Extraction and characterization, and determination of biological activities of astaxanthin from deep water pink shrimp (Parapenaeus longirostris Lucas, 1846) shell wastes

In this study, astaxanthin extract was obtained from deep-water pink shrimp (Parapenaeus longirostris) shell waste by ultrasound- assisted extraction using six different organic solvents, the astaxanthin extract was characterized and compared with commercial astaxanthin standard. All extracts were tested quantitatively by HPLC. Astaxanthin extractions were performed for different times (2 and 4 hours) using selected apolar/ polar solvents (petroleum ether, hexane, isopropanol, ethanol, methanol, acetone). The results showed that the solvent with higher polarity was more suitable more for astaxanthin extraction and the effect of time on extraction yield varied according to the type of solvent. UV-VIS spectra for astaxanthin extract and astaxanthin standard showed maximum absorbance in the visible region in the range of 480-520 nm, which is the characteristic absorbance of astaxanthin. FT-IR spectrometry was used to confirm the fingerprint region of astaxanthin extract with C=O stretching vibration, methyl group (aliphatic) (-CH), ketone group (-C=O) (6-membered ring), alkenes (C-C, C=C) and C- CH₃ stretching bonds. In the Raman spectrum, all characteristic values reflect the molecular vibrations of the conjugated polyene chain and its bonded groups, providing a distinct spectral fingerprint for the astaxanthin extract. The % DPPH radical scavenging activity of astaxanthin extract varied with concentration and was found to be 64% at 100 µg/ml. Antimicrobial activity was determined by disc diffusion and agar well diffusion method for 7 different microorganisms. While the highest effect was observed against Bacillus subtilis in the disk diffusion method, inhibition effect was observed on all microorganisms tested in the agar well diffusion method. Antibiofilm activities for Brevibacillus parabrevis, Bacillus amyloliquefaciens spp. plantarum, Acinetobacter lwoffii and Bacillus endophyticus were examined and MIC values were determined. It showed the highest biofilm reducing activity on Bacillus endophyticus with 92% at a concentration of 50 μL. Different concentrations of astaxanthin extract were applied to A549 (adenocarcinomic human alveolar basal epithelial cells) and MCF-7 (human breast cancer cell line) cells, IC50 values were calculated and it was observed that the decrease in cell viability was related to astaxanthin concentration.