Search Results (6)

Anthocyanins are a class of natural pigments that accumulate transiently or permanently in plant tissues, often in response to abiotic and biotic stresses. They play a photoprotective role by attenuating the irradiance incident on the photochemical apparatus and quenching oxyradicals through their powerful anti-oxidative function. The objective of the current study is to understand the impact of introducing Vitis vinifera mybA1 (VvmybA1) in ‘Hamlin’ sweet orange trees on various aspects, including photosynthetic performance, pigment composition, and gene expression related to photosynthesis and light harvesting. We describe the relationship between anthocyanin accumulation and photosynthetic measurements in genetically modified ‘Hamlin’ sweet orange trees expressing the grapevine-derived Vitis vinifera mybA1 (VvmybA1). The juvenile leaves of transgenic plants displayed an intense purple color compared to the mature leaves, and microscopic visualization showed anthocyanin accumulation primarily in the leaf epidermal cells. Under optimal growth conditions, there were no significant differences in leaf gas exchange variables, suggesting normal photosynthetic performance. The chlorophyll fluorescence maximum quantum yield of PSII was slightly reduced in VvmybA1 transgenic leaves compared to the performance of the control leaves, while the total performance index per absorbance remained unaffected. Comparison of the chlorophyll and carotenoid pigment contents revealed that chlorophyllide a and carotenoid pigments, including trans-neoxanthin, trans-violaxanthin, cis-violaxanthin, zeaxanthin, antheraxanthin, and total xanthophylls were enhanced in VvmybA1 transgenic leaves. Although there were no significant changes in the rates of the gas exchange parameters, we recorded a high relative expression of the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (RuBP) and rubisco activase (RCA) in the mature leaves of transgenic plants, indicating activation of Rubisco. Our findings confirm an efficient photoacclimation of the photosynthetic apparatus, allowing the transgenic line to maintain a photosynthetic performance similar to that of the wild type. Full article

Lutein and its cis-isomers occur in a lot of plants, including a variety of flowers. In this study, lutein isomers were produced via iodine-catalyzed isomerization, and four cis-isomers (9Z-, 9′Z-, 13Z-, and 13Z′) were isolated by means of column chromatography and semipreparative HPLC. The structures of the 9′Z- and 13′Z-isomers were elucidated via NMR measurements. These compounds were used as standards for the HPLC-DAD-MS determination of the carotenoid composition of the flowers of 20 plant species, in which lutein and its geometrical isomers are the main components. The flowers showed great variation in their cis- and trans-lutein content, and also in the presence or absence of other carotenoids, such as violaxanthin, neoxanthin, β-cryptoxanthin, and β-carotene. Some of the investigated flowers were found to be rich sources of lutein without zeaxanthin. Full article

The present study was carried out to evaluate and compare in vitro antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), and ferric reducing antioxidant power (FRAP)), antimicrobial, anticancer activities, and the individual carotenoids and anthocyanins content of methanol extracts of the Cyclamen genotypes: Persian cyclamen accessions (Cyclamen persicum Mill.), sowbread (C. mirabile Hildebr.), and ivy-leaved cyclamen (C. hederifolium Mill.) aerial parts. The HPLC-PDA analysis revealed the presence of five individual carotenoids (i.e., neoxanthin, violaxanthin, lutein, β-carotene, and cis-β-carotene) as the main compounds in Cyclamen leaves, and the presence of seven individual anthocycanins (i.e., cyanidin 3,5-di-O-glucoside, peonidin-rutinoside, peonidin 3,5-di-O-glucoside, peonidin 3-O-glucoside, malvidin 3-O-glucoside, malvidin 3,5-di-O-glucoside, and malvidin-rutinoside) in Cyclamen flowers reported, hereby, for the first time. The highest phenolic content was found in the leaves of LC6, C. mirabile (46.32 ± 0.14 mg/g gallic acid equivalents [GAE]), and in the flowers of C. persicum Merengue Magenta (FC15) (58.63 ± 0.17 mg/g GAE), whereas the highest flavonoid content was reported in C. persicum Halios Falbala leaves, namely LC9 (54.90 ± 0.27 mg/g quercetin equivalents [QE]) and in flowers of C. persicum Victora (FC2) (77.87 ± 0.25 mg/g QE). The highest antioxidant activity in DPPH and FRAP assays was reported in C. persicum Dark Violet (LC1) and Victoria (LC2), whereas C. mirabile (LC6) had the highest activity in the TEAC assay. In flowers, high antioxidant activities in DPPH and TEAC were noticed in C. persicum Superserie Red (FC7) and Dark Violet (FC1), respectively, and Halios Falbala (FC9) exhibited the highest activity in the TEAC assay. Additionally, FC9 exhibited the highest antibacterial activity in almost all tested bacteria compared with the leaves extracts. Furthermore, the highest in vitro citotoxicity in MDA-MB-231 cells was noticed in C. hederifolium LC18 (56.71–69.35%) and FC18 (40.07–41.43%), with a lower effect against BJ cells demonstrating selective toxicity. The above findings, highlight the potential use of the Cyclamen flower and leaf extracts as significant anticancer agents along with their antioxidant and antimicrobial properties. Full article

