Bioactivities of Phenolic Compounds from Kiwifruit and Persimmon

Fruit used in the common human diet in general, and kiwifruit and persimmon particularly, displays health properties in the prevention of heart disease. This study describes a combination of bioactivity, multivariate data analyses and fluorescence measurements for the differentiating of kiwifruit and persimmon, their quenching and antioxidant properties. The metabolic differences are shown, as well in the results of bioactivities and antioxidant capacities determined by ABTS, FRAP, CUPRAC and DPPH assays. To complement the bioactivity of these fruits, the quenching properties between extracted polyphenols and human serum proteins were determined by 3D-fluorescence spectroscopy studies. These properties of the extracted polyphenols in interaction with the main serum proteins in the human metabolism (human serum albumin (HSA), α-β-globulin (α-β G) and fibrinogen (Fgn)), showed that kiwifruit was more reactive than persimmon. There was a direct correlation between the quenching properties of the polyphenols of the investigated fruits with serum human proteins, their relative quantification and bioactivity. The results of metabolites and fluorescence quenching show that these fruits possess multiple properties that have a great potential to be used in industry with emphasis on the formulation of functional foods and in the pharmaceutical industry. Based on the quenching properties of human serum proteins with polyphenols and recent reports in vivo on human studies, we hypothesize that HSA, α-β G and Fgn will be predictors of coronary artery disease (CAD).

Interaction study of monoisoamyl dimercaptosuccinic acid with bovine serum albumin using biophysical and molecular docking approaches

Monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA), a lipophilic chelator has been evaluated for its potential use as an antidote in arsenic poisoning. The pharmacokinetics and pharmacodynamics properties of a drug could be understood via study its mechanism of interaction with bovine serum albumin protein (BSA). Therefore, the interaction between MiADMSA with BSA was investigated using various spectroscopic techniques and computational methods. Linear quenching of BSA intrinsic fluorescence intensity with the increasing concentration of MiADMSA was observed in the fluorescence study. Furthermore, synchronous results revealed that MiADMSA slightly changed the conformation of BSA. The binding constant value of the BSA-MiADMSA complex was found 1.60 × 104 M−1 at 298 K. The value of thermodynamic parameters ΔG, ΔH, and ΔS described that the process is spontaneous, endothermic, and hydrophobic forces are involved in the interaction of MiADMSA with BSA. Competitive site marker experiments showed that MiADMSA binds to site-II of BSA. Conformational changes of BSA with the interaction of MiADMSA were apparent by CD, UV–Visible, FT-IR, and 3D fluorescence spectroscopy. To strengthen the experimental findings we have also performed a theoretical study on the BSA-MiADMSA complex. Two sites were identified with docking score of − 6.642 kcal/mol at site IIa and − 3.80 kcal/mol for site IIb via molecular docking study. Molecular dynamics simulation study inferred the stability of the BSA-MiADMSA complex which was analyzed in a long simulation run. The experimental and computational studies have shown the effective binding of MiADMSA with BSA which is essential for the transportation and elimination of a drug from the body.

Study of the Fluorescence based Applications of Water Soluble (N, P) Doped Carbon Dots Synthesized via Microwave Assisted Green Pyrolysis

Background: Water soluble nitrogen and phosphorus doped carbon dots (CD) have been synthesized using citric acid, tris(2-aminoethyl)amine and orthophosphoric acid via one step microwave assisted pyrolytic method. Methods: The CD synthesized has been characterized using FTIR, UV-Vis, fluorescence spectroscopy and EDAX coupled with SEM techniques. Results: SEM study has shown the formation of nanosized CD with an average size of ~18 nm. Elemental analysis via EDAX has confirmed successful incorporation of nitrogen (30.8% wt) and phosphorus (5.7% wt) atoms in it. The steady state and 3D fluorescence spectroscopic studies have shown its efficient fluorescence emission with emission maxima in the region of ~450 nm. It has shown efficient “turn off” fluorescence behaviour towards transition metal ions like Fe2+ and Co2+ ions and toxic nitrophenolic compounds like p-nitrophenol and picric acid. Its efficient interaction with BSA has been revealed in terms of fluorescence quenching of BSA by steady state, synchronous and 3D fluorescence spectroscopy. It has shown very good in vitro biocompatibility and enhanced cell adhesion properties towards NIH 3T3 fibroblast cells. Moreover, fluorescence microscopy has shown significant uptake of CD by the tested cell line. Conclusion: Such bio-compatible nitrogen and phosphorous doped CD can be potentially useful to estimate metal ions, p-nitrophenol and picric acid using fluorescence spectroscopy and for fluorescence based bio-imaging.

