Low Extract Concentrations Research Articles

Recent perspectives on the anticancer properties of aqueous extracts of Nigerian Vernonia amygdalina.

Innovative developments are necessary for treating and defeating cancer, an oftentimes deadly group of diseases characterized by the uncontrolled growth and spread of abnormal cells. Breast cancer (BC) is the second leading cause of cancer-related deaths of women in the USA, and prostate cancer (PC) is the second leading cause of cancer-related deaths of American men. Although some efficacious BC drugs are pharmaceutically marketed, they affect the quality of life for some patients because they are toxic in that their usages have been accompanied by side effects such as stroke, thrombosis, slow heart rate, seizure, increased blood pressure, nausea, emesis, and more. Therefore, there is an urgent need for the discovery of molecular markers for early detection of this disease and discovery of targets for the development of novel, less toxic therapeutics. A botanical plant Vernonia amygdalina has been widely used in Nigerian and other Central and West African cultures for centuries as an herbal medicine. Mounting evidence suggests that treatment with low concentrations of aqueous leaf extracts of the edible Nigerian V. amygdalina plant (Niger-VA) arrests the proliferative activities and induces apoptosis in estrogen receptor-positive, estrogen receptor-negative, and triple-negative human breast cancerous cells and in androgen-independent human PC-3. Also, in athymic mice, Niger-VA potentiates increased efficacies and optimizes treatment outcomes when given as a cotreatment with conventional chemotherapy drugs. Evidence of its noticeable cytostatic activities ranging from changes in DNA synthesis to growth inhibition, mechanisms of inducing apoptosis in different cancer cell lines, and in vivo antitumorigenic activities and chemopreventive efficacy reinforce the idea that Niger-VA deserves increased attention for further development as a phytoceutical, anticancer drug entity. Hence, the present review article highlights impactful published literature on the anticancer effects of Niger-VA in multiple cancerous cell lines and in a nude mouse model, supporting its potential usefulness as a natural product, chemotherapeutic medicine for treatment of both BC and PC.

Larvicidal Potentiality of Root Extracts of <i>Annona reticulata</i> Linn. Against the Filarial Vector <i>Culex quinquefasciatus</i> Say (Diptera: Culicidae)

Present study was undertaken to evaluate the mosquito larvicidal potentiality of root extracts of Annona reticulata Linn. ( A. reticulata ), family Annonaceae against filarial vector Culex quinquefasciatus Say, 1823 ( Cx. quinquefasciatus ). Petroleum ether, hexane, and ethyl acetate root extracts of the plant were examined to established their larvicidal potentiality against 3 rd instar larvae of Cx. quinquefasciatus mosquito species. Crude and only ethyl acetate root extracts of the plant at different concentrations were examined on 1 st - 4 th instars larvae of Cx. quinquefasciatus . LC 50 value of ethyl acetate extract after 24 h of exposure against 3 rd instar larvae of Cx. quinquefasciatus were also examined on some non target organisms. Phytochemical analyses of the root extracts of A, reticulata were also investigated. 100% mortality were noticed at very low concentrations of petroleum ether, hexane, and ethyl acetate root extracts of A. reticulata against 3 rd instar larvae of Cx. quinquefasciatus . LC 50 and LC 90 values of ethyl acetate root extract was lower than petroleum ether and hexane root extracts after 24, 48, and 72 h of exposure. Crude and ethyl acetate root extracts showed excellent larvicidal activity against Cx. quinquefasciatus mosquito species. 100% mortality was observed at very low concentration for crude and ethyl acetate root extracts. LC 50 and LC 50 values gradually decreased with time of exposure for crude and ethyl acetate root extracts of A. reticulata . No mortality and sluggishness were observed in control experiments as well as on examined non target organisms. Phytochemical analyses of root extracts of the plant revealed the presence of different secondary metabolites. So crude and ethyl acetate root extracts of A. reticulata can effectively be used for larval mortality against Cx. quinquefasciatus mosquito species at a very low concentration.

