1H NMR Spectroscopy and MVA to Evaluate the Effects of Caulerpin-Based Diet on Diplodus sargus Lipid Profiles

Abstract

The biological invasion of the green algae Caulerpa cylindracea represents a serious scientific and public issue in the Mediterranean Sea, essentially due to strong modifications both to habitat structure and native benthic communities. Although alterations in health status and changes in flesh quality of some marine species (dietary exposed to C. cylindracea) have been observed, no studies on cause-effect relationships have been carried out. Here, for the first time, through a controlled feeding experiment followed by 1H NMR Spectroscopy and multivariate analysis (PCA, OPLS-DA), we showed that caulerpin taken with diet is directly responsible of changes observed in metabolic profile of fish flesh, including alteration of lipid metabolism, in particular with a reduction of ω3 PUFA content. The potential of caulerpin to directly modulate lipid metabolism opens up new questions about causal mechanism triggered by algal metabolite also in view of a possible exploitation in the nutraceutical/medical field.

1H NMR Metabolic Profile of Scyphomedusa Rhizostoma pulmo (Scyphozoa, Cnidaria) in Female Gonads and Somatic Tissues: Preliminary Results

“…Representative 1D 1 H NMR spectra of lipid and aqueous extracts of female gonads and somatic tissues (umbrella and oral arms) of R. pulmo are shown in Figures 1 and 2, respectively. All the 1 H NMR spectra of lipid extracts of body fractions showed the characteristic signals of saturated (SFAs), mono-(MUFAs), di-(DUFAs) and polyunsaturated (PUFAs) fatty acids, triglycerides (TG), and minor components, such as sterols (cholesterol, CHO), phosphatidycholine (PC) and phosphatidylethanolamine (PE) (Table 1, Figure 1), according to the literature data [21][22][23][24] and previously reported by Stabili et al [4]. Interestingly, homarine was clearly identified only in the female gonad lipid extracts, together with a more intense concentration of the fatty acid content with respect to somatic tissues, as already reported in the literature for other scyphozoan jellyfish species [25,26].…”

“…Interestingly, homarine was clearly identified only in the female gonad lipid extracts, together with a more intense concentration of the fatty acid content with respect to somatic tissues, as already reported in the literature for other scyphozoan jellyfish species [25,26]. Analogously, for the 1 H NMR aqueous spectra, the metabolites were assigned on the basis of analysis of 2D NMR spectra (2D 1 H J-RES, 1 H COSY, 1 H 13 C HSQC, and HMBC) and by comparison with published data [21][22][23][24]27,28]. The NMR aqueous spectra of R. pulmo body compartments were characterized by essential amino acids, such as branched-chain isoleucine, leucine and valine, threonine, and no-essential amino acids (alanine, proline, glutamate, β-alanine, glycine, tyrosine).…”

“…In this work, the PLS-DA method was also performed in order to justify the number of components used in the OPLS-DA model [50][51][52][53]. The OPLS-DA analysis is a modification of the usual PLS-DA method which filters out variation that is not directly related to the response and produces models of clearer interpretation, focusing the predictive information in one component, as shown in several recent studies of metabolomics [21,54]. The further improvements made by the OPLS-DA in MVA resides in the ability to separate the portion of the variance useful for predictive purposes from the not predictive variance (which is made orthogonal) [55].…”

“…The minimal number of components required can be easily defined since R 2 (cum) and Q 2 (cum) parameters display a completely diverging behavior as the model complexity increases [58,59]. The results were shown by the optimal bi-dimensional scores plots and relative loadings plots, which were used to identify the molecular components responsible of separation among groups [21,60,61].…”

“…The resulting FIDs were multiplied by an exponential weighting function corresponding to a line broadening of 0.3 Hz before Fourier transformation, automated phasing, and baseline correction. The metabolites were assigned on the basis of 2D NMR spectra analysis (2D 1 H Jres, 1 H COSY, 1 H-13 C HSQC, and HMBC) and by comparison with published data [21][22][23]27,28].…”