Antibacterial and cytotoxic activities of extracts from (Tunisian)Rhamnus alaternus (Rhamnaceae)

The petroleum ether, chloroformic, ethyl acetate, methanolic, Total Oligomers Flavonoids (TOF) enriched extracts, water extract as well as its fractions A₁, A₂, A₃ obtained from aerial parts ofRhamnus alaternus, a Tunisian-Mediterranean medicinal species, were investigated for the contents of phenolic compounds, cytotoxic activity against the K562 human chronic myelogenous leukaemia cell line and L1210 leukaemia murine cells and for antibacterial activity against Gram positive and Gram negative bacterial reference strains. A pronounced cytotoxic effect on both the cell lines was shown in the TOF, ethyl acetate, methanolic, aqueous extracts and A₂ fraction, with respectively IC₅₀ values 75, 232, 298, 606 and 571 μg/ml on K562 cells and 198, 176, 767, 560 and 614 μg/ml on L1210 cell line. Significant activity against bacterial reference strains:Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Salmonella enteritidis andSalmonella typhimurium was shown with ethyl acetate, TOF extracts and A2 fraction. The antimicrobial and cytotoxic activities showed byR. alatemus depended on the chemical composition of the tested extracts.     

Antibacterial and free-radical scavenging activities of Sonoran propolis

AIMS: To evaluate the antibacterial and free-radical scavenging (FRS) activities of propolis collected from three different areas of Sonoran Desert in northwestern Mexico [Pueblo de Alamos (PAP), Ures (UP) and Caborca (CP)]. METHODS AND RESULTS: The antibacterial and FRS activities of Sonoran propolis were determined by the broth microdilution method and the DPPH (1,1-diphenyl-2-picrylhydracyl) assay, respectively. Propolis samples had antibacterial activity against only Gram-positive bacteria. The UP sample showed the highest antibacterial activity against Staphylococcus aureus [minimal inhibitory concentration (MIC) 100 microg ml(-1)] in a concentration-dependent manner (UP > CP > PAP). Caffeic acid phenethyl ester (CAPE), a UP propolis constituent, had very high growth-inhibitory activity towards Gram-positive bacteria, particularly against S. aureus (MIC 0.1 mmol l(-1)). To our knowledge, this is the first study showing a strong antibacterial activity of CAPE against S. aureus. Additionally, propolis CP exhibited high FRS activity (86% +/- 0.3 at 100 microg ml(-1)) comparable with those of the reference antioxidants vitamin C (87.4% +/- 1.7 at 70 micromol l(-1)) and BHT (66.07% +/- 0.76 at 140 micromol l(-1)). The propolis compounds CAPE and rutin showed high FRS activity (90.4% +/- 0.2 and 88.5% +/- 0.8 at 70 micromol l(-1), respectively). CONCLUSIONS: Sonoran propolis UP and CAPE had strong antibacterial activity against S. aureus. In addition, propolis CP showed potent FRS activity comparable with those of vitamin C and BHT. SIGNIFICANCE AND IMPACT OF THE STUDY: The strong antibacterial and antioxidant properties of Sonoran propolis and some of its constituents support further studies on the clinical applications of this natural bee product against S. aureus and several oxidative damage-related diseases.     

Evaluation of antioxidant effect of different extracts of Myrtus communis L

Oxidative stress is involved in the pathogenesis of numerous diseases. Nevertheless, no optimal natural antioxidant has been found for therapeutics, therefore polyphenol antioxidants have been looked for in myrtle leaves, a plant that in folk medicine has been used as anti-inflammatory drug. Antioxidant-rich fractions were prepared from myrtle (Myrtus communis L.) leaves liquid-liquid extraction (LLE) with different solvents. All myrtle extracts were very rich in polyphenols. In particular, hydroalcoholic extracts contain galloyl-glucosides, ellagitannins, galloyl-quinic acids and flavonol glycosides; ethylacetate extract and aqueous residues after LLE are enriched in flavonol glycosides and hydrolysable tannins (galloyl-glucosides, ellagitannins, galloyl-quinic acids), respectively. Qualitative and quantitative analysis for the single unidentified compound was also performed. Human LDL exposed to copper ions was used to evaluate the antioxidant activity of the myrtle extracts. Addition of these extracts did not affect the basal oxidation of LDL but dose-dependently decreased the oxidation induced by copper ions. Moreover, the myrtle extracts reduce the formation of conjugated dienes. The antioxidant effect of three myrtle extracts decreased in the following order: hydroalcoholic extracts, ethylacetate and aqueous residues after LLE. The extracts had the following IC₅₀: 0.36, 2.27 and 2.88 μM, when the sum of total phenolic compounds was considered after the correction of molecular weight based on pure compounds. Statistical analysis showed a significant difference among hydroalcoholic extracts vs. the ethylacetate and aqueous residues after LLE. These results suggest that the myrtle extracts have a potent antioxidant activity mainly due to the presence of galloyl derivatives.     

