Antimicrobial activity of Buchenavia tetraphylla against Candida albicans strains isolated from vaginal secretions

Context: Buchenavia tetraphylla (Aubl.) RA Howard (Combretaceae: Combretoideae) is an ethnomedicinal plant with reported antifungal action.

Objective: This study evaluates the antimicrobial activity of B. tetraphylla leaf extracts against clinical isolates of Candida albicans. The morphological alterations, combinatory effects with fluconazole and the cytotoxicity of the active extract were analyzed.

Materials and methods: Extracts were obtained using different solvents (hexane: BTHE; chloroform: BTCE; ethyl acetate: BTEE; and methanol: BTME). Antimicrobial activity was determined by the broth microdilution method using nine strains of C. albicans isolated from vaginal secretions and one standard strain (UFPEDA 1007).

Results: All extracts showed anti-C. albicans activity, including against the azole-resistant strains. The MIC values ranged from 156 to 2500?μg/mL for the BTHE; 156 to 1250?μg/mL for the BTCE; 625 to 1250?μg/mL for the BTME and 625?μg/mL to 2500?μg/mL for the BTEE. BTME showed the best anti-C. albicans activity. This extract demonstrated additive/synergistic interactions with fluconazole. Scanning electron microscopy analysis suggested that the BTME interferes with the cell division and development of C. albicans. BTME showed IC₅₀ values of 981 and 3935?μg/mL, against J774 macrophages and human erythrocytes, respectively. This extract also enhanced the production of nitric oxide by J774 macrophages.

Discussion and conclusion: Buchenavia tetraphylla methanolic extract (BTME) is a great source of antimicrobial compounds that are able to enhance the action of fluconazole against different C. albicans strains; this action seems related to inhibition of cell division.     

Antimicrobial,modulatory and chemical analysis of the oil of Croton limae

Context: Croton sp. are plants with a well-reported antimicrobial activity. Croton limae A.P. Gomes, M.F. Sales P.E. Berry (Euphorbiaceae), known as ‘marmeleiro-prateado’, is commonly used to manage abdominal pain in Brazil.

Objective: This work evaluates the phytochemical composition, antimicrobial and modulatory activities of the essential oil of C. limae leaves (EOCL).

Materials and methods: The minimum inhibitory concentration (MIC) and the modulation of the antibiotic activity were determined using a microdilution method. The concentration of EOCL ranged between 512 and 8?μg/mL. Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Candida tropicalis, C. krusei and C. albicans strains were used in the MIC and modulation assays. The antibiotics, amikacin, gentamicin and neomycin, and the antifungals, amphotericin B, benzoylmetronidazole and nystatin, were used in concentrations ranging between 2500 and 2.5?μg/mL. The phytochemical analysis of the EOCL was performed through gas chromatography coupled to a mass spectrometer (GC/MS).

Results: Only Staphylococcus aureus was inhibited by a clinically relevant concentration of EOCL (MIC 512?μg/mL). Synergism between the EOCL and amikacin against S. aureus (9.76?μg/mL) and E. coli (39.062?μg/mL); neomycin against E. coli (2.44?μg/mL); and benzoylmetronidazole against C. krusei (256?μg/mL) were observed. The GC/MS analysis identified cedrol, eucalyptol and α-pinene as the main compounds of EOCL.

Conclusion: EOCL inhibited the growth of S. aureus and potentiated the antibiotic and antifungal effects of drugs against all bacterial and Candida strains, respectively.     

In vitro antimicrobial and anti-proliferative activities of plant extracts from Spathodea campanulata,Ficus bubu,and Carica papaya

Context African medicinal plants represent a prominent source of new active substances. In this context, three plants were selected for biological investigations based on their traditional uses.

Objective The antimicrobial and anti-proliferative features of three plants used for medicinal purpose were evaluated.

Materials and methods The antimicrobial activities of methanol extracts of Ficus bubu Warb. (Moraceae) stem bark and leaves, of Spathodea campanulata P. Beauv. (Bignoniaceae) flowers, as well as those of Carica papaya Linn. (Caricaceae) latex, were determined using the microbroth dilution method against a set of bacteria and fungi pathogens including: Enterococcus faecalis, Staphylococcus aureus, S. saprophyticus, S. epidermididis, Escherichia coli, Klebsiella pneumonia, Salmonella typhimurium, Candida albicans, and Trichophyton rubrum. The tested concentrations of extracts ranged from 2500.0 to 2.4?μg/mL and MIC values were evaluated after 24?h incubation at 37?°C. Subsequently, MTT assay was used to estimate anti-proliferative activity of these methanol extracts and of F. bubu latex on three human cancer cell lines (U373 glioblastoma, A549 NSCLC, and SKMEL-28 melanoma).

