The analysis and stability of carotenoids in the flowers of daylily (Hemerocallis disticha) as affected by soaking and drying treatments were studied. The various carotenoids in the flowers of daylily were analyzed using a reversed-phase C(30) HPLC column and a mobile phase of methanol/methylene chloride/2-propanol (89:1:10, v/v/v) with methanol/methylene chloride (45:55, v/v) as sample solvent. Twenty-one pigments were resolved, of which 14 carotenoids were identified, including neoxanthin, violaxanthin, violeoxanthin, lutein-5,6-epoxide, lutein, zeaxanthin, beta-cryptoxanthin, all-trans-beta-carotene, and their cis isomers, based on spectral characteristics and Q ratios. Prior to hot-air-drying (50 degrees C) or freeze-drying, some of the daylily flowers were subjected to soaking in a sodium sulfite solution (1%) for 4 h. Under either the hot-air- or the freeze-drying treatment, the amounts of most carotenoids were higher in the soaked daylily flowers than in those that were not soaked. With hot-air-drying, the amount of cis carotenoids showed a higher yield in soaked samples than in nonsoaked samples. However, with freeze-drying, only a minor change of each carotenoid was observed for both soaked and nonsoaked samples. Also, air-drying resulted in a higher loss of carotenoids than freeze-drying.
An HPLC method was developed to determine the various carotenoids in Taiwanese mango (Mangifera indica L.). Initially, the peel and seed of mangoes were removed, the pulps were cut into pieces, freeze-dried, ground into powder, extracted and subjected to HPLC analysis. A mobile phase of methanol-isopropanol (99:1, v/v) (A) and methylene chloride (100%) (B) with the following gradient elution was developed: 100% A and 0% B in the beginning, maintained for 15 min, decreased to 70% A in 45 min, maintained for 15 min and returned to 100% A in 65 min. A total of 25 carotenoids were resolved within 53 min by using a C-30 column with flow rate at 1 mL/min and detection at 450 nm. alpha-Carotene was used as an internal standard to quantify all the carotenoids. All-trans-beta-carotene was present in largest amount (29.34 microg/g), followed by cis isomers of beta-carotene (9.86 microg/g), violaxanthin and its cis isomers (6.40 microg/g), neochrome (5.03 microg/g), luteoxanthin (3.6 microg/g), neoxanthin and its cis isomers (1.88 microg/g), zeaxanthin (1.16 microg/g) and 9- or 9'-cis-lutein (0.78 microg/g).
The plasma membrane (PM) of higher plants contains numerous proteins; however, due to their low abundance, only a few have been identified and characterized by direct biochemical approaches. The major intrinsic protein (MIP) family is a class of highly hydrophobic integral membrane proteins thought to function as channels that facilitate the passage of water, small solutes, and possibly other moieties through the membrane. A family of P M intrinsic proteins was purified and characterized from P M vesicles derived from storage tissue of Befa vulgaris L. using the detergent 3-[(3-~holamidopropyI)dimethylammonio]-l -propane sulfonate. This P M intrinsic protein-enriched fraction also contains high levels of UDP-glucose:(l,3)-P-glucan (callose) synthase activity. Dithiothreitol is required to visualize the monomeric species of these highly hydrophobic integral membrane proteins. Sequence analysis of tryptic fragments derived from polypeptides of 31 and 27 kD revealed significant homologies to plant MIPs identified from cloned sequences. These MIPs include clone 7a from pea and RD28 from Arabidopsis, both of which are water-stress proteins, a tomato ripening-associated membrane protein, and PIP 2b, a PM-bound water channel protein from Arabidopsis. MIPs, therefore, represent abundantly occurring components of PMs derived from beet storage tissue.
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