Improved performance of stretchable piezoelectric energy harvester based on stress rearrangement.

With the development of wearable devices and soft electronics, the demand for stretchable piezoelectric energy harvesters (SPEHs) has increased. Energy harvesting can provide energy when large batteries or power sources cannot be employed, and stretchability provides a user-friendly experience. However, the performance of SPEHs remains low, which limits their application. In this study, a wearable SPEH is developed by adopting a kirigami structure on a polyvinylidene fluoride film. The performance of the SPEH is improved by rearranging the stress distribution throughout the film. This is conducted using two approaches: topological depolarization, which eliminates the opposite charge generation by thermal treatment, and optimization of the neutral axis, which maximizes the stress applied at the surface of the piezoelectric film. The SPEH performance is experimentally measured and compared with that of existing SPEHs. Using these two approaches, the stress was rearranged in both the x-y plane and z-direction, and the output voltage increased by 21.57% compared with that of the original film with the same stretching motion. The generated energy harvester was successfully applied to smart transmittance-changing contact lenses.

Exogenous pyruvate alleviates UV-induced hyperpigmentation via restraining dendrite outgrowth and Rac1 GTPase activity.

BACKGROUND: Melanin is synthesized in melanocytes and transferred to keratinocytes through dendrites. Endogenous pyruvate is a key metabolite for ATP production in glycolysis, and the tricarboxylic acid (TCA) cycle and exogenous pyruvate provide protection against oxidative stress and acidosis in the intercellular space. The function of pyruvate in the regulation of dendrite outgrowth remains to be elucidated. OBJECTIVE: We examined the effect of pyruvate on dendritic elongation and skin pigmentation METHODS: Murine B16F10 melanoma cells and human primary melanocytes were used for in vitro analysis. Melanin quantitation and histochemical staining were performed in a 3D pigmented human skin model. RESULTS: We demonstrated the participation of monocarboxylate transporters (MCTs) responsible for the membrane transport of pyruvate in B16F10 melanoma cells. The accumulation of pyruvate occurred in a pH-dependent manner, which was highly sensitive to a specific MCT inhibitor (α-cyano-4-hydroxycinnamic acid). α-MSH-induced morphological changes, including dendrite elongation and growth-cone-like structure, were diminished in B16F10 cells upon treatment with pyruvate. In addition, the number of dendrite branches was reduced in normal human epidermal melanocytes. As the Rho-subfamily of monomeric GTP-binding proteins modulates dendrite formation, we subsequently examined the suppression of Rac1 activation by pyruvate, but not RhoA and Cdc42. Furthermore, pyruvate showed anti-melanogenic effects against UV-induced pigmentation in reconstructed pigmented epidermis, established by co-seeding autologous melanocytes and keratinocytes, which act similar to in vivo skin tissue. CONCLUSION: These results suggest that pyruvate treatment may be an alternative or additive therapeutic strategy to prevent hyperpigmentation.

Lenzimycins A and B, Metabolites With Antibacterial Properties From Brevibacillus sp. Associated With the Dung Beetle Onthophagus lenzii.

Symbiotic microorganisms associated with insects can produce a wide array of metabolic products, which provide an opportunity for the discovery of useful natural products. Selective isolation of bacterial strains associated with the dung beetle, Onthophagus lenzii, identified two strains, of which the antibiotic-producing Brevibacillus sp. PTH23 inhibited the growth of Bacillus sp. CCARM 9248, which is most closely related to the well-known entomopathogen, Bacillus thuringiensis. A comprehensive chemical investigation based on antibiotic activity discovered two new antibiotics, named lenzimycins A and B (1-2), which inhibited growth of Bacillus sp. CCARM 9248. The 1H and 13C NMR, MS, MS/MS, and IR analyses elucidated the structures of 1 and 2, which comprised a novel combination of fatty acid (12-methyltetradecanoic acid), glycerol, sulfate, and N-methyl ethanolamine. Furthermore, the acid hydrolysis of 1 revealed the absolute configuration of 12-methyltetradecanoic acid as 12S by comparing its optical rotation value with authentic (R)- and (S)-12-methyltetradecanoic acid. In addition to inhibition of Bacillus sp. CCARM 9248, lenzimycins A and B were found to inhibit the growth of some human pathogenic bacteria, including Enterococcus faecium and certain strains of Enterococcus faecalis. Furthermore, the present study elucidated that lenzimycins A and B activated a reporter system designed to detect the bacterial cell envelope stress, thereby indicating an activity against the integrity of the bacterial cell wall.

