M. Polissiou

Ultrasound-assisted extraction of volatile compounds from citrus flowers and citrus honey

The volatile fraction of honey is believed to facilitate satisfactory discrimination between honeys of different botanical origin. A new methodology for extracting volatile compounds was developed, using n-pentane:diethylether organic solvent and a water bath with ultrasound assistance. Analysis of the extracts of four Citrus species’ flowers showed linalool to be the predominant compound (11.3% in lemon, 51.6% in orange, 80.6% in sour orange and 75.2% in tangerine). The extracts from citrus honey were predominated by an array of linalool derivatives (more than 80% of the total extract). (E)-2,6-dimethyl-2,7-octadiene-1,6-diol was the predominant compound (44.7%), while significant proportions of 2,6-dimethyl-3,7-octadiene-2,6-diol (15.4%) and (Z)-2,6-dimethyl-2,7-octadiene-1,6-diol (7.2%) were also present.

DNA Interaction with Naturally Occurring Antioxidant Flavonoids Quercetin, Kaempferol, and Delphinidin

Abstract Flavonoids are strong antioxidants that prevent DNA damage. The anticancer and antiviral activities of these natural products are implicated in their mechanism of actions. However, there has been no information on the interactions of these antioxidants with individual DNA at molecular level. This study was designed to examine the interaction of quercetin (que), kaempferol (kae), and delphinidin (del) with calf-thymus DNA in aqueous solution at physiological conditions, using constant DNA concentration (6.5 mmol) and various drug/DNA(phosphate) ratios of 1/65 to 1. FTIR and UV-Visible difference spectroscopic methods are used to determine the drug binding sites, the binding constants and the effects of drug complexation on the stability and conformation of DNA duplex. Structural analysis showed quercetin, kaempferol, and delphinidin bind weakly to adenine, guanine (major groove), and thymine (minor groove) bases, as well as to the backbone phosphate group with overall binding constants Kque = 7.25 × 104M−1, Kkae = 3.60 × 104M−1, and Kdel = 1.66 × 104M−1. The stability of adduct formation is in the order of que>kae>del. Delphinidin with a positive charge induces more stabilizing effect on DNA duplex than quercetin and kaempferol. A partial B to A-DNA transition occurs at high drug concentrations.

Comparison of classical and ultrasound-assisted isolation procedures of cellulose from kenaf (Hibiscus cannabinus L.) and eucalyptus (Eucalyptus rodustrus Sm.)

A comparative study of classical and ultrasound-assisted extraction and purification of cellulose from kenaf (Hibiscus cannabinus L.) and eucalyptus (Eucalyptus rodustrus Sm.), has been conducted. The isolated cellulose samples were studied by diffuse reflectance infrared Fourier transform spectroscopy and 13C nuclear magnetic resonance (13C-NMR) spectroscopy and the crystallinity was also determined. The use of ultrasound decreased the total time of treatment, in addition the purity of the obtained cellulose was very high.

An overview of structural features of DNA and RNA complexes with saffron compounds: Models and antioxidant activity.

Saffron is the red dried stigmas of Crocus sativus L. flowers and used both as a spice and as a drug in traditional medicine. Its numerous applications as an antioxidant and anticancer agent are due to its secondary metabolites and their derivatives (safranal, crocetin, dimethylcrocetin). In this work we are comparing the spectroscopic results and antioxidant activities of saffron components safranal, crocetin (CRT) and dimethylcrocetin (DMCRT) complexes with calf-thymus DNA (ctDNA) and transfer RNA (tRNA) in aqueous solution at physiological conditions Intercalative and external binding modes of saffron compounds to DNA and RNA were observed with overall binding constants of K(safranal)=1.24x10(3)M(-1), K(CRT)=6.20x10(3)M(-1) and K(DMCRT)=1.85x10(5)M(-1), for DNA adducts and K(safranal)=6.80x10(3)M(-1), K(CRT)=1.40x10(4)M(-1) and K(DMCRT)=3.40x10(4)M(-1) for RNA complexes. A partial B- to A-DNA transition occurred at high ligand concentrations, while tRNA remained in A-conformation in saffron-RNA complexes. The antioxidant activity of CRT, DMCRT and safranal was also tested by the DPPH (2,2-diphenyl-1-picrylhydrazyl) antioxidant activity assay and their IC(50) values were compared to that of well known antioxidants such as Trolox and Butylated Hydroxy Toluene (BHT). The IC(50) values were 95+/-1microg/mL for safranal and 18+/-1microg/mL for crocetin. The inhibition of DMCRT reached a point of 38.8%, which corresponds to a concentration of 40microg/mL.

