Development of a water-soluble fluorescent Al3+ probe based on phenylsulfonyl-2-pyrone in biological systems

BACKGROUND

Al exists naturally in the environment and is an important component in acidic soils, which harm almost all plants. Furthermore, Al is widely used in food additives, cosmetics, and medicines, resulting in living organisms ingesting traces of Al orally or dermally every day. Accordingly, Al accumulates in the body, which can cause negative bioeffects and diseases, and this concern is gaining increasing attention. Therefore, to detect and track Al in the environment and in living organisms, the development of novel Al-selective probes that are water-soluble and exhibit fluorescence at long wavelengths is necessary.

RESULTS

In this study, an Al3+-selective fluorescent probe PSP based on a novel pyrone molecule was synthesized and characterized to detect and track Al in biological systems. PSP exhibited fluorescence enhancement at 580 nm in the presence of Al3+ in aqueous media. Binding analysis using Job's plot and structural analysis using 1H NMR showed that PSP formed a 1:1 complex with Al3+ at the two carbonyl groups of the dimethyl malonate of the pyrone ring. Upon testing in biological systems, PSP showed good cell membrane permeability, detected intracellular Al3+ in human breast cancer cells (MDA-MB-231), and successfully imaged accumulated Al3+ in Microcystis aeruginosa and the larvae of Rheocricotopus species.

SIGNIFICANCE

The novel Al3+-selective fluorescent probe PSP is highly effective and is expected to aid in elucidating the role of Al3+ in the environment and living organisms.

Synthesis of a Novel Pyrazine⁻Pyridone Biheteroaryl-Based Fluorescence Sensor and Detection of Endogenous Labile Zinc Ions in Lung Cancer Cells

A small extent of endogenous labile zinc is involved in many vital physiological roles in living systems. However, its detailed functions have not been fully elucidated. In this study, we developed a novel biheteroaryl-based low molecular weight fluorescent sensor, 3-(phenylsulfonyl)-pyrazine–pyridone (5b), and applied it for the detection of endogenous labile zinc ions from lung cancer cells during apoptosis. The electron-withdrawing property of the sulfonyl group between the phenyl ring as an electron donor and the pyridone ring as a fluorophore inhibited the intramolecular charge transfer state, and the background fluorescence of the sensor was decreased in aqueous media. From the structure–fluorescence relationship analysis of the substituent effects with/without Zn²⁺, compound 5b acting as a sensor possessed favorable properties, including a longer emission wavelength, a large Stokes shift (over 100 nm), a large fluorescence enhancement in response to Zn²⁺ under physical conditions, and good cell membrane permeability in living cells. Fluorescence imaging studies of human lung adenocarcinoma cells (A549) undergoing apoptosis revealed that compound 5b could detect endogenous labile zinc ions. These experiments suggested that the low molecular weight compound 5b is a potential fluorescence sensor for Zn²⁺ toward understanding its functions in living systems.

Synthesis, solid-state fluorescence properties, and computational analysis of novel 2-aminobenzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides

New fluorescent compounds, benzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides (3a-g), 2-amino-4-methylsulfanylbenzo[4,5]thieno[3,2-d]pyrimidine (6), and 2-amino-4-methylsulfanyl-7-methoxybenzo[4,5]furo[3,2-d]pyrimidine (7), were synthesized in good yields from heterocyclic ketene dithioacetals (1a-c) and guanidine carbonate (2a) or (S)-methylisothiourea sulfate (2b) in pyridine under reflux. Among the fused pyrimidine derivatives, compound 3c, which has an amino group at the 2-position and a benzylamino group at the 4-position of the pyrimidine ring, showed the strongest solid-state fluorescence. The absorption and emission properties of the compounds were quantitatively reproduced by a series of ab initio quantum-chemical calculations.

[Clinical trial work at Hospital of UOEH]

A clinical trial management room was established in the pharmacy at UOEH hospital in June, 2001, and we support the clinical trials in our hospital. Meanwhile, the number of clinical trials and CRC have increased as a result of this. Moreover, there have been changes in the work contents due to the introduction of the electronic clinical record system. At this time, we will report on the various current activities, and discuss the future problems.