Antimicrobial and antioxidative activity of extracts and essential oils of Myrtus communis L.

Since synthetic antimicrobial agents and food additives can cause a number of adverse effects, there is a growing interest from consumers in ingredients from natural sources. Medicinal plants, such as Myrtus communis L. are a source of new compounds which can be used in both the food industry and for medical purposes, primarily as antimicrobial agents. In this review, the characteristics of myrtle essential oils and extracts are summarized, with particular attention to their chemical composition, biological activities and potential applications.     

Antioxidant activity of oligomeric acylphloroglucinols from Myrtus communis L

The use of myrtle (Myrtus communis L.) as a culinary spice and as a flavoring agent for alcoholic beverages is widespread in the Mediterranean area, and especially in Sardinia. Myrtle contains unique oligomeric non-prenylated acylphloroglucinols, whose antioxidant activity was investigated in various systems. Both semimyrtucommulone (1) and myrtucommulone A (2) showed powerful antioxidant properties, protecting linoleic acid against free radical attack in simple in vitro systems, inhibiting its autoxidation and its FeCl3- and EDTA-mediated oxidation. While both compounds lacked pro-oxidant activity, semimyrtucommulone was more powerful than myrtucommulone A, and was further evaluated in rat liver homogenates for activity against lipid peroxidation induced by ferric-nitrilotriacetate, and in cell cultures for cytotoxicity and the inhibition of TBH- or FeCl3-induced oxidation. The results of these studies established semimyrtucommulone as a novel dietary antioxidant lead.     

Biochemical activities of Iranian Mentha piperita L. and Myrtus communis L. essential oils

GC-MS analysis of essential oils of Iranian Mentha piperita and Myrtus communis extracted by hydrodistillation lead to identification of 26 and 32 compounds, respectively. The oils had good to excellent antimicrobial activities against Escherichia coli, Staphylococcus aureus and Candida albicans with the oil of M. piperita being more active. The findings suggest feasibility of application of M. piperita oil in treatment of the infections caused by C. albicans and E. coli. D-values on exposure to M. piperita and Myrtus communis oils were (2.14 and 2.8min), (1.4 and 12.8min) and (4.3 and 8.6min) for E. coli, S. aureus and C. albicans , respectively. The oils were screened for their possible antioxidant activities by two complementary test systems, namely DPPH free radical scavenging and beta-carotene/linoleic acid systems. M. piperirta oil exerted greater antioxidant activity than that of M. communis. Phytochemical and phytobiological characteristics of these oils may lead to extraction and production of active compounds in single or combined forms with useful applications.     

Structure and development of the elaiosome in Myrtus communis L. (Myrtaceae) seeds

Myrtus communis L. (Myrtaceae) is a fleshy-fruited shrub occurring in the Mediterranean area, whose seeds are snail shaped, with a very thick coat and a central elaiosome. This structure is a fleshy and edible appendage responsible of seed dispersal by ants, a phenomenon known as myrmecochory. The elaiosome develops very early from the external integument cells near the funicular and micropylar area, through cell enlargement and cell divisions. At the latest stages of development, some internal integument cells participate to its formation so that myrtle elaiosome can be classified among those originating from both epidermal and inner tissues.The low content of lipids, starch and proteins revealed by histochemical and biochemical analyses on M. communis elaiosomes suggests that the myrtle is a plant with a multiple pattern of seed dispersal. Myrmecochory seems to play a secondary role.     

香桃木叶片粗多酚抗氧化活性的研究

以香桃木叶片为材料,60%乙醇提取获得粗多酚样品,并对样品的油脂抗氧化性和自由基清除能力进行研究。结果表明,未经纯化的香桃木粗多酚对油脂抗氧化效果优于BHT和V_C等人工合成抗氧化剂;在清除自由基的实验中,相同浓度的香桃木粗多酚对DPPH自由基的清除率为V_E的5倍,对羟自由基的清除效果也略优于V_C。由此可以预见香桃木粗多酚在精细加工、经纯化后抗氧化效果会更加显著。     

Chemical Variability of Algerian Myrtus communis L.

