Complementarity of Raman and Infrared spectroscopy for rapid characterization of fucoidan extracts

Abstract

Background Fucoidans are sulfated polysaccharides from the cell-wall of brown algae. They have a wide range of applications in medicine, including regenerative medicine, ophthalmology, cancer, and autoimmune disease. Biological activity of fucoidans directly depends on their structure, which remains poorly understood. This is primarily because the polymeric nature of these molecules limits the use of nuclear magnetic resonance and mass spectrometry, classical tools of structural biology for their structural characterization. Raman and Infrared spectroscopies are non-invasive and non-destructive techniques that can be used to probe the structural organization of biological specimens. In this study, we investigate the potential of Raman and Infrared spectroscopy for structural analysis of several fucoidan extracts. Results Our results show that Infrared and Raman provide different but complimentary information about the structure of crude extracts of fucoidans, revealing the presence of minor impurities from co-extractants. We also found that at high extraction temperatures acidic conditions limit formation of melanoidins, while also yielding relatively high sulfate ester fucoidan. However, at high temperatures, water extraction may potentially result in formation of advanced glycation end products. Their presence could be problematic for fucoidan extracts intended for medicinal use, as advanced glycation end products have been linked to endocrine interruption mechanisms in vivo by crosslinking to and permanently altering extracellular matrix proteins. Conclusion Raman and Infrared can be used as complementary tools for rapid screening of crude fucoidan extracts, which can be a valuable tool for assessing impurities that remain after extraction.

Characterization and Cytotoxic Activity of Microwave-Assisted Extracted Crude Fucoidans from Different Brown Seaweeds

“…The IR spectra in Figure 1 confirmed the previous findings and showed that L. saccharina fucoidan is atypical, where the S=O band at 1240 cm −1 was wide and compressed, in addition to the C-O-S band at 874 cm −1 was reduced to a narrow band without showing any complicated pattern. Nevertheless, fucoidans derived from Fucales , i.e., F. spiralis and F. vesiculosus showed relatively similar IR spectra revealing the complicated region at 840 cm −1 being suggestive for the equatorial pattern of sulfation at C-4 and C-2 consistent with previous publications [ 41 , 54 ]. Though, with comparison with the purified form of F. vesiculosus , all extracted fucoidans showed an additional band at around 1420 cm −1 , which may correspond to -C-H deformation of formed melanoidins [ 54 ].…”

“…Nevertheless, fucoidans derived from Fucales , i.e., F. spiralis and F. vesiculosus showed relatively similar IR spectra revealing the complicated region at 840 cm −1 being suggestive for the equatorial pattern of sulfation at C-4 and C-2 consistent with previous publications [ 41 , 54 ]. Though, with comparison with the purified form of F. vesiculosus , all extracted fucoidans showed an additional band at around 1420 cm −1 , which may correspond to -C-H deformation of formed melanoidins [ 54 ]. The higher intensity of this band in MAE products suggested that the higher temperature accompanied with MAE helped in Maillard reaction occurrence between protein and carbohydrate contents resulting in formation of melanoidins.…”

Characterization of Silver Nanoparticle Systems from Microalgae Acclimated to Different CO2 Atmospheres

“…On the other hand, in Raman, the sample is excited by scattering light that characterizes the rotational and vibrational modes of the sample. Therefore, FTIR is useful for identifying functional groups and determining the molecular structure of the sample, while Raman is better suited for identifying specific chemical bonds and detecting impurities in similar samples without the need of destructive and time-consuming analytical techniques . Additionally, when a molecule is Raman active, it is IR -inactive and vice versa .…”

Rapid analysis of Radix Astragali using a portable Raman spectrometer with 1064-nm laser excitation and data fusion with PLS-DA

“…NIR dispersive Raman scattering, typically excited in the range of 780-1100 nm, produces minimal uorescence and makes detection of the weak Raman signal easier. The use of a longer wavelength (such as 1064 nm) can improve the identi cation of minerals [24], dyes [25], cells [26], and cell extracts [27]. However, among the reported reviews, little attention has been paid to the application of 1064-nm Raman spectroscopy in the identi cation of Chinese medicinal materials and herbs.…”