Licheng Ren's research while affiliated with Xiangtan University and other places

Ultrafiltration coupled with liquid chromatography-mass spectrometry (LC-MS) was established to screen xanthine oxidase (XO) inhibitors from Pueraria lobata root extract. Four compounds were screened out and identified as puerarin, daidzin, daidzein and genistein with half-maximal inhibitory concentration (IC50) values of 30.8, 5.31, 14.5 and 3.02 µg mL−1 on XO, respectively. The interactions between these compounds and XO were investigated by fluorescence spectroscopic method. The hydrogen peroxide induced oxidative stress model of human normal gastric epithelial cell lines (GES-1) was used to investigate the protections on injured cell. As a result, four XO inhibitors exhibited protective effects without cytotoxicity. With the increased concentrations of four inhibitors, cell viability was higher with decreased mortality rate, the decrease of superoxide dismutase activity, leakage of lactate dehydrogenase and increase of intracellular superoxide anion production induced by hydrogen peroxide were restrained. It showed that these four XO inhibitors could effectively enhance cell viability and protect injury of GES-1 cells from oxidative stress.

Polyphenols have been used as natural medicaments for the management of hyperuricemia for a long history. They have been attracted many interests because of the little side effects in curing hyperuricemia, which is an important advantage over the antihyperuricemic drugs. In this review, the structure–activity relationships for polyphenols as xanthine oxidase (XO) inhibitors were discussed. It is concluded that the presence of hydroxyl groups, which influences the inhibitory effects, is closely related to whether the substitutions increase the steric hindrance or disturb the interaction of flavonoid with the catalytic site of XO, and the increased size of the molecule after glycosylation may increase the steric hindrance between flavonoid and XO, and consequently reducing the competitive inhibition behaviors. However, there is no obtained simple general rule that can comprehensively describe the effects of structural alteration on the inhibition activity because the results are varied among different subclasses of polyphenols. In addition, the inhibition mechanisms are mainly assumed as polyphenol binding to the active site of XO and hindering the entrance of xanthine or the discharge of uric acid and diffusion of O2− radical. Polyphenols have been used as natural medicaments for the management of hyperuricemia for a long history. With little side effects, they have attracted many interests and have been regarded as the alternatives for antihyperuricemic drugs. The antihyperuricemic effects of polyphenols are mainly attributed to their inhibitory activities against xanthine oxidase (XO), which catalyzes the formation of uric acid from xanthine. In this review, the structure–activity relationships for polyphenols as XO inhibitors were discussed.

In this study, an electrochemical biosensor based on guanine and chitosan immobilized MoS 2 nanosheet modified glassy carbon electrode (guanine/CS/MoS 2 /GCE) was developed and employed for antioxidant screening and antioxidant capacity evaluation. The oxidation peak current of guanine was improved and nearly tripled after modifications of chitosan and MoS 2 nanosheet. The immobilized guanine could be damaged by hydroxyl radicals generated in Fenton solution. However, in the presence of antioxidants, the guanine was protected and the oxidation peak current of guanine increased. This process mimics the mechanism of antioxidant protection in human body. The factors affecting preparation of sensor and detection of antioxidant capacity were optimized. At the optimum conditions, the guanine/CS/MoS 2 /GCE showed wide linear range, low detection limit, satisfactory reproducibility and stability for detection. Ascorbic acid was used as a model antioxidant to evaluate the antioxidant capacity. A good linearity was observed with a correlation coefficient of 0.9959 in the concentrations between 0.5 and 4.0 mg L ⁻¹ . The antioxidant capacities of three flavonoids were also tested and the rank of antioxidant capacities was ascorbic acid (51.84%), quercetin (45.82%), fisetin (34.39%) and catechin (16.99%). Due to the rapid measurement and low cost, this sensor could provide an available sensing platform for antioxidant screening and evaluation.

Background: The head and neck regions are frequent sites of burns, but few studies have analysed and reported the epidemiology of facial burns. As the face is the centre of one's identity and persona, facial injuries often result in physical and psychological morbidity. The aim of this article is to describe the epidemiology and outcome of facial burns in China and to suggest future preventive strategies. Methods: This retrospective analysis included all patients with facial burns in a database at eight institutions from 2011-2015. The data collected included sex, age, month distribution, aetiology, location, presence of inhalation injury, total burn surface area, burn surface area with full-thickness and outcome including Post-traumatic stress disorder Checklist-Civilian Version scores and mortality. SPSS 19.0 software was used to analyse the data. Results: A total of 1126 patients were included; 65.63% (739) had facial burns, of which 546 (73.88%) were male patients and 193 (26.12%) were female patients. Predictors of facial burns were being of male sex, working-related place, flame burns, total body surface area, and full-thickness burns. In addition, total body surface area and full-thickness burns increased the risk of poor prognosis for post-traumatic stress disorder and mortality. Conclusions: Facial burns benefit not only the healing of wound, but also the prevention of their incidence and PTSD symptom. This study may contribute to the elaboration of strategies to prevent facial burns and the establishment of a nationwide burn database in China.

Background Severe burns injury is a serious pathology, leading to teratogenicity and significant mortality, and it also has a long-term social impact. The aim of this article is to describe the hospitalized population with severe burns injuries in eight burn centers in China between 2011 and 2015 and to suggest future preventive strategies. Methods This 5-year retrospective review included all patients with severe burns in a database at eight institutions. The data collected included gender, age, month distribution, etiology, location, presence of inhalation injury, total burn surface area, depth of the burn, the length of hospitalization, and mortality. SPSS 19.0 software was used to analyze the data. Results A total of 1126 patients were included: 803 (71.3%) male patients and 323 (28.7%) female patients. Scalds were the most common cause of burns (476, 42.27%), followed by fire (457, 40.59%). The extremities were the most frequently affected areas, followed by the trunk. The median length of hospitalization was 30 (15, 52) days. The overall mortality rate was 14.21%. Conclusions Although medical centers have devoted intensive resources to improving the survival rates of burn patients, expenditures for prevention and education programs are minimal. Our findings suggest that more attention should be paid to the importance of prevention and the reduction of injury severity. This study may contribute to the establishment of a nationwide burn database and the elaboration of strategies to prevent severe burns injury.

Flavonoids are well known as antibacterial agents against a wide range of pathogenic microorganism. With increasing prevalence of untreatable infections induced by antibiotic resistance bacteria, flavonoids have attracted much interest because of the potential to be substitutes for antibiotics. In this review, the structure-relationship of flavonoids as antibacterial agents is summarized, and the recent advancements on the antibacterial mechanisms of flavonoids are also discussed. It is concluded that hydroxyls at special sites on the aromatic rings of flavonoids improve the activity. However, the methylation of active hydroxyl groups generally decreases the activity. Besides, the lipopholicity of ring A is vital for the activity of chalcones. Hydrophobic substituents such as prenyl groups, alkylamino chains, alkyl chains, and nitrogen or oxygen containing heterocyclic moieties usually enhance the activity for all the flavonoids. The proposed antibacterial mechanisms of flavonoids are as follows: inhibition of nucleic acid synthesis, inhibition of cytoplasmic membrane function, inhibition of energy metabolism, inhibition of the attachment and biofilm formation, inhibition of the porin on the cell membrane, alteration of the membrane permeability, and attenuation of the pathogenicity.