On-Demand Opioid Effect Reversal with an Injectable Light-Triggered Polymer-Naloxone Conjugate.

Misuse of opioids can lead to a potential lethal overdose. Timely administration of naloxone is critical for survival. Here, we designed a polymer-naloxone conjugate that can provide on-demand phototriggered opioid reversal. Naloxone was attached to the polymer poly(lactic-co-glycolic acid) via a photocleavable coumarin linkage and formulated as injectable nanoparticles. In the absence of irradiation, the formulation did not release naloxone. Upon irradiation with blue (400 nm) light, the nanoparticles released free naloxone, reversing the effect of morphine in mice. Such triggered events could be performed days and weeks after the initial administration of the nanoparticles and could be performed repeatedly.

Upregulation of p53 through induction of MDM2 degradation: Amino acid prodrugs of anthraquinone analogs.

Previously, we reported a class of MDM2-MDM4 dimerization inhibitors that upregulate p53 and showed potent anticancer activity in animal models. However, water solubility hinders their further development. Herein we describe our effort to develop a prodrug approach that overcomes the solubility problem. The prodrug of BW-AQ-238, a potent anthraquinone analog, was made by esterification of the hydroxyl group with various natural amino acids. Cytotoxicity of these compounds toward Hela and EU-1 cells, their aqueous solubility, and the release kinetics of these prodrugs in buffer and in the presence of hydrolytic enzymes were studied. The results demonstrate that the amino acid prodrug approach significantly improved the water solubility while maintaining the potency of the parent drug.

Click and release: bioorthogonal approaches to "on-demand" activation of prodrugs.

Prodrug approaches represent an excellent solution to certain pharmaceutical issues commonly encountered in the drug discovery and development process. Along this line, the chemistry needed for the bio-reversible derivatization of drug functional groups for on-demand release is critical. In recent years, "click and release" approaches have shown great promise in the design of prodrugs because of their bioorthogonality and controlled bond-cleavage, which help ensure prodrug stability during circulation and ready cleavage at the desired site of action. This review highlights recent developments of this research field and discusses issues yet to be addressed.

Toward Hydrogen Sulfide Based Therapeutics: Critical Drug Delivery and Developability Issues.

Hydrogen sulfide (H2 S), together with nitric oxide (NO) and carbon monoxide (CO), belongs to the gasotransmitter family and plays important roles in mammals as a signaling molecule. Many studies have also shown the various therapeutic effects of H2 S, which include protection against myocardial ischemia injury, cytoprotection against oxidative stress, mediation of neurotransmission, inhibition of insulin signaling, regulation of inflammation, inhibition of the hypoxia-inducible pathway, and dilation of blood vessels. One major challenge in the development of H2 S-based therapeutics is its delivery. In this manuscript, we assess the various drug delivery strategies in the context of being used research tools and eventual developability as therapeutic agents.

Toward Direct Protein S-Persulfidation: A Prodrug Approach That Directly Delivers Hydrogen Persulfide.

A general strategy of delivering hydrogen persulfide (H2S2) is described herein. Esterase- and phosphatase-sensitive H2S2 prodrugs with tunable release rates have been synthesized. Their utility is validated in examining protein S-persulfidation. With this unique approach of directly delivering H2S2, our findings reaffirmed that S-persulfidation leads to decreased activity of glyceraldehyde 3-phosphate dehydrogenase. This new approach complements available prodrugs/donors that directly deliver a single species, including hydrogen sulfide, perthiol, and COS, and will be very useful as part of the toolbox for delineating the mechanisms of sulfur signaling.

An Esterase-Sensitive Prodrug Approach for Controllable Delivery of Persulfide Species.

A strategy to deliver a well-defined persulfide species in a biological medium is described. Under near physiological conditions, the persulfide prodrug can be activated by an esterase to generate a "hydroxymethyl persulfide" intermediate, which rapidly collapses to form a defined persulfide. Such persulfide prodrugs can be used either as chemical tools to study persulfide chemistry and biology or for future development as H2 S-based therapeutic reagents. Using the persulfide prodrugs developed in this study, the reactivity between S-methyl methanethiosulfonate (MMTS) with persulfide was unambiguously demonstrated. Furthermore, a representative prodrug exhibited potent cardioprotective effects in a murine model of myocardial ischemia-reperfusion (MI/R) injury with a bell shape therapeutic profile.

A metal-free turn-on fluorescent probe for the fast and sensitive detection of inorganic azides.

