Determination of carotenoids in two algae species from the saline water of Kapulukaya reservoir by HPLC

The local algae species, Chlorella vulgaris and Scenedesmus regularis, from a highly saline water body of Kapulukaya Reservoir were isolated to analyze their carotenoid composition and content using HPLC method. The gradient solvent system of methanol–acetonitrile–water (84:14:2, v/v/v) and methylene chloride (100%), used to resolve a range of carotenoids from the saponified cells, proved an acceptable separation as inferred from the retention factor (k) ranging between 0.75 and 7.76 and the separation factor (α) values greater than 1. Resolution peaks assigned to carotenoids, 21 for C. vulgaris extracts and 22 for S. regularis extracts, were reached within the duration time of 45?min. Main carotenoids identified either tentatively or positively were all-trans-lutein, 9- or 9′-cis-lutein, 13- or 13′-cis-lutein, cis-lutein, All-trans-α-carotene, 9- or 9′-cis-α-carotene, All-trans-β-carotene, 9- or 9′-cis-β-carotene in the species except for all-trans-β-cryptoxanthin found only in S. regularis. Auroxanthin, neochrome, neoxanthin, and cis-neoxanthin were identified as epoxy-containing compounds. Quantitatively, C. vulgaris was distinguished to have greater amount of lutein and cis-isomers (2.74?mg/g), 77.89% while S. regularis was predominated by β-carotene and cis isomers as major component, being 80.72% (5.76?mg/g) in total carotenoids (TC). In terms of total carotenoids, the species were considered to be efficient sources for further practical applications.     

Cis/trans ISOMERIZATION OF CAROTENOIDS BY THE TRIPLET CARBONYL SOURCE 3-HYDROXYMETHYL-3,4,4-TRIMETHYL-1,2-DIOXETANE*

Abstract— The interaction of biological carotenoids with 3-hydroxymethyl-3,4,4-trimethyl-1,2-dioxetane (HTMD), a thermodissociable source of electronically excited ketones, was investigated using reversed-phase high-performance liquid chromatography. Incubation of the all-trans isomers of β-carotene, lycopene and canthaxanthin with HTMD led to significant trans-to-cis isomerization, with cis isomers accounting for 20–50% of products formed (the balance assigned as oxidation products). The isomers forming from all-trans-β-carotene were identified as 9-cis-, 13-cis- and 15-cis-β-carotene by cochromatography of cis isomer standards and by on-line diode array absorbance spectroscopy. An HTMD-dependent cis-to-trans isomerization was observed in incubations started with 15-cis-β-carotene, and it occurred more rapidly and to a greater extent than the isomerization of all-trans-β-carotene. The isomer patterns generated from lycopene and β-carotene are generally similar to those reported recently for various human tissues (Stahl et al, 1992, Arch. Biochem. Biophys. 294 , 173–177).     

An improved method for extraction of β-carotene from blakeslea trispora

An improved method for the extraction of β-carotene from Blakeslea trispora is described. The fermentation broth was steamed at 121°C for 15 min, and the liquid was centrifuged at 5000g for 20 min. β-Carotene was removed from the biomass by extraction with absolute ethanol at a ratio of 1:100 at 30°C for 2 h in a rotary shaker incubator at 300 rpm. The carotenoid pigment was completely removed from the cells after three repeated extractions. The removal of β-carotene from B. trispora was higher during the first stage (75%) whereas in the other stages it was very slow.     

The photoisomerization of retinal

Abstract— –Quantum efficiencies have been measured for the photoisomerization of four stereoisomers of retinal (all-trans, 13-cis, 11 cis, and 9-cis) in two solvents at different wavelengths of irradiation and at various temperatures. In heane at 25°C the quantum efficiencies for isomerization at 365 nm are: 9-cis to trans, 0.5; 13-cis to trans, 0.4; 11-cis to trans, 0.2; all-trans to monocis isomers, 0.2-0.06, depending upon assumptions made regarding the stereo-isomeric composition of the product. These values vary somewhat with the wavelength of the irradiating light. The quantum efficiency for the photoisomerization of all-trans retinal in hexane decreases by a factor of 30 when the temperature is lowered from 25° to – 65°C; the activation energy for this photoisomerization is about 5 kcal/mole. The quantum efficiencies for the isomerization of the monocis isomers to all-trans retinal in hexane are virtually independent of temperature. In ethanol the rates of photoisomerization from trans to cis or cis to trans depend only slightly on the temperature between 25° and – 65°C. The photosensitivities of the stereoisomers of retinal are of the same order of magnitude as those of the retinylidene chromophores of rhodopsin (11 -cis), metarhodopsin I (all-trans), and isorhodopsin (9-cis); but it is not yet possible to derive the photochemistry of rhodopsin uniquely and quantitatively from that of retinal.     