Rhizolutin, a Novel 7/10/6-Tricyclic Dilactone, Dissociates Misfolded Protein Aggregates and Reduces Apoptosis/Inflammation Associated with Alzheimer's Disease.

Rhizolutin (1) was discovered as a natural product of ginseng-rhizospheric Streptomyces sp. WON17. Its structure features an unprecedented 7/10/6-tricyclic dilactone carbon skeleton composed of dimethylcyclodecatriene flanked by a 7-membered and a 6-membered lactone ring based on spectroscopic analysis. During an unbiased screening of natural product libraries, this novel compound was found to dissociate amyloid-ß (Aß) plaques and tau tangles, which are key pathological hallmarks of Alzheimer's disease (AD). Rhizolutin treatment of APP/PS1 double transgenic mice with AD significantly dissociated hippocampal plaques. In vitro, rhizolutin substantially decreased Aß-induced apoptosis and inflammation in neuronal and glial cells. Our findings introduce a unique chemical entity that targets Aß and tau concurrently by mimicking misfolded protein clearance mechanisms of immunotherapy, which is prominently investigated in clinical trials.

Donghaecyclinones A-C: New Cytotoxic Rearranged Angucyclinones from a Volcanic Island-Derived Marine Streptomyces sp.

Chemical profiling of the Streptomyces sp. strain SUD119, which was isolated from a marine sediment sample collected from a volcanic island in Korea, led to the discovery of three new metabolites: donghaecyclinones A-C (1-3). The structures of 1-3 were found to be rearranged, multicyclic, angucyclinone-class compounds according to nuclear magnetic resonance (NMR) and mass spectrometry (MS) analyses. The configurations of their stereogenic centers were successfully assigned using a combination of quantum mechanics-based computational methods for calculating the NMR shielding tensor (DP4 and CP3) as well as electronic circular dichroism (ECD) along with a modified version of Mosher's method. Donghaecyclinones A-C (1-3) displayed cytotoxicity against diverse human cancer cell lines (IC50: 6.7-9.6 µM for 3).

Camporidines A and B: Antimetastatic and Anti-inflammatory Polyketide Alkaloids from a Gut Bacterium of Camponotus kiusiuensis.

Chemical studies of gut bacteria of the carpenter ant Camponotus kiusiuensis led to the discovery of two new alkaloids, camporidines A and B (1 and 2), from Streptomyces sp. STA1. The structures of 1 and 2 were established as new polyketide alkaloids bearing a piperidine-cyclopentene-epoxide 6/5/3 tricyclic system based on NMR spectroscopic and mass spectrometric analysis. The relative configurations of the camporidines were determined by their 1H-1H NOESY/ROESY and 1D NOE NMR correlations. The experimental ECD spectra of 1 and 2 were compared with their calculated ECD spectra to assign their absolute configurations. Camporidine A (1) displayed antimetastatic activity by suppression of cell invasion against the metastatic breast cancer cell line MDA-MB-231 and showed an anti-inflammatory effect by suppressing nitric oxide production induced by lipopolysaccharide. In addition, the putative biosynthetic gene cluster of the camporidines was identified, and the biosynthetic pathway of the camporidines was proposed based on bioinformatic analysis of the full genome of Streptomyces sp. STA1. Camporidines A and B (1 and 2) could be biosynthesized by a modular type I PKS containing an acyl transferase domain that accepts an unusual extender unit, which becomes the (C1'-C6') hexyl side chain. The post-PKS modification enzymes were predicted to perform an amination and an oxidation along with spontaneous Schiff base formation and generate the unique piperidine-cyclopentene-epoxide 6/5/3 tricyclic framework.