Urolithin A alleviates advanced glycation end-product formation by altering protein structures, trapping methylglyoxal and forming complexes.

Urolithin A (UroA) is a first-in-class natural compound derived from the gut microbiota-derived metabolites of ellagitannins. This research for the first time evaluates the mechanisms of UroA inhibiting advanced glycation end-product (AGE) formation by fluorescence spectroscopy, molecular docking, liquid chromatography (LC) and LC-Oribitrap tandem mass spectrometry. The results indicated that UroA exhibited a good suppression effect on the formation of AGEs in human serum albumin (HSA)-fructose and HSA-methylglyoxal (MGO) systems. Further mechanism analysis revealed that UroA alleviated AGE formation by changing the conformational structure of HSA, trapping reactive MGO to form mono-MGO-UroA complexes, promoting the exposure of chromophores to a more hydrophobic micro-environment, and forming stable UroA-HSA complexes. UroA bound with HSA in an equimolar manner, the binding was an exothermic spontaneous process, subdomain IIIA was the preferred binding pocket, and hydrogen bonding, hydrophobic interactions and van der Waals forces were the major interaction forces. The number of glycation sites detected in glycated HSA was reduced by 1 and 2, respectively, when 181.82 and 363.64 µM UroA was added. These could provide an insight into the mechanism of UroA inhibiting HSA glycation, and highlight its value as a promising glycation inhibitor in the prevention of diabetic complications.

Influence of Hydroxyl Substitution on the Suppression of Flavonol in Harmful Glycation Product Formation and the Inhibition Mechanism Revealed by Spectroscopy and Mass Spectrometry.

Quercetin (Que), kaempferol (Kaem), isorhamnetin (Irh), and myricetin (Myri) are typical flavonols that are abundant in plant resources. This research investigated their ability in attenuating harmful glycation product formation and the effect of hydroxyl substitution. The inhibition mechanisms were elucidated by fluorescence spectroscopy and nano-liquid chromatography Orbitrap tandem mass spectrometry. The results indicated that the 3'-OH on the B-ring is critical in alleviating harmful glycation product formation, methylation reduced its inhibition, and the 5'-OH showed much less contribution than the 3'-OH. Que showed the strongest suppression on initial product, 5-hydroxymethylfurfural, and advanced glycation end product formation, with the corresponding percentage inhibitions at 36.58 µM of 81.1, 56.9, and 95.4%. Que and Myri also clearly inhibited fructosamine and acrylaminde production, while no suppression was observed by Irh and Kaem. The number of glycated sites was reduced from ten to seven, five, six, and nine, respectively, when 36.58 µM Que, Myri, Kaem, and Irh was added. Suppressing the conformational changes of ovalbumin induced by glycation, trapping dicarbonyl compounds, altering the microenvironment around tryptophan, and reducing the glycation activity of potential sites were the major inhibition mechanisms. These results suggest that Que and Myri may be promising natural agents for inhibiting harmful glycation and provide theoretical support for the effective screening of natural antiglycation reagents.

Effects of the oligostilbenes from Iris lactea Pall. var. chinensis (Fisch.) Koidz on the adipocytes differentiation of 3T3-L1 cells.

The dried seeds of Iris lactea Pall. var. chinensis (Fisch.) Koidz, an important traditional Chinese medicine, are regarded to have effects of clearing heat, eliminating dampness and pharyngitis and so on. It has been used in the treatment of jaundice, diarrhea, leucorrhea and carbuncles. Previous phytochemical studies of Iris species showed the presence of flavones, isoflavones, triterpenes and stilbenes. In our previous research, we isolated five known oligostilbenes, vitisin A, vitisin B, vitisin C, vitisin D, and cis-vitisin A were successfully isolated from Iris lactea for the first time. The aim of this study was to assess the effects of these oligostilbenes on the differentiation and adipogenes in 3T3-L1 cells. Our results showed that vitisin A, vitisin B, cis-vitisin A significantly inhibited adipocytes differentiation and reduced lipid accumulation in 3T3-L1 cells. In addition, vitisin A, vitisin B, cis-vitisin A strongly suppressed the expression levels of adipocyte-specific genes including peroxisome proliferator activated receptor-γ (PPARγ), CCAAT/enhancer binding protein-α (C/EBPα) and adipocyte fatty acid binding protein 4 (FABP4). In contrast, vitisin C and vitisin D significantly promoted adipogenesis and increased intracellular lipid accumulation, while the two oligostilbenes markedly increased the expression of adipocyte marker genes. In the present study, we found that vitisin A, vitisin B and cis-vitisin A inhibit the adipogenesis and adipocytes differentiation by their influence on the expression of PPARγ, which leads to subsequenet downregulation of PPARγ mediated adipocyte-specific gene during adipogenesis.

Comparison of Body, Auricular, and Abdominal Acupuncture Treatments for Insomnia Differentiated as Internal Harassment of Phlegm-Heat Syndrome: An Orthogonal Design.

Objective. To identify the optimum treatment protocol for insomnia among auricular, body, and abdominal needling methods. Methods. A three-factor (3 needling protocols) and three-level experimental scheme was designed based on orthogonal method. 54 patients of insomnia differentiated as internal harassment of phlegm-heat syndrome were given two courses of acupuncture treatment (each with 20 times of acupuncture). The therapeutic effects were evaluated by comparing the Pittsburgh sleep quality index (PSQI), Hamilton Depression Scale (HAMD) scores, and Hamilton Anxiety Scale (HAMA) scores of patients before treatment, after one course of treatment, and after two courses of treatment as well as one month after treatment. Results. Body, auricular, and abdominal acupuncture treatments all alleviated symptoms of insomnia, depression, and anxiety, but body and auricular acupuncture had stronger therapeutic effects. Conclusions. Body acupuncture at basic points shall be given priority in protocol selection for insomnia. The second-best choice is auricular acupuncture with basic points combined with points based on Traditional Chinese Medicine (TCM) theories. Abdominal needling with very quick effect can be an alternative protocol with basic points combined with syndrome differentiation points.