Interaction-based screening, Monte Carlo Bayesian inference-based de novo design and in vitro verification of adenine-binding peptide.

One of the main reasons for hyperuricemia is high purine intake. The primary strategy for treating hyperuricemia is blocking the purine metabolism enzyme. However, by binding the purine bases directly, we suggested a unique therapeutic strategy that might interfere with purine metabolism. There have been numerous reports of extensive interactions between proteins and purine bases. Adenine, constituting numerous protein co-factors, can interact with the adenine-binding motif. Using Bayesian Inference and Markov chain Monte Carlo sampling, we created a novel adenine-binding peptide Ile-Tyr-Val-Thr based on the structure of the adenine-binding motifs. Ile-Tyr-Val-Thr generates a semi-pocket that can clip the adenine within, as demonstrated by docking. Then, using thermodynamic techniques, the interaction between Ile-Tyr-Val-Thr and adenine was confirmed. The KD value is 1.50e-5 (ΔH = -20.2 kJ/mol and ΔG = -27.6 kJ/mol), indicating the high affinity. In brief, the adenine-binding peptide Ile-Tyr-Val-Thr may help lower uric acid level by blocking the absorption of food-derived adenine.

Comparison of 3 hyperuricemia mouse models and evaluation of food-derived anti-hyperuricemia compound with spontaneous hyperuricemia mouse model.

Hyperuricemia animal models have long been used for evaluating food-derived anti-hyperuricemia compounds. Fructose and potassium oxonate are commonly used for developing hyperuricemia mouse model. Recent research also developed spontaneous hyperuricemia model by uricase knockout (Uox-/-). In this work, we evaluated 3 kinds of models with the same gene background to illustrate the differences between the treatments. Unlike the uric acid levels in potassium oxonate (224.79 ± 33.62 µmol/L) and Uox-/- groups (458.39 ± 38.29 µmol/L), fructose treatment did not lead to higher serum uric acid level (174.93 ± 30.46 µmol/L) comparing to the control group (153.53 ± 40.96 µmol/L). However, abnormal glycometabolism only developed in the fructose and the Uox-/- group. In addition, anemia, inflammasome and severe renal injury occurred in the Uox-/- group. The Uox-/- mice were then treated with puerarin and allopurinol, and found that puerarin could reduce serum uric acid and alleviated the serious renal damage associated with high uric acid. Thus, the Uox-/- mice could be a suitable model for screening and evaluating anti-hyperuricemia compounds.

A modified xanthine oxidase cell model for screening of antihyperuricemic functional compounds.

Hyperuricemia is a purine metabolism disorder, with increasing prevalence worldwide. Here, a high throughput cell model for screening of antihyperuricemic compounds was set up. Human kidney cells (HK2 cells) were stimulated with adenosine and the resulting supernatant and lysate were then analyzed using high performance liquid chromatography (HPLC). The results showed that hypoxanthine content was increased in both HK2 cells supernatant and xanthine oxidase (XO)-overexpressing HK2 cells lysate, but no uric acid was detected due to lower endogenous XO content in these cells. Exogenous XO was added to the supernatant, and then used to evaluate the antihyperuricemic activity of Febuxostat and two the previously identified peptides, Pro-Gly-Ala-Cys-Ser-Asn (PGACSN) and Trp-Met-Leu (WML). By adding exogenous XO, this combined-adenosine-XO-induced hyperuricemia model was optimized and established, and the Febuxostat and peptides were confirmed to significantly reduce uric acid production in the HK2 cells supernatant (p < 0.05). Therefore, this cell model could be recommended for screening potential bioactive antihyperuricemic compounds.

Effect on purine releasement of Lentinus edodes by different food processing techniques.

Lentinus edodes (LE) is very popular in the world and also considered as high purine food. However, few focuses on purine types and its change during food processing. Here, we first compared 3 drying techniques, including roast-drying, freeze-drying, sun-drying on purine contents of LE by using acidolysis and HPLC. It showed that adenine decreased significantly after roast-drying (120 °C), which may be caused by thermal damage of DNA. Total purine decreased significantly after freeze-drying, while roast-dried and sun-dried LE remained unchanged. The effect of moist heat (boiling) on LE purine were also evaluated. Total purine increased due to xanthine increasement (331.72 ± 50.07%). And purine contents transferred into boiled liquid was higher than that in boiled solid. Compared with sun-dry and roast-dry processing, freeze-drying could notably affect the purine release from LE and decrease purine contents. Therefore, freeze-drying is recommended for process techniques for hyperuricemia and gouts populations.

Establishment of a 3D hyperuricemia model based on cultured human liver organoids.

Hyperuricemia (HUA) is a metabolic disorder caused by abnormal purine metabolism, the prevalence of which has increased worldwide. Here, a 3D organoid culture system for mimicking HUA in vitro was established using cultured human liver organoids. Liver organoids can be generated from single hepatocytes and passaged for several months, retaining key morphological features, functional purine metabolism and global gene expression profile. Furthermore, organoids can be differentiated into hepatocytes with high expression of maturation markers including the hepatocyte nuclear factor-4-alpha (HNF4α), E-cadherin (E-Ca), and albumin (ALB). Importantly, organoids can produce high level of uric acid after xanthine induction which is the substrate of xanthine oxidase. Furthermore, the preclinical application potential of this organoid model was verified by measuring the antihyperuricemic effect of the widely used allopurinol, as well as the reported bioactive substance puerarin. The results demonstrate that this novel organoid model could be used for high-throughput screening of both chemical and food-derived compounds with antihyperuricemic bioactivity.