The composition of 55 samples of essential oil isolated from the aerial parts of wild growing Myrtus communis L. harvested in 16 locations from East to West Algeria were investigated by GC (determination of retention indices) and ¹³C‐NMR analyses. The essential oils consisted mainly of monoterpenes, α‐pinene (27.4–59.2%) and 1,8‐cineole (6.1–34.3%) being the major components. They were also characterized by the absence of myrtenyl acetate. The compositions of the 55 oils were submitted to k‐means partitioning and principal component analysis, which allowed the distinction of two groups within the oil samples, which could be subdivided into two subgroups each. Groups I (78% of the samples) and II were differentiated on the basis of the contents of α‐pinene, linalool, and linalyl acetate. Subgroups IA and IB could be distinguished by their contents of α‐pinene and 1,8‐cineole. Subgroups IIA and IIB differed substantially in their contents of 1,8‐cineole and limonene. All the samples contained 3,3,5,5,8,8‐hexamethyl‐7‐oxabicyclo[4.3.0]non‐1(6)‐ene‐2,4‐dione (up to 4.9%).     

Carnivorous mammals as seed dispersers of Myrtus communis (Myrtaceae) in the Mediterranean shrublands

ABSTRACT

The role of carnivorous mammals as seed dispersers of Myrtus communis L. in the Mediterranean environment was studied. Seeds of M. communis were found in faeces of red fox (Vulpes vulpes L.) and carnivores from the genus Martes, at four sites on the Tyrrhenic coast of Southern Italy in the period autumn-winter 1993–1995. All the study sites are covered by Mediterranean shrublands with M. communis as one of the dominant species. Content analysis of fox scats showed that fruits of M. communis constitute a relevant component of the diet of these carnivores, although other food categories were also well represented. Further investigations on the effect of mammal digestion on seed germinability showed that carnivores not only moved the seeds away from the mother plant but also enhanced their germinability. This species was known to be bird- and ant-dispersed and the adaptive implications of a multi-vectorial seed dispersal process is discussed.     

Myrtucommulone production by a strain of Neofusicoccum australe endophytic in myrtle (Myrtus communis)

Myrtucommulones are acylphloroglucinol compounds reported from myrtle (Myrtus communis) and a few more plant species belonging in the Myrtaceae that have recently attracted the attention of pharmacologists for their anti-oxidant, anti-inflammatory and anti-tumor properties. An endophytic strain of Neofusicoccum australe recovered from a myrtle branch was selected based on the bioactivity of its culture extracts, and found to produce myrtucommulones A and D. A mixture of these compounds induced anti-proliferative effects on the human prostatic cancer cell lines DU145 and PC3, with a IC₅₀ of respectively 4.64 and 3.11 mg/l. Along the lines of recent evidences of the ability by endophytic fungi to produce bioactive compounds originally extracted from their host plants, this is the first report of myrtucommulones as secondary metabolites of an endophytic fungal strain. The availability of a microbial strain to be cultured in vitro may provide access to more substantial amounts of these products for further investigations in view of their possible pharmaceutical use.     

Secondary somatic embryogenesis and plant regeneration in myrtle (Myrtus communis L.)

Immature seeds, as well as hypocotyls and cotyledons excised from seedlings of Myrtus communis L., were cultured on media containing half-strength Murashige and Skoog macronutrients (MS/2) with combinations of auxins and cytokinins, in order to study their morphogenetic competence. Somatic embryogenesis was obtained from cotyledons, hypocotyls and 2-month-old immature seeds with 0.1 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). The percentage of explants showing this primary somatic embryogenesis ranged from 4% for hypocotyls to 12% for 2-month-old immature seeds. In the latter, somatic embryogenesis was also obtained in media containing 2,4-D plus a cytokinin, and with only a cytokinin. Somatic embryos obtained from hypocotyls, cotyledons or immature seeds were able to develop on MS/2 medium without plant growth regulators. Subculture of primary somatic embryos obtained from immature seeds on MS/2 medium without plant growth regulators gave rise to clusters with secondary somatic embryos and embryogenic calli. These clusters were subcultured every 8 weeks, and they were the source of highly embryogenic cultures. An average of 10% of the secondary somatic embryos developed into plantlets in each subculture. Therefore, the same culture on MS/2 medium without growth regulators yielded both plantlets and de novo secondary embryos. Received: 6 April 1998 / Revision received: 10 July 1998 / Accepted: 21 July 1998     