Results The methanol extract of F. bubu stem bark exhibited the highest antimicrobial activity against C. albicans with a MIC value of 9.8?μg/mL, while the F. bubu latex and the methanol extract of F. bubu leaves induced significant anti-proliferative activity against lung (IC₅₀ values of 10 and 14?μg/mL, respectively) and glioma (IC₅₀ values of 13 and 16?μg/mL, respectively) cancer cells.

Conclusion These results indicate that effective drugs could be derived from the three studied plants.     

Potential anti-inflammatory,antioxidant and antimicrobial activities of Sambucus australis

Context: Sambucus australis Cham. &; Schltdl. (Adoxaceae) is used in Brazilian folk medicine to treat inflammatory disorders.

Objective: To evaluate the in vitro anti-inflammatory, antioxidant and antimicrobial properties of S. australis.

Materials and methods: The anti-in?ammatory activity of ethanol extracts of the leaf and bark of S. australis (1–100?μg/mL) were studied in lipopolysaccharide/interferon γ stimulated murine macrophages RAW 264.7 cells (24?h incubation) by investigating the release of nitric oxide (NO) and tumour necrosis factor-alpha (TNF-α) and in the TNF-α-induced nuclear factor kappa (NF-κB) assay. Minimum inhibitory concentration (MIC) was determined by the microdilution test (24?h incubation). Antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and the NO scavenging assays. Chemical composition was assessed by LC-MS/MS.

Results: Antioxidant activities in the DPPH (IC₅₀ 43.5 and 66.2?μg/mL), FRAP (IC₅₀ 312.6 and 568.3?μg/mL) and NO radical scavenging assays (IC₅₀ 285.0 and 972.6?μg/mL) were observed in the leaf and bark ethanol extracts, respectively. Solely the leaf extract showed significant inhibition of NO and TNF-α production in RAW264.7 cells at concentrations of 2 and 100?μg/mL, respectively, and suppression of TNF-α inhibition of NF-κB by 12.8 and 20.4% at concentrations of 50 and 100?μg/mL, respectively. The extract also exhibited antibacterial activity against Salmonella typhimurium (MIC 250?μg/mL) and Klebsiella pneumoniae (MIC 250?μg/mL). LC-MS/MS revealed the presence of chlorogenic acid and rutin as major compounds.

Discussion and conclusion: The results indicate that the ethanol leaf extract of S. australis exhibit prominent anti-in?ammatory effects.     

Variation of alkaloid contents and antimicrobial activities of Papaver rhoeas L. growing in Turkey and northern Cyprus

Context: Papaver rhoeas L. (Papaveraceae) corn poppy, widely distributed in Turkey, is used to make a cough syrup for children, as a tea for disturbed sleep, for pain relief and as a sedative in folk medicine.

Objective: Samples of P. rhoeas collected from eight different locations in Turkey and three from northern Cyprus were investigated for their alkaloid content and screened for their antimicrobial activities.

Materials and methods: From the aerial parts of P. rhoeas samples, alkaloids were isolated by column and preparative thin-layer chromatography. The alkaloids were identified by comparing their spectral data (UV, IR and ¹H-NMR) and TLC Rf values with those of authentic samples. The antimicrobial study was carried out by microbroth dilution technique against six strains of bacteria and three strains of fungi.

Results: Twelve different alkaloids belonging to proaporphine (mecambrine), aporphine (roemerine), promorphinan (salutaridine), protopine (coulteropine and protopine) and rhoeadine (epiglaucamine, glaucamine, glaudine, isorhoeadine, isorhoeagenine, rhoeadine and rhoeagenine) groups were isolated. The most significant activity was observed with the alkaloid extract of P8 against Staphylococcus aureus with a MIC value of 1.22?μg/mL and against Candida albicans with a MIC value of 2.4?μg/mL.

Discussion: The results indicate that P. rhoeas samples (P8 and P9), which contain roemerine as their major alkaloid, were the most active extracts.     

Anti-cryptococcal activity of ethanol crude extract and hexane fraction from Ocimum basilicum var. Maria bonita: mechanisms of action and synergism with amphotericin B and Ocimum basilicum essential oil

Context: Ocimum basilicum L. (Lamiaceae) has been used in folk medicine to treat headaches, kidney disorders, and intestinal worms.

