Iridoids from Canthium subcordatum iso-butanol fraction with potent biological activities.

BACKGROUND: The continuous emergence of multi-drug-resistant bacteria drastically reduces the efficacy of antibiotic armory and, consequently, increases the frequency of therapeutic failure. The discovery of new antibacterial drugs is an urgent need. The present study reports the antibacterial and antioxidant activities of the methanol extract, fractions and iridoids from Canthium subcordatum, a plant traditionally used as antidiabetic, anti-inflammatory, and antimicrobial. METHODS: Broth microdilution assay was used to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of extracts and iridoids against Staphylococcus aureus, Vibrio cholerae and Shigella flexneri. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays. The samples were also tested for their cytotoxicity against human red blood cells (RBC). RESULTS: The methanol extract, hexane, ethyl acetate and iso-butanol fractions from C. subcordatum fruits displayed different degrees of antioxidant (EC50 = 62.83-70.17 µg/ml; GAEAC = 45.63-58.23 µg/ml) and antibacterial (MIC = 128-512 µg/ml) activities. Canthiumoside 1(1) and linearin (7) were the most active antioxidant (EC50 = 1.12-2.03 µg/ml; GAEAC = 79.82-92.35 µg/ml) and antibacterial (MIC = 8-64 µg/ml) compounds while the most sensitive bacterium was Staphylococcus aureus. The tested samples were non-toxic to normal cells. CONCLUSION: Our results demonstrated that compounds 1 and 7 were potent antibacterial agents and DPPH/ABTS·+ radical scavengers, so they warrant further investigation.

GC/MS profiling, in vitro anti-leptospiral and haemolytic activities of Boesenbergia rotunda (L.) Mansf. used as a medicinal plant by Nicobarese of Andaman and Nicobar Islands.

Leaves of the plant Boesenbergia rotunda are used by the Nicobarese tribe of Andaman and Nicobar Islands, India, to prepare traditional medicine for treating fever, headache and body ache. In the present investigation, methanol fraction of these leaves were analysed by GC/MS that revealed the presence of 25 compounds. The anti-leptospiral activity of methanol crude extract was determined by both microdilution and macrodilution methods. The MICs of the extract were tested against 24 pathogenic leptospiral strains and ranged between 62.5-125 µg/mL in both microdilution and macrodilution. The range of MBCs was 250 and 500 µg/mL in macrodilution and microdilution respectively. The crude extract was subjected to cytotoxic studies and found to have negligible or no haemolytic activity, exhibiting IC50 values of greater than 4 mg/mL. Further in vivo studies are needed to investigate the pharmacological and toxicological properties of Boesenbergia rotunda, before it can be considered as a new anti-leptospiral agent.

Biological activities of organic extracts of four Aureobasidium pullulans varieties isolated from extreme marine and terrestrial habitats.

We report on the screening for biological activities of organic extracts from seven strains that represent four varieties of the fungus Aureobasidium pullulans, that is A. pullulans var. melanogenum, A. pullulans var. pullulans, A. pullulans var. subglaciale and A. pullulans var. namibiae. We monitored haemolysis, cytotoxicity, antioxidant capacity and growth inhibition against three bacterial species. The haemolytic activity of A. pullulans var. pullulans EXF-150 strain was due to five different haemolytically active fractions. Extracts from all of the other varieties contained at least one haemolytically active fraction. Short-term exposure of cell lines to these haemolytically active organic extracts resulted in more than 95% cytotoxicity. Strong antioxidant capacity, corresponding to 163.88 µg ascorbic acid equivalent per gram of total solid, was measured in the organic extract of the strain EXF-3382, obtained from A. pullulans var. melanogenum, isolated from the deep sea. Organic extracts from selected varieties of A. pullulans exhibited weak antibacterial activities.

Characterization of the venom from the Australian scorpion Urodacus yaschenkoi: Molecular mass analysis of components, cDNA sequences and peptides with antimicrobial activity.

