Dehydroabietylamine exerts antitumor effects by affecting nucleotide metabolism in gastric cancer.

Nucleotide metabolism is the ultimate and most critical link in the self-replication process of tumors, including gastric cancer (GC). However, in clinical treatment, classic anti-tumor drugs such as 5-fluorouracil (5-FU) are mostly metabolic analogues of purines or pyrimidines, which lack specificity for tumor cells and therefore have significant side effects. It is unclear whether there are other drugs that can target nucleotide metabolism, except for nucleic acid analogues. Here, we found that a natural compound, dehydroabietylamine (DHAA), significantly reduced the viability and proliferation of GC cells and organoids. DHAA disrupts purine and pyrimidine metabolism of GC cells, causing DNA damage and further inducing apoptosis. DHAA treatment decreased transcription and protein levels of key enzymes involved in nucleotide metabolism pathway, with significant reductions in the expression of pyrimidine metabolism key enzymes CAD, DHODH, and purine metabolism key enzymes PAICS. We also found that DHAA directly binds to and reduces the expression of Forkhead box K2 (FOXK2), a common transcription factor for these metabolic enzymes. Ultimately, DHAA was shown to delay tumorigenesis in K19-Wnt1/C2mE transgenic mice model and reduce levels of CAD, DHODH, and PAICS in vivo. We demonstrate that DHAA exerts an anticancer effect on GC by targeting transcription factor FOXK2, reducing transcription of key genes for nucleotide metabolism and impairing nucleotide biosynthesis, thus DHAA is a promising candidate for GC therapy.

Tailoring an aldo-keto reductase KmAKR for robust thermostability and catalytic efficiency by stepwise evolution and structure-guided consensus engineering.

t-Butyl 6-cyano-(3R,5R)-dihydroxyhexanoate ((3R,5R)-2) is an advanced chiral diol intermediate of the cholesterol-lowering drug atorvastatin. KmAKRM5 (W297H/Y296W/K29H/Y28A/T63M) constructed in our previous work, displayed good biocatalytic performance on (3R,5R)-2. In the present work, stepwise evolution was applied to further enhance the thermostability and activity of KmAKRM5. For thermostability enhancement, N109 and S196 located far from the active site were picked out by structure-guided consensus engineering, and mutated by site-directed mutagenesis (SDM). For catalytic efficiency improvement, the residues A30 and T302 adjacent to the substrate-binding pocket were subjected to site-saturation mutagenesis (SSM). As a result, the "best" mutant KmAKRM9 (W297H/Y296W/K29H/Y28A/T63M/A30P/T302S/N109K/S196C) was developed, of which T5015 and Tm were 5.0 °C and 8.2 °C higher than those of KmAKRM5. Moreover, compared to KmAKRM5, KmAKRM9 displayed a 1.9-fold (846 vs 2436 min) and 6.7-fold (126 vs 972 min) longer half-lives at 40 and 50 °C, respectively. Structural analysis suggested that beneficial mutations introduced additional hydrophobic interactions and hydrogen bonds, contributing rigidification of the flexible loops and the increase of internal forces, hence increasing the thermostability and activity. 5 g DCW (dry cell weight) L-1KmAKRM9 completely reduced 350 g L-1t-butyl 6-cyano-(5R)-hydroxy-3-oxo-hexanoate ((5R)-1), within 3.7 h at 40 °C, yielding optically pure (3R,5R)-2 (d.e.p > 99.5%) with a space-time yield (STY) of 1.82 kg L-1 d-1. Hence, KmAKRM9 is a robust biocatalyst for the synthesis of (3R,5R)-2.

Extraction Methods Affect the Structure of Goji (Lycium barbarum) Polysaccharides.

Polysaccharides are considered to be the most important active substances in Goji. However, the structure of polysaccharides varies according to the extraction methods applied, and the solution used to prepare Goji polysaccharides (LBPs) were limited. Thus, it is important to clarify the connection between extraction methods and structure of Goji polysaccharide. In view of the complex composition of cell wall polysaccharides and the various forms of interaction, different extraction methods will release different parts of the cell wall. The present study compared the effects of different extraction methods, which have been used to prepare different types of plant cell wall polysaccharides based on various sources, on the structure of cell-wall polysaccharides from Goji, by the single separate use of hot water, hydrochloric acid (0.4%) and sodium hydroxide (0.6%), at both high and low temperatures. Meanwhile, in order to explore the limitations of single extraction, sequential extraction methods were applied. Structural analysis including monosaccharide analysis, GPC-MALLS, AFM and 1H-NMR suggested the persistence of more extensively branched rhamnogalacturonan I (RG-I) domains in the procedures involving low-temperature-alkali, while procedures prepared by high-temperature-acid contains more homogalacturonan (HG) regions and results in the removal of a substantial part of the side chain, specifically the arabinan. A kind of acidic heteropolysaccharide was obtained by hot water extraction. SEC-MALLS and AFM confirmed large-size polymers with branched morphologies in alkali-extracted polysaccharides. Our results provide new insight into the extraction of Goji polysaccharides, which differ from the hot water extraction used by traditional Chinese medicine.