Objective: This study evaluates the anti-cryptococcal activity of ethanol crude extract and hexane fraction obtained from O. basilicum var. Maria Bonita leaves.

Materials and methods: The MIC values for Cryptococcus sp. were obtained according to Clinical and Laboratory Standards Institute in a range of 0.3–2500?μg/mL. The checkerboard assay evaluated the association of the substances tested (in a range of 0.099–2500?μg/mL) with amphotericin B and O. basilicum essential oil for 48?h. The ethanol extract, hexane fraction and associations in a range of 0.3–2500?μg/mL were tested for pigmentation inhibition after 7?days of treatment. The inhibition of ergosterol synthesis and reduction of capsule size were evaluated after the treatment with ethanol extract (312?μg/mL), hexane fraction (78?μg/mL) and the combinations of essential oil?+?ethanol extract (78?μg/mL?+?19.5?μg/mL, respectively) and essential oil?+?hexane fraction (39.36?μg/mL?+?10?μg/mL, respectively) for 24 and 48?h, respectively.

Results: The hexane fraction presented better results than the ethanol extract, with a low MIC (156?μg/mL against C. neoformans T₄₄₄ and 312?μg/mL against C. neoformans H99 serotype A and C. gattii WM779 serotype C). The combination of the ethanol extract and hexane fraction with amphotericin B and essential oil enhanced their antifungal activity, reducing the concentration of each substance needed to kill 100% of the inoculum. The substances tested were able to reduce the pigmentation, capsule size and ergosterol synthesis, which suggest they have important mechanisms of action.

Conclusions: These results provide further support for the use of ethanol extracts of O. basilicum as a potential source of antifungal agents.     

Chemical composition and evaluation of modulatory of the antibiotic activity from extract and essential oil of Myracrodruon urundeuva

Context: The combination of antibiotics with natural products has demonstrated promising synergistic effects in several therapeutic studies.

Objective: The aim of this study was to determine the effect of a combination of an ethanol extract of Myracrodruon urundeuva Fr. All. (Anacardiaceae) (aroeira plant) and its essential oil with six antimicrobial drugs against multiresistant strains of Staphylococcus aureus and Escherichia coli from clinical isolates.

Materials and methods: After identification of the chemical components by GC-MS, the antibacterial activity of the natural products and antibiotics was assessed by determining the minimal inhibitory concentration (MIC) using the microdilution method and concentrations ranging 8–512?μg/mL and 0.0012–2.5?mg/mL, respectively. Assays were performed to test for a possible synergistic action between the plant products and the antimicrobials, using the extract and the oil at a sub-inhibitory concentration (128?μg/mL) and antibiotic at concentrations varying between 8 and 512?μg/mL.

Results: The GC-MS analysis identified the main compound as δ-carene (80.41%). The MIC of the natural products was >1024?μg/mL, except against S. aureus ATCC25923. Only the combinations of the natural products with gentamicin, amikacin and clindamycin were effective against S. aureus 358, enhancing the antibiotic activity by reducing the MIC.

Conclusions: The extract from aroeira showed a higher antibacterial activity and the oil was more effective in potentiating the activity of conventional antibiotics.     

Bioassay-guided isolation and evaluation of antimicrobial compounds from Ixora megalophylla against some oral pathogens

Context Ixora megalophylla Chamch. (Rubiaceae) is a new plant species recently found in southern Thailand. Ethyl acetate extracts of its leaves and stems showed antimicrobial activities.

Objectives To isolate and identify the antimicrobial compounds from I. megalophylla leaves and stems.

Materials and methods The dried leaves (1.7?kg) and stems (3.5?kg) were consecutively extracted with petroleum ether (5?L?×?4), ethyl acetate (5?L?×?3) and ethanol (5?L?×?4) under reflux conditions. The ethyl acetate extract was subjected to an antimicrobial assay guided isolation with Candida albicans and Streptococcus mutans. Compounds 1–10 were identified by ¹H NMR, ¹³C NMR and EI-MS. Minimal lethal concentration (MLC) against C. albicans and Streptococcus spp. was determined using a broth microdilution method for 48 and 24?h, respectively.

