Antimicrobial Properties of Compounds Isolated from Syzygium malaccense (L.) Merr. and L.M. Perry and Medicinal Plants Used in French Polynesia.

A preliminary ethnopharmacological survey, achieved in French Polynesia, led to the collection of the most cited plants among 63 species used to treat "infectious" diseases, with a description of their medicinal uses. Bibliographical investigations and antimicrobial screening permitted the selection of the botanical species Syzygium malaccense (Myrtaceae) for phytochemical analysis. Leaves of Syzygium malaccense were usually used in mixture with rhizomes of Curcuma longa to treat infectious diseases such as cystitis. The methanolic plant extracts were tested in vitro with an agar microdilution method on 33 bacteria strains and 1 yeast to obtain their Minimal Inhibitory Concentration (MIC), and cytotoxicity against HepG2 cells were evaluated. Antimicrobial synergistic effects of methanolic plant extracts from leaves of Syzygium malaccense and rhizomes from Curcuma longa were also evaluated. The bio-guided isolation of leaf extract from Syzygium malaccense led to the identification of seven alkyl-salicylic acids (anacardic acids or ginkgolic acids C15:0, C15:1, C17:0, C17:1, C17:2, C17:3 and C19:1) described for the first time in this species. All compounds were tested against Staphylococcus aureus (18.75 < MIC < 75.0 µg/mL), Streptococcus pyogenes (2.34 < MIC < 18.75 µg/mL) and Pseudomonas aeruginosa (MIC = 150 µg/mL), and their structure−activity relationships were discussed. The methanolic extract and salicylic derivatives from S. malaccense showed an interesting antimicrobial activity against Gram+ bacteria, without toxicity on hepG2 cells at 400 µg/mL. Moreover, these antibacterial compounds have already been studied for their anti-inflammatory activity, which supports the therapeutic interest of S. malaccense against infectious diseases.

Anti-HCV Tannins From Plants Traditionally Used in West Africa and Extracted With Green Solvents.

Millions of people are still infected with hepatitis C virus (HCV) nowadays. Although recent antivirals targeting HCV proteins are very efficient, they are not affordable for many people infected with this virus. Therefore, new and more accessible treatments are needed. Several Ivorian medicinal plants are traditionally used to treat "yellow malaria", a nosological category including illness characterized by symptomatic jaundice such as hepatitis. Therefore, some of these plants might be active against HCV. An ethnobotanical survey in Côte d'Ivoire allowed us to select such medicinal plants. Those were first extracted with methanol and tested for their anti-HCV activity. The most active ones were further studied to specify their IC50 and to evaluate their toxicity in vitro. Greener solvents were tested to obtain extracts with similar activities. Following a phytochemical screening, tannins of the most active plants were removed before re-testing on HCV. Some of these tannins were identified by UPLC-MS and pure molecules were tested against HCV. Out of the fifteen Ivorian medicinal plants selected for their putative antiviral activities, Carapa procera DC. and Pericopsis laxiflora (Benth. ex Baker) Meeuwen were the most active against HCV (IC50: 0.71 and 0.23 µg/ml respectively) and not toxic for hepatic cells. Their crude extracts were rich in polyphenols, including tannins such as procyanidins A2 which is active against HCV. The same extracts without tannin lost their anti-HCV activity. Replacing methanol by hydro-ethanolic solvent led to tannins-rich extracts with similar antiviral activities, and higher than that of aqueous extracts.

Viral hepatitis in the Peruvian Amazon: Ethnomedical context and phytomedical resource.