Characterization of Bioactive Ligands with Antioxidant Properties of Kiwifruit and Persimmon Cultivars Using In Vitro and in Silico Studies

The current study attempted to understand the interaction profiles of phytoconstituents in new and traditionally used fruit cultivars with human serum albumin (HSA) in the context of predicting the biological role under in vivo conditions. Therefore, polyphenols, flavonoids, flavanols, tannins, vitamin C, secondary metabolites and their antioxidant capacities of organic kiwifruit Actinidia (A.) eriantha cv. Bidan (AEB) and A. arguta cv. Cheongsan (AAC), as new cultivars grown in Korea, and widely consumed A. deliciosa cv. Hayward (ADH) and Diospyros kaki Thunb. cv. Fuyu (DKF) were determined and compared. All investigated fruits showed relatively high antioxidant capacities. To complement the bioactivity of these fruits, the binding properties between extracted polyphenols and HSA were determined by 3D-fluorescence spectroscopy and docking studies. The most bioactive was AEB with the highest percentage of binding, following by AAC, ADH and DKF. Our study for the first time unveils the differential binding properties of kiwifruit and persimmon phytoconstituents with HSA. Although cultivars possess virtually the same phytoconstituents, presence of one unique compound significantly alters the binding properties of HSA. The results of fluorescence quenching and molecular docking showed that these fruits possess multiple properties, which have a great potential to be used in industry with emphasis on the formulation of functional foods and medicinal applications.

The First Identification of the Uniqueness and Authentication of Maltese Extra Virgin Olive Oil Using 3D-Fluorescence Spectroscopy Coupled with Multi-Way Data Analysis

The potential application of multivariate three-way data analysis techniques, namely parallel factor analysis (PARAFAC) and discriminant multi-way partial least squares regression (DN-PLSR), on three-dimensional excitation emission matrix (3D-EEM) fluorescent data were used to identify the uniqueness and authenticity of Maltese extra virgin olive oil (EVOO). A non-negativity constrained PARAFAC model revealed that a four-component model provided the most appropriate solution. Examination of the extracted components in mode 2 and 3 showed that these belonged to different fluorophores present in extra virgin olive oil. Application of linear discriminate analysis (LDA) and binary logistic regression analysis on the concentration of the four extracted fluorophores, showed that it is possible to discriminate Maltese EVOOs from non-Maltese EVOOs. The application of DN-PLSR provided superior means for discrimination of Maltese EVOOs. Further inspection of the extracted latent variables and their variable importance plots (VIPs) provided strong proof of the existence of four types of fluorophores present in EVOOs and their potential application for the discrimination of Maltese EVOOs.

Influence of salinity gradient on Ni complexation by Fluorescent Dissolved Organic Matter (FDOM) and dispersal across estuaries in New Caledonia

<p>Dissolved organic matter (DOM) is ubiquitous in the environment. Its composition and properties depend on water type (freshwater, estuarine, brackish, marine) and are influenced by the geological nature (ultramafic, volcano-sedimentary, metamorphic) and occupancy (mangrove, forest, agriculture, urbanized) of the upstream catchment. Due to its capacity  to form complexes with dissolved trace metals, DOM can render them hardly available to living organisms, and thus limit their toxicity. Considering its capacity to be transported on large distances, DOM can significantly contribute to the dispersal of trace metals in aquatic ecosystems. In this study, we used 3D fluorescence spectroscopy to characterize the actual nature of FDOM (a fraction of DOM that shows specific fluorescence properties) across estuaries downstream of two contrasted catchments (ultramafic vs. volcano-sedimentary) in New Caledonia. In a first step, Excitation-Emission Matrix (EEM) were obtained on 0.2 µm filtered water samples and a parallel factor analysis (PARAFAC) allowed to identify the different FDOM components in the two catchments. These data indicated a dramatic decrease of all components as a function of increasing salinity, with a threshold value around 25 g/L whatever the catchment. This trend is considered to reflect an aggregation-flocculation behavior of FDOM across the salinity gradient of the studied estuaries. In a second step, fluorescence quenching experiments emphasized the complexing capacity of the different components toward dissolved Ni. FDOM might thus play a significant role on Ni dispersal in aquatic ecosystems through the formation of FDOM-Ni complexes. However, this dispersal capacity might be hampered in estuaries due to the suspected aggregation-flocculation behavior of FDOM across the salinity gradient. Rather than the geological setting of the upstream catchment, salinity appears thus as the major driver of Ni dynamics across estuaries through FDOM-Ni complexes.</p>

Morphological Grayscale Reconstruction and ATLD for Recognition of Organic Pollutants in Drinking Water Based on Fluorescence Spectroscopy

This paper proposes a morphological grayscale reconstruction method combined with an alternating trilinear decomposition (ATLD) and threshold method based on 3D fluorescence spectroscopy to detect pollutants present at low concentrations in drinking water. First, the morphological grayscale reconstruction method was used to locate the fluorescence peaks of pollutants by comparing the original and reconstructed spectra obtained through expansion. The signal in the characteristic spectral region was then enhanced using an amplification factor. Feature extraction was subsequently performed by ATLD, and the threshold method was used to qualitatively distinguish water quality. By comparing the proposed method with the direct use of the ATLD and threshold method—which is a commonly used feature-extraction method—this study found that the application of the morphological grayscale reconstruction method can extrude characteristics of 3D fluorescence spectra. Given the typical spectral characteristics of phenol, salicylic acid, and rhodamine B, they were selected as experimental organic pollutants. Results illustrated that the morphological grayscale reconstruction with ATLD improved the spectral signal-to-noise ratio of pollutants and can effectively identify organic pollutants, especially those present at low concentrations.