Results and discussion On the basis of the antimicrobial assay guided isolation, 10 known compounds, including vanillic acid (1), syringic acid (2), 4-hydroxy benzaldehyde (3), scopoletin (4), loliolide (5), syringaldehyde (6), sinapaldehyde (7), coniferaldehyde (8), syringaresinol (9) and 2,2′-dithiodipyridine (10), were identified. Compounds 1–5 were purified from the ethyl acetate extract of the leaves, while 6–9 and 10 were from the ethyl acetate and ethanol extracts of the stems, respectively. Among these isolates, 10 showed the strongest antibacterial activities against S. mutans and Streptococcus mitis, with minimum inhibitory concentrations (MICs) of 2–4?μg/mL, and MLC of 4?μg/mL, as well as having a weak antifungal activity against C. albicans (MIC of 125?μg/mL). This is the first report of the antimicrobial activities of 10.     

Antimicrobial,anticancer, and antioxidant compounds from Premna resinosa growing in Saudi Arabia

Context: Premna resinosa (Hochst.) Schauer (Lamiaceae) is used in many places to treat bronchitis, respiratory illness and convulsions of the rib cage.

Objective: This study evaluates the anticancer, antimicrobial and antioxidant activities of P. resinosa, and isolates some responsible constituents.

Materials and methods: The methanol extract of P. resinosa aerial parts and its fractions (n-hexane, dichloromethane, ethyl acetate and n-butanol) were tested. Antimicrobial activity was tested using microdilution method against three Gram-positive and four Gram-negative bacteria. The tested concentrations ranged from 4000 to 7.8?μg/mL and MIC values were determined after 24?h incubation. Anticancer activity was evaluated against three human cancer cell lines (Daoy, HepG2 and SK-MEL28) using MTT assay. Antioxidant activity was investigated by DPPH scavenging method and β-carotene-linoleic acid assay.

Results: The greatest antimicrobial activity was exhibited by n-hexane fraction (MIC 10?μg/mL) against Staphylococcus aureus, Enterococcus faecalis, and Shigella flexneri. The n-hexane fraction induced the greatest cytotoxic activity against Daoy, HepG2, and SK-MEL28 cell lines with IC₅₀ values of 9.0, 8.5 and 13.2, respectively. Moreover, the dichloromethane and ethyl acetate fractions showed the highest antioxidant potential. A bioassay-guided fractionation led to the isolation and characterization of seven compounds for the first time, namely, quercetin (1), 3-methoxy quercetin (2), kaempferol (3), 3-methoxy kaempferol (4), myricetin 3,7,3′-trimethyl ether (5), lupeol (6), and stigmasterol (7).

Conclusion: Our results indicate that P. resinosa is a source for antimicrobial and cytotoxic compounds. However, further work is required to isolate other active principles and to determine the mechanism of action.     

Bioactive potential of endophytic Myrothecium sp. isolate M1-CA-102, associated with Calophyllum apetalum

Context: Endophytes colonizing medicinal plants are diverse, constituting a rich bioresource for novel natural products.

Objective: Myrothecium sp. isolate M1-CA-102 was the most promising among the 16 Myrothecium isolates screened. The bioactive potential of the crude extract from the Calophyllum apetalum Willd. endophytic Myrothecium sp. (Alb. &; Schwein.) Ditmar (Incertae sedis) isolate M1-CA-102 and its thin layer chromatography (TLC) fractions were screened based on antioxidant, anti-inflammatory, antimicrobial activities, and cytotoxicity.

Materials and methods: The antioxidant activity was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging capacities. Further, 15-lipoxygenase (15-LOX) and human cyclooxygenase-2 (COX-2) inhibition were assessed at different concentrations (25, 50, and 100?μg/mL for the crude extract, 5, 25, and 50?μg/mL for the TLC fractions). DNA-nicking assay as an indicator of the capacity of extracts to scavenge hydroxyl radical was recorded at a concentration of 50?μg/mL. Cell cytotoxicity was recorded by colorimetric 3-(4,5-dimethylthylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Antibacterial (Bacillus subtilis) and anti-Candida (Candida albicans) assays were performed by the microdilution method.

Results: The DPPH and ABTS IC₅₀ values of M1-CA-102 extract were 10 and 6?μg/mL compared with 6.1 and 7.03?μg/mL for the positive control quercetin. The cytotoxicity IC₅₀ value of M1-CA-102 extract was 37?μg/mL, while the M-I TLC fraction was 21?μg/mL. The M1-CA-102 extract gave an IC₅₀ value of 58 and 8?μg/mL for 15-LOX and COX-2, respectively. The MIC values for antimicrobial activity for M1-CA-102 extract ranged from 35 to 54?μg/mL, while for the TLC fractions, it ranged from 91 to 515?μg/mL.

Conclusion: The results indicate that Myrothecium M1-CA-102 isolated from C. apetalum is a potential source of natural metabolites of pharmaceutical importance.     

