Chemical composition,antioxidant activity and antimicrobial properties of propolis extracts from Greece and Cyprus

Chemical composition, antioxidant activity and in vitro antimicrobial activity of twelve propolis ethanolic extracts (PEE) from mainland Greece, Greek islands, and east Cyprus were determined. The PEE studied contained significant amounts of terpenes and/or flavonoids, anthraquinones – mainly emodin and chrysophanol – and low amounts of phenolic acids and their esters, presenting differences from typical European propolis, and similarities to East Mediterranean propolis. Simple polyphenols and terpenic acids content ranged between 11.9–373.5 and 7.23–286.5 mg/g of PEE, respectively, with anthraquinones representing the 1.3–28.9% of simple polyphenols. Despite differences in composition, the PEE samples exhibited significant antioxidant, antibacterial, and antifungal activities, affecting a wider spectrum of microorganisms than the food grade antibacterial nisin, and presenting lower or no activity against several Lactobacillus strains. The presence of significant amounts of terpenoids seemed to enhance the antimicrobial activity of PEE. The conclusion, given the non-toxic and natural origin of PEE, is that, besides their potential pharmaceutical and nutraceutical value, propolis balsams from Greece and Cyprus are attractive candidates for use as natural antioxidant and microbicidal additives in food systems, especially those containing lactic acid bacteria.     

Antifungal activity and action mode of pinocembrin from propolis against Penicillium italicum

The antifungal activity and possible mode of action of pinocembrin isolated from propolis against Penicillium italicum were investigated. Pinocembrin exhibited strong antifungal activity against P. italicum in a dose-dependent manner. Respiration rates of P. italicum during spore germination and mycelial growth were significantly inhibited when exposure to pinocembrin. The respirations of mitochondria in state 2 and state 3 from mycelia were significantly inhibited in the presence of this compound. The phosphorylated adenosine nucleotides levels in hyphae of P. italicum treated with pinocembrin were significantly low and energy charge value became unstable. Unltrastructure of hyphae was seriously damaged with pinocembrin incubation for 24 h, which was further confirmed by the increase of relative ionic leakage and soluble protein loss of P. italicum mycelia treated with pinocembrin. It was concluded that pinocembrin inhibited the mycelial growth of P. italicum by interfering energy homeostasis and cell membrane damage of the pathogen. Pinocembrin would be a promising bioactive compound for treatment of P. italicum infections on postharvest citrus fruit.     

The specific chemical profile of Mediterranean propolis from Malta

Seventeen Maltese propolis samples were studied by GC–MS after silylation. They exhibited the typical Mediterranean chemical profile, rich in diterpene compounds (18–92% of TIC, GC–MS): 32 individual diterpenes were identified; 22 of them were present in each specimen. The other abundant compound group was that of sugars and sugar derivatives. In some samples, however, another compound group was observed (0–12% of TIC, GC–MS); the corresponding mass spectra were consistent with mono- and sesquiterpenyl esters of substituted benzoic acids. Two new propolis constituents of this group, daucane diterpene esters of hydroxybenzoic acids, were isolated. Their origin is suggested to be Ferula communis, as they are taxonomic markers for this species. All propolis samples were active against Staphylococcus aureus but only those with high concentrations of terpenyl esters showed antifungal activity against Candida albicans. The present results confirm that Mediterranean propolis is a valuable natural product with potential to improve human health.     

Antimicrobial potential of Coriandrum sativum L. against different Candida species in vitro

The aim of this study was to evaluate the chemical and antifungal activity of the essential oil from Coriandrum sativum L. (Apiaceae) against different Candida species. The essential oil (EO) was obtained by hydrodistillation and submitted to dry-column chromatography, resulting in six fractions, which were then submitted to TLC and GC–MS analysis. The main compounds identified were alcohols: 1-decanol (24.20%); 2E-decenol (18.00%); 2Z-dodecenol (17.60%); and aldehydes (89%). Antibacterial activity of the EO and its fractions was tested against five species of Candida albicans. The EO showed antimicrobial activity against all the species of Candida tested, except for Candida tropicalis CBS 94. Fractions 4 and 6 had a greater antibiotic spectrum, probably due to the presence of such alcohols as 3-hexenol, 1-decanol, 2E-decenol and 2Z-dodecenol. In conclusion, the EO and its fractions could be used as potential antimicrobial agents to treat or prevent Candida yeast infections.     