The Urodacidae scorpions are the most widely distributed of the four families in Australia and represent half of the species in the continent, yet their venoms remain largely unstudied. This communication reports the first results of a proteome analysis of the venom of the scorpion Urodacus yaschenkoi performed by mass fingerprinting, after high performance liquid chromatography (HPLC) separation. A total of 74 fractions were obtained by HPLC separation allowing the identification of approximately 274 different molecular masses with molecular weights varying from 287 to 43,437 Da. The most abundant peptides were those from 1 K Da and 4-5 K Da representing antimicrobial peptides and putative potassium channel toxins, respectively. Three such peptides were chemically synthesized and tested against Gram-positive and Gram-negative bacteria showing minimum inhibitory concentration in the low micromolar range, but with moderate hemolytic activity. It also reports a transcriptome analysis of the venom glands of the same scorpion species, undertaken by constructing a cDNA library and conducting random sequencing screening of the transcripts. From the resultant cDNA library 172 expressed sequence tags (ESTs) were analyzed. These transcripts were further clustered into 120 unique sequences (23 contigs and 97 singlets). The identified putative proteins can be assorted in several groups, such as those implicated in common cellular processes, putative neurotoxins and antimicrobial peptides. The scorpion U. yaschenkoi is not known to be dangerous to humans and its venom contains peptides similar to those of Opisthacanthus cayaporum (antibacterial), Scorpio maurus palmatus (maurocalcin), Opistophthalmus carinatus (opistoporines) and Hadrurus gerstchi (scorpine-like molecules), amongst others.

Triterpene glycosides from the sea cucumber Eupentacta fraudatrix. Structure and biological action of cucumariosides A1, A3, A4, A5, A6, A12 and A15, seven new minor non-sulfated tetraosides and unprecedented 25-keto, 27-norholostane aglycone.

Seven new minor triterpene glycosides, cucumariosides A1 (1), A3 (2), A4 (3), A5 (4), A6 (5), A12 (6) and A15 (7) have been isolated from the Far Eastern sea cucumber Eupentacta fraudatrix. Structures of the glycosides were elucidated by 2D NMR spectroscopy and MS. Glycosides 1-7 belong to the group of cucumariosides A, having linear tetrasaccharide carbohydrate moieties without any sulfate group and possessing 3-O-methyl-D-xylose as a terminal monosaccharide unit. The latter peculiarity is rare in sea cucumber glycosides, but typical for the glycosides from E. fraudatrix. Glycosides 1-7 differ from each other by side chain structures in the aglycone moieties; three of them have unique structural features. The first is the presence of a 25-butoxy-group in the side chain of cucumarioside A3 (2), the second is a 23E,25-diene system in cucumarioside A6 (5) and the third is a 25-keto-27-nor-holostane aglycone in cucumarioside A12 (6); these were never previously found in sea cucumber glycosides. Cytotoxic activity of glycosides 1-7 against mouse spleen lymphocytes and the cells of the ascite form of mouse Ehrlich carcinoma, along with hemolytic activity against mouse erythrocytes and antifungal activity were studied. Glycosides 1 and 5 were the most active in all the tests.

A new steroidal saponin with antiinflammatory and antiulcerogenic properties from the bulbs of Allium ampeloprasum var. porrum.

A new steroidal saponin was isolated from the bulbs of Allium ampeloprasum var. porrumL. On the basis of chemical evidence, comprehensive spectroscopic analyses and comparison of known compounds, its structure was established as (3ß,5α,6ß,25R)-6-[(ß-D-glucopyranosyl)oxy]-spirostan-3-yl O-ß-D-glucopyranosyl-(1→2)-O-[ß-D-glucopyranosyl-(1→3)]-ß-D-galactopyranoside. Results of the present study indicated that the steroidal saponin showed haemolytic effects in the in vitro assays and demonstrated antiinflammatory activity and gastroprotective property using in vivo models.

Antifungal activity of lariciresinol derived from Sambucus williamsii and their membrane-active mechanisms in Candida albicans.

