Photodynamic Therapy

Kang, Kyungsu; Bacci, Stefano

doi:10.3390/biomedicines10112701

Cited by 9 publications

(16 citation statements)

References 22 publications

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“…Hypericin has been shown to have a high quantum yield of triplet formation (0.5−0.7). 19,20 The assignment of these transient absorption bands at 450−550 and 630−800 nm to triplet state 3 Hyp* can be confirmed by their accelerated quenching in the presence of O 2 , with the lifetime being shortened to ∼2.14 μs (Figure S1A,B). Moreover, the absorption spectra of triplet 3 Hyp* obtained here in DMSO are consistent with that obtained in ethanol solution.…”

Section: A Characterizing the Excited-state Property Of Hypmentioning

confidence: 69%

“…19,20 The assignment of these transient absorption bands at 450−550 and 630−800 nm to triplet state 3 Hyp* can be confirmed by their accelerated quenching in the presence of O 2 , with the lifetime being shortened to ∼2.14 μs (Figure S1A,B). Moreover, the absorption spectra of triplet 3 Hyp* obtained here in DMSO are consistent with that obtained in ethanol solution. 19 However, as shown in Figure S2, the characteristic triplet signal of Hyp is absent in water solution, owing to the We thus testify that Hyp can bind with the water-soluble Gquadruplex to form a complexed photosensitizer.…”

Section: A Characterizing the Excited-state Property Of Hypmentioning

confidence: 69%

“…Moreover, the overhang base at the 5′-end is found to affect the binding extent, possibly due to the hydrogen-bonding interaction between Hyp and overhang base at this site. Importantly, the 1 O 2 quantum yields for different Hyp/G-quadruplexs are derived using methylene blue as a reference standard, revealing a consistent trend that the better the Hyp/G4 binding, the longer the triplet 3 Hyp* lifetime and the higher the efficiency to produce singlet oxygen. These results clearly reveal the conformational effect of the G-quadruplex on the binding behavior and photosensitizing activity of Hyp/G-quadruplex.…”

Section: Introductionmentioning

confidence: 80%

“…Second, we performed transient spectroscopy utilizing the triplet excited state as sensitive reporters. Presumably, the decay lifetimes of triplet 3 Hyp* are highly sensitive to the confined environment where Hyp binds to Gquadruplex; thereby, they should make it possible to distinguish a different binding mode. 23−25 If Hyp is sandwiched between two c-kit2 with a 1:2 binding ratio, the triplet 3 Hyp* lifetime should be longer than that of the 1:1 binding ratio, due to the better two sides' protection from bulk O 2 quenching.…”

Section: A Characterizing the Excited-state Property Of Hypmentioning

confidence: 99%

“…Hypericin (Hyp) (Scheme A), a natural polycyclic quinone pigment, is one of the major active constituents of hypericum with diverse biological activities, such as antiviral, antiretroviral, anticancer, proteasome inhibition, antidepressant, anti-inflammatory, and photodynamic activities. , As Hyp preferentially accumulates in cancerous tissues, it is currently being investigated as a promising photosensitizer for use in the photodynamic therapy of cancer and as a dye in fluorescence imaging of cancer. As a photosensitizer, under the combined action of oxygen and a laser of appropriate wavelength, cytotoxic reactive oxygen species (ROS), particularly singlet oxygen ( 1 O 2 ), are generated via electron or energy transfer pathways, resulting in the ablation of tumor. − …”

Section: Introductionmentioning

confidence: 99%

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Complexed Photosensitizer of Hypericin with G-Quadruplex: Structure-Dependent Behavior

Hu,

Wang,

Zhou

et al. 2024

J. Phys. Chem. B

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Despite the increased interest of visible-lightabsorbing compound Hypericin (Hyp) in photodiagnosis, photocatalysis, and photodynamic therapy (PDT) applications, a major obstacle still exists; i.e., the photoactivity is diminished due to the facile aggregation of Hyp in aqueous environment that induces excited-state quenching. Herein, we explore the excited-state property of Hyp bound to the DNA G-quadruplex by combining multiple steady-state and time-resolved spectroscopy. We find that the aggregation-induced quenching effect can be successfully prevented by appropriate G-quadruplex binders that disperse Hyp into monomer. The binding of Hyp/G-quadruplex is selective, however, exhibiting a preferential binding toward parallel Gquadruplexes (c-kit2, C14B1, STAT3, S50, and PS2.M), over antiparallel or hybrid G-quadruplex (Tel22, TBA). The excited-state property of Hyp is highly related to the binding behavior, showing a consistent trend that the better the Hyp/G-quadruplex binding, the longer the triplet 3 Hyp* lifetime and the higher the efficiency to produce 1 O 2 . For Hyp/c-kit2, the major binding mode is 5′-end stacking, which offers protection from collisional quenching reactions and ensures a stable photocycle of 3 Hyp*-O 2 energy transfer forming 1 O 2 , leading to the highest 1 O 2 quantum yield (0.67) with superior photostability. These findings open possibilities of developing Hyp/G-quadruplex complex as a biocompatible photosensitizer for PDT applications, etc.

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