Antioxidant properties of extracts from juemingzi (Cassia tora L.) evaluated in vitro

Methanol extract from juemingzi (Cassia tora L.) was fractionated by liquid-liquid partition using ethyl acetate, n-butanol and water, respectively. The antioxidant activity of three different fractions was evaluated using different antioxidant tests, including inhibition of peroxidation of linoleic acid, reducing power, free-radical scavenging and ferrous ions chelating activity. In the above four assays, all the fractions showed antioxidant potential to varying degrees. Among these fractions, ethyl acetate fraction exhibited more antioxidant potency than other fractions. Furthermore, ethyl acetate fraction was found to be more effective in protecting LDL against oxidation in a concentration-dependent manner. The data suggest that juemingzi especially ethyl acetate-soluble fraction may have a preventive effect against atherosclerosis by inhibiting LDL oxidation.     

Antioxidant activity and phenolic composition of sumac (Rhus coriaria L.) extracts

Antioxidant activity and phenolic compounds of sumac extracts were investigated. Sumac was extracted in methanol and subjected to solvent–solvent partitioning to yield two fractions as ethyl acetate and aqueous. Methanol extract was further fractioned over Sephadex LH-20 column. Antioxidant activity of extracts and fractions were screened using ferric thiocyanate and DPPH radical scavenging methods. Phenolic composition of active fraction(s) was determined by HPLC–MS systems. Those fractions which exhibited strong antioxidant activity were rich in anthocyanins and hydrolysable tannins. While gallic acid was the main phenolic acid in the extracts, anthocyanin fraction contained cyanidin, peonidin, pelargonidin, petunidin, and delphinidin glucosides and coumarates. Pentagalloyl glucose was abundant in the hydrolysable tannin fraction. Effective scavenging concentration (EC₅₀) on DPPH radical was 0.70 μg/mL both in ethyl acetate and tannin fractions, and 5.33 μg/mL in anthocyanin rich fraction. Same extracts and fractions showed moderate lipid peroxidation inhibition effect compared with the synthetic antioxidants. The findings demonstrate that sumac can be used as a natural antioxidant.     

Chemical composition and biological activity of Citrus jambhiri Lush

The fresh peel of Citrus jambhiri was extracted with aqueous methanol and the residue was fractionated using light petroleum, chloroform and ethyl acetate. The constituents of the extracts were separated by column chromatography employing solvents of different polarity. The chemical structure of the isolated compounds was then identified by MS and NMR. Column chromatography of the petroleum fraction resulted in the isolation of nobiletin, 5-O-demethylnobiletin, tangeretin, 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone, 3,5,6,7,8,3′,4′-heptamethoxyflavone, and a mixture of β-sitosterol and stigmasterol. The chloroform fraction afforded 6-demethoxynobiletin, 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone, limonin and nomilin. The flavonoid glycosides naringin, hesperidin and neohesperidin were isolated from the ethyl acetate fraction. The chemical structure of the isolated compounds was established by MS and NMR (APT, COSY, HSQC, HMBC, and NOESY). LC–ESI-MS analysis of the ethyl acetate fraction afforded eight flavonoid glycosides, while the dichloromethane fraction of the defatted seeds contained seven limonoid aglycones. The chloroform fraction exerted the strongest DPPH^∗ free radical scavenging activity in comparison to other fractions. The petroleum fraction showed a significant inhibition of lipoxygenase indicating an anti-inflammatory action (IC₅₀ 29 ± 1 μg/mL). Some of the isolated polymethoxyflavones exhibited strong cytotoxicity against COS7, HeLa and Caco-2 cell lines.     

Control of citrus green and blue molds by Chinese propolis

Green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, are economically important postharvest diseases of citrus fruits. In this study, Chinese propolis ethyl acetate extract (PEAE) was evaluated to control P. digitatum and P. italicum on postharvest citrus fruits. The results indicated PEAE strongly inhibited mycelia growth and induced hyphae prominent abnormal morphological alterations. Also, PEAE had strong detrimental effect on spore germination of the tested pathogens in a concentrationdependent manner. For in vivo tests, PEAE could both reduce decay caused by P. digitatum and P. italicum respectively in wound-inoculated fruit and naturally infected fruit; meanwhile, no negative influences on the overall quality of the citrus fruits were observed with PEAE treatment. Therefore, PEAE could be used as a natural antifungal agent to control citrus blue and green mold.     

