Konstantia Graikou

Chemical analysis of Greek pollen - Antioxidant, antimicrobial and proteasome activation properties

BackgroundPollen is a bee-product known for its medical properties from ancient times. In our days is increasingly used as health food supplement and especially as a tonic primarily with appeal to the elderly to ameliorate the effects of ageing. In order to evaluate the chemical composition and the biological activity of Greek pollen which has never been studied before, one sample with identified botanical origin from sixteen different common plant taxa of Greece has been evaluated.ResultsThree different extracts of the studied sample of Greek pollen, have been tested, in whether could induce proteasome activities in human fibroblasts. The water extract was found to induce a highly proteasome activity, showing interesting antioxidant properties. Due to this activity the aqueous extract was further subjected to chemical analysis and seven flavonoids have been isolated and identified by modern spectral means. From the methanolic extract, sugars, lipid acids, phenolic acids and their esters have been also identified, which mainly participate to the biosynthetic pathway of pollen phenolics. The total phenolics were estimated with the Folin-Ciocalteau reagent and the total antioxidant activity was determined by the DPPH method while the extracts and the isolated compounds were also tested for their antimicrobial activity by the dilution technique.ConclusionsThe Greek pollen is rich in flavonoids and phenolic acids which indicate the observed free radical scavenging activity, the effects of pollen on human fibroblasts and the interesting antimicrobial profile.

GC-MS Profiling of Diterpene Compounds in Mediterranean Propolis from Greece

The objective of this work is to analyze and identify the diterpene compounds in Mediterranean propolis samples from different Greek regions by GC-MS. The chemical composition of six propolis samples was established using previously isolated diterpenes from Cretan propolis as authentic standards for identification, based on mass spectral fragmentation of the TMS derivatives and retention index. More than 30 diterpenes, among which were new propolis constituents, were identified and characterized by means of authentic standards and interpretation of MS fragmentation as well. This is the first detailed profiling of a new type of propolis, rich in diterpenes. The chromatographic and mass- spectral characteristics of the diterpenes identified could be very useful for rapid GC-MS profiling of this propolis type and for revealing its plant sources.

Chemosystematic Value of the Essential Oil Composition of Thuja species Cultivated in Poland—Antimicrobial Activity

In the framework of the correlation between chemotaxonomy and chemical analysis studies, the chemical composition of the essential oils of four varieties of Thuja species cultivated in Poland − T. occidentalis ‘globosa’, T. occidentalis ‘aurea’, T. plicata and T. plicata ‘gracialis’ − were investigated by GC and GC-MS. Thirty-one compounds were identified from T. occidentalis ‘globosa’, representing 96.92% of the total oil; twenty-seven from T. occidentalis ‘aurea’ (94.34%); thirty-one from T. plicata (94.75%); and thirty compounds from T. plicata ‘gracialis’ (96.36%). The main constituents in all samples were the monoterpene ketones α- and β-thujone, fenchone and sabinene, as well as the diterpenes beyerene and rimuene. The chemosystematic value of the total ketone content of all samples (which varied from 54.30–69.18%) has been discussed and investigated. The constituents, beyerene and the mixture of α- and β-thujone, were isolated from the oils and tested against six Gram-positive and -negative bacteria and three pathogenic fungi. The oils of the two T. plicata species exhibited significant antimicrobial activity, while the mixture of α- and β-thujone showed very strong activity as well.

Dittany of Crete: A botanical and ethnopharmacological review

Origanum dictamnus (Lamiaceae family), an endemic plant of the Greek island of Crete, is widely used as a traditional medicine since antiquity, all over Europe. The aim of the present review is to present comprehensive information of the plants botanical taxonomy and morphology, as well as of the chemical constituents, biological and pharmacological research on O. dictamnus, which will be presented and critically evaluated. The paper also highlights particularly interesting aspects and common medicinal uses not previously described in the specific ethnobotanical literature. An increasing number of chemical and pharmacological studies have been reported recently, some of which strongly support its traditional medicinal uses against various illnesses such as sore throat, cough and gastric ulcer. A variety of compounds, including flavonoids, lipids and terpenoids (mainly carvacrol and thymol) have been identified from the plant. Current studies have showed that the extracts, the essential oil, as well as their active principles possess several pharmacological properties, like antimicrobial, antioxidant and anti-ulcer ones. The recent scientific data and the rich historical evidence of its medicinal uses could support further research as well as its use as a safe herbal medicinal product.

Chemosystematic value of chemical constituents from Scabiosa hymettia (Dipsacaceae).

The first phytochemical investigation of Scabiosa hymettia led to the isolation and characterization of nine known compounds, 2–10, and of the new kaempferol derivative 1. In total, two flavonoids, three coumarins, three iridoids, and two phenolic constituents were obtained. The chemosystematic value of these compounds, as well as the metabolic relationship between swertiamarin (6) and the other isolated coumarins, are discussed. Both the extracts as well as all isolated constituents of S. hymettia were evaluated for their antimicrobial activities against six Gram‐positive or Gram‐negative bacteria, and against three human pathogenic fungi. The new compound 1 was found to exhibit the highest activity against all organisms tested.

Cantleyoside-dimethyl-acetal and other iridoid glucosides from Pterocephalus perennis: Antimicrobial activities

Cantleyoside-dimethyl-acetal (6), was isolated from the endemic Greek plant Pterocephalus perennis subsp. perennis in addition to five other known iridoid glucosides, loganin, loganic acid, cantleyoside, secologanin, and secologanin-dimethyl-acetal. The structure of these compounds was determined by all spectroscopic means mainly by NMR and MS techniques. The above compounds as well as their acetyl derivatives were tested against six Gram positive and negative bacteria and three pathogenic fungi.