Sodium azide is toxic and widely used in agricultural, commercial products, and research laboratories. Thus it is of a significant environmental concern and there is a need for the development of a rapid detection method. A fluorogenic dibenzylcyclooctyne derivative (Fl-DIBO) is herein described as a fluorescent probe for the rapid detection of inorganic azide via Strain-Promoted Azide-Alkyne Cycloaddition (SPAAC). Fl-DIBO was found to be highly selective toward NaN3 in comparison to other common anions with good sensitivity and detection limit of 10µM.

Esterase-Sensitive Prodrugs with Tunable Release Rates and Direct Generation of Hydrogen Sulfide.

Prodrugs that release hydrogen sulfide upon esterase-mediated cleavage of an ester group followed by lactonization are described herein. By modifying the ester group and thus its susceptibility to esterase, and structural features critical to the lactonization rate, H2 S release rates can be tuned. Such prodrugs directly release hydrogen sulfide without the involvement of perthiol species, which are commonly encountered with existing H2 S donors. Additionally, such prodrugs can easily be conjugated to another non-steroidal anti-inflammatory agent, leading to easy synthesis of hybrid prodrugs. As a biological validation of the H2 S prodrugs, the anti-inflammatory effects of one such prodrug were examined by studying its ability to inhibit LPS-induced TNF-α production in RAW 264.7 cells. This type of H2 S prodrugs shows great potential as both research tools and therapeutic agents.

Post-synthesis DNA modifications using a trans-cyclooctene click handle.

Post-synthesis DNA modification is a very useful method for DNA functionalization. This is achieved by using a modified NTP, which has a handle for further modifications, replacing the corresponding natural NTP in polymerase-catalyzed DNA synthesis. Subsequently, the handle can be used for further functionalization after PCR, preferably through a very fast reaction. Herein we describe polymerase-mediated incorporation of trans-cyclooctene modified thymidine triphosphate (TCO-TTP). Subsequently, the trans-cyclooctene group was reacted with a tetrazine tethered to other functional groups through a very fast click reaction. The utility of this DNA functionalization method was demonstrated with the incorporation of a boronic acid group and a fluorophore. The same approach was also successfully used in modifying a known aptamer for fluorescent labelling applications.

3,6-Substituted-1,2,4,5-tetrazines: tuning reaction rates for staged labeling applications.

Cycloaddition reactions involving tetrazines have proven to be powerful bioorthogonal tools for various applications. Conceivably, sequential and selective labeling using tetrazine-based reactions can be achieved by tuning the reaction rate. By varying the substituents on tetrazines, cycloaddition rate variations of over 200 fold have been achieved with the same dienophile. Upon coupling with different dienophiles, such as norbornene, the reaction rate difference can be over 14,000 fold. These substituted tetrazines can be very useful for selective labeling under different conditions.

Enhanced Antibacterial and Wound Healing Using a Metal-Organic Cluster Inspired by Artificial Photosynthesis.

Bacterial infection poses a constant threat to human health. It is crucial to develop cost-effective and multifunctional solutions to combat bacteria. In this study, inspiration has been taken from artificial photosynthesis and a hydrogel containing a photocatalytic metal-organic cluster (MOC) has been creatively formulated for wound healing and antibacterial purposes. Complete photocatalytic cycles have been achieved by combining the oxidative Ti-center and the reductive Cu-center, in which reactive oxygen species (1 O2 and ·OH) have been generated. The MOC has the capability to eliminate Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) at a concentration of 40 µg mL-1 . In addition, the hydrogel formulation (H-MOC) has been applied to wounds infected with S. aureus, resulting in improved healing efficiency. This work presents an innovative approach to utilizing photocatalytic biomaterials as non-antibiotic medications.

Nitrogen Deficiency Enhances Eggplant Defense against Western Flower Thrips via the Induction of the Jasmonate Pathway.

Plant nutrition is connected to defense against insect herbivores, but the exact mechanism underlying the effect of the nitrogen (N) supply on the anti-herbivore capacity of eggplants (Solanum melongena) has not been studied in detail. Therefore, we examined the impact of low (LN, 0.5 mM) and high (HN, 5 mM) nitrate levels on eggplant resistance against the western flower thrips Frankliniella occidentalis (WFT), a major destructive eggplant pest. Our results showed that LN plants displayed enhanced defense responses to WFT compared to HN plants. This included increased transcript levels of key genes in the jasmonic acid (JA) pathway, the accumulation of JA-amido conjugates (jasmonoyl-isoleucine, jasmonoyl-phenylalanine, and jasmonoyl-valine), JA precursor (12-oxophytodienoic acid), and methyl jasmonate, higher transcript levels of defense marker genes (MPK3, MPK7, and WRKY53), and increased activities of polyphenol oxidase and peroxidase upon a WFT attack. Our findings suggest that N deficiency can prime JA-mediated defense responses in eggplants, resulting in increased anti-herbivore resistance.