In vivo antitumoural activity and composition of an oil extract of Brazilian propolis

The present study aimed to evaluate in vivo and in vitro the antitumoural activity of a propolis extract obtained with edible vegetable oil and its fractions and also to investigate its chemical composition by LC–MS and LC–MS/MS. To evaluate the toxicological aspects related to the propolis extract treatment, hematological, biochemical, histopathological and morphological analyses of treated animals were performed. All propolis extracts showed an in vivo antitumour activity in the experimental model with a moderate toxicity effect at experimental exposure levels. The oil extract was as effective as the ethanolic extract at inhibiting tumour growth. In vitro assays showed that the whole oil extract produced better inhibition of tumour cells than its fractions. LC–MS and LC–MS/MS identified four phenolic acids and three flavonoids. The anticancer potential of the oil extract of propolis has been demonstrated and the edible vegetable oil was shown as an attractive alternative solvent to extract bioactive natural propolis components.     

Antioxidant activity and chemical constituents of essential oil and extracts of Rhizoma Homalomenae

Antioxidant activity and composition of essential oil and extracts of Rhizoma Homalomenae were determined. The extracts, especially the ethyl acetate extract (QJ4 fraction) of the aqueous residue after oil distillation, had considerable antioxidant potency which was significantly associated with their total phenolic and flavonoid contents, but the essential oil showed only weak or moderate activity. GC–MS analysis of the essential oil (yield: 0.82%, v/w) resulted in the identification of 77 compounds, accounting for 96.5% of the content of the oil. The major components, epi-α-cadinol (14.8%), α-cadinol (14.8%), α-terpineol (13.8%), linalool (11.1%), terpinen-4-ol (4.92%), and δ-cadinene (4.91%) constituted 64.3% of it. LC–MS/MS and HPLC analyses showed seven phenolic compounds (protocatechuic acid, vanillic acid, syringic acid, caffeic acid, p-coumaric acid, ferulic acid and apigenin) with a great amount in the ethyl acetate extract (QJ4 fraction). The strong antioxidant properties of the plant extracts may be attributed to the presence of these phenolics.     

HPLC–MS analyses and bioactivities of novel chemicals in Devil’s club (Oplopanax horridus (Sm.) Miq.)

Devil’s club (Oplopanax horridus (Sm.) Miq.) has traditionally been used as a folk medicine by native North Americans for the treatment of various chronic diseases. A methanolic extract and its sub-fractions by liquid–liquid re-extraction, i.e., chloroform (CHCl₃), ethyl acetate (EtOAc), n-butanol (BuOH), and water fractions, were analysed by their anti-cancer activity with in vitro cell proliferative bioassays, and their antioxidant capacities in terms of the determination of total phenolic content (TPC), ORAC value, and DPPH free radical scavenging activity. The whole extract of the dried root contained high TPC and possessed strong ORAC and DPPH radical scavenging activities. In addition, the extract exhibited a strong anti-proliferative ability against HT-29 cancer cells, e.g., with an inhibitive rate of 56.5% with a 0.2-mg/mL extract. Further investigation by HPLC–UV–MS identified significant bioactive phenolic compounds in the chloroform fraction, including gallic acid, caffeic acid, 4-O-feruloylquinic acid, 5-O-feruloylquinic acid, ferulic acid, methyl feruloylquinate, methyl ferulate, and quercetin. These results suggested that the associated bioactivity of the plant might result from the contribution of phenolic compounds.     

蜂胶乙酸乙酯提取物对意大利青霉菌的抑制作用及稳定性研究

本实验以青霉属的意大利青霉菌(Penicillium italicum)为研究材料,研究蜂胶不同溶剂提取物对意大利青霉菌的抑制作用及其对温度和pH 值的稳定性的影响。结果表明,乙酸乙酯提取物和乙醇提取物活性最高,氯仿提取物次之,石油醚提取物和水提取物活性最弱。提取物的抑菌活性与提取物中的黄酮含量和总酚呈显著正相关。乙酸乙酯提取物对意大利青霉的孢子萌发具有同样的抑制作用。蜂胶乙酸乙酯提取物溶液分别经过25、35、50、70、100℃的温度处理后其抑菌活性没有明显差异;在pH3.6～7.6 的范围内,随着pH 值的升高,提取物的抑菌活性先升高后降低,于pH5.2 时抑制率最高,pH4.4 时次之。这表明该蜂胶提取物能够有效的抑制意大利青霉的生长,在采后柑橘的防腐保鲜中具有良好的应用前景。     