Bioactive compounds from Hypericum humifusum and Hypericum perfoliatum: inhibition potential of polyphenols with acetylcholinesterase and key enzymes linked to type-2 diabetes

Context: Natural products are reported to have a wide spectrum of pharmacological properties such as antimicrobial, anti-inflammatory and anti-cholinesterase. The genus Hypericum (Hypericaceae) is a source of a variety of molecules with different biological activities, notably hypericin and various phenolics.

Objectives: The goals of the present work were the determination of total phenolic and flavonoid content, hypericin and hyperforin concentration as well as the evaluation of biological of Hypericum humifusum L. (Hhu) and Hypericum perfoliatum L. (Hper).

Materials and methods: The various extracts of aerial parts were powdered, and then extracted with methanol. Antibacterial activity was performed according to minimum inhibitory concentration (MIC) and minimum bactericidal (MBC) methods against four Gram-positive bacteria, four Gram-negative bacteria and yeast.

Results: The results revealed that H. humifusum, bear the highest total phenolic and flavonoid content (48–113?mg GAE/g and 8–41?mg RE/g, respectively) as well as hypericin (60–90?mg/g) and hyperforin (8–30?mg/g) concentration. Both species showed significant antioxidant activity as revealed by DPPH, FRAP, ABTS, and metal chelating assays. H. humifusum exhibited a strong acetylcholinesterase (3.86–4.57?mg GALAEs/g), α-glucosidase (0.73–2.55?mmol ACEs/g) and α-amylase (3–8?mmol ACEs/g) inhibitory activity. The extract of H. humifusum exhibited strong antibacterial activity mainly against Staphylococcus epidermidis, Staphylococus aureus, and Enterococcus faecium (MIC values ranging from 200 to 250?μg/mL). The highest antifungal activity was showed for H. perfoliatum extract (MIC value = 250?μg/mL).

Conclusion: The data suggest that H. humifusum could be used as valuable new natural agents with functional properties for pharmacology industries.     

Antimicrobial activity of pomegranate fruit constituents against drug-resistant Mycobacterium tuberculosis and β-lactamase producing Klebsiella pneumoniae

Abstract

Context: The global surge in multi-drug resistant bacteria and the imminence of tuberculosis pandemic necessitate alternative therapeutic approaches to augment the existing medications. Pomegranate, the fruit of Punica granatum Linn. (Punicaceae), widely recognized for potency against a broad spectrum of bacterial pathogens, deserves further investigation in this respect.

Objective: This study determines the therapeutic potential of pomegranate juice, extracts of non-edible peel prepared with methanol/water, and its four polyphenolic constituents, namely caffeic acid, ellagic acid, epigallocatechin-3-gallate (EGCG) and quercetin, against drug-resistant clinical isolates.

Materials and methods: Phenotypic characterisation of Mycobacterium tuberculosis, extended-spectrum β-lactamase (ESBL) and KPC-type carbapenemase producing Klebsiella pneumoniae was performed by biochemical and molecular methods. Resistance profiles of M. tuberculosis and K. pneumoniae were determined using LJ proportion and Kirby–Bauer methods, respectively. Pomegranate fruit extracts, and the compounds, were evaluated at a dose range of 1024–0.5?µg/mL, and 512–0.25?µg/mL, respectively, to determine minimum inhibitory (MIC) and bactericidal concentrations (MBC) against the drug-resistant isolates by the broth micro-dilution method.

Results: The peel extracts exhibited greater antimycobacterial activity (MIC 64–1024?μg/mL) than the potable juice (MIC 256?-?>?1024?μg/mL). EGCG and quercetin exhibited higher antitubercular (MIC 32–256?μg/mL) and antibacterial (MIC 64–56?μg/mL) potencies than caffeic acid and ellagic acid (MIC 64–512?μg/mL).

Discussion and conclusion: The pomegranate fruit peel and pure constituents were active against a broad panel of M. tuberculosis and β-lactamase producing K. pneumoniae isolates. EGCG and quercetin need further investigation for prospective application against respiratory infections.     

Wound healing activity of Pluchea indica leaf extract in oral mucosal cell line and oral spray formulation containing nanoparticles of the extract

Context: Pluchea indica (L.) Less (Asteraceae) is an herb used as a traditional medicine for wound healing. The chemical compounds found in Pluchea indica leaves are phenolic acids, flavonoids, anthocyanins and carotenoids.

Objective: This study investigates the effect of Pluchea indica leaf ethanol extract and its nanoparticles (NPs) on cytotoxicity, cell survival and migration of human oral squamous carcinoma cell line.

