Functional characterization,structural basis,and protein engineering of a rare flavonoid 2′-O-glycosyltransferase from Scutellaria baicalensis

Glycosylation is an important post-modification reaction in plant secondary metabolism,and contributes to structural diversity of bioactive natural products.In plants,glycosylation is usually catalyzed by UDP-glycosyltransferases.Flavonoid 2′-O-glycosides are rare glycosides.However,no UGTs have been reported,thus far,to specifically catalyze 2′-O-glycosylation of flavonoids.In this work,UGT71AP2 was identified from the medicinal plant Scutellaria baicalensis as the first flavonoid 2′-O-glycosyltransferase.It could preferentially transfer a glycosyl moiety to 2′-hydroxy of at least nine flavonoids to yield six new compounds.Some of the 2′-O-glycosides showed noticeable inhibitory activities against cyclooxygenase 2.The crystal structure of UGT71AP2(2.15Å)was solved,and mechanisms of its regio-selectivity was interpreted by pKa calculations,molecular docking,MD simulation,MM/GBSA binding free energy,QM/MM,and hydrogen‒deuterium exchange mass spectrometry analysis.Through structure-guided rational design,we obtained the L138T/V179D/M180T mutant with remarkably enhanced regio-selectivity(the ratio of 7-O-glycosylation byproducts decreased from 48%to 4%)and catalytic efficiency of 2′-O-glycosylation(kcat/Km,0.23 L/(s·μmol),12-fold higher than the native).Moreover,UGT71AP2 also possesses moderate UDP-dependent de-glycosylation activity,and is a dual function glycosyltransferase.This work provides an efficient biocatalyst and sets a good example for protein engineering to optimize enzyme catalytic features through rational design.

pH-triggered dynamic erosive small molecule chlorambucil nano-prodrugs mediate robust oral chemotherapy

Currently,the dynamic erosive small molecule nano-prodrug is of great demand for oral chemotherapy,owing to its precise structure,high drug loading and improved oral bioavailability via overcoming various physiologic barriers in gastrointestinal tract,blood circulation and tumor tissues compared to other oral nanomedicines.Herein,this work highlights the successful development of pH-triggered dynamic erosive small molecule nano-prodrugs based on in vivo significant pH changes,which are synthesized via amide reaction between chlorambucil and star-shaped ortho esters.The precise nano-prodrugs exhibit extraordinarily high drug loading(68.16%),electric neutrality,strong hydrophobicity,and dynamic large-to-small size transition from gastrointestinal pH to tumoral pH.These favorable physicochemical properties can effectively facilitate gastrointestinal absorption,blood circulation stability,tumor accumulation,cellular uptake,and cytotoxicity,therefore achieving high oral relative bioavailability(358.72%)and significant tumor growth inhibition while decreasing side effects.Thus,this work may open a new avenue for robust oral chemotherapy attractive for clinical translation.

Dynamic crosslinked polymeric nano-prodrugs for highly selective synergistic chemotherapy

To achieve highly selective synergistic chemotherapy attractive for clinical translation,the precise polymeric nano-prodrugs(PPD-NPs)were successfully constructed via the facile crosslinking reaction between p H-sensitive poly(ortho ester)s and reduction-sensitive small molecule synergistic prodrug(Pt(IV)-1).PPD-NPs endowed the defined structure and high drug loading of cisplatin and demethylcantharidin(DMC).Moreover,PPD-NPs exhibited steady long-term storage and circulation via the crosslinked structure,suitable negative potentials and low critical micelle concentration(CMC),improved selective tumour accumulation and cellular internalization via dynamic size transition and surficial amino protonation at tumoural extracellular p H,promoted efficient disintegration and drug release at tumoural intracellular p H/glutathione,and enhanced cytotoxicity via the synergistic effect between cisplatin and DMC with the feed ratio of 1:2,achieving significant tumour suppression while decreasing the side effects.Thus,the dynamic crosslinked polymeric nano-prodrugs exhibit tremendous potential for clinically targeted synergistic cancer therapy.

pH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages for enhanced MDR reversal and chemotherapy

