The aim of the present research was 1) to extract carnosine from different low economic value poultry tissues and 2) to measure their antioxidant activities using different analytical methods. Low economic value poultry tissues such as the head, liver, lungs, tail, gizzard, brain, and heart were used in this study. Results have indicated that carnosine was present in all the tissue samples investigated. The liver had the highest (102.29 mg/g) and brain the lowest carnosine content (0.95 mg/g; P ≤ 0.05). Except for the brain, all tissue ultrafiltrates and reconstituted dry powders showed TBA reactive species inhibition ranging from 20.87 to 39.57% and 5.66 -14.47%, respectively. Free radical scavenging activity of ultrafiltrate from all tissues samples ranged from 25.11 to 79.38%, whereas this activity was higher (29.76 to 84.05%) in the reconstituted dry powder of all tissue samples. Conclusions include that extraction of bioactive dipeptide carnosine can be exploited from low economic value poultry tissues to increase the economy of the poultry industry.

The objective of the present study was to compare carnosine levels in tissues of broilers under stress conditions with those of broilers under nonstress conditions. Blood heterophil:lymphocyte ratio and corticosterone levels were measured as indicators of the level of stress. Corticosterone levels of stressed broilers (24,358.67 pg/mL) were 10-fold higher (P = 0.002) than those of nonstressed broilers (2,275.46 pg/mL). However, no difference (P = 0.29) was found in heterophil:lymphocyte ratio of nonstressed (0.29) and stressed (0.31) birds. Carnosine content in breast of stressed birds (17.39 mg/g) was 10 times higher (P = 0.005) than that of nonstressed birds (1.85 mg/g). Carnosine content in thigh of stressed birds (21.25 mg/g) was approximately 2-fold higher (P = 0.001) than that of nonstressed birds (11.10 mg/g). Carnosine content in brain of stressed birds did not differ (P = 0.82) from that of nonstressed birds. Based on the present study, muscle carnosine recovery levels increase during short-term stress, whereas levels in the brain are not affected.

A study was conducted to compare and analyze the antioxidant mechanism of carnosine to its constituent amino acids (β-alanine and L-histidine) and to imidazole. Concentrations ranging from 5 to 100 mM of carnosine, β-alanine, L-histidine and imidazole were prepared and antioxidant activity assays (TBARS inhibition, metal chelating activity, free radical scavenging activity) were conducted. The TBARS inhibition of carnosine was due to the imidazole ring present in the histidine and with no inhibition contributed to β-alanine. Metal chelating properties of carnosine was also due to the imidazole ring and not to histidine or β-alanine, while free radical scavenging activity of carnosine was attributed to histidine and not due to imidazole or β-alanine. Overall, results demonstrate that β-alanine and the peptide bond between L- histidine and β-alanine do not play a role in the antioxidant activity of carnosine. Furthermore, results show that  imidazole has antioxidant properties alone, and therefore, it could be used as an antioxidant in various foods and feed applications.