Probing the binding sites of resveratrol, genistein, and curcumin with milk β-lactoglobulin

We determined the binding sites of curcumin (cur), resveratrol (res), and genistein (gen) with milk β-lactoglobulin (β-LG) at physiological conditions. Fourier transform infrared spectroscopy, circular dichroism, and fluorescence spectroscopic methods as well as molecular modeling were used to determine the binding of polyphenol–protein complexes. Structural analysis showed that polyphenols bind β-LG via both hydrophilic and hydrophobic contacts with overall binding constants of Kcurcumin–β-LG = 4.4 (± .4) × 104 M−1, Kresveratrol–β-LG = 4.2 (± .2) × 104 M−1, and Kgenistein–β-LG = 1.2 (± .2) × 104 M−1. The number of polyphenol molecules bound per protein (n) was 1 (cur), 1.1 (res), and 1 (gen). Molecular modeling showed the participation of several amino acid residues in polyphenol–protein complexation with the free binding energy of −12.67 (curcumin–β-LG), −12.60 (resveratrol–β-LG), and −10.68 kcal/mol (genistein–β-LG). The order of binding was cur > res > gen. Alteration of the protein conformation was observed in the presence of polyphenol with a major reduction of β-sheet and an increase in turn structure, causing a partial protein structural destabilization. β-LG might act as a carrier to transport polyphenol in vitro.

Quantitative analysis of α-pinene and β-myrcene in mastic gum oil using FT-Raman spectroscopy

Abstract α-Pinene and β-myrcene are compounds that are contained in mastic gum in high concentrations. The β-myrcene percentage determines the marketability of mastic gums. The chemical composition of mastic gum oil of a representative resin quality was evaluated by gas chromatography–mass spectrometry (GC–MS) technique. FT-Raman spectroscopy, based on band intensity measurements, was used for the determination of α-pinene and β-myrcene content in mastic gum. Bands at 1658 and 1633 cm −1 were used for the calibration of α-pinene and β-myrcene, respectively. Calibration curves were linear (correlation coefficient for α-pinene was 0.992 and 0.997 for β-myrcene) in the range 30–80 and 3–45%, respectively. Normalization of calibration curves, against the 802 cm −1 cyclohexane band, minimized the effect of laser beam power fluctuations. The proposed method is rapid and simple. Accordingly, mastic gum oils from Chios island (Greece) contained 38.1–69.5% α-pinene and 4.5–57.9% β-myrcene.

Locating the binding sites of retinol and retinoic acid with milk β-lactoglobulin

β-lactoglobulin (β-LG) is a member of lipocalin superfamily of transporters for small hydrophobic molecules such as retinoids. We located the binding sites of retinol and retinoic acid on β-LG in aqueous solution at physiological conditions, using FTIR, CD, fluorescence spectroscopic methods, and molecular modeling. The retinoid-binding sites and the binding constants as well as the effect of retinol and retinoic acid complexation on protein stability and secondary structure were determined. Structural analysis showed that retinoids bind strongly to β-LG via both hydrophilic and hydrophobic contacts with overall binding constants of K retinol- β -LG = 6.4 (± .6) × 106 M−1 and K retinoic acid- β -LG = 3.3 (± .5) × 106 M−1. The number of retinoid molecules bound per protein (n) is 1.1 (± .2) for retinol and 1.5 (± .3) for retinoic acid. Molecular modeling showed the participation of several amino acids in the retinoid–protein complexes with the free binding energy of −8.11 kcal/mol for retinol and −7.62 kcal/mol for retinoic acid. Protein conformation was altered with reduction of β-sheet from 59 (free protein) to 52–51% and a major increase in turn structure from 13 (free protein) to 24–22%, in the retinoid–β-LG complexes, indicating a partial protein destabilization.

Prediction of the pH in Wood by Diffuse Reflectance Infrared Fourier Transform Spectroscopy

The diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) spectrum of the peeled wood of kenaf (Hibiscus cannabinus L.), cotton (Gossypium barbadense), and pine (Pinus brutia) revealed three broad absorptions in the region of 1800–1540 cm−1. The deconvolution of spectra in this region revealed the existence of 10 major peaks contributing to that spectrum in the aforementioned region. The absorption peaks at 1710 and 1608 cm−1 have been assigned to carboxylic (–COOH) and carboxylate (–COO−) groups, respectively. Since their relative size is pH dependent, the ratio of their area was used as a pH indicator. A linear relationship was then established between that ratio and the amount of acid need to bring the pH of the wood to 3, as it is measured by the pH determination of a water extract of the wood. This is the pH at which the wood is processed during manufacturing of chipboards.

Determination of Kenaf (Hibiscus cannabinus L.) Lignin in Crude Plant Material Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy

Hibiscus cannabinus L. (kenaf) is a plant of the Malvaceae family and is a renewable resource for industry. The determination of kenaf lignin in crude plant material of four varieties using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is described. In particular, a linear relationship was established between the peak area at 1506 cm−1 and the lignin content in the plant material. With the use of the DRIFTS method, lignin was found in the bark, wood, and pith of four kenaf varieties at 10.4 to 10.8%, 20.5 to 20.6%, and 14.9 to 15.3% of plant material, respectively.

Geographical differentiation of dried lentil seed (Lens culinaris) samples using Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) and discriminant analysis

Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and discriminant analysis were used for the geographical differentiation of dried lentil seed (Lens culinaris) samples. Specifically, 18 Greek samples and nine samples imported from other countries were distinguished using the 2250-1720 and 1275-955 cm⁻¹ spectral regions. The differentiation is complete. The combination of DRIFTS and discriminant analysis enables simple, rapid, cheap and accurate differentiation of commercial lentil seeds in terms of geographical origin.