Extraction optimization, partial purification, and characterization of sialoglycoproteins from Labeo rohita roes.

In India, fish roes are generally considered worthless garbage and disposed of without recovering the valuable molecules, creating environmental and disposal problems. The present investigation aimed to optimize the extraction conditions, partial purification, and characterization of sialoglycoproteins (RRSGP) from Labeo rohita (rohu) roes. RSM generated optimum conditions for maximum RRSGP (70.49 %) extraction, which were 1.25 M NaCl, 1:32.5(w/v) solid-to-liquid ratio, 47.5 °C temperature, and 3 h time. Further, sialoglycoproteins from RRSGPs were partially purified, and result revealed that obtained peak-1 (PRRSGP) using QFF anion exchange chromatography exhibited higher glycoprotein and sialic acid content (p < 0.05). SDS-PAGE pattern of PRRSGP presented dominant bands of 97 kDa and 27 kDa glycoproteins. FTIR spectrum of PRRSGP confirmed the presence of glycated proteins. HPLC analysis revealed that PRRSGP consists of Neu5Ac. Furthermore, ß-elimination reaction elucidated that PRRSGP contained N-glycosidic linkage. PRRSGP exhibited tyrosine and glutamate as primary amino acids. Glycan part of PRRSGP presented mannose and N-acetyl galactosamine as dominant neutral and amino sugar, respectively. Furthermore, PRRSGP exhibited antioxidant activity with EC50 value for DPPH (8.79 mg/ml) and ABTS (2.21 mg/ml). Besides, RRSGP displayed better protein solubility, foaming, and emulsion properties. Therefore, rohu roes are potential source of sialoglycoproteins that can be recovered and used as bio-functional ingredients in food and nutraceutical applications.

Preparation, purification, and identification of novel antioxidant peptides from red-bellied pacu (Piaractus brachypomus) fish meat protein hydrolysate.

The current study investigates the preparation, purification, and identification of novel antioxidant peptides from Piaractus brachypomus fish (RBPF) meat. Antioxidant peptides from RBPF meat protein hydrolysate (RPMPH) were fractionated by ultrafiltration (3 kDa MWCO membrane). RPMPH-IF (MW < 3 kDa) fraction displayed significantly higher antioxidant activities (P < 0.05) (DPPH, ABTS, FRAP, and Fe2+chelating activity). RPMPH-IF was purified by Sephadex G-25 gel filtration chromatography, and the RPMPH-1 fraction exhibited significantly higher antioxidant activities (P < 0.05). Subsequently, the RPMPH-1 fraction was purified by reversed-phase high-performance liquid chromatography. RPH-8 showed the highest antioxidant activities. The sequence of peptides of the RPH-8 fraction was later identified by LC-MS/MS and MASCOT software. RPH-8 fraction showed the two peptides with MW of 1105.52 Da and 748.25 Da, and the sequence of peptides was identified as His-Asn-Leu-Gly-Leu-Leu-His-Gly-Asp-Met and Asp-Ala-Pro-Ser-Met-Asn-Asp, respectively. Thus, RPMPH or purified antioxidant peptides produced by probiotic Bacillus strain could be a bio-functional ingredient in food and nutraceutical applications.