The ionic characteristics and extraction of porphyra-334 from Bangia atropurpurea
Date Issued
2016
Date
2016
Author(s)
Chuang, Li-Fan
Abstract
Mycosporine-like amino acids (MAAs) exist in Bangia atropurpurea which probably has the highest content of MAAs, compared with the other studied organisms. Porphyra-334 (p-334) was found the major component of MAAs in B. atropurpurea. Hence, we choose the species as the object material for extraction and purification for p-334. The major material applied for the p-334 isolation was purchased from Putian in 2008 and has been stored in refrigeration since then. Water extract of B. atropurpurea was forced to pass through the cationic AG® 50W-X8 resins, then eluted by 0.2% acetic acid to obtain the p-334 of 63% purity, and futher purified by a C-18 reversed phase high performance chromatography. Tedious 1H-NMR and 13C-NMR measurements of p-334 were performed following a series of pH changes from titration. It was found that a siginificant upfield change of chemical shifts at H2-9, H-11, H-13 and C-1, C-2, C-3 with the increase of pH. We assumed that the structure of p-334 was deprotonated following the increase of pH. (1) bisprotonated at pD 0.9; (2) monoprotonated at pD 3; and (3) zero net charge at a pD over 4. This result also verified the condition of p-334 desorption from resins. Based on the literatures which indicate a complete MAAs extraction can be got after three subsequent extractions of 25% methanol at 45oC for 2 hours on any organisms. We found that more than 70% of the MAAs in the B. atropurpurea of commercial product could be easily extracted by a simple percolation. In such cases, some of the materials were treated by mimicking the natural conditions or the commercial operations on the specimen after collected from the northeast coast of Shicheng. In order to understand the chemical nature of p-334 in thalli and the optimal extraction methodology that can be applied in the commercial operation, we performed various treatments. We observed the leaching of MAAs of the dried specimen were less in sea water than in fresh water, and less in freshly prepared sample than old storage sample. From these observations, we presumed the algae inhabiting at the high tide zone developed extracellular MAAs as sunscreen to protect the cells during low tide and remained as a bound form, and gradually become dissociated form during the storage.
Subjects
Bangia atropurpurea
mycosporine-like amino acids
extraction
titration
ionic state
Type
thesis
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