TPGS approved by FDA can be used as a P-gp inhibitor to effectively reverse multi-drug resistance(MDR)and as an anticancer agent for synergistic antitumor effects.However,the comparatively high critical micelle concentration(CMC),low drug loading(DL)and poor tumor target limit its further clinical application.To overcome these drawbacks,the pH-sensitive star-shaped TPGS copolymers were successfully constructed via using pentaerythritol as the initial materials,ortho esters as the pH-triggered linkages and TPGS active-ester as the terminated MDR material.The amphiphilic star-shaped TPGS copolymers could self-assemble into free and doxorubicin(DOX)-loaded micelles at neutral aqueous solutions.The micelles exhibited the lower CMC(8.2×10^(−5) mg/ml),higher DL(10.8%)and long-term storage and circulation stability,and showed enhanced cellular uptake,apoptosis,cytotoxicity,and growth inhibition for in vitro MCF-7/ADR and/or MCF-7/ADR multicellular spheroids and in vivo MCF-7/ADR tumors via efficiently targeted drug release at tumoral intracellular pH(5.0),MDR reversal of TPGS,and synergistic effect of DOX and TPGS.Therefore,the pH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages are potentially useful to clinically transform for enhanced MDR cancer treatment.

Immobilization and characterization of the Lactarius deliciosus mycelia-embedded polylysine-alginate beads and their decolorization performance

Liquid fermented fungal mycelia with decolorization capability have potential applications in scale-up. In this work, the Lactarius deliciosus mycelia were immobilized on ε-polylysine-alginate beads, and the decolorization effects of ε-polylysine-alginate beads were demonstrated along with Coomassie brilliant blue G-250 as a model dye. Morphology observation confirmed the beads had an exterior film and interior capsule with honeycomb microstructures suitable for mycelia growth. It was manifested that the maximum decolorization efficiency for mycelia was 98.5% at a removal rate of 0.68 mg·L^(-1)·h after 3 days. In comparison, the decolorization efficiency of the immobilized mycelia reached the maximum value of 97.3% at a removal rate of 6.1 mg·L^(-1)·h after 8 h. The enzyme activities of lignin peroxidase and laccase tested in the immobilized mycelia were significantly higher than in that of the free ones, such as the lignin peroxidase had the highest enzyme activity of 77.6 ± 7.4 U·L^(-1) in the former, while of 27.4 ± 8.7 U·L^(-1) in the latter. The immobilization of L. deliciosus mycelia could improve the decolorization of Coomassie brilliant blue G-250 efficiently. The prepared ε-polylysine-alginate beads embedded with L. deliciosus mycelia have very good reusability and a great potential in decolorizing analog dyes.

Biodegradation and detoxification of the triphenylmethane dye coomassie brilliant blue by the extracellular enzymes from mycelia of Lactarius deliciosus

Fungi play an important role in dying wastewater treatment.In this work,the mycelia of Lactarius deliciosus exhibited an excellent capacity in decolorizing coomassie brilliant blue(CBB).The results demonstrated that the mycelia could treat CBB with high concentrations over a broad range of pH and temperature.The decolorization rate of 99.19%and the removal rate of 16.31 mg·L^(‒1)·h were realized.The mycelia could be recycled from decolorizing process for 19 times,indicating a good re-usability.It verified that the lignin peroxidase(121.65 U·L^(‒1))and manganese peroxidase(36.77 U·L^(‒1))were involved in the degradation and decolorization process of CBB.Toxicity assessments indicated the seed germination rate was up to 82.22%while inhibition to Escherichia coli decreased dramatically and no significant effect on Caenorhabditis elegans growth was found.The removal of CBB was a synergistic process accomplished by adsorption and biodegradation.The mycelia could be used for eco-friendly CBB treatment.

Fluorine-defects induced solid-state red emission of carbon dots with an excellent thermosensitivity

Up to date,solid-state carbon dots(CDs)with bright red fluorescence have scarcely achieved due to aggregation-caused quenching(ACQ)effect and extremely low quantum yield in deep-red to near infrared region.Here,we report a novel fluorine-defects induced solid-state red fluorescence(λ_(em)=676 nm,the absolute fluorescence quantum yields is 4.17%)in fluorine,nitrogen and sulfur co-doped CDs(F,N,S-CDs),which is the first report of such a long wavelength emission of solid-state CDs.As a control,CDs without fluorine-doping(N,S-CDs)show no fluorescence in solid-state,and the fluorescence quantum yield/emission wavelength of N,S-CDs in solution-state are also lower/shorter than that of F,N,S-CDs,which is mainly due to the F-induced defect traps on the surface/edge of F,N,S-CDs.Moreover,the solid-state F,N,S-CDs exhibit an interesting temperature-sensitive behavior in the range of 80-420 K,with the maximum fluorescence intensity at 120 K,unveiling its potential as the temperature-dependent fluorescent sensor and the solid-state light-emitting device adapted to multiple temperatures.