Non-acid reflux and esophageal dysmotility is associated with early esophageal squamous cell carcinoma.

BACKGROUND: Studies have demonstrated that non-acid reflux (NAR) is associated with esophageal squamous cell carcinoma (ESCC). Esophageal dysmotility is associated with NAR but few studies have focused on the esophageal motility of ESCC patients. We explored the relationship between ESCC, NAR and esophageal dysmotility with the aid of multichannel intraluminal impedance and pH (MII-pH) and high-resolution manometry (HRM). METHODS: From Jan 2021 to Oct 2022, 20 patients with superficial ESCC were enrolled as the ESCC group, while 20 age and gender matched individuals without gastroesophageal reflux disease (GERD) symptoms and 20 age and gender matched patients with GERD symptoms were recruited as the control groups. Patients received 24 h MII-pH and HRM procedure before endoscopic submucosal dissection (ESD), and the data were then collected to identify the type of reflux and esophageal dysmotility. RESULTS: Prevalence of esophageal dysmotility was significantly different among the three groups, 75.0% in the ESCC group, 35.0% in the non-GERD group and 70.0% in the GERD group (P = 0.029). NAR episodes at 15 cm above the lower esophageal sphincter (LES) in the ESCC group were significantly higher than that in the non-GERD group (6.5 (3.5-9.3) vs 1.0 (0.8-4.0), P = 0.001) and were similar with that in the GERD group (6.5 (3.5-9.3) vs 5.5 (3.0-10.5), P > 0.05). NAR episodes at 5 cm above LES was significantly higher in the ESCC group than that in the non-GERD group (38.0 (27.0-60.0) vs 18.0 (11.8-25.8), P = 0.001) and was significantly higher than that in the GERD group (38.0 (27.0-60.0) vs 20.0 (9.8-30.5)), P = 0.010). Prevalence of pathologic non-acid reflux was significantly different among the three groups, 30.0% in the ESCC group, 0.0% in the non-GERD group and 10.0% in the GERD group (P < 0.001). CONCLUSION: Our study found NAR and esophageal dysfunction frequently occur in ESCC patients. NAR and esophageal dysmotility may be associated with ESCC. CLINICAL TRIAL REGISTRATION NUMBER: ChiCTR2200061456.

Aromatized liposomes for sustained drug delivery.

Insufficient drug loading and leakage of payload remain major challenges in designing liposome-based drug delivery systems. These phenomena can limit duration of effect and cause toxicity. Targeting the rate-limiting step in drug release from liposomes, we modify (aromatized) them to have aromatic groups within their lipid bilayers. Aromatized liposomes are designed with synthetic phospholipids with aromatic groups covalently conjugated onto acyl chains. The optimized aromatized liposome increases drug loading and significantly decreases the burst release of a broad range of payloads (small molecules and macromolecules, different degrees of hydrophilicity) and extends their duration of release. Aromatized liposomes encapsulating the anesthetic tetrodotoxin (TTX) achieve markedly prolonged effect and decreased toxicity in an application where liposomes are used clinically: local anesthesia, even though TTX is a hydrophilic small molecule which is typically difficult to encapsulate. Aromatization of lipid bilayers can improve the performance of liposomal drug delivery systems.

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Plants, grown in the immobile soils, have evolved various strategies in response to environmental stresses, including the "stress memory" and "defense priming" mechanisms. The environmental stresses cannot immediately change the DNA base sequence in plants in the short-term. Therefore, epigenetic inheritance is a key mechanism for stress memory and defense priming. In particular, histone modification is considered to be the most important mechanism, which offers the possibility of stress memory. We summarized research advances in plant histone modifications involved in stress memory and defense priming under biotic and abiotic stresses, and proposed pro-blems in the field and the focus and directions in the future research. In-depth understanding of the relationship between histone modification and environmental stresses would facilitate the quick adaptation of plants to harsh environments, and provide theoretical and technical guidance for plant phenotype shaping, organ regeneration, and crop genetic improvement.

Permeation of polyethylene glycols across the tympanic membrane.

