Essential Oils Derived from Cistus Species Activate Mitochondria by Inducing SIRT1 Expression in Human Keratinocytes,Leading to Senescence Inhibition

Cistus L. is a genus of dicotyledonous perennial herbaceous plants. Cistus species have been commonly used in folk medicine in the Mediterranean region. In the present study, the biological activities of essential oils derived from Cistus species (Cistus laurifolius, C. monspeliensis, C. creticus, and C. salviifolius) were evaluated. Essential oils derived from C. laurifolius and C. monspeliensis were found to augment the expression of SIRT1, an anti-aging gene, in the normal culture of HaCaT cells. Furthermore, these essential oils increased the number and size of mitochondria and augmented their activity. These effects were thought to be caused by the up- and downregulated expression of MITOL and Drp1 in HaCaT cells, respectively, in response to the essential oil treatment. In addition, these essential oils were found to attenuate ultraviolet-B-induced mitochondrial damage and cellular senescence in HaCaT cells. These findings indicate that essential oils derived from C. laurifolius and C. monspeliensis may inhibit skin aging through mitochondrial regulation via SIRT1 activation.     

Two new brominated C15-acetogenins from the red alga Laurencia japonensis

Abstract

We report on the chemical characteristics of the red alga Laurencia japonensis, collected off the coast of Yoshio, Katsuura, Boso Peninsula, Japan. We isolated two new brominated C₁₅-acetogenins in this species, which we name katsuurenyne A (1) and katsuurenyne B (2), along with two already known halogenated terpenes [2,10-dibromo-3-chloro-α-chamigrene (7) and aplysiadiol (8)]. We extensively analysed spectral data (from IR, ESI-MS, 1D-NMR and 2D-NMR) to confirm the structure of these compounds.     

Synthesis of Bicyclo[1.1.1]pentane (BCP)-Based Straight-Shaped Diphosphine Ligands**

[1.1.1]Propellane, which is structurally simple and compact, exhibits promising potential for the synthesis of disubstituted straight-shaped bicyclo[1.1.1]pentane (BCP) compounds by manipulation of its highly reactive internal C−C bond. BCPs are considered to be isosteres of 1,4-disubstituted benzenes, which have found broad applications in the areas of functional molecules and drug discovery. The internal C−C single bond of [1.1.1]propellane is regarded as a charge-shift bond, which can be readily cleaved by radical means to construct BCPs. We herein report a novel synthetic method for (un)symmetric diphosphines based on the BCP motif, which can be interpreted as isosteres of 1,4-bis(diphenylphosphino)benzenes. The obtained BCP-diphosphine derivatives were used to generate a straight-shaped Au complex and an Eu-based coordination polymer.     

Cold Denaturation of α‐Synuclein Amyloid Fibrils

Although amyloid fibrils are associated with numerous pathologies, their conformational stability remains largely unclear. Herein, we probe the thermal stability of various amyloid fibrils. α‐Synuclein fibrils cold‐denatured to monomers at 0–20 °C and heat‐denatured at 60–110 °C. Meanwhile, the fibrils of β2‐microglobulin, Alzheimer’s Aβ1‐40/Aβ1‐42 peptides, and insulin exhibited only heat denaturation, although they showed a decrease in stability at low temperature. A comparison of structural parameters with positive enthalpy and heat capacity changes which showed opposite signs to protein folding suggested that the burial of charged residues in fibril cores contributed to the cold denaturation of α‐synuclein fibrils. We propose that although cold‐denaturation is common to both native proteins and misfolded fibrillar states, the main‐chain dominated amyloid structures may explain amyloid‐specific cold denaturation arising from the unfavorable burial of charged side‐chains in fibril cores.     

Systematic Interaction Analysis of Anti-Human Immunodeficiency Virus Type-1 Neutralizing Antibodies with High Mannose Glycans Using Fragment Molecular Orbital and Molecular Dynamics Methods

A series of broadly neutralizing antibodies called PGT have been shown to be bound directly to human immunodeficiency virus type-1 via high mannose glycans on glycoprotein gp120. Despite the sequence similarities of amino acids of the antibodies, their affinities to the glycan differ. Glycan–antibody interactions among these antibodies are systematically compared with quantum chemical fragment molecular orbital calculations and molecular dynamics simulations. The differences among structural stability of the glycan in the active site of the complexes and total interaction energies as well as binding free energies between the glycan and antibodies agree well with the experimentally shown affinities of the glycan to the antibodies. The terminal saccharide, Man D3, is structurally stable and responsible for the glycan–antibody binding through electrostatic and dispersion interactions. The structural stability of nonterminal saccharides such as Man 4 or Man C plays substantial roles in the interaction via direct hydrogen bonds. © 2019 Wiley Periodicals, Inc.     

Divergent synthesis of pseudoenantiomers for ABC-ring moiety of steroids

Steroid family has various bioactivities and characteristic polycyclic structure. Although several synthetic methods have been reported, more efficient way is desired for medicinal chemistry. In this Letter, we synthesized pseudoenantiomers of tricyclic enones toward both enantiomers for ABC-ring moiety of steroids utilizing d-mannitol as a chiral source. The key steps are radical domino cyclization of polyalkenyl-β-keto ester into tricyclic keto ester and subsequent dealkoxycarbonylation.     

Synthesis of trans,trans,cis-fused tetracyclic skeleton via radical domino cyclization

Limonoids are characterized by a polycyclic structure and show a wide variety of bioactivities. In particular, mesendanin L, 12-hydroxyamoorastatone, and meliatoosenin F have unique structures containing a trans-A/B/C and cis-C/D-fused tetracyclic skeleton. We synthesized the core structure of these limonoids via Mn(OAc)₃ and Cu(OAc)₂-mediated radical domino cyclization of an acyclic tetraene precursor having a terminal β-keto ester. To the best of our knowledge, this is the first example of the radical-mediated construction of a 6/6/6/5-membered tetracyclic skeleton.     

A 7.72% efficient dye sensitized solar cell based on novel necklace-like polymer gel electrolyte containing latent chemically cross-linked gel electrolyte precursors

Novel necklace-like polymer gel electrolytes containing latent chemically cross-linked gel electrolyte precursors were prepared for quasi-solid dye sensitized solar cells with a highest efficiency of 7.72% and an active area of 0.25 cm2 under AM1.5 condition at 100 mW cm(-2) irradiation.