Accumulation and Interaction of Hypericin in Low‐density Lipoprotein— A Photophysical Study

Mukherjee, Prasun; Adhikary, Ramkrishna; Halder, Mintu; Petrich, Jacob W.; Miškovský, Pavol

doi:10.1111/j.1751-1097.2007.00234.x

Cited by 30 publications

(30 citation statements)

References 41 publications

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“…In addition, starting at ca Hyp/LDL = 60:1 ratio, Hyp fluorescence kinetics exhibit more complex behavior with two fluorescence lifetimes. As it was previously suggested, the multiple decay components may indicate that the various fractions of Hyp molecules are differently self‐quenched in different parts of LDL particle (21,22,37,38).…”

Section: Resultsmentioning

confidence: 89%

“…2. The observed fluorescence is due to Hyp monomeric form incorporated in LDL particles (19–22). It is evident that there are at least two phases of the Hyp incorporation into LDL.…”

Section: Resultsmentioning

confidence: 99%

“…We have shown that high Hyp/LDL ratios (>30:1) lead to a significant decrease of quantum yield of Hyp fluorescence (19). The decrease is caused by the formation of nonfluorescent Hyp aggregates inside of LDL molecules and by dynamic self‐quenching of Hyp fluorescence (21,22). It was shown that only the monomeric form of Hyp is able to produce the excited triplet state of Hyp in LDL, which in aerobic conditions leads to singlet oxygen production (22).…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Hypericin Association With Low‐Density Lipoproteins

Buriánková

Búzová

Chorvát

et al. 2010

Photochem & Photobiology

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Steady-state and time-resolved fluorescence spectroscopy have been used for the study of the incorporation kinetics of hypericin (Hyp) into low-density lipoproteins (LDL). Biphasic kinetics of Hyp association with LDL was observed when solutions of Hyp and LDL were mixed at various concentration ratios. The rapid phase of Hyp incorporation is completed within seconds, while the slow phase lasts several minutes. The relative contributions of the individual phases show that a higher amount of Hyp molecules (65%) are incorporated into LDL in the second phase. The kinetics of the incorporation of Hyp into LDL particles preloaded with Hyp (Hyp/LDL=25:1) was also investigated. The decreased intensity of Hyp fluorescence is a sign of the formation of Hyp aggregates after penetration of additional Hyp molecules into Hyp/LDL=25:1 complex. The time dependence of Hyp fluorescence was measured after mixing the complex Hyp/LDL =200:1 with appropriate amounts of free LDL molecules. For each final Hyp/LDL ratio, an increase in the intensity and lifetime of Hyp fluorescence was observed, suggesting a monomerization of Hyp aggregates. The half-time of Hyp transfer from Hyp/LDL complex to LDL particles is similar to the half-time of the slow phase of Hyp incorporation into free LDL particles.

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Section: Resultsmentioning

confidence: 89%

“…2. The observed fluorescence is due to Hyp monomeric form incorporated in LDL particles (19–22). It is evident that there are at least two phases of the Hyp incorporation into LDL.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetics of Hypericin Association With Low‐Density Lipoproteins

Buriánková

Búzová

Chorvát

et al. 2010

Photochem & Photobiology

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“…These results strongly suggested that the lipoprotein might serve as a vehicle only during hypericin transport, and that hypericin was released from the lipoprotein complex before reaching the necrotic tumor tissue 12, 60. Several reports have confirmed that the LDL and LDL receptor pathway plays an important role in the delivery of hypericin into the cells 61-63.…”

Section: The Mechanism Of Necrosis Avidity Behind Hypericinmentioning

confidence: 76%

Necrosis Avidity: A Newly Discovered Feature of Hypericin and its Preclinical Applications in Necrosis Imaging

Jiang¹,

Jichen²,

Ni³

et al. 2013

Theranostics

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Hypericin has been widely studied as a potent photosensitizer for photodynamic therapy in both preclinical and clinical settings. Recently, hypericin has also been discovered to have a specific avidity for necrotic tissue. This affinity is also observed in a series of radiolabeled derivatives of hypericin, including [123I]iodohypericin, [124I]iodohypericin, and [131I]iodohypericin. Hypericin, along with other necrosis-avid contrast agents, has been investigated for use in noninvasively targeting necrotic tissues in numerous disorders. Potential clinical applications of hypericin include the identification of acute myocardial infarction, evaluation of tissue viability, assessment of therapeutic responses to treatments, and interventional procedures for solid tumors. The mechanisms of necrosis avidity in hypericin remain to be fully elucidated, although several hypotheses have been suggested. In particular, it has been proposed that the necrosis avidity of hypericin is compound specific; for instance, cholesterol, phosphatidylserine, or phosphatidylethanolamine components in the phospholipid bilayer of cellular membranes may be the major targets for its observed selectivity. Further investigations are needed to identify the specific binding moiety that is responsible for the necrosis avidity of hypericin.

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“…In the presence of the plasma (lipo)proteins Hyp aggregates can redissociate resulting in fluorescent monomeric and biological active form of this molecule (Falk and Meyer 1994;Lavie et al 1995;Huygens et al 2005;Kascakova et al 2005). Our group has published several articles about the properties of Hyp/LDL complexes (Kascakova et al 2005;Mukherjee et al 2008;Gbur et al 2009;Huntosova et al 2010;Buriankova et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Solubilization of poorly soluble photosensitizer hypericin by polymeric micelles and polyethylene glycol

Búzová¹,

Kasák²,

Miškovský³

et al. 2013

gpb

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Abstract. Hypericin (Hyp) is a promising photosensitizer for photodiagnosis and photodynamic therapy of cancer. However, Hyp has a large conjugated system and in aqueous solutions forms insoluble aggregates which do not possess biological activity. This makes intravenous injection of Hyp problematic and restricts its medical applications. To overcome this problem, Hyp is incorporated into drug delivery systems which can increase its solubility and bioavailability. One of the possibilities is utilization of polymeric micelles. The most used hydrophilic block for preparation of polymeric micelles is polyethylen glycol (PEG). PEG is a polymer which for its lack of immunogenicity, antigenicity and toxicity obtained approval for use in human medicine. In this work we have studied the solubilization of Hyp aggregates in the presence of PEG-PE and PEG-cholesterol micelles. The concentration of polymeric micelles which allows total monomerization of Hyp corresponds to the critical micellar concentration of these micelles (~10 -6 M). We have also investigated the effect of the molecular weight and concentration of PEG on the transition of aggregated Hyp to its monomeric form. PEGs with low molecular weight (<1000 g/mol) do not significantly contribute to the solubilization of Hyp. However, PEGs with molecular weight >2000 g/mol efficiently transform Hyp aggregates to the monomeric state of this photosensitizer.

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Accumulation and Interaction of Hypericin in Low‐density Lipoprotein— A Photophysical Study

Cited by 30 publications

References 41 publications

Kinetics of Hypericin Association With Low‐Density Lipoproteins

Kinetics of Hypericin Association With Low‐Density Lipoproteins

Necrosis Avidity: A Newly Discovered Feature of Hypericin and its Preclinical Applications in Necrosis Imaging

Solubilization of poorly soluble photosensitizer hypericin by polymeric micelles and polyethylene glycol

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