides on silica gel plates with Pastuska s mixture. Piattelli and Guidici de Nicola (1968) isolated anthraquinones, Santesson (1970a) isolated bis-anthraquinones and Santesson (1969b) isolated xan-thones, in all cases on silica-gel plates. Bloomer et al. (1970a,b) reported on preparative-layer chromatography of some aliphatic lichen acids and Aberhart et al. (1970) isolated portentol and its acetate by PLC. [Pg.648]

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