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Open AccessArticle

Excited-State Dynamics of All the Mono-cis and the Major Di-cis Isomers of β-Apo-8′-Carotenal as Revealed by Femtosecond Time-Resolved Transient Absorption Spectroscopy

by Kota Horiuchi, Chiasa Uragami, Ruohan Tao, Daisuke Kosumi, Richard J. Cogdell and Hideki Hashimoto

Molecules 2023, 28(11), 4424; https://doi.org/10.3390/molecules28114424 - 29 May 2023

Cited by 6 | Viewed by 3327

Abstract

Cis isomers of carotenoids play important roles in light harvesting and photoprotection in photosynthetic bacteria, such as the reaction center in purple bacteria and the photosynthetic apparatus in cyanobacteria. Carotenoids containing carbonyl groups are involved in efficient energy transfer to chlorophyll in light-harvesting complexes, and their intramolecular charge–transfer (ICT) excited states are known to be important for this process. Previous studies, using ultrafast laser spectroscopy, have focused on the central-cis isomer of carbonyl-containing carotenoids, revealing that the ICT excited state is stabilized in polar environments. However, the relationship between the cis isomer structure and the ICT excited state has remained unresolved. In this study, we performed steady-state absorption and femtosecond time-resolved absorption spectroscopy on nine geometric isomers (7-cis, 9-cis, 13-cis, 15-cis, 13′-cis, 9,13′-cis, 9,13-cis, 13,13′-cis, and all-trans) of β-apo-8′-carotenal, whose structures are well-defined, and discovered correlations between the decay rate constant of the S₁ excited state and the S₀−S₁ energy gap, as well as between the position of the cis-bend and the degree of stabilization of the ICT excited state. Our results demonstrate that the ICT excited state is stabilized in polar environments in cis isomers of carbonyl-containing carotenoids and suggest that the position of the cis-bend plays an important role in the stabilization of the excited state. Full article

(This article belongs to the Special Issue Novelties in Carotenoid Chemistry: From Isolation and Synthesis to Properties, Structural Elucidation and Function)

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15 pages, 13531 KB

Open AccessArticle

Carotenoid Contents of Lycium barbarum: A Novel QAMS Analyses, Geographical Origins Discriminant Evaluation, and Storage Stability Assessment

by Ruru Ren, Yanting Li, Huan Chen, Yingli Wang, Lingling Yang, Chao Su, Xiaojun Zhao, Jianyu Chen and Xueqin Ma

Molecules 2021, 26(17), 5374; https://doi.org/10.3390/molecules26175374 - 3 Sep 2021

Cited by 15 | Viewed by 2664

Abstract

Given the standard substances of zeaxanthin and its homologues obtained from Lycium barbarum L. (LB) are extremely scarce and unstable, a novel quantitative analysis of carotenoids by single marker method, named QAMS, was established. Four carotenoids including lutein, zeaxanthin, β-carotene, and zeaxanthin dipalmitate were determined simultaneously by employing trans-β-apo-8′-carotenal, a carotenoid component which did not exist in LB, as standard reference. Meanwhile, β-carotene, another carotenoid constituent which existed in LB, was determined as contrast. The QAMS methods were fully verified and exhibited low standard method difference with the external standard method (ESM), evidenced by the contents of four carotenoids in 34 batches of LB samples determined using ESM and QAMS methods, respectively. HCA, PCA, and OPLS-DA analysis disclosed that LB samples could be clearly differentiated into two groups: one contained LB samples collected from Ningxia and Gansu; the other was from Qinghai, which was directly related to the different geographical location. Once exposed under high humidity (RH 75 ± 5%) at a high temperature (45 ± 5 °C) as compared with ambient temperature (25 ± 5 °C), from day 0 to day 28, zeaxanthin dipalmitate content was significantly decreased, and ultimately, all the decrease rates reached about 80%, regardless of the storage condition. Our results provide a good basis for improving the quality control of LB. Full article

(This article belongs to the Special Issue Advancements in Phytochemical Analysis: Development and Application of Novel Instruments and Techniques)

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14 pages, 2085 KB

Open AccessArticle

Dietary β-Carotene Rescues Vitamin A Deficiency and Inhibits Atherogenesis in Apolipoprotein E-Deficient Mice

by Ayelet Harari, Nir Melnikov, Michal Kandel Kfir, Yehuda Kamari, Lidor Mahler, Ami Ben-Amotz, Dror Harats, Hofit Cohen and Aviv Shaish