ETHNOPHARMACOLOGICAL RELEVANCE: An extensive ethnopharmacological survey was carried out in the Peruvian Amazonian district of Loreto with informants of various cultural origins from the surroundings of Iquitos (capital city of Loreto) and from 15 isolated riverine Quechua communities of the Pastaza River. A close attention was paid to the medical context and plant therapy, leading to the selection of 35 plant species (45 extracts). The extracts were tested for antiviral activity against HCV with counting of Huh-7 cellular death in case of toxicity, and cytotoxicity was evaluated in HepG2 cells. AIM OF THE STUDY: The aim of the study was to inventory the plants used against hepatitis in Loreto, then to evaluate their antiviral activity and to suggest a way to improve local therapeutic strategy against viral hepatitis, which is a fatal disease that is still increasing in this area. MATERIALS AND METHODS: An ethnographic survey was carried out using "participant-observation" methodology and focusing on plant therapy against hepatitis including associated remedies. 45 parts of plant were extracted with methanol and tested in vitro for anti-HCV activity in 96-well plate, using HCV cell culture system with immunofluorescent detection assisted by automated confocal microscopy. Toxicity of plant extracts was also evaluated in microplates on hepatic cells by immunofluorescent detection, for the Huh-7 nuclei viability, and by UV-absorbance measurement of MTT formazan for cytotoxicity in HepG2 cells. RESULTS: In vitro assay revealed interesting activity of 18 extracts (50% infection inhibition at 25 µg/mL) with low cytotoxicity for 15 of them. Result analysis showed that at least 30% of HCV virus were inhibited at 25 µg/mL for 60% of the plant extracts. Moreover, the ethnomedical survey showed that remedies used with low and accurate dosing as targeted therapy against hepatitis are usually more active than species indicated with more flexible dosing to alleviate symptoms of hepatic diseases. CONCLUSION: Together with bibliographic data analysis, this study supported the traditional medicinal uses of many plants and contributed to a better understanding of the local medical system. It also permitted to refine the therapeutic plant indications regarding patients' liver injuries and vulnerability. Only 2 of the 15 most active plant species have already been studied for antiviral activity against hepatitis suggesting new avenues to be followed for the 13 other species.

Antimicrobial and Light-Enhanced Antimicrobial Activities, Cytotoxicity and Chemical Variability of All Tunisian Eryngium Species.

This study was performed on all Eryngium species growing in Tunisia in order to evaluate their intra and interspecies variabilities and to investigate their biological activities. These species are used in traditional medicine, and literature about the phytochemical investigations of most of them is scarce. Antimicrobial and light-enhanced activities were tested against multiresistant microorganisms and extended spectrum beta-lactamase producing bacteria (ESBL). All studied species showed antimicrobial effect with several MIC values lower than 70 µg/ml. Tested Eryngium species have proven to be a promising source of photoactive compounds, while light-enhanced activity offers an alternative for the inactivation of pathogenic microorganisms which is currently subjected to a great interest. This is the first report of this activity in genus Eryngium. A significant improvement of antimicrobial activity with UV irradiation was observed, mainly for E. dichotomum, E. ilicifolium and E. triquetrum. Cytotoxicity, studied for the first time for the most species, was evaluated against cancer (J774) and non-cancer (WI38) human cell lines. Chemical composition of volatile compounds presented in the most active crude extracts (petroleum ether extracts) of the aerial parts was investigated using GC/MS analysis and was submitted to statistical analyses. It revealed their high content of bioactive phytochemicals, particularly oxygenated sesquiterpenes like spathulenol, ledol and α-bisabolol but also hydrocarbon sesquiterpenes such as ß-bisabolene and copaene, as well as polyacetylene derivatives such as falcarinol. Statistical analyses permitted to evaluate the interrelations between all Tunisian Eryngium species.

Plant therapy in the Peruvian Amazon (Loreto) in case of infectious diseases and its antimicrobial evaluation.

ETHNOPHARMACOLOGICAL RELEVANCE: The plant species reported here are used in contemporary phytotherapies by native and neo-urban societies from the Iquitenian surroundings (district of Loreto, Peruvian Amazon) for ailments related to microbial infections. Inhabitants of various ethnic origins were interviewed and 81 selected extracts were evaluated for their antimicrobial properties against a panel of 36 sensitive and multi-resistant bacteria or yeast. Medicinal plant researches in the Peruvian Amazon are now significant, but none of them has focused on an exhaustive listing of identified species tested on so many microbes with standardized experiments (to obtain MIC value). AIM OF THE STUDY: The aim of the study was to inventory the plants used against infections in the Loreto, an Amazonian region of Peru. It led to the new identification of secondary metabolites in two plant species. MATERIALS AND METHODS: Ethnographic survey was carried out using "participant-observation" methodology and focus on bioprospecting of antimicrobial remedies. Selected plant extracts and antimicrobial drugs were tested in vitro with agar dilution method on 35 bacteria strains and 1 yeast to evaluate their Minimal Inhibitory Concentration (MIC). Microdilution methods using 96-well microtiter plates were used for the determination of MIC from isolated compounds, and cytotoxicity in HepG2 cells from some selected extracts were also evaluated. Activity-guided isolation and identification of compounds were performed by various chromatographic methods and structural elucidations were established using HRMS and NMR spectroscopy. RESULTS: This study outlined antimicrobial activities of 59 plant species from 33 families (72 single plant extracts and 2 fermented preparations), 7 mixtures, and one insect nest extract against 36 microorganisms. Of the 59 species analysed, 12 plants showed relevant antibacterial activity with MIC ≤0.15 mg/mL for one or several of the 36 micro-organisms (Aspidosperma excelsum, Brosimum acutifolium, Copaifera paupera, Erythrina amazonica, Hura crepitans, Myrciaria dubia, Ocotea aciphylla, Persea americana, Spondias mombin, Swartzia polyphylla, Virola pavonis, Vismia macrophylla). Examination by bioautography of E. amazonica, M. dubia and O. aciphylla extracts allowed the phytochemical characterization of antimicrobial fractions and compounds. CONCLUSION: This study suggested an a posteriori correlation of the plant extract antimicrobial activity with the chemosensory cues of the drugs and attested that those chemosensory cues may be correlated with the presence of antimicrobial compounds (alkaloids, tannins, saponosids, essential oil, oleoresin …). It also led to the first isolation and identification of three secondary metabolites from E. amazonica and M. dubia.

