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Aaptamine: A Versatile Marine Alkaloid for Antioxidant, Antibacterial, and Anticancer Therapeutics

Aaptamine (8,9-dimethoxy-1H-benzo[de][1,6]naphthyridine), an alkaloid obtained from marine sponges of the genus Aaptos (Demospongiae, Suberitida, Suberitidae), has attracted significant attention as a promising scaffold for the development of antioxidant, antibacterial, and anticancer agents. This review offers an extensive overview of updated research on aaptamine, focusing on its multifaceted pharmacological properties. The antioxidant potential of aaptamine reflects its potential ability for use in the DPPH free radical scavenging assay, for suppressing ROS, and subsequently deactivating the MAPK and AP-1 signaling pathway. Moreover, it demonstrates notable antibacterial activity against pathogenic bacteria, including mycobacterial active and dormant states, making it a potential candidate for combating bacterial infections. Additionally, aaptamine shows promising anticancer activity by inhibiting cancer cell proliferation, apoptosis induction, and suppressing tumor growth through various signaling pathways, including the regulation of PTEN/PI3K/Akt and CDK2/4, and the regulation of cyclin D1/E in cell cycle arrest. The unique chemical structure of aaptamine offers opportunities for structural modifications aimed at enhancing its antioxidant, antibacterial, and anticancer activities. The exploration of aaptamine as a scaffold in the development of novel therapeutic agents offers great promise for addressing various challenges associated with oxidative stress, bacterial infections, and cancer. This article underscores the potential of aaptamine as a valuable marine-derived scaffold in the fields of antioxidant, antibacterial, and anticancer therapy.

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Visible Light-sensitized CO2 Methanation along a Relaxed Heat Available Route.

In photocatalysis, the resulted heat by the relaxation of most of incident light no longer acts as the industrially favorite driving force back to the target photo-reaction due to more or less the negative relation between photocatalytic efficiency and temperature. Here, we reported a visible light-sensitized protocol that completely reversed the negatively temperature-dependent efficiency in photo-driven CO2 methanation with saturated water vapor. Uniform Pt/N-TiO2/PDI self-assembly material decisively injects the excited electron of PDI sensitizer into N-TiO2 forming Ti-H hydride which is crucially temperature-dependent nucleophilic species to dominate CO2 methanation, rather than conventionally separated and trapped electrons on the conductor band. Meanwhile, the ternary composite lifts itself temperature from room temperature to 305.2 °C within 400s only by the failure excitation upon simulated sunlight of 2.5 W/cm2, and smoothly achieves CO2 methanation with a record number of 4.98 mmol g-1 h-1 rate, compared to less than 0.02 mmol g-1 h-1 at classic Pt/N-TiO2/UV photocatalysis without PDI sensitization. This approach can reuse ~53.9% of the relaxed heat energy from the incident light thereby allow high-intensity incident light as strong as possible within a flowing photo-reactor, opening the most likely gateways to industrialization.

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Highly Active Immobilized Catalyst for Ethylene Polymerization: Neutral Single Site Y(III) Complex Bearing Bulky Silylallyl Ligand.

Exploring the surface organometallic chemistry on silica of highly electrophilic yttrium complexes is a relatively uncommon endeavor, particularly when focusing on tris-alkyl complexes characterized by Y-C σ-alkyl bonds. A drawback with this class of complexes once grafted on silica, is the frequent occurrence of alkyl transfer by ring opening of siloxane groups, resulting in a mixture of species. Herein, we employed a more stable homoleptic yttrium allyl complex bearing bulky η3-1,3-bis(trimethylsilyl)allyl ligand to limit this transfer reaction. This strategy has been validated by comparing the reactivity between [Y{η3-1,3-C3H3(SiMe3)2}3] and [Y(o-CH2PhNMe2)3] with SiO2-700, where the undesired alkyl transfer reaction occurred for [Y(o-CH2PhNMe2)3] leading to a bipodal [(≡SiO)2Y(o-CH2PhNMe2)] as major surface species, 2, while [Y{η3-1,3-C3H3(SiMe3)2}3] resulted selectively in a monopodal species, [(≡SiO)Y{η3-1,3-C3H3(SiMe3)2}2], 1. The materials obtained were characterized by DRIFT, solid state NMR, mass balance analysis and EXAFS. Catalyst 1 showed high activity compared to 2 in ethylene polymerization. The catalytic performance of this neutral catalyst 1 was extended to pre-industrial scale in the presence of hydrogen and 1-hexene. An unprecedented activity, up to 7400 gPE·gcat-1·h-1 was obtained even with very low concentration of scavenger AliBu3 (TIBA/Y = 1.2). The obtained HDPE exhibited desired spherical particle morphology with broad molar mass distribution.

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