Materials and methods: Cell viability was measured using MTT assay to assess the effect of Pluchea indica leaf extract and NPs (1–500?μg/mL) on cytotoxicity and cell survival. The effect of Pluchea indica leaf extract and NPs on cell migration was determined by scratch assay. The % relative migration was calculated after 24, 48 and 72?h of treatment.

Results: The sizes of Pluchea indica leaf extract NPs were in a range of nanometers. NPs possessed negative charge with the polydispersity index (PDI) smaller than 0.3. After the treatment for 24, 48 and 72?h, Pluchea indica leaf extract had IC₅₀ value of 443.2, 350.9 and 580.5?μg/mL, respectively, whereas the IC₅₀ value of NPs after the treatment for 24, 48 and 72?h were 177.4, 149.2 and 185.1?μg/mL, respectively. The % relative migration of cells was significantly increased when the cells were treated with 62.5 and 125?μg/mL of the extract and 62.5?μg/mL of NPs.

Discussion and Conclusions: NPs increased cytotoxicity of the Pluchea indica leaf extract, increased the migration of cells at low concentration and increased colloidal stability of the extract in an oral spray formulation.     

Antimicrobial activities of some Thai traditional medical longevity formulations from plants and antibacterial compounds from Ficus foveolata

Context: Medicinal plants involved in traditional Thai longevity formulations are potential sources of antimicrobial compounds.

Objective: To evaluate the antimicrobial activities of some extracts from medicinal plants used in traditional Thai longevity formulations against some oral pathogens, including Streptococcus pyogenes, Streptococcus mitis, Streptococcus mutans, and Candida albicans. An extract that possessed the strongest antimicrobial activity was fractionated to isolate and identify the active compounds.

Materials and methods: Methanol and ethyl acetate extracts of 25 medicinal plants used as Thai longevity formulations were evaluated for their antimicrobial activity using disc diffusion (5?mg/disc) and broth microdilution (1.2–2500?µg/mL) methods. The ethyl acetate extract of Ficus foveolata Wall. (Moraceae) stems that exhibited the strongest antibacterial activity was fractionated to isolate the active compounds by an antibacterial assay-guided isolation process.

Results and discussion: The ethyl acetate extract of F. foveolata showed the strongest antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 19.5–39.0 and 39.0–156.2?µg/mL, respectively. On the basis of an antibacterial assay-guided isolation, seven antibacterial compounds, including 2,6-dimethoxy-1,4-benzoquinone (1), syringaldehyde (2), sinapaldehyde (3), coniferaldehyde (4), 3β-hydroxystigmast-5-en-7-one (5), umbelliferone (6), and scopoletin (7), were purified. Among these isolated compounds, 2,6-dimethoxy-1,4-benzoquinone (1) exhibited the strongest antibacterial activities against S. pyogenes, S. mitis, and S. mutans with MIC values of 7.8, 7.8, and 15.6?µg/mL, and MBC values of 7.8, 7.8, and 31.2?µg/mL, respectively. In addition, this is the first report of these antibacterial compounds in the stems of F. foveolata.     

Glucosinolates profile,volatile constituents,antimicrobial, and cytotoxic activities of Lobularia libyca

Context: Brassicaceae plants are associated with protection against cancers due to their glucosinolate contents.

Objectives: We investigate fresh leaves, roots and ripe seeds of Lobularia libyca (Viv.) C.F.W. Meissn. (Brassicaceae) to identify their glucosinolate constituents, antimicrobial and cytotoxic activities

Materials and methods: The glucosinolates were identified using GC-MS analysis of their hydrolysis products and LC-MS analysis in the case of seeds. Disc diffusion (1?mg/disc) and minimum inhibitory concentration (0–160?μg/mL) methods were used to evaluate the antimicrobial activity of seed hydrolysate. In vitro cytotoxicity against colorectal HCT-116, hepatic HUH-7, breast MCF-7 and lung A-549 cells was evaluated for seed hydrolysate (0.01–100?μg/mL) using the sulforhodamine B assay and doxorubicin as a standard

Results: Three glucosinolates were identified for the first time in this plant and genus Lobularia. Glucoiberverin was the major compound accumulated in the seeds and leaves, while glucoiberin and glucoerucin were detected only in the seeds. No glucosinolates were detected in roots under the same experimental conditions. Other volatile constituents, e.g., terpenes and fatty acids were only identified in the seeds. The seed hydrolysate showed significant antimicrobial activities against Candida albicans and Pseudomonas aeruoginosa (MIC?=?64 and 82?μg/mL, respectively). The seed hydrolysate exhibited a marked selective cytotoxicity in vitro against colorectal, hepatic and breast cancer cell lines. The IC₅₀ values were 0.31, 2.25 and 37?μg/mL, respectively.

