A pair of ruthenium­(II) complex enantiomers, Δ- and Λ-[Ru­(bpy)2MBIP]2+ (bpy = 2,2′-bipyridine, MBIP = 2-(3-bromophenyl)­imidazo­[5,6-f]­phenanthroline), were designed, synthesized, and characterized. Comparative studies between the enantiomers on their binding behaviors to calf thymus DNA (CT-DNA) were conducted using UV−visible, fluorescence, and circular dichroism spectroscopies, viscosity measurements, isothermal titration calorimetry, a photocleavage experiment, and molecular simulation. The experimental results indicated that both the enantiomers spontaneously bound to CT-DNA through intercalation stabilized by the van der Waals force or the hydrogen bond and driven by enthalpy and that Δ-[Ru­(bpy)2MBIP]2+ intercalated into DNA more deeply than Λ-[Ru­(bpy)2MBIP]2+ did and exhibited a better DNA photocleavage ability. Molecular simulation further indicated that Δ-[Ru­(bpy)2MBIP]2+ more preferentially intercalated between the base pairs of CT-DNA to the major groove, and Λ-[Ru­(bpy)2MBIP]2+ more favorably intercalated to the minor groove. These research findings should be very helpful to the understanding of the stereoselectivity mechanism of DNA-bindings of metal complexes, and be useful for the design of novel metal-complex-based antitumor drugs with higher efficacy and lower toxicity.

On the basis of our previous comparative studies on the DNA-binding of a pair of ruthenium(II) complex enantiomers, Δ-[Ru(bpy)2PBIP]2+ and Λ-[Ru(bpy)2PBIP]2+ {bpy = 2,2'-bipyridine, PBIP = 2-(4-bromophenyl)imidazo[4,5-f]1,10-phenanthroline}, in this study,...

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Ultraviolet (UV) radiation-induced oxidative stress damage is a significant catalyst for skin aging and can even contribute to the development of skin cancer. In this study, the mechanism of how water-soluble intracellular extract (WIE) of Desmodesmus sp.YT (YT) prevent human skin fibroblast (HSF) against the oxidative damage caused by UV radiation were explored. Results showed that YT-WIE exhibited great antioxidant activity. The potent scavenging ability activity was observed in DPPH (IC50 = 0.55 mg mL-1), ABTS (IC50 = 3.11 mg mL-1), ·OH (IC50 = 2.21 mg mL-1) and O2•-(IC50 = 0.98 mg mL-1). Additionally, the findings indicated that when compared to the control group, YT-WIE group exhibited an 89.30% enhancement in the viability of HSF and a 44.63% increase in the survival rate following UV irradiation. To investigate the underlying mechanism, comprehensive analysis of gene transcription and translation was conducted using RT-qPCR and Western blot. The results demonstrated a significant upregulation of antioxidant genes (GCLC, GCLM, TXNRD1, HMOX1, NQO1) by YT-WIE treatment at a concentration of 400 µg mL-1, with fold increases ranging from 1.13 to 5.85 times. Therefore, YT-WIE exhibited a great potential to serve as antioxidants that can protect human cells from excessive oxidative stress caused by outer stimulus, such as UV.