Culture and establishment of self-renewing human liver 3D organoids with high uric acid for screening antihyperuricemic functional compounds.

Hyperuricemia (HUA) is a metabolic disease caused by disorders of purine metabolism, the prevalence of which has increased worldwide. At present, most drugs aimed at lowering uric acid have toxic side effects, and in vitro screening of uric acid-lowering active substances are inefficient. Here, a long-term 3D human liver organoid culture system with high uric acid for screening and evaluating the efficacy of uric acid-lowering functional compounds. This liver organoids can be established from single hepatocytes and grown for multiple months, while retaining key morphological and functional features. Furthermore, establishment of HUA organoids model was verified by antihyperuricemic drugs allopurinol, as well as reported bioactive peptides, which significantly reduced uric acid production in the liver organoids (p < 0.05). The results demonstrated that it has the potential to be used as a rapid and valid in vitro model to screen antihyperuricemic compounds that mimics in vivo cell growth patterns.

Structural characterization of two Hericium erinaceus polysaccharides and their protective effects on the alcohol-induced gastric mucosal injury.

Hericium erinaceus, a traditional edible mushroom, is known as a medicine food homology to ameliorate gastrointestinal diseases. However, the relationship between the structural characteristics of Hericium erinaceus and its stomach-protecting activity remains unclear. Here, the structural properties of two polysaccharides from Hericium erinaceus, mycelium polysaccharide (HMP) and fruiting body polysaccharide (HFP) were investigated by spectral approaches. The results showed that the distribution of HMP was more uniform compared to HFP. Both HMP and HFP have triple helix structures, but the HMP conformation showed greater stability. Subsequently, the preventive effect of HMP and HFP on ethanol-induced gastric mucosal injury was also evaluated in rats and GES-1 cells, and it showed that both HMP and HFP had significant protective activity against gastric mucosal injury, but HMP showed better activity than HFP. These results suggested that conformational stability polysaccharide in Hericium erinaceus is more related to its gastric-protecting activity.

New Discoveries in Hybrid Orbitals to Characterize Molecules and Predict Biomolecular Interactions.

Taking hydrogen bonds as a basis to explore biomolecular properties and interactions, we constructed the lone-pair electron (LPE) index and a molecular orbital fingerprint based on molecular hybrid orbitals to represent the ability of molecules to form hydrogen bonds. Then, a computational model was constructed to predict molecular interactions. The LPE and orbital fingerprint could effectively predict the biological properties and bioactivities of molecules. This study revealed the significance of hybrid orbitals for understanding cell biochemistry.

Novel xanthine oxidase-based cell model using HK-2 cell for screening antihyperuricemic functional compounds.

Hyperuricemia is a metabolic disease caused by disorders of purine metabolism, the prevalence of which has increased worldwide. Here, a cell model for high uric acid production was established in vitro employing cultured human kidney cells (HK-2 cells), and its molecular basis was analyzed using gene expression profile. High performance liquid chromatography (HPLC) was used to monitor the content of metabolites in cell culture media. Adenosine addition was found to induce HK-2 cells to produce uric acid precursors (inosine and hypoxanthine). Furthermore, the cell model was verified by confirming the antihyperuricemic effect of the widely used antihyperuricemic drugs allopurinol, probenecid, and febuxostat, as well as reported bioactive peptides and amino acids, encompassing glutathione, tryptophan and carnosine, which significantly reduced uric acid production in the HK-2 cells (p < 0.05). RNA-Seq technology was used to perform a wide transcriptome analysis of the hyperuricemic cell model, and the results demonstrated that it has the potential to be used as a rapid and valid in vitro model to screen antihyperuricemic compounds that mimics in vivo cell growth patterns.

A polysaccharide isolated and purified from Platycladus orientalis (L.) Franco leaves, characterization, bioactivity and its regulation on macrophage polarization.

The structure and bioactivity of a novel polysaccharide from Platycladus orientalis (L.) Franco leaves (POP2) were investigated in the present study. Structure characterization demonstrated that the average molecular weight of POP2 was 9.69 kDa and consisted of arabinose (14.39%), mannose (10.24%), glucose (63.95%) and galactose (11.42%). The main linkage types of POP2 consisted of (1→4)-linked α-d-Glc and (1→6)-linked α-d-Glc based on methylation and NMR analysis. Bioactivity evaluation showed that POP2 could effectively promote the secretion of inflammatory cytokines (IL-6 and TNF-α), as well as the anti-inflammatory cytokines (IL-10) in LPS-induced cells. Besides, the secretion of NO was significantly inhibited by POP2 in M1 model. POP2 could enhance the level of inflammatory cytokines (NO, IL-6 and TNF-α), while the secretion of the anti-inflammatory cytokine TGF-ß was markedly suppressed in IL-4 induced cells. Our work attempted to elucidate the regulation of macrophage polarization and support the potential application of POP2 as bioactive ingredient for functional foods.