Bioactivity of Carotenoids From Shrimp Shell Waste

Abstract- Shrimp processing waste is the single largest industrial waste in the country causing diverse environmental problems. A study was carried out to assess the extractability of astaxanthin from shrimp waste in different organic solvents and vegetable oils. Extraction was tried using wet and dried waste, with and without deproteinisation. Waste was subjected to deproteinisation using alkali and enzyme (pancreatin). The different solvent systems tried were ether:acetone:water (15:75:10 v/v/v), acetone, hexane:isopropanol (3:2 v/v) and 90% acetone v/v. Astaxanthin in the extract was quantified by measuring the OD at 470 nm in hexane. Extraction was also done using vegetable oils viz. coconut oil, soybean oil and sunflower oil. Quantification of astaxanthin in pigmented oil was done by measuring the absorbance at 485 nm using 2155 as extinction coefficient.
Astaxanthin yields from deproteinised samples were significantly lower than those from non deproteinised samples. The highest astaxanthin yield of 87.14 ± 4.55µg/g was obtained with non deproteinised wet waste extracted using acetone. The astaxanthin yield was significantly lower when oil was used as the extraction medium. Of the three oils coconut oil gave the highest yield. The results showed that acetone is the best solvent for extracting astaxanthin from shrimp shell waste in wet condition. The astaxanthin content in Aristeus alcocki shell waste is double that of Pandalus borealis shell waste, which is currently used as the commercial source of astaxanthin. The deep sea species Aristeus alcocki can thus be considered as a better source of astaxanthin for commercial exploitation than Pandalus borealis.
TLC analysis of the shell waste extract showed that it contains free astaxanthin, astaxanthin monoester and astaxanthin diester in the ratio 1:1:2. GLC identification of the fatty acids esterified with astaxanthin revealed that saturated fatty acids, MUFA and PUFA are in the ratio 5:3:2 in monoester, whereas in diester they are in the ratio 4:3:3. The main fatty acids in monoester and diesters are palmitic acid, oleic acid, stearic acid and PUFAs: DHA and EPA.
The in vitro antioxidant activity of the astaxanthin extract showed significant hydroxyl radical scavenging activity, superoxide anion scavenging activity and inhibition of lipid peroxidation. The IC50 values obtained were 56.43 ± 1.06 ng/ml, 27.91 ± 0.54 ng/ml and 26.54 ± 0.42 ng/ml, respectively. The antioxidant activity of astaxanthin from Aristeus alcocki was obtained at nanogram levels. This powerful antioxidant function may be due to the unique molecular structure of astaxanthin and synergistic effect of astaxanthin and PUFAs present in the astaxanthin monoester and diester fractions.
The astaxanthin extract from shrimp shell waste significantly reduced carageenan induced paw edema in mice, percentage inhibition being 47.83 and 67.11 percent at astaxanthin concentrations of 0.5 mg/kg body weight and 1.0 mg/kg body weight, respectively. The inhibition of inflammation at 1.0mg/kg body weight was greater than that produced by the standard reference drug diclofenac. Cardioprotective effect of astaxanthin was examined in isoproterenol induced myocardial infarction in rats. Levels of diagnostic marker enzymes, LDH, CPK, GOT, GPT, CK, CK-MB in plasma, lipid peroxides, ascorbic acid, reduced glutathione and the activities of glutathione-dependent antioxidant enzymes GPx, GR, GST and antiperoxidate enzymes CAT, SOD and the membrane bound enzyme Na+ - K+ ATPase in the heart tissues of experimental groups of rats were determined. The prior administration of astaxanthin @ 10mg/kg feed for 45 days significantly prevented the isoproterenol-induced elevation in the levels of diagnostic marker enzymes in plasma, induction of lipid peroxidation and alterations in the level of reduced glutathione and in the activities of glutathione dependent antioxidant enzymes and antiperoxidative enzymes of experimental rats. Feeding astaxanthin caused a decrease in the inhibition of Na+ - K+ ATPase activity against isoproterenol induced myocardial infarction. The powerful cardioprotective effect of astaxanthin can be attributed to the multiple independent mechanisms viz. antioxidant effects, singlet oxygen quenching ability and inhibition of lipid peroxidation of membranes, increased functional gap junctional intercellular communication, anti-inflammatory effects etc.
Immunostimulatory action of astaxanthin extract was evaluated in experimental mice. Astaxanthin administration was found to enhance the proliferation of spleen cells and bone marrow cells. Esterase activity was found to be enhanced in bone marrow cells indicating increased maturation of cells of lymophoid linkage. Astaxanthin also enhanced number of antibody forming cells and circulating antibody titre. Thus astaxanthin exhibits strong immunomodulating properties.
A significant reduction in the viability of ascites tumour cells DLA in vitro was noted in the current study. The % viability was reduced to 4.34 % at a concentration of 15μg astaxanthin/ml. The cytotoxic action of astaxanthin against DLA may be through induction of apoptosis or through a different pathway. Antitumour activity of astaxanthin was studied by ascite and solid tumour models in mice. An increase in life span of about 67 % was noted in DLA bearing mice administered with astaxanthin at 5 mg/kg body weight. The tumour volume and tumour weight were significantly lower in mice injected with 5 mg/kg body weight astaxanthin. In vitro studies revealed that astaxanthin from shrimp shell waste of Aristeus alcocki inhibited the proliferation of cervical cancer cells HeLa in a dose dependent manner.