Plants of the genus Allium as antibacterial agents: From tradition to pharmacy

Plants belonging to the genus Allium are widely cultivated and used all over the world as food and medicinal plants. Since ancient times, these plants, particularly garlic (Allium sativum L.) and onion (Allium cepa L.), have represented important components of typical recipes and traditional healing systems. Not the least of which, their use as food biopreservatives is well documented, due to the relevant antibacterial activity of their extracts and essential oils. In addition to garlic and onion, this review article deals with the main members of the genus Allium, including A. ampeloprasum (Leek), A. schoenoprasum (Chive) and A. ascalonicum (Shallot), focusing both on their ethnonutritional uses and potential as promising food biopreservative agents. Noteworthy, recent research has demonstrated Allium derivatives to be novel components in active edible coatings as well as nanoformulates.

Tordylium persicum Boiss. & Hausskn extract: A possible alternative for treatment of pediatric infectious diseases

Antimicrobial herbal compounds are one of the important medical resources, and in order to help alleviate the spread of the pediatric infectious diseases, identification of additional bioactive phytochemicals and herbal extracts will be practical in treating illnesses. In the present work, antimicrobial activities various extracts of Tordylium persicum Boiss. & Hausskn aerial parts were determined against five Gram-positive bacteria, five Gram-negative bacteria, two fungi, and Echinococcus granulosus. Antimicrobial activities were assayed using both disk diffusion and microbroth dilution methods. Scolicidal activity was assayed by the Smyth and Barrett method. Also total phenol and total flavonoid contents for plant extracts were assayed. Results showed that the methanolic extract was more effective on all microbes. The results showed that Streptococcus pyogenes was the most susceptible to the methanolic extract (MIC = 25.9 ± 0.0 µg/mL), while Proteus vulgaris was the most resistant strain (MIC = 295.3 ± 0.0 µg/mL) among all bacteria evaluated. The extracts showed significant activity versus E. granulosus (P < 0.5) with dose-dependent inhibitions of the protoscolices. The high concentration of total polyphenolics (294.5 ± 0.1 GAE/g DW) and flavonoids (105.7 ± 0.3 mg CE/g DW) may be responsible for these activities. Our study is first evaluation on antimicrobial and scolicidal activities of T. persicum. Due to the appearance of antibiotic-resistance, ourstudy suggested that methanol extracts of this plant are appropriate candidate for traditional curative uses and it can be utilized in the pediatric infectious disease therapy, especially pediatric infectious disease.

Mutagenic, antimutagenic, antioxidant, anti-lipoxygenase and antimicrobial activities of Scandix pecten-veneris L

Scandix pecten-veneris L. or Shepherd's-needle is a weed species used in some countries for medicinal purposes. In this study S. pecten-veneris leaves were shade dried, powdered and extracted with methanol. The purpose of this study was to assay the in vitro mutagenic, antimutagenic, antioxidant, antilipoxygenase and antimicrobial activities of S. pecten-veneris leaf extract. The methanolic extract indicated no mutagenicity when tested with Salmonella typhimurium strains TA98 and TA100. Antimutagenic activity was reported with inhibition of mutagenicity in a concentration dependent fashion. The methanolic extract demonstrated antioxidant activity in the DPPH radical-scavenging test (IC50 = 4.57 mg/mL), comparable to ascorbic acid and BHT. Moreover, the extract presented a remarkable and potent inhibition against soybean lipoxygenase (IC50 = 641.57 µg/mL). The methanolic extract was examined for its antimicrobial powers against four different bacteria with MIC values >100. Our results introduced this plant as a useful factor for the treatment of cancer, inflammatory and infectious diseases.

Chemical composition, antimicrobial, and cytotoxicity studies on S. erianthum and S. macranthum essential oils

CONTEXT

Solanum erianthum D. Don and Solanum macranthum Dunal (Solanaceae) are widely used in traditional medicine. The leaves act as an abortifacient and in particular to treat leucorrhoea, sores, and skin irritations.

OBJECTIVE

This study was undertaken to characterize the volatile constituents of the leaf and fruit essential oils of S. erianthum and S. macranthum; their antimicrobial and in vitro cytotoxic bioassay against human breast and prostate tumor cells.

METHODS

The volatile oils were obtained by hydrodistillation and analyzed for their constituents by gas chromatography-mass spectrometry (GC-MS). Minimum Inhibitory Concentrations (MIC) were determined using the microbroth dilution technique while the cytotoxic potentials were evaluated using the Cell Titre 96((R)) AQ(ueous) Non-Radioactive Cell Proliferation Assay method.

