Sofia Mitaku

Methanolic Extract of Verbascum macrurum as a Source of Natural Preservatives against Oxidative Rancidity

The antioxidant properties of various fractions of a methanolic extract obtained from the aerial parts of Verbascum macrurum have been determined by monitoring their capacity to scavenge the stable free-radical DPPH. They were also evaluated as natural preservatives against oxidative rancidity using the accelerated Rancimat method. Their activities expressed as protection factor (PF(r)) indicated that the fractions rich with phenylpropanoid glycosides were more potent compared to alpha-tocopherol and of the same magnitude as BHT, which were used as reference standards. Ten natural compounds were identified as components of this methanolic extract and were isolated by medium-pressure liquid chromatography (MPLC). Assessment of their antioxidant activities established that acteoside, a polyhydroxylated phenylpropanoid glycoside derivative, is the most potent free radical scavenger and showed the highest protection factor (PF(r)) against sunflower-oil-induced oxidative rancidity. Its activity is comparable to the synthetic antioxidant BHT and clearly superior to natural alpha-tocopherol. This compound therefore represents a very interesting candidate for use in food preservation as natural protecting agent against oxidative rancidity.

Chemistry of Plants from Crete: Stachyspinoside, a New Flavonoid Glycoside And iridoids from Stachys spinosa

Abstract The new flavonoid glycoside stachyspinoside (1), and the three iridoids, 7-O-acetyl-8-epi-loganic acid (2), ajugol (3) and harpagide (4) were isolated from Stachys spinosa. The structures of these compounds were established on the basis of mass spectrometry (ESMS and tandem MS), one-and two-dimensional nuclear magnetic resonance experiments (COSY, COSY LR, HMQC, TOCSY and HMBC) as well as simple chemical derivatization.

Diterpene esters of malonic acid from the resin Ladano of Cistus creticus

Abstract Four labdane diterpenes, esterified with malonic acid were isolated from the resin ‘Ladano’ of the plant Cistus creticus subsp. creticus . Two of them, i.e. (13 E )-labd-7, 13-diene-15-yl malonic acid and di-[(13 E )-labd-13-ene, 8α-ol-15-yl] malonate, were new compounds. Their structures were determined by spectroscopic methods and confirmed by chemical correlations.

Antiviral in vitro activity of Hypericum perforatum L. extract on the human cytomegalovirus (HCMV)

The total methanol extract and chromatographic fractions of the extract of the aerial parts of Hypericum perforatum L. were investigated for their antiviral activity against human cytomegalovirus (HCMV) AD‐169 laboratory strain by modification of the widely used diagnostic method ‘shell‐vial’ culture. The plant selection was based on its traditional use against viruses of the Herpes family in Greece. The results showed extract fraction III had the most potent antiviral activity against HCMV which was also superior to that of ganciclovir. Copyright

Essential Oil Constituents of Valeriana italica and Valeriana tuberosa. Stereochemical and Conformational Study of 15-Acetoxyvaleranone

The chemical composition of the essential oils obtained by hydrodistillation of roots, stems with leaves and inflorescences of Valeriana italica Lam. and Valeriana tuberosa L. were studied by GC/MS. Seventy-three and fourty-one constituents were identified from each plant, respectively. The major constituent of the oil obtained from the roots of V. italica was isolated and identified as 15-acetoxyvaleranone. Its stereochemistry and conformation has been studied using NMR spectroscopy and molecular modelling. The oils obtained from V. tuberosa completely lacked the characteristic valerane or kessane sesquiterpenes. Running title: Essential oils of Valeriana italica and V. tuberosa

Quantitation of oleuropein and related metabolites in decoctions of Olea europaea leaves from ten Greek cultivated varieties by HPLC with diode array detection (HPLC-DAD)

Abstract An extraction procedure and chromatographic methodology for the simultaneous quantitation of four major constituents in the boiling water extracts (decoctions) of Olea europaea leaves has been developed. The four studied constituents were oleuropein, elenolic acid, hydroxytyrosol, and tyrosol. The quantitation was performed using HPLC‐DAD, whereas qualitative data were acquired using LC‐MS. The developed methodology was applied in the study of ten Olea europaea varieties commonly cultivated in Greece. The chromatographic analysis revealed important differences among the varieties. The decoction of variety gaidouroelia was identified as the best source of oleuropein, but it was completely lacking of elenolic acid. The decoction of variety koronaiiki was the best source of hydroxytyrosol, whereas the variety mastoides was the best source of tyrosol and elenolic acid. In addition, the methanol and acetone extracts of one of the studied varieties (koranaiiki) were investigated, in order to compare the concentration of oleuropein in the extracts and the decoction. Interestingly, only a very low percent of the total oleuropein is present in the traditionally prepared decoction, while elenolic acid, which is a minor constituent of the extracts, was found to be one of the major constituents of the decoction.

Antibacterial Labdane-type Diterpenes from the Resin “Ladano” of Cistus creticus Subsp. creticus

Abstract The antibacterial activity of seven labdane-type diterpenes is reported. Five were isolated from the resin of the plant Cistus creticus, from which 13(E)-labd-13-ene, 8α-ol-15-yl malonic acid (5) 1 is a new natural product, while the two others were hemisynthetic derivatives.

New Alkaloids from Sarcomelicope dogniensis 1

Abstract Two novel alkaloids, 1-oxo-1,2-dihydro-12-demethyl-12-hydroxyacronycine (1) and 2,3-dicarbomethoxy-1-methyl-4(1H)-quinolinone (3) have been isolated from the leaves of Sarcomelicope dogniensis. The biogenesis of this latter most probably involves oxidation of the A aromatic ring of a 1,2,3,4-tetra-O-subtituted acridone, such as melicopidine.

Furomegistines I and II, two furanopyridine alkaloids from the bark of Sarcomelicope megistophylla

Two alkaloids, furomegistine I (1) and furomegistine II (2), were isolated from the bark of Sarcomelicope megistophylla. Their structures have been elucidated on the basis of MS and NMR data. Both belong to the category of furanopyridine alkaloids and should be considered as oxidation products of a furo[2,3-b]quinoline precursor. The two alkaloids exhibited moderate cytotoxic activity.

Acretoside, a new sucrose ester from Aristolochia cretica *

A new sucrose ester, acretoside, has been isolated from the roots of the Greek endemic species Aristolochia cretica and identified as 6-O-p-coumaroyl-β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranoside (1). In addition, a known sucrose ester, identified as arillatose B, two phenylpropanoid glucose esters, and five derivatives of aristolochic acids have been isolated. Their structures have been elucidated on the basis of MS and NMR data.