Chemical Analysis and Antimicrobial Activity of Essential Oils from the Aromatic Plants Artemisia afra Jacq. and Leonotis ocymifolia (Burm. F.) Iwarsson var. raineriana (Vision1) Iwarsson Growing In Tanzania

Abstract Hydrodistilled volatile oils from the aerial parts of Artemisia afra and leaves of Leonotis ocymifolia var. raineriana were investigated, by a combination of GC and GC/MS. From A. afra 37 compounds were identified, representing 95.3% (area percent) of the total oil and from L. ocymifolia var. raineriana, 27 compounds were identified, representing 91.1% of the total oil. Among the identified components camphor (46.2%), α-thujone (15.2%), artemisia ketone (7.4%) and 1,8-cineole (4.2%) were found as the main components of A. afra oil and germacrene D (36.8%), (Z)-β-ocimene (7.9%), β-caryophyllene (7.0%) and (E)-β-ocimene (4.4%) were the major components of L. ocymifolia oil. Furthermore, the oils, as well as nine of their constituents, were evaluated for their antimicrobial activity, against six bacteria, two oral pathogens and three pathogenic fungi. The results showed that the oil of A. afra has a moderate antimicrobial activity, while the oil of L. ocymifolia exhibited a stronger one against Gram-negative bacteria and oral pathogens, and a weaker one against Gram-positive bacteria. This interesting profle can be attributed to the high content of the oil, of germacrene D which is known for its antimicrobial activity.

Long-term administration of Greek Royal Jelly improves spatial memory and influences the concentration of brain neurotransmitters in naturally aged Wistar male rats

ETHNOPHARMACOLOGICAL RELEVANCE Royal Jelly (RJ) is a bee-derived product that has been traditionally used in the European and Asian systems of medicine for longevity. RJ has various pharmacological activities that may prevent aging e.g., anti-inflammatory, anti-oxidative, anti-hypercholesterolemic and anti-hyperglycemic properties. AIM OF THE STUDY To evaluate the behavioral and neurochemical effects of long-term oral, previously chemically analyzed, Greek RJ administration to aged rats. MATERIALS AND METHODS RJ powder was given to 18-month old male Wistar rats (50 and 100mg of powder/kg b.w./day) by gastric gavage for 2 months. The spatial memory was assessed in the water maze and next the level of neurotransmitters, their metabolites and utilization in the selected brain regions were estimated. RESULTS The improvement of memory in rats pretreated with the smaller dose of RJ was observed compared with controls. In biochemical examination mainly the depletion of dopamine and serotonin in the prefrontal cortex along with an increase in their metabolite concentration and turnover were seen. CONCLUSION Better cognitive performance in the old animals using a non-toxic, natural food product in the view of the process of the aging of human population is noteworthy. Our results contribute towards validation of the traditional use of RJ in promoting a better quality of life in old age.

A monoterpene, unique component of thyme honeys, induces apoptosis in prostate cancer cells via inhibition of NF-κB activity and IL-6 secretion

We have previously demonstrated that Greek thyme honey inhibits significantly the cell viability of human prostate cancer cells. Herein, 15 thyme honey samples from several regions of Greece were submitted to phytochemical analysis for the isolation, identification and determination (through modern spectral means) of the unique thyme honey monoterpene, the compound trihydroxy ketone E-4-(1,2,4-trihydroxy-2,6,6-trimethylcyclohexyl)-but-3-en-2-one. We investigated the anti-growth and apoptotic effects of the trihydroxy ketone on PC-3 human androgen independent prostate cancer cells using MTT assay and Annexin V-FITC respectively. The molecular pathways involved to such effects were further examined by evaluating its ability to inhibit (a) the NF-κB phosphorylation (S536), (b) JNK and Akt phosphorylation (Thr183/Tyr185 and S473 respectively) and (c) IL-6 production, using ELISA method. The anti-microbial effects of the trihydroxy ketone against a panel of nine pathogenic bacteria and three fungi were also assessed. The trihydroxy ketone exerted significant apoptotic activity in PC-3 prostate cancer cells at 100 μM, while it inhibited NF-κB phosphorylation and IL-6 secretion at a concentration range 10(-6)-10(-4)M. Akt and JNK signaling were not found to participate in this process. The trihydroxy ketone exerted significant anti-microbial profile against many human pathogenic bacteria and fungi (MIC values ranged from 0.04 to 0.57 mg/ml). Conclusively, the Greek thyme honey-derived monoterpene exerted significant apoptotic activity in PC-3 cells, mediated, at least in part, through reduction of NF-κB activity and IL-6 secretion and may play a key role in the anti-growth effect of thyme honey on prostate cancer cells.

Characterization and Biological Evaluation of Propolis from Poland

In this study, we assessed the therapeutic potential of propolis from Poland and performed chemical analysis by GC–MS, as well as determined its botanical origin. Chemical constituents typical for bud exudates of Populus nigra (section Aigeiros) were determined, however, glycerol esters of phenolic acids, as well as unusually high amounts of p-coumaric and ferulic acid and their benzyl esters, were also detected. These constituents are characteristic for buds of Populus tremula (section Leuce). We also evaluated the antiproliferative effect of propolis extracts against nine human cancer cell lines. Additionally, promising antibacterial activity of the dichloromethane extract (Minimal Inhibitory Concentration MIC values of 0.95–1.24 mg/mL), as well as a moderate antifungal activity (MIC values of 1.25–1.40 mg/mL), was noticed. Propolis from Poland appeared as a rich source of antibacterial and antiproliferative compounds and this confirmed that it is a valuable natural product with the potential to improve human health.