一些裸子植物鲜叶提取物清除自由基的活性研究

用二苯基苦基苯肼自由基酶标仪法,对常见的60余种裸子植物鲜叶的自由基清除活性进行了比较.发现不同科属,不同树种鲜叶的80%甲醇提取物的自由基清除活性有很大差异,其中罗汉松科罗汉松属树木鲜叶在浓度在0.5mg/mL,于37℃下孵育20min时的自由基清除率平均可达55.9%,而柏科侧柏属平均仅为7.1%;罗汉松,孔雀柏、小叶罗汉松、湿地松、杉木和刺柏等鲜叶有很强的自由基清除活性,它们的自由基清除率分别可达61.1%,58.4,57.6%,57.1%,51.8%和50.4%,表明这些树种有较大的开发潜力。     

Structure and development of the secretory cavities of Myrtus communis leaves

The structure and development of Myrtus communis L. secretory cavities has been studied in young and expanded leaves, using light and scanning electron microscope. Secretory cavities are continuously formed during leaf development, but in mature leaves the rhythm of their appearance shows steep decrease. Each secretory cavity is developed from a single epidermal cell, which undergoes a periclinal division followed by anticlinal and several oblique cell divisions. The lumen of the secretory cavity is initiated by cell wall separation, i.e., schizogenously. The secretory cells line the cavity, where the secreted material is collected. Secretory cavities are covered by modified epidermal cells, which do not seem to form any special aperture. Essential oils seem to be discharged after mechanical treatment of the leaf.     

Free radical scavenging of grape pomace extracts from Cabernet sauvingnon (Vitis vinifera)

Pressed grape pomace obtained from the wine production of Cabernet sauvignon (Vitis vinifera) vintage was dried until 9.8% moisture content, ground and submitted to extraction of soluble components from different extraction techniques. Low pressure extractions were performed with ethanol maceration followed by fractionation with n-hexane, dichloromethane, butanol and ethyl acetate. These solvents were furthermore applied for soxhlet extraction. Supercritical fluid extraction (SFE) was also performed to obtain grape pomace extracts by using pure CO(2) and CO(2) with ethanol as co-solvent in concentrations of 10, 15 and 20%w/w. The operating condition used in high pressure extractions was 150bar and 40 degrees C. The antioxidant activity of the grape pomace extracts was determined considering the free radical scavenging assay using 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and was correlated with the total phenol content determined according to the Folin-Ciocalteu method. The results obtained in DPPH tests indicate the highest antioxidant activity of 96.6+/-0.3%AA, with an IC(50) value of 13+/-1, for the extracts obtained with ethyl acetate in solid-liquid extraction. The highest yield values were achieved in soxhlet extraction with ethanol (13.2%w/w) and with butanol (12.2%w/w), and also by SFE with 15% ethanol (9.2%w/w). The lipophilic composition of grape pomace extracts was evaluated by gas chromatography-mass spectrometry with the identification of components like linoleic acid and ethyl linoleate, with important therapeutic activities.     

Phloroglucinol Derivatives from Myrtus communis ‘Variegata’ and Their Antibacterial Activities

Myrtucomvalones D–F, three new triketone‐phloroglucinol‐triketone adducts, and three known ones (myrtucommulone E, myrtucommulone D and callistenone D) were obtained from Myrtus communis ‘Variegata’. Myrtucomvalone D is a pair of enantiomers which was further resolved into (+)‐myrtucomvalone D and (?)‐myrtucomvalone D by chiral HPLC. Their structures and complete stereochemistry were established from interpretation of NMR and crystallographic data and chemical calculations. Myrtucomvalone F, myrtucommulone D and callistenone D showed significant antibacterial activities.     