Discussion and conclusion: The results indicated the antimicrobial activity of L. libyca and the selective effect of the seed hydrolysate as a cytotoxic drug that is potentially more active than doxorubicin against HCT-116.     

Antibacterial,antioxidant and anti-proliferative properties and zinc content of five south Portugal herbs

Context: Crataegus monogyna L. (Rosaceae) (CM), Equisetum telmateia L. (Equisataceae) (ET), Geranium purpureum Vil. (Geraniaceae) (GP), Mentha suaveolens Ehrh. (Lamiaceae) (MS), and Lavandula stoechas L. spp. luisieri (Lamiaceae) (LS) are all medicinal.

Objective: To evaluate the antioxidant, antiproliferative and antimicrobial activities of plant extracts and quantify individual phenolics and zinc.

Material and methods: Aerial part extracts were prepared with water (W), ethanol (E) and an 80% mixture (80EW). Antioxidant activity was measured with TAA, FRAP and RP methods. Phenolics were quantified with a HPLC. Zinc was quantified using voltammetry. Antibacterial activity (after 48?h) was tested using Enterococcus faecalis, Bacillus cereus, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Listeria monocytogenes. Antiproliferative activity (after 24?h) was tested using HEP G2 cells and fibroblasts.

Results: Solvents influenced results; the best were E and 80EW. GP had the highest antioxidant activity (TAA and FRAP of 536.90?mg AAE/g dw and 783.48?mg TE/g dw, respectively). CM had the highest zinc concentration (37.21?mg/kg) and phenolic variety, with neochlorogenic acid as the most abundant (92.91?mg/100?g dw). LS was rich in rosmarinic acid (301.71?mg/100?g dw). GP and LS inhibited the most microorganisms: B. cereus, E. coli and S. aureus. GP also inhibited E. faecalis. CM had the lowest MIC: 5830?μg/mL. The antibacterial activity is explained by the phenolics present. LS and CM showed the most significant anti-proliferative activity, which is explained by their zinc content.

Conclusion: The most promising plants for further studies are CM, LS and GP.     

Phytochemical screening and evaluation of in vitro antioxidant and antimicrobial activities of the indigenous medicinal plant Albizia odoratissima

Context: Albizia odoratissima (L. f.) Benth has been used in Indian folk medicine to treat numerous inflammatory pathologies, such as leprosy, ulcers, burns and asthma.

Objective: To evaluate the antioxidant and antimicrobial properties of A. odoratissima.

Materials and methods: Dried leaves of A. odoratissima were extracted in organic solvents (hexane, chloroform, ethyl acetate, and methanol). The total phenolic content (TPC) and total flavonoid content (TFC) were determined using the Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. The antioxidant activity was examined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide (H₂O₂), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP) assays. The antibacterial activity was examined using minimum inhibitory concentration (MIC) and the minimum bacterial concentration (MBC), determined by broth microdilution method against Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Proteus vulgaris) and Gram-positive bacterium (Staphylococcus aureus).

Results: The TPC ranged from 4.40?±?1.06 to 1166.66?±?31.85?mg GAE/g of dry weight (DW), and the TFC ranged from 48.35?±?3.62 to 109.74?±?1.84?mg QE/g of DW. The IC₅₀ values of the ethyl acetate extract for DPPH, ABTS, and H₂O₂ were 10.96?±?0.40, 4.35?±?0.07, and 163.82?±?1.52?μg/mL, respectively. Both methanol and ethyl acetate extracts demonstrated effective antibacterial activity with MICs and MBCs values ranging 136–546?μg/mL and 273–1093?μg/mL, respectively, against the tested pathogenic species.

Conclusions: The leaves of A. odoratissima showed potent free radical scavenging property and antimicrobial activity.     

Unlocking the in vitro anti-inflammatory and antidiabetic potential of Polygonum maritimum

Context: Several Polygonum species (Polygonaceae) are used in traditional medicine in Asia, Europe and Africa to treat inflammation and diabetes.

Objective: Evaluate the in vitro antioxidant, anti-inflammatory and antidiabetic potential of methanol and dichloromethane extracts of leaves and roots of the halophyte Polygonum maritimum L.