Concordance between antioxidant activities and flavonol contents in different extracts and fractions of Cuscuta chinensis

Chinese herbs employed in traditional Chinese medicine (TCM) have been used for centuries in the practice of medicated diet and dietetic therapy. The seed of Cuscuta chinensis Lam. (Convolvulaceae), a commonly used traditional Chinese herb, is frequently added in Chinese cooking and preparation of refreshments, including porridge and alcoholic beverages, to nourish the human body. In the present study, we compared the antioxidant activities of water and ethanol extracts from the seeds C. chinensis and also of its different organic fractions, including n-hexane, ethyl acetate, n-butanol and organic water, by assessing their DPPH (1,1-diphenyl-2-picryl hydrazine) free radical-scavenging, superoxide anion scavenging, anti-superoxide anion formation and anti-lipid peroxidation abilities. The flavonol contents of all test samples were analyzed by high-performance liquid chromatography with an ultraviolet (HPLC–UV) detector. The results showed that there is a direct correlation of the flavonol content with the antioxidant activities from the extracts and fractions of C. chinensis. Moreover, the ethyl acetate fraction demonstrated significantly better and higher antioxidant effects, and also had a higher flavonol content than had the remaining samples (P < 0.05). The water fractions, however, exhibited the weakest antioxidant activity, and had low concentrations of flavonols. Thus, we suggest that the ethanol extract of C. chinensis, but not its water extract, could be used as a dietary nutritional supplement to promote human health and prevent oxidation-related diseases, due to its antioxidant properties.     

Acetylcholinesterase inhibitory-active components of Rhodiola rosea L.

An activity-directed fractionation and purification process was used to identify the acetylcholinesterase inhibitory-active components of Rhodiola rosea L. (RR). Dried rhizome of RR was extracted with boiled ethanol. After removal of tannins, the extract was separated into chloroform, ethyl acetate, n-butanol and water fractions. Among these, chloroform and n-butanol fractions showed stronger activity by bioassay for anti-cholinesterase activity than did ethyl acetate and water fractions. The chloroform fraction was then subjected to separation and purification using silica gel column chromatography and Sephadex LH-20 chromatography. One compound, showing strong anti-cholinesterase activity, was identified by spectral methods (NMR, UV and MS) and by comparison with authentic samples. It proved to be hydroquinone.     

Chemical composition,antimicrobial, cytotoxic and antioxidant activities of the essential oil of Artemisia indica Willd

Essential oil from the aerial parts of Artemisia indica was analysed by GC-FID and GC–MS. A total of 43 compounds representing 96.8% of the oil were identified and the major components were found to be artemisia ketone (42.1%), germacrene B (8.6%), borneol (6.1%) and cis-chrysanthenyl acetate (4.8%). Antimicrobial activity of the oil was evaluated against seven clinically significant bacterial and two fungal strains. The essential oil and its major constituents exhibited moderate to potent, broad-spectrum antibacterial and antifungal activities targeting both Gram-positive and Gram-negative bacteria. In vitro cytotoxicity evaluation against four human cancer cell lines THP-1 (leukemia), A-549 (lung), HEP-2 (liver) and Caco-2 (colon) showed that the essential oil exhibited concentration dependant growth inhibition in the 10–100 μg/ml dilution range, with IC₅₀ values of 10 μg/ml (THP-1), 25 μg/ml (A-549), 15.5 μg/ml (HEP-2) and 19.5 μg/ml (Caco-2). It was interesting to note that the essential oil also exhibited potent antioxidant activity.     

