Stabilization of 5-aminolevulinic acid by the zinc(II) ion in an aqueous solution

Sakiyama, Hiroshi; Inoue, Hidetatsu; Kudrat‐E‐Zahan, Md.; Hueki, Shoichi; Tachiya, Naohisa; Nishida, Yuzo

doi:10.5155/eurjchem.1.4.373-376.101

Cited by 1 publication

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“…Thus, the stability of the 5‐ALA solution is a problem that still needs to be solved before it can become applicable in the industry. In addition, the zinc (II) ion can stabilize 5‐ALA solution at neutral pH, however the process of forming zinc (II) complex is complicated . The solid form of 5‐ALA, known as 5‐aminolevulinic acid hydrochloride, is more stable but it is expensive and must be stored at –20°C.…”

Section: Introductionmentioning

confidence: 99%

Entrapment of 5‐aminolevulinic acid under edible composite film of konjac glucomannan and chitosan

Tripetch

Borompichaichartkul

Duangmal

et al. 2016

Engineering in Life Sciences

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Entrapment of 5-aminolevulinic acid under edible composite film of konjac glucomannan and chitosan5-Aminolevulinic acid (5-ALA) is a known plant regulator and growth promoter. It is a very sensitive and highly unstable compound that is easy to deteriorate. Here we propose a novel approach to stabilize 5-ALA into a film. Films from konjac glucomannan (KGM), KGM treated with alkali solution (KGOH), chitosan (CHI) as well as blends between KGOH and CHI were fabricated for 5-ALA entrapment. It was found that the efficiency of KGM film, KGOH film and CHI film for 5-ALA entrapment was 55.7 ± 0.73%, 58.3 ± 0.36% and 60.3 ± 0.18 %, respectively. A 25:75 (%w/w) blended film (KGOH/CHI) showed the highest entrapment efficiency of 5-ALA (65.9 ± 0.37%) versus other films. The possible mechanism for entrapment of 5-ALA in blended film was postulated under two mechanisms. A secondary amide that leads to the interaction between the amino group of CHI and carboxyl group of 5-ALA is proposed as the first mechanism. The fact that the 5-ALA molecule was entrapped within the complexity of KGOH structure is proposed as the second mechanism. Therefore, stabilizing 5-ALA in a film may be an alternative way to use and preserve 5-ALA for further applications. able herbicide but acts as an insecticide when used at high concentrations [5]. Moreover, 5-ALA has attracted attention for use in medicine since it destroys malignant cells in photodynamic diagnosis and therapy [6]. 5-ALA is safe for using in food, cosmetics, medicine and agricultural purposes. However, the stability of 5-ALA in aqueous solution is a critical problem for its use in various fields. Stability of 5-ALA depends on pH, concentration, temperature and degree of oxygenation [1]. The degradation mechanism of 5-ALA under alkaline conditions occurs when two molecules of 5-ALA are condensed with a nucleophilic attack by a lone pair of the amino group of 5-ALA to a γ-carbonyl of another 5-ALA molecule to form 3, 6-dihydropyrazine 2,5-dipropionic acid (DHPY). The DHPY is then oxidized to pyrazine 2, 5-diproipionic acid (PY) under aerobic conditions [7]. An aqueous solution at lower pH values (<2) would be required to preserve the 5-ALA stability for long-term storage [8,9].Thus, the stability of the 5-ALA solution is a problem that still needs to be solved before it can become applicable in the industry. In addition, the zinc (II) ion can stabilize 5-ALA solution at neutral pH, however the process of forming zinc (II) complex is complicated [10]. The solid form of 5-ALA, known as 5-aminolevulinic acid hydrochloride, is more stable

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Section: Introductionmentioning

confidence: 99%