Safety and cosmesis of gasless endoscopic thyroidectomy: a retrospective study.

Despite growing interest in gasless endoscopic unilateral thyroid lobectomy via the axillary approach, there are a lack of sufficient data on its safety and cosmetic outcomes. This retrospective study analysed the clinical outcomes and postoperative complications of 161 patients who underwent this surgery for thyroid cancer and nodules, with particular attention given to complications and patient satisfaction with cosmetic outcomes. All 161 patients (143 females, 18 males) successfully underwent the operation without conversion to open surgery. Temporary vocal cord paralysis occurred in five patients, with no other serious complications observed. The cosmetic outcomes were generally good, with no recurrences or tumour implantations observed during follow-up. For carefully selected patients, gasless endoscopic unilateral thyroid lobectomy via the axillary approach is not only safe but also provides excellent cosmetic results.

Mental fatigue decreases complexity: Evidence from multiscale entropy analysis of instantaneous frequency variation in alpha rhythm.

Mental fatigue (MF) jeopardizes performance and safety through a variety of cognitive impairments and according to the complexity loss theory, should represent "complexity loss" in electroencephalogram (EEG). However, the studies are few and inconsistent concerning the relationship between MF and loss of complexity, probably because of the susceptibility of brain waves to noise. In this study, MF was induced in thirteen male college students by a simulated flight task. Before and at the end of the task, spontaneous EEG and auditory steady-state response (ASSR) were recorded and instantaneous frequency variation (IFV) in alpha rhythm was extracted and analyzed by multiscale entropy (MSE) analysis. The results show that there were significant differences in IFV in alpha rhythm either from spontaneous EEG or from ASSR for all subjects. Therefore, the proposed method can be effective in revealing the complexity loss caused by MF in spontaneous EEG and ASSR, which may serve as a promising analyzing method to mark mild mental impairments.

Preparation of a novel emulsifier by self-assembling of proanthocyanidins from Chinese bayberry (Myrica rubra Sieb. et Zucc.) leaves with gelatin.

A physicochemically stable emulsion was developed by using a novel emulsifier, which was self-assembled colloidal complex of gelatin (GLT) and proanthocyanidins from Chinese bayberry (Myrica rubra Sieb et Zucc.) leaves (BLPs), with epigallocatechin-3-O-gallate (EGCG) as structure units. The GLT-BLP colloidal complexes were spherically shaped by transmission electron microscope (TEM). The data of Fourier transform infrared spectrum (FTIR), circular dichroism (CD), isothermal titration calorimetry (ITC) revealed that the main binding force between GLT and BLPs of the colloidal complexes was hydrogen bond. The incorporation of BLPs to GLT provided GLT with stronger affinity at oil-water interface and thus enhanced the physical stability of GLT-stabilizing emulsion. In addition, the emulsions stabilized by the colloidal complexes showed higher oxidation stability than that stabilized by free GLT only. The novel emulsifier developed in this study have potential applications as functional emulsifiers in food-grade emulsions with high anti-oxidation activity.

Depolymerized RG-I-enriched pectin from citrus segment membranes modulates gut microbiota, increases SCFA production, and promotes the growth of Bifidobacterium spp., Lactobacillus spp. and Faecalibaculum spp.

Rhamnogalacturonan-I (RG-I)-enriched pectin (WRP) was recovered from citrus processing water by sequential acid and alkaline treatments in a previous study. RG-I-enriched pectin was proposed as a potential supplement for functional food and pharmaceutical development. However, previous studies illustrated that favorable modulations of gut microbiota by RG-I-enriched pectin were based on in vitro changes in the overall microbial structure and the question of whether there is a structure-dependent modulation of gut microbiota remains largely enigmatic. In the present study, modulations of gut microbiota by commercial pectin (CP), WRP and its depolymerized fraction (DWRP) with different RG-I contents and Mw were compared in vivo. It was revealed by 16s rRNA high-throughput sequencing that WRP and DWRP mainly composed of RG-I modulated the gut microbiota in a positive way. DWRP significantly increased the abundance of prebiotic such as Bifidobacterium spp., Lactobacillus spp., while WRP increased SCFAs producers including species in Ruminococcaceae family. By maintaining a more balanced gut microbiota composition and enriching some SCFA producers, dietary WRP and DWRP also elevated the SCFA content in the colon. Collectively, our findings offer new insights into the structure-activity correlation of citrus pectin and provide impetus towards the development of RG-I-enriched pectin with small molecular weight for specific use in health-promoting prebiotic ingredients and therapeutic products.