RETRACTED ARTICLE: Antimicrobial and antifungal effects of green tea extracts against microorganisms causing vaginitis

Green tea extracts (GTE) including catechins and caffeine possess strong antimicrobial activity against a variety of microorganisms. In this study, we examined their possible antimicrobial and antifungal effects on bacteria (Proteus mirabilis and Streptococcus pyogenes) and yeast species (Candida albicans) that cause vaginitis. The GTE and ethyl acetate fractions exhibited strong growth inhibitory activity against P. mirabilis and S. pyogenes, whereas the aqueous fraction possessed poor antimicrobial activity. Among the catechins, epigallocatechin gallate showed strong antibacterial activity. C. albicans was potently inhibited by the methylene chloride fraction and caffeine, while antifungal activity of GTE was contributed by caffeine. Furthermore, we evaluated whether in vitro activity of GTE included purified solvent fractions that were stable to heat and pH. Antimicrobial activity was potent in alkaline environment for P. mirabilis and acid environment for S. pyogenes and C. albicans. Herein GTE can be a valuable therapeutic agent for the treatment of vaginal-related pathogens.     

Identification of phenolics in the fruit of emblica (Phyllanthus emblica L.) and their antioxidant activities

An activity-directed fractionation and purification process was used to identify the antioxidative components of emblica fruit. Dried fruit of emblica was extracted with methanol and then partitioned by ethyl ether, ethyl acetate, butanol and water. The ethyl acetate fraction showed the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity among four fractions. The ethyl acetate fraction was then subjected to separation and purification using Sephadex LH-20 chromatography and reverse-phase high-performance liquid chromatography (HPLC). Six compounds were identified to be geraniin (1), quercetin 3-β-d-glucopyranoside (2), kaempferol 3-β-d-glucopyranoside (3), isocorilagin (4), quercetin (5), and kaempferol (6), respectively, by spectral methods, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, ultraviolet–visible (UV–Vis) spectrophotometry and mass spectroscopy (MS), and comparison with literatures. Compounds 2–4 and 6 were identified from emblica fruit for the first time. Furthermore, the antioxidant activities of purified compounds were screened for their antioxidative potential using lipid peroxidation and DPPH systems. All the purified compounds showed strong antioxidant and radical scavenging activities. Amongst, geraniin showed the highest antioxidant activity (4.7 and 65.7 μM of IC₅₀ values for DPPH and lipid peroxidation assay, respectively) than other purified compounds.     

Cyphomandra betacea Sendt. phenolics protect LDL from oxidation and PC12 cells from oxidative stress

Cyphomandra betacea Sendt. (tamarillo) is a subtropical fruit containing rich contents of anthocyanins and carotenoids. The antioxidant activity was investigated using a crude ethanol extract of C. betacea fruit and its partitioned fractions, i.e. the ethyl acetate, butanol and water fractions. The ethyl acetate fraction exhibited the highest DPPH scavenging activity, Trolox equivalent antioxidant capacity (TEAC) and total phenol content. C. betacea phenolics in ethyl acetate fraction inhibited copper-induced LDL oxidation equally to or more effectively than dl-α-tocopherol, as measured by decreased formation of thiobarbituric acid-reactive substances (TBARS), conjugated diene and relative electrophoretic mobility (REM). Furthermore, 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) reduction assay showed that C. betacea phenolics in ethyl acetate fraction prevent oxidative stress-induced cell death in neuronal PC12 cells in a dose-dependent manner via attenuation of ROS production. In conclusion, C. betacea phenolics are potent antioxidants which can inhibit LDL oxidation in vitro and ROS production in PC12 cells.     

Evaluation of the antioxidant activity of extracts from buntan (Citrus grandis Osbeck) fruit tissues

The goal of the present work was to evaluate the antioxidant properties of buntan (Citrus grandis Osbeck) using various solvents, such as n-hexane, ethyl acetate (EtOAc), butanol and methanol. The antioxidant activities of crude extracts were evaluated by using the free radical scavenging β-carotene assay and total polyphenol. Ethyl acetate extracts of falvedo exhibited high antioxidative activities, followed by albedo and segment membrane extracts. Chromatography separation of EtOAc extract of flavedo using a silica gel column, yielded six fractions (A, B, C, D, E and F) using gradient elution with benzene and acetone (19:1, 14:1, 9:1, 5:1, 1:1 and 0:l). Among them, two fractions (C and D) showed strong antioxidant activities using the free radical scavenging activity (DPPH) antioxidant assay. These two fractions were further purified using silica gel column chromatography and preparative TLC. Their extracts could well be useful to prevent oxidation in fruit juices and essential oil food products as well as for health supplements. Identification of the responsible components is underway.