Material and methods: Antioxidant activity was determined (up to 1?mg/mL) as radical-scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), copper (CCA) and iron (ICA) chelating activities and iron reducing power (FRAP). NO production was measured in lipopolysaccharide (LPS)-stimulated macrophages for 24?h at concentrations up to 100?μg/mL and antidiabetic potential was assessed by α-amylase and α-glucosidase inhibition (up to 10?mg/mL) assays. The phytochemical composition of the extracts was determined by gas chromatography-mass spectrometry (GC-MS).

Results: The methanol leaf extract had the highest activity against DPPH? (IC₅₀ =?26?μg/mL) and ABTS⁺? (IC₅₀ =?140?μg/mL), FRAP (IC₅₀ =?48?μg/mL) and CCA (IC₅₀ =?770?μg/mL). Only the dichloromethane leaf extract (LDCM) showed anti-inflammatory activity (IC₅₀ =?48?μg/mL). The methanol root (IC₅₀ =?19?μg/mL) and leaf (IC₅₀ =?29?μg/mL) extracts strongly inhibited baker’s yeast α-glucosidase, but LDCM had higher rat’s α-glucosidase inhibition (IC₅₀ =?2527?μg/mL) than acarbose (IC₅₀ =?4638?μg/mL). GC-MS analysis identified β-sitosterol, stigmasterol, 1-octacosanol and linolenic acid as possible molecules responsible for the observed bioactivities.

Conclusions: Our findings suggest P. maritimum as a source of high-value health promoting commodities for alleviating symptoms associated with oxidative and inflammatory diseases, including diabetes.     

Preliminary studies on the antibacterial activity of crude extracts and alkaloids from species of Aspidosperma

Screening tests of hydroethanolic crude extracts of six species of Aspidosperma (Apocynaceae) against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa were performed. Aspidosperma ramiflorum Muell. Arg. showed good activity against Bacillus subtilis with MIC and MBC of 15.7 and 125?μg/mL, moderate activity against Staphylococcus aureus with MIC and MBC of 250 and 500?μg/mL, and weak activity against Escherichia coli with MIC and MBC of 1000?μg/mL. Aspidosperma pyricolum Muell. Arg. (MIC/MBC 125/250?μg/mL) and Aspidosperma olivaceum Muell. Arg. (MIC/MBC 250/?>?1000?μg/mL) displayed moderate antibacterial activity against Bacillus subtilis. Separation of the crude extract of Aspidosperma ramiflorum was performed according to the usual acid–base process, which produces alkaloid mixtures and closely related metabolites. The basic fraction was active against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli, with MICs of 31.2, 62.5, and 250?μg/mL, respectively. The basic fractions were more active than the acid fractions, probably because they contained some active alkaloids and/or closely related metabolites absent from the other fractions, or they contained a higher concentration of these active compounds.     

Antimicrobial bioassay-guided fractionation of a methanol extract of Eupatorium triplinerve

Abstract

Context: Eupatorium triplinerve Vahl (Asteraceae), popularly known as Japana, is widely used in folk medicine, due its analgesic, anticoagulant, antianorexic, antiparasitic, anthelmintic, sedative, antifungal, and antibacterial properties.

Objective: The present study evaluated the chemical composition and antimicrobial activity of E. triplinerve extracts from different parts of the plant and identified the extract with the highest antimicrobial potential.

Materials and methods: Extracts were obtained by maceration of all parts of plant, and subjected to bioassay-guided fractionation of methanol extract by partition column chromatography. The major chemical groups, saponins, reducing sugars, alkaloids, steroids, triterpenoids, phenols, tannins, flavonoids, and others were screened by standard techniques. The antimicrobial activity of the different extracts was performed by microdilution assay and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were reported.

Results: Phytochemical screening of hydroalcoholic extract from all parts of E. triplinerve identified mainly steroids, coumarins, alkaloids, saponins, tannins, depsides and absence of polysaccharides and flavonoids. The methanol extract of leaves presented the highest content of coumarins and lower MIC values of 62 and 75?µg/mL against Enterococcus faecalis and Staphylococcus aureus, respectively. In addition, its non-polar fractions showed antimicrobial activity with MIC ranging from 16 to 125?µg/mL against Gram-negative bacteria, mainly Escherichia coli.

Discussion and conclusion: Data showed that non-polar fractions of E. triplinerve methanolic extract has better antimicrobial activity and most likely depends on the presence of several compounds, such as depsidones, coumarins, saponins, and triterpenes on crude extract. The results can be exploited largely in research of new antibacterial agents.