Localized and non-invasive delivery of therapeutics across barriers in the body is challenging. Examples include the flux of drugs across the tympanic membrane (TM) for the treatment of middle ear infections, and across the round window to treat inner ear disease. With the emergence of macromolecular therapies, the question arises as to whether such delivery can be achieved with macromolecules. Here, we have used polyethylene glycols (PEGs) in solutions to investigate macromolecular permeation across the TM in the chinchilla ex vivo. As the molecular weight of PEG increased, flux across the TM decreased, with an exponential relationship between the apparent diffusion coefficient and the molecular weight of the polymers. PEG flux was further decreased if it was released from a poloxamer 407 hydrogel, and lessened with increasing hydrogel concentration. Our results provide a framework for understanding the permeation of macromolecules noninvasively across barriers.

Nitrogen Supply Alters Rice Defense Against the Striped Stem Borer Chilo suppressalis.

Plant nutrition status is closely associated with plant defense against insect herbivores. However, the way nitrogen supply regulates rice anti-herbivore is not clear. This study investigated the effects of low (LN, 0.3 mM) and high (HN, 3 mM) nitrate levels on rice resistance against the striped stem borer Chilo suppressalis (SSB), one of the major destructive rice pests. Seven-day-old rice seedlings were cultured with different nitrate levels for 30 days and then inoculated with third instars of SSB. LN significantly enhanced rice anti-herbivore defense and lowered the total nitrogen content in the plants, but increased the content of free amino acids after SSB infestation. Additionally, LN significantly increased the accumulation of phenolic acids and flavonoids, especially lignin, resulting in enhanced constitutive defense in SSB-infested plants. SSB feeding led to a rapid accumulation of secondary metabolites. HN application led to the accumulation of metabolites derived from cinnamic acid, p-coumaric acid, p-coumaric CoA, feruloyl CoA, and apigenin, while LN led to the accumulation of metabolites derived from 3-dehydroquinic acid, phenylalanine, acetyl CoA, and aspartic acid. Collectively, our finding suggests that nitrogen deficiency enhances rice anti-herbivore defense via constitutive defense by the accumulation of phenolic acids and flavonoids.

Prodrugs of hydrogen sulfide and related sulfur species: recent development.

Hydrogen sulfide (H2S) is commonly referred to as the third gasotransmitter with firmly established physiological roles. Prodrug approaches have been broadly applied to deliver H2S for various applications and mechanistic studies. Since S-persulfidation and glutathionylation are known to be important in cellular signaling by sulfur species, there have been interests in developing donors of persulfide and glutathione persulfide as well. In this review, we discuss the recent development in area of prodrugs for various sulfur species.

Light-triggered release of conventional local anesthetics from a macromolecular prodrug for on-demand local anesthesia.

An on-demand anesthetic that would only take effect when needed and where the intensity of anesthesia could be easily adjustable according to patients' needs would be highly desirable. Here, we design and synthesize a macromolecular prodrug (P407-CM-T) in which the local anesthetic tetracaine (T) is attached to the polymer poloxamer 407 (P407) via a photo-cleavable coumarin linkage (CM). P407-CM-T solution is an injectable liquid at room temperature and gels near body temperature. The macromolecular prodrug has no anesthetic effect itself unless irradiated with a low-power blue light emitting diode (LED), resulting in local anesthesia. By adjusting the intensity and duration of irradiation, the anesthetic effect can be modulated. Local anesthesia can be repeatedly triggered.

Functionalized Multiarmed Polycaprolactones as Biocompatible Tissue Adhesives.

Existing tissue adhesives have a trade-off between adhesive strength and biocompatibility. Here, we report a series of biocompatible multiarmed polycaprolactones (PCL) as tissue adhesives that can be released from a hot glue gun and the length of each arm was kept at ∼2-3 kg mol-1 in all the polymers. The adhesion properties were dependent on the number of functionalized (N-hydroxysuccinimide ester (NHS), aldehyde (CHO), and isocyanate (NCO)) arms of the multiarmed polymers. The more arms, the higher the adhesion strength. For example, the adhesion strength in binding cut rat skin increased from 2.3 N cm-2 for 2PCL-NHS to 11.2 N cm-2 for 8-PCL-NHS. CHO- and NCO-modified 8PCL also had suitable adhesive properties. All the multiarmed polymers had minimal cytotoxicity in vitro and good biocompatibility in vivo, suggesting their potential as promising alternative surgical adhesives.