Nutrients 2020, 12(6), 1625; https://doi.org/10.3390/nu12061625 - 1 Jun 2020

Cited by 23 | Viewed by 5033

Abstract

Vitamin A deficiency (VAD) is a major health problem, especially in developing countries. In this study, we investigated the effect of VAD from weaning to adulthood in apoE^−/− mice. Three-week-old male mice were allocated into four diet groups: I. VAD II. VAD+vitamin A (VA), 1500 IU retinyl-palmitate; III. VAD+β-carotene (BC), 6 g/kg feed, containing 50% all-trans and 50% 9-cis BC. IV. VAD with BC and VA (BC+VA). After 13 weeks, we assessed the size of atherosclerotic plaques and measured VA in tissues and BC in plasma and tissues. VAD resulted in diminished hepatic VA levels and undetectable brain VA levels compared to the other groups. BC completely replenished VA levels in the liver, and BC+VA led to a two-fold elevation of hepatic VA accumulation. In adipose tissue, mice fed BC+VA accumulated only 13% BC compared to mice fed BC alone. Atherosclerotic lesion area of BC group was 73% lower compared to VAD group (p < 0.05). These results suggest that BC can be a sole source for VA and inhibits atherogenesis. Full article

(This article belongs to the Special Issue Carotenoids in Human Nutrition)

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11 pages, 1540 KB

Open AccessArticle

Apo-14´-Carotenoic Acid Is a Novel Endogenous and Bioactive Apo-Carotenoid

by Gamze Aydemir, Marta Domínguez, Angel R. de Lera, Johanna Mihaly, Dániel Törőcsik and Ralph Rühl

Nutrients 2019, 11(9), 2084; https://doi.org/10.3390/nu11092084 - 4 Sep 2019

Cited by 6 | Viewed by 4480

Abstract

Carotenoids can be metabolized to various apo-carotenoids and retinoids. Apo-15´-carotenoic acid (retinoic acid, RA) is a potent activator of the retinoic acid receptor (RAR) in its all-trans- (ATRA) and 9-cis- (9CRA) forms. In this study we show firstly, that apo-14´-carotenoic acid (A14CA), besides retinoic acids, is present endogenously and with increased levels in the human organism after carrot juice supplementation rich in β-carotene. All-trans-A14C (ATA14CA) is just a moderate activator of RAR-transactivation in reporter cell lines but can potently activate retinoic acid response element (RARE)-mediated signalling in DR5/RARE-reporter mice and potently increase retinoid-reporter target gene expression in ATA14CA-supplemented mice and treated MM6 cells. Further metabolism to all-trans-13,14-dihydroretinoic acid (ATDHRA) may be the key for its potent effects on retinoid target gene activation in ATA14CA-treated MM6 cells and in liver of supplemented mice. We conclude that besides RAs, there are alternative ways to activate RAR-response pathways in the mammalian organism. ATA14CA alone and in combination with its metabolite ATDHRA may be an alternative pathway for potent RAR-mediated signalling. Full article

(This article belongs to the Special Issue Carotenoids in Human Nutrition)

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13 pages, 1369 KB

Open AccessArticle

9-cis β-Carotene Increased Cholesterol Efflux to HDL in Macrophages

by Sapir Bechor, Noa Zolberg Relevy, Ayelet Harari, Tal Almog, Yehuda Kamari, Ami Ben-Amotz, Dror Harats and Aviv Shaish

Nutrients 2016, 8(7), 435; https://doi.org/10.3390/nu8070435 - 19 Jul 2016

Cited by 41 | Viewed by 6972

Abstract

Cholesterol efflux from macrophages is a key process in reverse cholesterol transport and, therefore, might inhibit atherogenesis. 9-cis-β-carotene (9-cis-βc) is a precursor for 9-cis-retinoic-acid (9-cis-RA), which regulates macrophage cholesterol efflux. Our objective was to assess whether 9-cis-βc increases macrophage cholesterol efflux and induces the expression of cholesterol transporters. Enrichment of a mouse diet with βc from the alga Dunaliella led to βc accumulation in peritoneal macrophages. 9-cis-βc increased the mRNA levels of CYP26B1, an enzyme that regulates RA cellular levels, indicating the formation of RA from βc in RAW264.7 macrophages. Furthermore, 9-cis-βc, as well as all-trans-βc, significantly increased cholesterol efflux to high-density lipoprotein (HDL) by 50% in RAW264.7 macrophages. Likewise, food fortification with 9-cis-βc augmented cholesterol efflux from macrophages ex vivo. 9-cis-βc increased both the mRNA and protein levels of ABCA1 and apolipoprotein E (APOE) and the mRNA level of ABCG1. Our study shows, for the first time, that 9-cis-βc from the diet accumulates in peritoneal macrophages and increases cholesterol efflux to HDL. These effects might be ascribed to transcriptional induction of ABCA1, ABCG1, and APOE. These results highlight the beneficial effect of βc in inhibition of atherosclerosis by improving cholesterol efflux from macrophages. Full article

(This article belongs to the Special Issue Vitamin A Update 2016)

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