Silk oak flowers as a source of β-carotene

The pigment of the yellow flowers of the silk oak (Grevillea robusta, Cunningham) does not appear to have been investigated heretofore. If the dried material is extracted with ether, the solution shows typical absorption maxima at 483 and 453 mµ,corresponding to the spectrum of p-carotene. The rather blurred borders of these bands indicate, however, the presence of other polyenic pigments in small quantities. After saponification a photometric analysis of the total extract gave values which would correspond to 270 mg. of β-carotene in 1 kilo of the dry flowers if no other pigments were present. After a chromatographic separation the true β-carotene content was found to be about 215 mg. per kilo. Two-thirds of this amount was isolated as crystals; lycopene or γ- and α-carotene were not present [1]. The non-carotene fraction is a complicated xanthophyll mixture in which no single compound predominates. From this fraction two very small amounts of crystalline material were isolated, one of which was kryptoxanthin and the other a new carotenoid possessing a remarkably short wave-length spectrum. For the separation and study of carotenoids contained in extracts we suggest the systematic use of the ultraviolet lamp which has been so helpful in the chromatography of colorless substances (2). Plant pigments are frequently accompanied by large amounts of colorless material which prevent the formation of sharp pigment zones in the Tswett column and thus a satisfactory separation of the components. Furthermore, the crystallization of some carotenoids may be hindered. Fortunately many such colorless substances show an intense fluorescence (3). An observation made in ultraviolet light during the chromatographic separation of the pigments may furnish a good indication of the best method and optimum extent of developing the chromatogram. The distribution of the fluorescence may also indicate the lines at which it is best to cut the column. By sacrificing small amounts of pigment large portions of colorless associated material may be eliminated in this simple way

The carotenoid and provitamin A content of the watermelon

10 years ago lycopene, C40H56, and carotene, C40H56, were isolated from the pulp of the European watermelon (Citrullus vulgaris, Schrad. = Cucumis citrullus, L.) by Zechmeister and Tuzson (l), and it was shown that the chief pigment, lycopene, is responsible for the red color. As the chromatographic method was not available at that time, no precise information as to the composition of the pigment was obtained. In some new experiments described below we have carried out a quantitative analysis of the components and have estimated the provitamin A content of the California watermelon. 1 kilo of the pulp examined contained 1.0 mg. of a complicated xanthophyll mixture, 6.1 mg. of lycopene, 0.06 mg. of γ-carotene, 0.16 mg. of unknown carotenoids (located in the column between γ- and β-carotene), 0.46 mg. of β-carotene, 0.01 mg. of α-carotene. The figures include the fractions of lycopene, and γ- and β-carotene which underwent isomerization during the experimental procedure (2). The calorimetric value of the total extract of 1 kilo of pulp corresponded to 7 to 8 mg. of “lycopene”; some samples were, however, considerably richer in pigment. Our material, picked in California in September, contained, according to the above figures, 0.5 mg. of provitamin A in 1 kilo of pulp, or about one-fifth to one-sixth of the daily β-carotene requirement of an adult person. It is interesting to note that a considerable number of yellow and pink unidentified oxygen-containing carotenoids were found in minute quantities; i.e., to the extent of about 0.01 mg. per kilo of pulp. Even with the use of chromatography 1000 or more kilos of melon would be needed for a satisfactory study of these pigments. One of them is spectroscopically identical with torulene, detected by Lederer in red yeast (3)

Isolation of prolycopene and pro-γ-carotene from Evonymus fortunei

It has been reported (1) that the ripe seeds of Evonymus europaeus L. (Celastraceae) contain unesterified zeaxanthin, C40H56O2, as the main polyene pigment. The same statement is valid for Evonymus fortunei, var. color., Rehd., commonly termed “winter-creeper euonymus,” from 1 kilo of which 1300 mg. of zeaxanthin were isolated. Upon evaporation of its saponified ether extract and addition of petroleum ether, abundant quantities of zeaxanthin crystallize. This paper describes an investigation of some of the pigments (about 200 mg. per kilo, of which one-fourth is β-carotene) which remain in the mother liquor. The mixture can be resolved by chromatographic analysis. In addition to some twenty less interesting pigments, two representatives of a stereochemically new class of natural carotenoids (2) were separated; viz., prolycopene, C40H56, and pro-γ-carotene, C40H66. The yields of pure crystals were 11 mg. and 0.5 mg. per kilo of seeds respectively. Hence, Evonymus fortunei may serve as a source of prolycopene while it does not offer any larger yield of pro-γ-carotene than does the fruit of Butia capitata (3). According to the foregoing paper (4) Pyracantha angustifolia is the best starting material for the isolation of pro-γ-carotene at the present time

Prolycopene, a Naturally Occurring Stereoisomer of Lycopene

In this paper we record the observation that there occurs in the variety of tomato called "tangerine tomato" a carotenoid, prolycopene, which is an isomer of lycopene; the isomeric relationship is similar to that between lycopene and neolycopene,I and in our opinion prolycopene is to be classed as a naturally occurring neolycopene, being the first observed natural neo form of a C40-carotenoid

Precise radial velocities of giant stars VIII. Testing for the presence of planets with CRIRES Infrared Radial Velocities

We have been monitoring 373 very bright (V < 6 mag) G and K giants with high precision optical Doppler spectroscopy for more than a decade at Lick Observatory. Our goal was to discover planetary companions around those stars and to better understand planet formation and evolution around intermediate-mass stars. However, in principle, long-term, g-mode nonradial stellar pulsations or rotating stellar features, such as spots, could effectively mimic a planetary signal in the radial velocity data. Our goal is to compare optical and infrared radial velocities for those stars with periodic radial velocity patterns and to test for consistency of their fitted radial velocity semiamplitudes. Thereby, we distinguish processes intrinsic to the star from orbiting companions as reason for the radial velocity periodicity observed in the optical. Stellar spectra with high spectral resolution have been taken in the H-band with the CRIRES near-infrared spectrograph at ESO's VLT for 20 stars of our Lick survey. Radial velocities are derived using many deep and stable telluric CO2 lines for precise wavelength calibration. We find that the optical and near-infrared radial velocities of the giant stars in our sample are consistent. We present detailed results for eight stars in our sample previously reported to have planets or brown dwarf companions. All eight stars passed the infrared test. We conclude that the planet hypothesis provides the best explanation for the periodic radial velocity patterns observed for these giant stars.Comment: 14 pages, 6 figures, 3 tables, accepted by Astronomy & Astrophysic

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