550

cn~orfr. 4131

Thin-layer chromatography

NOTES

of furanocoumarins

Thin-layer chromatography (TLC) of furanocoumarins has been described in a series of papers l--8, but no satisfactory separation has been achieved for the eight com- pounds listed in Table I. While studying coumarin derivatives present in the roots of Heracleum madegazziamm Somm. & Lev. 4, these simple furanocoumarins became of interest. Thus the development of TLC conditions necessary to separate these com- pounds was important.

TABLE I

Rp VALUES AND SPOT COLOURS OF BURANOCOUMARINS

AVO. l3wa?zocoumavin RF values x zoo” ColoacY

SoEvev2t I SohmE- (puol’mc?zce 254 figw)

I Psoralen 51 46 l3lue 2 Bcrgaptcn 43 51 Yellow 3 Xanthotoxin 33 40 Yellow 4 Isopimpinellin

2 Angelicin :: 4:

Brownish yellow Blue

Isobergapten 58 GO Yellow

87 Sphondin Blue Pimpincllin 4; 5”: Brown

a The Rp values are the average values of ten chromatograms.

BEVRICW~ studied the chrornatographic separation of furanocoumarins on silica gel and reported RF values in several solvent systems. However, when all eight furano- coumarins listed in Table I were present in a mixture, neither solvent system de- scribed gave clearly separated spots corresponding to the eight compounds. Forma- mide-impregnated silica layers’ also cause considerable variation in the Rp values recorded.

BAERHEIM SVENDSEN described the use of aluminium oxide as an adsorbent in column chromatography of furanocoumarins 6--7. We extended this work to TLC on aluminium oxide layers and wish to report the successful separation by two-dimen- sional TLC of the compounds listed in Table I.

We adopted the following method: Fifty grams of Aluminiumoxid G (Merck) were mixed with 60 ml of water, and the slurry was applied to 20 x 20 cm glass plates with a Desaga spreading device. The thickness of the layers was 0~25 mm. The coated plates were air-dried for 20 min at room temperature and were activated in a drying oven for 6 11 at 110~. The samples were applied in diethyl ether solutions. The chroma- tograms were first developed in purified chloroform (Solvent I), were air-dried and were then developed in dibutyl ether-ethyl acetate (88 : 12) (Solvent 2). After drying, the spots were detected by fluorescence in U.V. light (254 nm). The fluorescence of angelicin was first evident after spraying with 0.5 O/o KOEI in methanol, The fluor- escence colours vary from brown-red to blue and facilitate identification of the sepa- rated compounds on the chromatogram.

J. Ciwomalog., 42 (W$) 550-551:

I I st

t

0 0

- 2nd

Fig. I, Two-dimensional chromstogram of tight furanocoumarins. I = psoralcn ; 2 = bergaptcn ; = xanthotoxin; &+ = isopimpincllin; 5 = angelicin; 6 = isobcrgapten; 7 = sphondin; 8 - pim-

$nellin.

The Rp values and spot colours of the eight furanocoumarins are shown inTable 1. Fig. I shows the same compounds separated on a two-dimensional thin layer chroma- togram.

I

De$artmem? of Pharmacognosy, Institute of Pkawnacy, J. KARLSEN University of Leidem, Leiden L. E. J. BOOMSMA (The Netherlands) A. BAIZRHEIM SVENDSEN

I TH. BRYRICH, J. Chyomatog., 2o,(Ig65) 173. 2 N. S.VULPSON,V. J,ZhnETs~;l1 AND L. S. CHETVLRNIICOVh,IZV. Ahad. Nash. SSSR,Sey. I<J&h.,

8 (w’%) 1503. 3 L. WtjRHhMMER, H. WAGNER AND B. LhY,PhaYt?ZaZiC, 15 (1960) 64.5. 4 J, KhRLsEN, I?. v. HAGEN AND A, BhmwEIM SVENDSEN, Medd. Novsiz Faym. Sclsk., 29 (x967)

153. 5 -4. BAERHEIM WENDSEN, Dissevtatiolz, Oslo, 1954. 6 A. BAERHEIM SVENDSEN AND E. OTTESTAD, PhaWL Acta H&J., 32 (1957) 457. 7 A. BAERHEIM SVENDSEN, M. BLYBERG AND E. OTTESThD,Pianta Med., 7 (1959) 113. 8 0. MIKE& Laboyatoyy Handboolz of CItromatogva~hic Metltods, D. Van Nostrand, London, 1966,

p. 204.

Received April 18th, 1969

J. Chyomatog., 42 (1969) 550-551