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Poultry viscera protein hydrolysate (PVPH) was fractionated using ultrafiltration membrane into three peptide fractions viz. Fractions I (>10 kDa), II (3–10 kDa) and III (<3 kDa) with yield of 13.4, 18.4 and 66.6%, respectively. Antioxidant activity of PVPH and its fractions was determined in terms of radical‐scavenging activity (RSA), reducing power (RP), total antioxidant activity (TAA) and antioxidant activity index (AAI). PVPH exhibited excellent RSA and TAA at peptide concentration of 0.2 and 2.0 mg/mL, respectively. It also showed RP value as 0.4, and AAI as 500 after 100 min at peptide concentration of 9 and 30 mg/mL, respectively. Scavenging of 2, 2′‐azinobis (3‐ethyl‐benzothiazoline‐6 sulfonic acid) and hydroxyl radicals by Fraction III was found to be significantly higher than other fractions, while superoxide scavenging activity was independent of peptide size. Fraction I exhibited better RP, TAA and AAI. PVPH and Fraction III showed the highest angiotensin‐converting enzyme (ACE) inhibitory activity (IC50 = 0.34 mg/mL). PRACTICAL APPLICATIONS Poultry viscera are an underutilized by‐product of poultry processing industry. A rapid autolytic method was developed in our laboratory to prepare a hydrolysate from this tissue. In order to find the potential application of this value‐added product, antioxidant and angiotensin‐converting enzyme inhibitory properties of the peptide fractions of the hydrolysate were evaluated.

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Michael addition reactions of bis(amino acidato)metal(II) complexes (metal = copper, nickel, zinc; amino acid = glycine, dl-alanine, l-alanine) with acrylonitrile have been carried out under various experimental conditions in the absence of a base, resulting in mono- and disubstituted products in high yield, including partially hydrolyzed products. A reaction mechanism for the Michael addition on the nitrogen atom of the coordinated amino acid moiety, replacing the amino hydrogen atom(s), is proposed. All of the products have been characterized by Fourier transform infrared spectroscopy, electron paramagnetic resonance spectra, and elemental and electrochemical analyses. The single-crystal structures of bis( N-cyanoethylglycinato)copper(II) monohydrate ( 1a), diaquabis( N-cyanoethylglycinato)nickel(II), aquabis( N, N-dicyanoethylglycinato)copper(II) ( 2a), and bis[( N-propionamido- N-cyanoethyl)glycinato]copper(II) dihydrate ( 4a) have been confirmed by X-ray diffraction techniques. The products 1a, 2a, 4a, and bis( N-propionamidoglycinato)copper(II) monohydrate ( 3a) have been used as catalysts for the degradation of a phenol red dye and mild oxidation of various organic substrates in the presence of hydrogen peroxide. The monosubstituted complexes have been found to catalyze the reactions to a greater extent than the disubstituted complexes.