This study aims to determine carotenoids in pomelo leaves (Citrus grandis Osbeck), a rich source of nutrients and phytochemicals, by high-performance liquid chromatography-mass spectrometry and prepare carotenoid nanoemulsions for the study of its inhibitory mechanism on melanoma cells A375. Fourteen carotenoids were separated within 27 min by using a YMC-C30 column and a gradient mobile phase of methanol-acetonitrile-water (84:14:2, v/v/v) and methylene chloride with a flow rate of 1 mL/min and detection wavelength of 450 nm. All-trans-lutein plus its cis-isomers were present in the largest amount (3012.97 μg/g), followed by all-trans-neoxanthin (309.2 μg/g), all-trans-violaxanthin (208.5 μg/g), all-trans-β-carotene plus its cis-isomers (203.17 μg/g), all-trans-α-carotene plus its cis-isomers (152.5 μg/g), all-trans-zeaxanthin (54.67 μg/g), and all-trans-β-cryptoxanthin plus its cis-isomers (24.56 μg/g). A stable carotenoid nanoemulsion was prepared with a mean particle size of 13.3 nm, zeta-potential of −66.6 mV, a polydispersity index of 0.132 and an encapsulation efficiency of 99%. Both the carotenoid extract and nanoemulsion could upregulate p53, p21, cyclin B and cyclin A expressions in melanoma A375 cells and downregulate CDK1 and CDK2 in a concentration-dependent manner. Also, they could upregulate Bax and cytochrome-C and downregulate Bcl-2, leading to cell apoptosis through activation of caspase-9, caspase-8 and caspase-3. Compared to extract, carotenoid nanoemulsion was shown to be more effective in inhibiting the growth of melanoma cells A375. This finding further demonstrated that a carotenoid nanoemulsion prepared from pomelo leaves possessed a great potential to be developed into functional foods or even botanic drugs. Full article

Light is a paramount parameter driving photosynthesis. However, excessive irradiance leads to the formation of reactive oxygen species that cause cell damage and hamper the growth of photosynthetic organisms. Xanthophylls are key pigments involved in the photoprotective response of plants and algae to excessive light. Of particular relevance is the operation of xanthophyll cycles (XC) leading to the formation of de-epoxidized molecules with energy dissipating capacities. Neoxanthin, found in plants and algae in two different isomeric forms, is involved in the light stress response at different levels. This xanthophyll is not directly involved in XCs and the molecular mechanisms behind its photoprotective activity are yet to be fully resolved. This review comprehensively addresses the photoprotective role of 9′-cis-neoxanthin, the most abundant neoxanthin isomer, and one of the major xanthophyll components in plants’ photosystems. The light-dependent accumulation of all-trans-neoxanthin in photosynthetic cells was identified exclusively in algae of the order Bryopsidales (Chlorophyta), that lack a functional XC. A putative photoprotective model involving all-trans-neoxanthin is discussed. Full article

Mature ‘Hamlin’ sweet oranges (Citrus sinensis (L.) Osbeck) were irradiated using light-emitting diodes (LEDs) and ultraviolet (UV) light for six days after harvest. Based on evaluation of the basic ripening parameters of fruits, the contents of soluble sugars, organic acids, and carotenoids were analyzed (in pulps) on the sixth day by high-performance liquid chromatography (HPLC). The results showed that LED and UV irradiation not only accelerated orange ripening but also caused significant changes in the soluble sugar, organic acid, and carotenoid content. Compared with fruit subjected to dark shade (DS) treatment, the total soluble sugar, fructose, and glucose contents increased significantly in UV-treated (UVA, UVB, and UVC) fruits, while the sucrose content increased remarkably in white light, UVB, and UVC-treated fruits (p < 0.05). UV treatment was associated with inducing the largest effect on the total soluble sugar content. Except for UVB, other types of light notably induced an accumulation of the total organic acid content, none but blue light and red light markedly induced citric acid accumulation (p < 0.05). Interestingly, only the red light and dark shade treatments had markedly positive effects in terms of inducing carotenoid accumulation, including the total carotenoid, isolutein, zeaxanthin, lutein, neoxanthin, all-trans-violaxanthin, phytofluene, cis-ζ-carotene, and β-carotene concentrations. Other light treatments had significantly negative effects on carotenoid accumulation (p < 0.05). Therefore, soluble sugar, organic acid, and carotenoid accumulation in sweet oranges vary depending on the levels of UV and LED irradiation. Appropriate light irradiation is a potentially effective way to maintain or improve postharvest fruit quality. Full article