RESULTS

Solanum erianthum essential oils were characterized by the abundance of α-terpinolene (17.8%), α-phellandrene (17.5%), p-cymene (15.7%) and β-pinene (11.7%) in the leaves; α-humulene (23.1%), humulene epoxide II (20.0%), caryophyllene oxide (16.5%), methyl salicylate (11.8%) and β-caryophyllene (10.9%) in the fruits. The leaf oil of S. macranthum consisted of (E)-phytol (29.0%), pentadecanal (28.1%) and pentadecane (7.7%) while the major fruit oil constituents were α-humulene (36.5%), β-caryophyllene (17.8%), ethyl palmitate (9.4%), and methyl salicylate (8.2%). Solanum erianthum leaf volatile oil demonstrated potent inhibitory activity against Hs 578T and PC-3 human breast and prostate tumor cells respectively. In addition, the Solanum essential oils exhibited significant antimicrobial activity (19.5-625 µg/mL) on pathogens employed in the assay.

CONCLUSION

The Solanum essential oils possess strong antimicrobial activity in addition to the potent cytotoxic potential of S. erianthum leaf oil against Hs 578T and PC-3 cells.

The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases - part II

Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen "Neglected Tropical Diseases" (NTDs) defined by the WHO. Furthermore, malaria (caused by various Plasmodium species) can be considered a neglected disease in certain countries and with regard to availability and affordability of the antimalarials. Living organisms, especially plants, provide an innumerable number of molecules with potential for the treatment of many serious diseases. The current review attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs. In part I, a general description of the diseases, the current state of therapy and need for new therapeuticals, assay methods and strategies applied in the search for new plant derived natural products against these diseases and an overview on natural products of terpenoid origin with antiprotozoal potential were given. The present part II compiles the current knowledge on natural products with antiprotozoal activity that are derived from the shikimate pathway (lignans, coumarins, caffeic acid derivatives), quinones of various structural classes, compounds formed via the polyketide pathways (flavonoids and related compounds, chromenes and related benzopyrans and benzofurans, xanthones, acetogenins from Annonaceae and polyacetylenes) as well as the diverse classes of alkaloids. In total, both parts compile the literature on almost 900 different plant-derived natural products and their activity data, taken from over 800 references. These data, as the result of enormous efforts of numerous research groups world-wide, illustrate that plant secondary metabolites represent an immensely rich source of chemical diversity with an extremely high potential to yield a wealth of lead structures towards new therapies for NTDs. Only a small percentage, however, of the roughly 200,000 plant species on earth have been studied chemically and only a small percentage of these plants or their constituents has been investigated for antiprotozoal activity. The repository of plant-derived natural products hence deserves to be investigated even more intensely than it has been up to present.

Plant-derived triterpenoids as potential antineoplastic agents

Man has relied on plants as a source of medicinal agents for centuries. Today, with the specter of antibiotic resistance, emerging infectious diseases, and cancers, phytochemicals continue to provide new structural leads for the chemotherapeutic industry. A number of triterpenoids have shown promise as antineoplastic agents. Members of the cycloartane, lupane, ursane, oleanane, friedelane (especially quinone methides), dammarane, cucurbitacin, and limonoid triterpenoids, have demonstrated anti-proliferative activity on various cancer cell lines. This review covers the recent developments regarding antineoplastic/cytotoxic triterpenoids, excluding saponins, from higher plants.

Isolation and frontier molecular orbital investigation of bioactive quinone-methide triterpenoids from the bark of Salacia petenensis

The crude dichloromethane bark extract of Salacia petenensis (Hippocrateaceae) from Monteverde, Costa Rica, shows antibacterial and cytotoxic activity. Bioactivity-directed separation led to the isolation of tingenone and netzahualcoyonol as the biologically active materials. Also isolated from the extract were 3-methoxyfriedel-2-en-1-one (a new natural product) and 29-hydroxyfriedelan-3-one. The structures of these compounds were elucidated on the basis of NMR spectral analysis. Molecular orbital calculations have been carried out using the semi-empirical PM3 and Hartee-Fock 3-21G ab initio techniques on the quinone-methide nortriterpenoids tingenone and netzahualcoyonol, as well as on the nucleotide bases adenine, guanine, cytosine, and thymine. The molecular orbital calculations suggest that a possible mode of cytotoxic action of quinone-methide triterpenoids involves quasi-intercalative interaction of the compounds with DNA followed by nucleophilic addition of the DNA base to carbon-6 of the triterpenoid.