Phenolic Compounds from Humulus lupulus as Natural Antimicrobial Products: New Weapons in the Fight against Methicillin Resistant Staphylococcus aureus, Leishmania mexicana and Trypanosoma brucei Strains.

New anti-infective agents are urgently needed to fight microbial resistance. Methicillin-resistant Staphylococcus aureus (MRSA) strains are particularly responsible for complicated pathologies that are difficult to treat due to their virulence and the formation of persistent biofilms forming a complex protecting shell. Parasitic infections caused by Trypanosoma brucei and Leishmania mexicana are also of global concern, because of the mortality due to the low number of safe and effective treatments. Female inflorescences of hop produce specialized metabolites known for their antimicrobial effects but underexploited to fight against drug-resistant microorganisms. In this study, we assessed the antimicrobial potential of phenolic compounds against MRSA clinical isolates, T. brucei and L. mexicana. By fractionation process, we purified the major prenylated chalcones and acylphloroglucinols, which were quantified by UHPLC-UV in different plant parts, showing their higher content in the active flowers extract. Their potent antibacterial action (MIC < 1 µg/mL for the most active compound) was demonstrated against MRSA strains, through kill curves, post-antibiotic effects, anti-biofilm assays and synergy studies with antibiotics. An antiparasitic activity was also shown for some purified compounds, particularly on T. brucei (IC50 < 1 to 11 µg/mL). Their cytotoxic activity was assessed both on cancer and non-cancer human cell lines.

Neoboutonia melleri var velutina Prain: in vitro and in vivo hepatoprotective effects of the aqueous stem bark extract on acute hepatitis models.

BACKGROUND: Hepatitis is a liver inflammation caused by different agents and remains a public health problem worldwide. Medicinal plants are an important source of new molecules being considered for treatment of this disease. Our work aims at evaluating the hepatoprotective properties of Neoboutonia velutina, a Cameroonian medicinal plant. METHODS: The aqueous extract has been prepared using phytochemical methods. HepG2 cells were used to assess anti-inflammatory properties of the extract at different concentrations. Acute hepatitis models (Carbon tetrachloride and Concanavalin A) were performed in mice receiving or not receiving, different extract doses by gavage. Liver injury was assessed using histology, transaminases and pro-inflammatory markers. Extract antioxidant and radical scavenging capacities were evaluated. RESULTS: The extract led to a significant decrease in pro-inflammatory cytokine expression in vitro and to a remarkable protection of mice from carbon tetrachloride-induced liver injury, as shown by a significant decrease in dose-dependent transaminases level. Upon extract treatment, inflammatory markers were significantly decreased and liver injuries were limited as well. In the Concanavalin A model, the extract displayed weak effects. CONCLUSIONS: Taking into account underlying mechanisms in both hepatitis models, we demonstrate the extract's radical scavenging capacity. Neoboutonia velutina displays a potent hepatoprotective effect mediated through radical scavenging properties.

Antiproliferative and Antibacterial Activities of Cirsium scabrum from Tunisia.

Several Cirsium species are known for their uses in traditional medicine and consequently are studied for their phytochemical content and their biological activities. In the framework of a previous study conducted on eight extremophile plants from Tunisia, we highlighted that the crude methanolic extract of C. scabrum, a not investigated thistle, showed moderate but quite selective cytotoxic activity against the cancerous cell line J774 compared to the noncancerous cell line WI38 (IC50 = 11.53 µg/ml on J774, IC50 = 29.89 µg/ml on WI38, and selectivity index = 2.6). In the current study, the partitions of the leaves of C. scabrum were analyzed for their antiproliferative activity on the same cell lines. From the most active petroleum ether partition, we isolated four triterpenoids including lupeol, taraxasterol acetate, and a (1 : 1) mixture of 25-hydroperoxycycloart-23-en-3ß-ol and 24-hydroperoxycycloart-25-en-3ß-ol. These two cycloartane-type triterpenoids are mostly responsible for this cytotoxic activity. On the other hand, the antimicrobial potential of this plant was also evaluated against 36 microorganisms. The moderate antibacterial activity against 6 Staphylococcus aureus and 2 Dermabacter hominis strains is mainly attributed to the butanol partition whose major compounds are glycosides of flavones.

