Ethanol extracts of brown seaweeds from Pakistan and China were isolated and compared for their antiallergenic activities. They included Sargassum tennerimum (ST) and Sargassum cervicorne (SC) from Pakistan, and Sargassum graminifolium turn (SG), Sargassum thunbergii (STH), and Laminaria japonica (LJ) from China. The ethanol extracts of these brown seaweeds were optimized at 85% (v/v) ethanol for the maximum yield of phlorotannin, an inhibitor against hyaluronidase. Total phlorotannins contained in the crude extracts were measured as 1.71% (SG), 0.74% (STH), 0.97% (LJ), 3.30% (SC), and 5.06% (ST). The 50% inhibitory concentrations (IC(50)) of Pakistani SC and ST were 109.5 and 21 microg/ml, respectively, lower than those of Chinese SG, STH, and LJ (134, 269, and 148 microg/ml, respectively). An antiallergic drug, disodium cromoglycate (DSCG), had an IC(50)=39 microg/ml, and a natural inhibitor of hyaluronidase, catechin, had an IC(50)=20 microg/ml. The IC(50) of ST extract was found similar to that of catechin (21 vs 20 microg/ml) and lower than that of DSCG (21 vs 39 microg/ml). This suggests that ST is a potent inhibitor of hyaluronidase, indicating a promising future development of natural antiallergic medicines or functional foods.
In order to better understand shrimp allergen, some basic characters of the major allergen of greasy-back shrimp (Metapenaeus ensis) were investigated. The major allergen was extracted and separated, and its peptide mass fingerprint (PMF) was analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). After screening in the NCBI database with Mascot searching engine, the results indicated that the major allergen of greasy-back shirmp was muscle tropomyosin. Database matching search showed that the top protein matched, i.e. the tropomyosin from giant tiger prawn (Penaeus monodon), had a Mowse value of 268. In addition, there were 27 queries matched with the allergen in greasy-back shirmp with an amino acid sequence coverage value of 65%. The matching scores and the sequence coverage values were also high with tropomyosins of other invertebrates, including Tyrophagus putrescentiae and Lepisma saccharina. These results indicated that the allergen of Metapenaeus ensis had high homology with other crustacean allergens, and provided molecular explanations for the high cross-reactivity of the major allergens between crustaceans and some other invertebrates.
Polyphenols from the ethanol extracts of Sargassum tenerrimum (ST) with potent antiallergic effects were studied to optimize separation process through column chromatography. The adsorption and desorption characteristics of three widely used adsorbents: macroporous resin, silica gel, and polyvinylpolypyrrolidone (PVPP), were critically evaluated respectively and studied for the optimization of preparative separation of polyphenols. Static operations on these adsorbents showed that macroporous resin had the best adsorption and desorption capability among the three adsorbents. Dynamic adsorption and desorption with macroporous resin packed column were also conducted to optimize the parameters such as: with the optimal values shown in brackets, the concentration of extract solution (4 times diluted), pH value (6−7), adsorption speed (3 BV h -1 , bed volumes/per hour), concentration of ethanol (80%), elution speed (3 BV h -1 ) and elution volume (7 BV). The chromatographic process so optimized gave a purity of 62.43% from the crude polyphenols, providing a promising basis for large scale preparation of bioactive polyphenols upon further scaling up tests.
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