The traditional nutritional and medical hemp (Cannabis sativa L.) seed protein were explored for the discovery and directional preparation of new xanthine oxidase inhibitory (XOI) peptides by structure-based virtual screening, compound synthesis, in vitro bioassay and proteolysis. Six subtypes of hemp seed edestin and albumin were in silico hydrolyzed by 29 proteases, and 192 encrypted bioactive peptides were screened out. Six peptides showed to be XOI peptides, of which four (about 67%) were released by elastase hydrolysis. The peptide DDNPRRFY displayed the highest XOI activity IC₅₀ = (2.10 ± 0.06) mg/mL, acting as a mixed inhibitor. The pancreatic elastase directionally prepared XOI hemp seed protein hydrolysates, from which six high-abundance XOI peptides encrypted three virtually-screened ones including the DDNPRRFY. The novel outstanding hemp seed protein-derived XOI peptides and their virtual screening and directed preparation methods provide a promising and applicable approach to conveniently and efficiently explore food-derived bioactive peptides.

This study investigated the combinatorial expression of xanthine dehydrogenase (XDH) and chaperone XdhC from Acinetobacter baumannii and Rhodobacter capsulatus and their applications in decreasing purine content in the beer, beef and yeast. Naturally occurring xdhABC gene clusters of A. baumannii CICC 10254 and R. capsulatus CGMCC 1.3366 as well as two refactored clusters constructed by exchanging their xdhC genes were overexpressed in Escherichia coli and purified to near homogeneity. RcXDH chaperoned by AbXdhC showed nearly the same catalytic performance as that by RcXdhC, except for the decreased substrate affinity. While the AbXDH co-expressed with RcXdhC displayed enhanced acidic adaptation but weakened catalytic activity. All the XDHs degraded purines in beer, beef and yeast extract effectively, indicating potential applications in low-purine foods to prevent hyperuricemia and gout. The study also presents a method for exploiting the better chaperone XdhC and novel XDHs by functional complement activity using existing XdhCs such as RcXdhC.

The aim of this study was to isolate a new purine-degrading potential probiotic strain from Chinese fermented rice-flour noodles and investigate its potential application in purine-degrading food development for promising anti-gout therapy. A new lactic acid bacteria strain designated as Lactobacillus fermentum 9-4 was screened out from 10 Shengzhamifen samples by a comprehensive method integrating agar plate selection, in vitro purine-metabolizing enzymatic activities of xanthine oxidase and urate oxidase, 16S rRNA gene sequencing and identification. The resting cells of L. fermentum 9-4 showed the maximum degradation rates of inosine and guanosine by respective 2.13 × 10⁻³ and 2.78 × 10⁻³ g/(L·min), and the highest assimilation ratio of guanosine by (55.93 ± 3.12)%, which are improvements over LAB strains characterized previously. Yogurt fermented by L. fermentum 9-4 also efficiently assimilated the inosine and guanosine, with respective degradation rates of 98.10 % and 98.56 % higher than those of the commercial ones. The L. fermentum 9-4 showed excellent survival (> 80 %) under the conditions of pH 2.5 and 0.1 % bile salt. The results suggest that L. fermentum 9-4 may be a promising candidate as a probiotic for developing low-purine foods.