An ecological approach to discover new bioactive extracts and products: the case of extremophile plants.

OBJECTIVES: Eight extremophile plants from Tunisia were screened to find natural products with benefits in human health. METHODS: These plants were collected in different areas in Tunisia. Their methanolic extracts were evaluated for their total phenolic content and for their antiradical (DPPH), antimicrobial (on 35 bacteria and one yeast), antiviral (hepatitis C virus, HCV) and cytotoxic activity (against WI38 and J774 cell lines). The most active species were subjected to a bioguided fractionation. KEY FINDINGS: The screening revealed promising activity for four plants, but two species have both antiradical and antimicrobial activity: Juncus maritimus and Limonium virgatum. The rhizomes extract of J. maritimus showed the highest activity against HCV, a selective antibacterial activity against Streptococcus dysgalactiae, and a moderate antiradical activity which is due to luteolin isolated in one step by centrifugal partition chromatography. The stems' and leaves' extracts of L. virgatum were rich in polyphenols responsible for the antiradical activity. Also, Limonium extracts showed an antibacterial activity with a broad spectrum. CONCLUSIONS: Extremophile plants have proven to be a promising source for bioactive metabolites. They have a powerful antioxidant system highly influenced by biotic and abiotic factors and the ability to produce secondary metabolites with antimicrobial activity.

Chemical Composition and Antimicrobial Activity of the Essential Oil from Aerial Parts and Roots of Eryngium barrelieri Boiss. and Eryngium glomeratum Lam. from Tunisia.

The study of chemical composition and biological activity of unexplored essential oils may open new perspectives on their potential use in facing major health concerns such as drug-resistant infections. The present study investigates the chemical composition and antimicrobial effects of previously unstudied essential oils obtained from genus Eryngium: Eryngium glomeratum Lam. and Eryngium barrelieri Boiss. The chemical compositions of the essential oils from aerial parts and roots of both species were studied using GC and GC/MS analytical technics. The analysis led to the identification of 102 compounds totalizing 85 - 94% of all detected compounds. Essential oils were characterized by the predominance of oxygenated sesquiterpenes. The oils obtained from aerial parts were tested against 36 microbial strains by agar dilution method and showed minimum inhibitory concentrations (MIC) in the range of 2 - 625 µg/ml. A strong antibacterial activity against multiresistant Pseudomonas aeruginosa was observed especially from E. glomeratum essential oil with MIC value up to 2 µg/ml. These findings give significant information about the pharmacological activity of these essential oils, which suggest their potential use to develop new remedies, or as sources of active compounds.

Antimicrobial prenylated benzoylphloroglucinol derivatives and xanthones from the leaves of Garcinia goudotiana.

Bioassay-guided fractionation using antimicrobial assay of the crude acetonic extract of Garcinia goudotiana leaves and of its five partitions led to the isolation of two new prenylated benzoylphloroglucinol derivatives, goudotianone 1 (1) and goudotianone 2 (2), in addition to two known compounds including one xanthone, 1,3,7-trihydroxy-2-isoprenylxanthone (3), and one triterpenoid, friedelin (4). Their structures were elucidated on the basis of different spectroscopic methods, including extensive 1D- and 2D-NMR spectroscopy and mass spectrometry. The crude acetonic extract, the methylene chloride and ethyl acetate partitions, and some tested compounds isolated from this species (1-3) demonstrated selective significant antimicrobial activities against Gram-positive bacteria, in particular Staphylococcus lugdunensis, Enterococcus faecalis and Mycobacterium smegmatis. The potential cytotoxic activities of these extracts and compounds were evaluated against human colon carcinoma HT29 and human fetal lung fibroblast MRC5 cells.

Antifungal and cytotoxic activity of withanolides from Acnistus arborescens.