Lariciresinol is an enterolignan precursor isolated from the herb Sambucus williamsii, a folk medicinal plant used for its therapeutic properties. In this study, the antifungal properties and mode of action of lariciresinol were investigated. Lariciresinol displays potent antifungal properties against several human pathogenic fungal strains without hemolytic effects on human erythrocytes. To understand the antifungal mechanism of action of lariciresinol, the membrane interactions of lariciresinol were examined. Fluorescence analysis using the membrane probe 3,3'-diethylthio-dicarbocyanine iodide (DiSC(3)-5) and 1,6-diphenyl-1,3,5-hexatriene (DPH), as well as a flow cytometric analysis with propidium iodide (PI), a membrane-impermeable dye, indicated that lariciresinol was associated with lipid bilayers and induced membrane permeabilization. Therefore, the present study suggests that lariciresinol possesses fungicidal activities by disrupting the fungal plasma membrane and therapeutic potential as a novel antifungal agent for the treatment of fungal infectious diseases in humans.

Free radical scavenging, cytotoxic, and hemolytic activities of an active antioxidant compound ethyl gallate from leaves of Acacia nilotica (L.) Wild. Ex. Delile subsp. indica (Benth.) Brenan.

UNLABELLED: In the present study, free radical scavenging, cytotoxic, and hemolytic activities of the polyphenolic compound ethyl gallate isolated from ethanol extract of Acacia nilotica Wild. Ex. Del. leaves were determined. The free radical-scavenging activities of the ethyl gallate were demonstrated in several in vitro assays in order to evaluate the possible antioxidant mechanism. The results revealed ethyl gallate as hydrogen donor, metal chelator, and free radical scavenger. Ethyl gallate was effective in scavenging 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radicals and the IC50 value was lower than all the positive controls used in this study. Deoxyribose degradation assay revealed that ethyl gallate had more iron-chelating ability than the direct hydroxyl radical-scavenging ability. The results of the cytotoxic study revealed that the compound was moderately active and IC50 value was found to be >100 µg/mL for Vero cell lines and 72 µg/mL for Hela cell lines. The compound possessed no hemolytic activity against rat and human erythrocytes revealing its cytotoxic mechanism and nontoxicity. The results from this work will provide an important information for the food and pharmacological industries with respect to the use of the compound as an antioxidant and a health-related drug. PRACTICAL APPLICATION: Antioxidant from plant sources is safe to use, as compared to synthetic products. It also can be used as a supplement to alleviate most of the diseases because of its free radical-scavenging activity.

Chemical constituents and biological applications of the genus Symplocos.

The genus Symplocos has been reviewed for its chemical constituents and biological activities including traditional importance of some common species. The plants of this genus contain terpenoids, flavonoids, lignans, phenols, steroids, alkaloids, and iridoids. Terpenoids are the major constituents within the genus Symplocos and most of them exhibit antiproliferative effects. Some phenolic glycoside derivatives showed inhibitory activity against snake-venom phosphodiesterase I and human nucleotide pyrophosphatase phosphodiesterase I. The members of genus Symplocos are well known for their traditional uses in the treatment of various diseases like leprosy, gynecological disorders, ulcers, leucorrhea, menorrhagia, malaria, and tumefaction. The aim of the present paper is to review the comprehensive knowledge of the plants of this genus including the traditional uses, chemistry, and pharmacology.

Cytotoxic diterpenoids from Croton argyrophylloides.

Two new diterpenes, 1 and 2, together with the known ent-15-oxo-kaur-16-en-18-oic acid (3), were isolated from the bark of Croton argyrophylloides. The structural characterization of 1 and 2 was determined on the basis of spectroscopic data interpretation. The cytotoxicity of each compound was evaluated against HL-60 (leukemia), MDAMB-435 (melanoma), SF-295 (glioblastoma), and HCT-8 (colon carcinoma) human tumor cell lines and against human peripheral blood mononuclear cells. The hemolytic potential in mouse erythrocytes was also tested for 1-3.