Polyphenolic Composition, Antioxidant and Antiproliferative Activity of Edible and Inedible Parts of Cultivated and Wild Pomegranate (Punica granatum L.).

Research background: The aim of this study is to determine and compare the antioxidant and antiproliferative activities of juices and extracts of the peel, aril and membrane of the cultivated and wild pomegranate fruits. Experimental approach: The content of total phenols, total flavonoids, total flavonols, total flavan-3-ols and total anthocyanins was determined spectrophotometrically. The individual phenolics were quantified by HPLC. Antioxidant activity was determined by DPPH and ABTS tests and neutralisation of hydroxyl radical, while the antiproliferative activity was measured in vitro by sulforhodamine B (SRB) assay. Results and conclusions: Total phenolics were statistically highest in wild pomegranate peel extract, expressed in gallic acid equivalents, 340.92 mg/g (p<0.05), while total flavonoid content was the highest in cultivated pomegranate peel extract, expressed in quercetin equivalents, 31.84 mg/g (p<0.05). The sample of wild pomegranate peel extract showed the highest antioxidant activity with respect to free DPPH and ABTS radicals. The samples of cultivated pomegranate peel and membrane extracts had almost identical and the strongest effect on the inhibition of hydroxyl radicals (41.24 and 41.23 µg/mL, respectively). The sample of wild pomegranate peel extract showed the strongest effect on the growth inhibition of all tested tumour cell lines. Novelty and scientific contribution: In this study, the bioactivity of different parts of cultivated and wild pomegranates was determined and compared. In the available literature, the individual antioxidant and antiproliferative activity of only some parts of the pomegranate fruit was investigated. All parts of the pomegranate fruit were investigated, including the membrane, which was barely analysed in other works. The wild pomegranate has also been less analysed in previous studies. Future research should focus on in vivo studies of the obtained pomegranate samples.

Superspace description of wagnerite-group minerals (Mg,Fe,Mn)2(PO4)(F,OH).

Reinvestigation of more than 40 samples of minerals belonging to the wagnerite group (Mg, Fe, Mn)2(PO4)(F,OH) from diverse geological environments worldwide, using single-crystal X-ray diffraction analysis, showed that most crystals have incommensurate structures and, as such, are not adequately described with known polytype models (2b), (3b), (5b), (7b) and (9b). Therefore, we present here a unified superspace model for the structural description of periodically and aperiodically modulated wagnerite with the (3+1)-dimensional superspace group C2/c(0ß0)s0 based on the average triplite structure with cell parameters a ≃ 12.8, b ≃ 6.4, c ≃ 9.6 Å, ß ≃ 117° and the modulation vectors q = ßb*. The superspace approach provides a way of simple modelling of the positional and occupational modulation of Mg/Fe and F/OH in wagnerite. This allows direct comparison of crystal properties.

Monoclinic structure and nonstoichiometry of 'KAlSiO4-O1'.

Crystals of KAlSiO4-O1 (potassium aluminium silicate) were synthesized using a flux method and analysed utilizing single-crystal X-ray diffraction and electron microprobe analysis. Both methods confirm that the crystals are nonstoichiometric according to K(1-x)Al(1-x)Si(1+x)O4 with x = 0.04 (1). KAlSiO4-O1 is closely related to the stuffed derivatives of tridymite, although the topology of the Si/Al-ordered framework is different. Six-membered rings of UUDDUD and UUUDDD (U = up and D = down; ratio 2:1) configurations are present in layers parallel to the ab plane. In contrast, the framework of tridymite exhibits UDUDUD rings. The crystals are affected by inversion, pseudo-orthorhombic and pseudo-hexagonal twinning.

Superstructure of Mullite-type KAl9O14.

Large whiskers of a new KAl9O14 polymorph with mullite-type structure were synthesized. The chemical composition of the crystals was confirmed by energy-dispersive X-ray spectroscopy, and the structure was determined using single-crystal X-ray diffraction. Nanosized twin domains and one-dimensional diffuse scattering were observed utilizing transmission electron microscopy. The compound crystallizes in space group P21/n (a = 8.1880(8), b = 7.6760(7), c = 8.7944(9) Å, ß = 110.570(8)°, V = 517.50(9) Å3, Z = 2). Crystals of KAl9O14 exhibit a mullite-type structure with linear edge-sharing AlO6 octahedral chains connected with groups of two AlO4 tetrahedra and one AlO5 trigonal bipyramid. Additionally, disproportionation of KAl9O14 into K ß-alumina and corundum was observed using in situ high-temperature optical microscopy and Raman spectroscopy.

Crystal chemistry and stability of "Li7La3Zr2O12" garnet: a fast lithium-ion conductor.