Three compounds were isolated from Acnistus arborescens, a tree commonly used in South and Central America in traditional medicine against several infectious diseases, some of which are caused by fungi. Bioassay-guided fractionation of a MeOH extract of leaves, based on its anti-Pneumocystis carinii activity, led to the isolation of compounds 1-3. Mono- and bidimensional NMR analyses enabled identification of two new withanolides, (20R,22R)-5beta,6beta-epoxy-4beta,12beta,20-trihydroxy-1-oxowith-2-en-24-enolide (1) and (20R,22R)-16beta-acetoxy-3beta,4beta;5beta,6beta-diepoxy-12beta,20-dihydroxy-1-oxowith-24-enolide (2), and withanolide D (3). Antifungal activity on 13 fungi responsible for human infections (five dermatophytes, one nondermatophyte mold, six yeasts, and Pneumocystis carinii) was examined. Cytotoxicity of these compounds was also evaluated in vitro.

Humulane and germacrane sesquiterpenes from Ferula lycia.

Five new juniferol esters (1-5), along with six known humulane derivatives (6-11), were isolated from the roots of Ferula lycia, an endemic Turkish species. The fruits of the same species were also investigated and led to the isolation of these same compounds, as well as two known germacrane esters (12 and 13). All isolated sesquiterpenes were assayed for cytotoxicity against two tyrosine kinase inhibitor-resistant cell lines, K562R and DA1-3b/M2(BCR-ABL). The two most active compounds, juniferinin (7) and 6-beta-p-hydroxybenzoyloxygermacra-1(10),4-diene (12), were moderately active against Raji lymphoma cells but also displayed some toxicity against healthy bone marrow cells.

Activity of ladanein on leukemia cell lines and its occurrence in Marrubium vulgare.

Three methoxylated flavones isolated from Marrubium peregrinum - ladanein, scutellarein-5,7,4'-trimethyl ether, and scutellarein-5,6,7,4'-tetramethyl ether - were assayed for their cytotoxicity towards a recently developed dasatinib-resistant murine leukemia cell line (DA1-3b/M2 (BCR-ABL)), together with the structurally related non-methylated flavone scutellarein. The most active compound, ladanein, was looked for in 20 common Lamiaceae species by a quick HPLC screening. Among the possible positive results, the most interesting source was found to be Marrubium vulgare, which led to the isolation and identification of ladanein for the first time in this species. Ladanein also displayed moderate (20-40 microM) activities against K562, K562R (imatinib-resistant), and 697 human leukemia cell lines but was toxic neither to MOLM13 nor to human peripheral blood mononuclear cells. This work provides a common natural source for the hemi-synthesis of future ladanein-derived flavones and the study of their antileukemic activity.

Isolation and antimalarial activity of alkaloids from Pseudoxandra cuspidata.

A novel and very unusual azaanthracene alkaloid, 1-aza-7,8,9,10-tetramethoxy-4-methyl-2-oxo-1,2-dihydroanthracene ( 1) and a new diastereoisomer of the bis-benzylisoquinoline alkaloid rodiasine, 1 S,1' R-rodiasine ( 2), as well as the alkaloids O-methylpunjabine ( 3) and O-methylmoschatoline ( 4) have been isolated from Pseudoxandra cuspidata bark, used in French Guiana as an antimalarial. Their structures were elucidated by spectroscopic analyses, especially 2D-NMR techniques (ADEQUATE and NOESY). We found that the antimalarial activity of this bark was mostly due to bis-benzylisoquinoline 1 S,1' R-rodiasine ( 2) (IC (50)= 1 microM) also displaying a low cytotoxicity.

Tannins and catechin gallate mediate the vasorelaxant effect of Arbutus unedo on the rat isolated aorta.

This study examined the vascular effect of Arbutus leaves (aqueous extract) and described the isolation of several fractions responsible for their vasorelaxant activity. The aqueous extract (AE) of leaves was tested on rat aortic rings precontracted with 0.1 microm noradrenaline. At 10(-2) g/L, AE produced an endothelium dependent relaxation of 66% +/- 5%, (n = 8). The leaves of Arbutus were then extracted successively with different solvents and the methanol extract was the most active. When tannins (primarily condensed tannins) were precipitated from the methanol extract, they showed a strong vasorelaxant activity (87% +/- 4%, n = 5), whereas the elimination of tannins in the methanol extract reduced significantly its vasorelaxant activity (42% +/- 8%, n = 8, p < 0.005). The methanol extract was further separated semi-preparatively by reversed-phase HPLC. Four fractions (Fr2, Fr3, Fr4 and Fr6) were the most active and produced 88% +/- 2% (n = 5), 75% +/- 6% (n = 5), 76% +/- 3% (n = 7) and 77% +/- 3% (n = 10) relaxation, respectively. These four fractions mainly correspond to polyphenol compounds. Analysis of Fr6 indicated that this fraction contained catechin gallate. In conclusion, the vasorelaxant activity of Arbutus is likely to be due to polyphenol compounds, primarily condensed tannins and catechin gallate.