Synthesis and cytotoxic activity of a series of diacetylenic compounds related to falcarindiol

The synthesis of a series of diacetylenic compounds related to the natural product falcarindiol has been carried out. Unsymmetrical diacetylenes were prepared by a modification of the Cadiot-Chodkiewicz coupling reaction, while a Glaser coupling was used to prepare symmetrical diacetylenes. These compounds have been tested for in vitro cytotoxic activity against Hep-G2, and H-4-II-E cell lines. Diacetylenes with additional unsaturation at C-1, 2, appended with hydroxyl groups at C-3 and C-8, or with long hydrophobic chains, exhibited IC50 values in the micromolar range.

A phytochemical investigation of Alchornea latifolia

A phytochemical investigation of the chloroform leaf extract of Alchornea latifolia has been undertaken. Along with the triterpenoids taraxerone, friedelin, epifriedelinol, and taraxerol, the plant also contains seco-3,4-friedelin (dihydroputranjivic acid) (1) and seco-3,4-taraxerone (2). These A-ring-opened triterpenoids show in vitro cytotoxic activity against Hep-G2 and A-431 human cancer cell lines and are potent inhibitors of topoisomerase II.

Biologically active triterpenoids of Syncarpia glomulifera bark extract from Paluma, north Queensland, Australia

The crude chloroform bark extract of Syncarpia glomulifera (Myrtaceae) shows antibacterial and cytotoxic activity. Bioactivity-directed separation led to the isolation of oleanolic acid-3-acetate, ursolic acid-3-acetate and betulinic acid. The relatively large abundance (10% of the crude extract) and high degree of activity of betulinic acid are responsible for the bioactivity of the crude bark extract.

Antibacterial hydroxycinnamic esters from Piper caninum from Paluma, north Queensland, Australia. The crystal and molecular structure of (+)-bornyl coumarate

The crude chloroform bark extract of Piper caninum (Piperaceae) exhibits antibacterial activity against the Gram-positive bacteria, Bacillus cereus, Staphylococcus aureus, and Streptococcus pneumoniae. The antibacterial agents in this extract have been isolated using bioactivity-directed chromatographic techniques and identified by NMR spectroscopy as (+)-bornyl p-coumarate and bornyl caffeate. A single-crystal X-ray structure has been carried out on (+)-bornyl p-coumarate. The compound crystallizes in the orthorhombic space group P2(1)2(1)2(1) (#19) with a = 12.659(4), b = 13.281(4), and c = 10.177(3) A. Fullmatrix least-squares refinement converged at R = 0.047, and Rw = 0.058.

Biological activity of the essential oil of Myrcianthes sp. nov. "black fruit" from Monteverde, Costa Rica

The leaf essential oil of an undescribed species of Myrcianthes has been obtained from Monteverde, Costa Rica. The essential oil exhibits in vitro cytotoxic activity against Hep-G2 and SK-Mel-28 human tumor cell lines. A GC/MS analysis shows the essential oil to be composed of 2-heptanol, alpha-pinene, beta-pinene, limonene, cineole, and alpha-terpineol, alpha-Pinene, beta-pinene, and limonene account for the cytotoxic activity of the leaf essential oil of Myrcianthes sp. nov. "black fruit".

Cyclic hemiacetals with seven-membered rings from an undescribed SalaciaSpecies from monteverde, costa rica

The two cyclic hemiacetals of 30-hydroxyfriedelan-3-on-28-al (1R and 1S) were found in an undescribed Salacia species from Costa Rica and characterized by spectral methods.

Lupeol is the cytotoxic principle in the leaf extract of Dendropanax cf. querceti

The crude ethanol extract from the leaves of Dendropanax cf. querceti (Araliaceae) from Monteverde, Costa Rica, exhibits cytotoxic activity against Hep-G2, A-431, and H-4IIE tumor cell lines. The active component has been isolated by activity-directed separation and identified by 1H- and 13C-NMR spectroscopy as the triterpene lupeol. The mechanism of cytotoxic activity of lupeol has been determined to be inhibition of topoisomerase II.

A cytotoxic diacetylene from Dendropanax arboreus

The crude ethanol extract from the leaves of Dendropanax arboreus (Araliaceae) from Monteverde, Costa Rica, exhibits cytotoxic activity against Hep-G2, A-431, H-4IIE, and L-1210 tumor cell lines, but is not toxic against normal hepatocytes. The active component has been isolated by activity-directed separation and identified by 1H- and 13C-NMR spectroscopy as the acetylenic compound cis-1,9,16-heptadecatriene-4,6-diyne-3,8-diol.

An antibacterial vitamin E derivative from Tovomitopsis psychotriifolia

The crude ethanol extract from the leaves of Tovomitopsis psychotriifolia (Clusiaceae) exhibits antibacterial activity against Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa. The biologically active agent in the extract has been isolated by chromatographic techniques and identified by NMR spectroscopy as trans-delta-tocotrienoloic acid.