Recent research has shown that certain Li-oxide garnets with high mechanical, thermal, chemical, and electrochemical stability are excellent fast Li-ion conductors. However, the detailed crystal chemistry of Li-oxide garnets is not well understood, nor is the relationship between crystal chemistry and conduction behavior. An investigation was undertaken to understand the crystal chemical and structural properties, as well as the stability relations, of Li(7)La(3)Zr(2)O(12) garnet, which is the best conducting Li-oxide garnet discovered to date. Two different sintering methods produced Li-oxide garnet but with slightly different compositions and different grain sizes. The first sintering method, involving ceramic crucibles in initial synthesis steps and later sealed Pt capsules, produced single crystals up to roughly 100 µm in size. Electron microprobe and laser ablation inductively coupled plasma mass spectrometry (ICP-MS) measurements show small amounts of Al in the garnet, probably originating from the crucibles. The crystal structure of this phase was determined using X-ray single-crystal diffraction every 100 K from 100 K up to 500 K. The crystals are cubic with space group Ia3̅d at all temperatures. The atomic displacement parameters and Li-site occupancies were measured. Li atoms could be located on at least two structural sites that are partially occupied, while other Li atoms in the structure appear to be delocalized. (27)Al NMR spectra show two main resonances that are interpreted as indicating that minor Al occurs on the two different Li sites. Li NMR spectra show a single narrow resonance at 1.2-1.3 ppm indicating fast Li-ion diffusion at room temperature. The chemical shift value indicates that the Li atoms spend most of their time at the tetrahedrally coordinated C (24d) site. The second synthesis method, using solely Pt crucibles during sintering, produced fine-grained Li(7)La(3)Zr(2)O(12) crystals. This material was studied by X-ray powder diffraction at different temperatures between 25 and 200 °C. This phase is tetragonal at room temperature and undergoes a phase transition to a cubic phase between 100 and 150 °C. Cubic "Li(7)La(3)Zr(2)O(12)" may be stabilized at ambient conditions relative to its slightly less conducting tetragonal modification via small amounts of Al(3+). Several crystal chemical properties appear to promote the high Li-ion conductivity in cubic Al-containing Li(7)La(3)Zr(2)O(12). They are (i) isotropic three-dimensional Li-diffusion pathways, (ii) closely spaced Li sites and Li delocalization that allow for easy and fast Li diffusion, and (iii) low occupancies at the Li sites, which may also be enhanced by the heterovalent substitution Al(3+) ⇔ 3Li.

Modulated structure and phase transitions of Sr10Ga6O19.

The crystal structure of Sr10Ga6O19 was investigated by in situ single-crystal X-ray diffraction in the temperature range 298-673 K. At ambient conditions the compound shows a (3 + 1)-dimensional modulated structure in the superspace group C2/c(0beta0)s0 [a = 34.9145 (13), b = 7.9369 (2), c = 15.9150 (7) A and beta = 103.551 (3) degrees] with a modulation wavevector of q = 0.4288 (2)b*. Whereas the presented structural model uses first-order harmonic modulation functions only, some features of the modulations are discussed utilizing an electron density derived by the maximum entropy method. Furthermore, two phase transitions were identified: between 453 and 503 K the incommensurate superstructure is replaced by a doubling of the a and b lattice constants, and between 503 and 673 K a phase with the basic cell is formed, identical to alpha-Sr10Ga6O19. Under some cooling conditions crystals showing a combined diffraction pattern of both superstructures can be obtained. The relation of these results to alpha-Sr10Ga6O19 [Kahlenberg (2001). J. Solid State Chem. 160, 421-429] is discussed.

Incommensurate structure of Ca2Al2O5 at high temperatures--structure investigation and Raman spectroscopy.

A high-temperature X-ray diffraction study revealed that brownmillerite-type Ca(2)Al(2)O(5) transforms to an incommensurately modulated structure at elevated temperatures. Single crystals of Ca(2)Al(2)O(5) were synthesized in an end-loaded piston cylinder press at 2.5 GPa and 1273 K. The diffraction pattern observed at 1090 (10) K by in situ single-crystal diffraction experiments can be indexed by an I-centred orthorhombic cell and a modulation wavevector of q = 0.595 (1)c(*). A (3 + 1)-dimensional model in superspace group Imma(00gamma)s00 was used to refine the modulated structure. The structure is assembled from two building units: (i) layers of corner-sharing [AlO(6)] octahedra, stacked along b alternate with (ii) layers of zweier single chains of [AlO(4)] tetrahedra running along a. The modulated structure arises from an aperiodic sequence of two different configurations of the chains within the tetrahedral layers. The modulated high-temperature phase of Ca(2)Al(2)O(5) is isotypic to the modulated high-temperature modification of Ca(2)Fe(2)O(5). A large hysteresis was found in the phase-transition temperature. On heating, the transition occurs at ca 1075 (10) K; on cooling, satellite reflections can be observed down to 975 (10) K. The characterization of Ca(2)Al(2)O(5) is completed by Raman spectroscopy, including a partial interpretation of the spectra.