Trennung und Charakterisierung von β-Carotin-Isomeren

Separation and Characterization of the cis-Isomers of β,β-Carotene A stable HPLC. system is described allowing the excellent separation of 11 different cis-isomers of β,β-carotene from the all-trans compound. The system is applied to the analysis of cis/trans mixtures obtained from plant extracts and by photoisomerization of the all-trans isomer. Al₂O₃ is used as the stationary phase while hexane with controlled H₂O content is utilized as the mobile phase. With the aid of the optimum conditions 8 sufficiently stable cis isomers were isolated and their structures shown to be the 9-, 13- and 15-cis, the 9,9′-, 9, 13-, 9, 13′- and 13,13′-di-cis and, tentatively, the 9,13,13′-tri-cis β,β-carotenes by application of 270-MHz-FT.-¹H-NMR. spectroscopy.     

9-CIS, 11-CIS-RETINAL* FROM DIRECT IRRADIATION OF ALL-TRANS-RETINAL. NEW GEOMETRIC ISOMERS OF VITAMIN A AND CAROTENOIDS 9

Abstract The irradiation mixture of all-trans-retinal in acetonitrile was shown to contain four cis,cis isomers as well as the four cis isomers reported earlier. The relatively new 9-cis, 11-cis-retinal was isolated and characterized.     

Optimization of the isocratic non-aqueous reverse phase (NARP) HPLC separation of trans/cis-α-and β-carotenes

Non-aqueous reverse phase chromatography was used to optimize the separation of all-trans-α- and β-carotenes and their cis isomers extracted from dried carrots. The technique can easily be applied to routine assays. Optimization was carried out by modifying the concentrations of methylene chloride and acetonitrile, and by studying the influence of temperature on the capacity factors and selectivity. The effect of the type of C 18 stationary phase bonding (mono- and polyfunctional) on separation was also examined. The need for polymeric bonding on the stationary phase is stressed for the realization of the trans/cis isomer separation.     

A 1H NMR study of tautomerism in some 1-arylamino-3-aryliminopropenes

¹H n.m.r. spectra at ambient temperatures reveal that an equilibrium exists between the ‘all-trans’ and ‘all-cis’ isomers of some of the 1-arylamino-3-aryliminopropenes. The ‘all-cis’ isomer predominates in nonpolar solvents, whereas the ‘all-trans’ isomer is favoured in hydrogen bonding solvents. From a consideration of the magnitudes of the ³J coupling constants, it is reported that the ‘cis-trans’ isomer is the most stable form of the 4-nitrophenyl derivative in dimethyl sulphoxide.     

Synthesis and the reversed-phase HPLC analysis ofcis andtrans-dichlorobis(ethylenediamine-ruthenium) chloride isomers

Summary In this work we report the monitoring of the synthesis ofcis andtrans-dichlorobis(ethylenedia-mine)ruthenium chloride isomers by HPLC. The preparation of thecis andtrans complexes were as described in the literature with modifications arising from reversed-phase HPLC results. Thecis andtrans complexes were separated with retention times of 3.0 min and 5.5 min respectively using an ODS column (250 mm×4.6 mm i.d. 5 μm particles, Alltech) and methanol/water 45/55 ratio as mobile phase. According to HPLC results the reaction time to completion is 48 h and not 72 h as previously described. The shorter time resulted in better yield 82% and reduced by-products.     

PREPARATION AND PROPERTIES OF NEW VISUAL PIGMENT ANALOGUES FROM 5,6-DIHYDRORETINAL AND CATTLE OPSIN*

Abstract— On irradiation of all-trans 5,6-dihydroretinal (I), two opsin-active isomers are formed. Both these isomers (believed to be the 11-cis and 9-cis isomers) individually couple with cattle opsin to form complexes which have maximal absorption at 465 nm. These complexes satisfy all the established criteria characteristic of synthetic visual pigments.