Self-assembled ternary hybrid nanodrugs for overcoming tumor resistance and metastasis

Traditional chemotherapy exhibits a certain therapeutic effect toward malignant cancer,but easily induce tumor multidrug resistance(MDR),thereby resulting in the progress of tumor recurrence or metastasis.In this work,we deigned ternary hybrid nanodrugs(PEI/DOX@CXB-NPs)to simultaneously combat against tumor MDR and metastasis.In vitro results demonstrate this hybrid nanodrugs could efficiently increase cellular uptake at pH 6.8 by the charge reversal,break lysosomal sequestration by the proton sponge effect and trigger drugs release by intracellular GSH,eventually leading to higher drugs accumulation and cell-killing in drug-sensitive/resistant cells.In vivo evaluation revealed that this nanodrugs could significantly inhibit MDR tumor growth and simultaneously prevent A549 tumor liver/lung metastasis owing to the specifically drugs accumulation.Mechanism studies further verified that hybrid nanodrugs were capable of down-regulating the expression of MDR or metastasis-associated proteins,lead to the enhanced anti-MDR and anti-metastasis effect.As a result,the multiple combination strategy provided an option for effective cancer treatment,which could be potentially extended to other therapeutic agents or further use in clinical test.

Biobased materials for food packaging

Consumers prefer foods that are healthier with high quality and safety.Food packaging are de-manded to effectively extend the shelf-life,preserve the nutrients and decrease the microbial contamination during the transport and storage of food.With the increasing concern on the envi-ronmental impacts caused by food packaging wastes,sustainable and green packaging are highly demanded to minimize the harmful effects of food packaging waste on the environment.Bio-based materials are derived from sustainable and renewable biomass,instead of finite petrochemicals.The applications of bio-based materials for food packaging are highlighted in this review.The emphasis is placed on the categories of related biobased materials,their characteristics and ad-vantages for food packaging,as well as the strategies used to improve their performances.Though a lot of trials have been done on biobased materials for food packaging,further attempts to im-prove their performances,understand the functioning mechanisms and develop greener methods for the production,processing and destiny of these bio-based materials are still highly needed for the future research.

Dual-stimuli-sensitive poly(ortho ester disulfide urethanes)-based nanospheres with rapid intracellular drug release for enhanced chemotherapy

Herein, new poly（ortho ester disulfide urethanes） （POEDU） and poly（ortho ester urethanes） （POEU） were successfully syn- thesized via polycondensation between active esters of 1,6-hexandiol （HD） and dual-stimuli-sensitive ortho ester disulfide diamine or pH-senstive ortho ester diamine. The corresponding POEDU and POEU nanospheres were easily fabricated using an oil-in-water emulsion technique. In vitro degradation experiments indicated that POEDU nanospheres degraded faster than POEU nanospheres in mildly acidic and reductive environments. Doxorubicin （DOX） as a model antitumor drug was suc- cessfully incorporated into these nanospheres to give DOX-loaded nanoparticles （POEDU-DOX and POEU-DOX）. In vitro drug release studies showed that release of DOX from dual-stimuli-sensitive POEDU-DOX was accelerated compared with release from the pH-sensitive POEU-DOX under DL-dithiothreitol （DTT） and mildly acidic conditions. In addition, in vitro uptake and cytotoxicity assays revealed that POEDU-DOX exhibited more efficient antitnmor effect than POEU-DOX did against both two- dimensional （2D） cells and three-dimensional （3D） multicellular tumor spheroids （MCTS）. Finally, in a mice H22 tumor model, POEDU-DOX exhibited preferable antitumor capability. In conclusion, the pH and redox dual-stimuli-sensitive POEDU na- nospheres can be superior drug carriers for cancer treatment.