Free radical and reactive oxygen species scavenging activities of the extracts from seahorse, Hippocampus kuda Bleeler

Seahorse, Hippocampus kuda (SH) a marine teleost fish, is well known not only for its special medicinal composition and used as one of the most famous and expensive materials of traditional Chinese medicine. It was extracted with water (SHW), methanol (SHM), and ethanol (SHE), respectively and evaluated by various antioxidant assays. The including reducing power, total antioxidant, DPPH radical scavenging, hydroxyl radical scavenging, superoxide anion radical scavenging, alkyl radical scavenging, and protective effect on DNA damage caused by hydroxyl radicals generated. Further, the ROS level was detected using a fluorescence probe, 2′,7′-dichlorofluorescin diacetate (DCFH-DA), which could be converted to highly fluorescent dichlorofluorescein (DCF) with the presence of intracellular ROS on mouse macrophages, RAW264.7 cell and inhibited myeloperoxidase (MPO) activity in human myeloid, HL60 cells, respectively. Those various antioxidant activities were compared to standard antioxidants such as α-tocopherol. Among SHM exhibited the highest antioxidant activity in linoleic acid system, effective reducing power, DPPH radical scavenging, hydroxyl radical scavenging, superoxide radical scavenging, alkyl radical scavenging, inhibitory intracellular ROS, and inhibited MPO activity. Furthermore, MTT assay showed no cytotoxicity on mouse macrophages cell (RAW264.7) and human cell lines (MRC-5, HL60, U937). This antioxidant property depends on concentration and increasing with increased amount of extracts. The results obtained in the present study indicated that the see horse (Hippocampus kuda Bleeker) is a potential source of natural antioxidant.     

Evaluation of Antioxidant Effect of Different Extracts of Myrtus communis L.

Oxidative stress is involved in the pathogenesis of numerous diseases. Nevertheless, no optimal natural antioxidant has been found for therapeutics, therefore polyphenol antioxidants have been looked for in myrtle leaves, a plant that in folk medicine has been used as anti-inflammatory drug. Antioxidant-rich fractions were prepared from myrtle (Myrtus communis L.) leaves liquid–liquid extraction (LLE) with different solvents. All myrtle extracts were very rich in polyphenols. In particular, hydroalcoholic extracts contain galloyl-glucosides, ellagitannins, galloyl-quinic acids and flavonol glycosides; ethylacetate extract and aqueous residues after LLE are enriched in flavonol glycosides and hydrolysable tannins (galloyl-glucosides, ellagitannins, galloyl-quinic acids), respectively. Qualitative and quantitative analysis for the single unidentified compound was also performed. Human LDL exposed to copper ions was used to evaluate the antioxidant activity of the myrtle extracts. Addition of these extracts did not affect the basal oxidation of LDL but dose-dependently decreased the oxidation induced by copper ions. Moreover, the myrtle extracts reduce the formation of conjugated dienes. The antioxidant effect of three myrtle extracts decreased in the following order: hydroalcoholic extracts, ethylacetate and aqueous residues after LLE. The extracts had the following IC⁵⁰: 0.36, 2.27 and 2.88?μM, when the sum of total phenolic compounds was considered after the correction of molecular weight based on pure compounds. Statistical analysis showed a significant difference among hydroalcoholic extracts vs. the ethylacetate and aqueous residues after LLE. These results suggest that the myrtle extracts have a potent antioxidant activity mainly due to the presence of galloyl derivatives.     

Antifungal and Herbicidal Effects of Fruit Essential Oils of Four Myrtus communis Genotypes

The chemical composition of the essential oils isolated by hydrodistillation from the fruits of four selected Myrtus communis L. genotypes from Turkey was characterized by GC‐FID and GC/MS analyses. 1,8‐Cineole (29.20–31.40%), linalool (15.67–19.13%), α‐terpineol (8.40–18.43%), α‐pinene (6.04–20.71%), and geranyl acetate (3.98–7.54%) were found to be the major constituents of the fruit essential oils of all M. communis genotypes investigated. The oils were characterized by high amounts of oxygenated monoterpenes, representing 73.02–83.83% of the total oil compositions. The results of the fungal growth inhibition assays showed that the oils inhibited the growth of 19 phytopathogenic fungi. However, their antifungal activity was generally lower than that of the commercial pesticide benomyl. The herbicidal effects of the oils on the seed germination and seedling growth of Amaranthus retroflexus L., Chenopodium album L., Cirsium arvense (L.) Scop ., Lactuca serriola L., and Rumex crispus L. were also determined. The oils completely or partly inhibited the seed germinations and seedling growths of the plants. The findings of the present study suggest that the M. communis essential oils might have potential to be used as natural herbicides as well as fungicides.