Fabrication, bioactivity, in vitro cytotoxicity and cell viability of cryo-treated nanohydroxyapatite–gelatin–polyvinyl alcohol macroporous scaffold

Freeze casting and cryogenic treatment both low temperature process have been employed to fabricate nanobiocomposite hydroxyapatite (HA)–gelatin–polyvinyl alcohol (PVA) macroporous scaffolds from synthesized three different spherical, rod and fibrous HA nanoparticles and composition optimized vis-á-vis porosity architecture, content and compressive strength. A critical HA morphology, solid loading and liquid nitrogen interaction time have a significant effect to enhance the mechanical response of developed scaffolds. Cryo-treated 40 wt.% nanorod HA–gelatin–PVA scaffold posses interconnected pore structure with 80 vol.% porosity, average pore diameter 50–200 μm and highest 5.8 MPa compressive strength. Different degree of the apatite deposition phenomenon in simulated body fluid solution at 37 °C and pH ∼ 7.4 varies with respect to time. In vitro cytotoxicity and L929 mouse fibroblast cell culture in the presence of Dulbecco's Modified Eagle Medium and 10% Fetal Bovine Serum at 37 °C and 5% CO2 atmosphere exhibit excellent cytocompatibility and cell viability at low extract concentration up to 25%.

Effect of fullerenes on the activation energy of the graphite-diamond phase transition

The modification of graphite used in diamond synthesis with low concentrations of the fullerene C60-C70 extract (from 0.045 to 0.225 wt % of graphite mass) in the presence of a Ni-Mn metal catalyst at a pressure of 5 GPa in the temperature range 1600–1800 K is found to decrease the activation energy of the graphite-diamond phase transition from 160 ± 40 to 100 ± 40 kJ/mol.

Effects of supercritical CO2 extracts of Melia azedarach L. on the control of fall armyworm (Spodoptera frugiperda)

This work reports the use of Melia azedarach L. extracts obtained from supercritical carbon dioxide extraction (SC-CO2) as an insecticidal agent against fall armyworm (Spodoptera frugiperda). For this purpose, SC-CO2 extractions were performed, varying the pressure (150–250bar), temperature (313–333K), sample particle size and extraction time. Secondary metabolites from the classes of coumarins, sterols and terpenes were identified in the extracts, with the triterpene melianone being the major constituent. For the biological activity tests, diets were prepared with different SC-CO2 extract concentrations (100, 500, 1000 and 5000mg/kg) and offered to S. frugiperda (Lepidoptera: Noctuidae). The results indicated that mortality increased with increasing extract concentrations with 50% mortality (LC50) at a concentration of 376.74mg/kg and reaching 100% mortality at 5000mg/kg. The inhibition of insect growth was observed at higher concentrations due to the antifeedant action of the extract. At the lowest extract concentration (100mg/kg), ingestion caused low pupal viability and adults presenting morphological deformities, which thus indicated a chronic toxicity effect.

Can manuka (Leptospermum scoparium) antimicrobial properties be utilised in the remediation of pathogen contaminated land?

Society is increasingly conscious of waste reduction and contaminant control. The application of biosolids to land (re-cycling) is one means of waste disposal that has been shown to improve various soil properties whilst re-using valuable nutrients. However, there is concern that land application of biosolids can introduce microbial contaminants to soil. The aim of this research was to investigate the potential use of manuka (Leptospermum scoparium), a shrub with known antimicrobial properties, to reduce microbial contaminants from land applied biosolids. We evaluated the efficacy of water extracted manuka components against five bacterial pathogens potentially found in biosolids. Water extracted manuka components significantly inhibited an Escherichia coli lux biosensor, as well as inhibited the growth of Salmonella typhimurium, E. coli 0157, Clostridium perfringins, Campylobacter jejuni and Listeria monocytogenes. EC50 calculations for these pathogens showed that 50% inhibition of growth occurred at relatively low manuka extract concentrations (0.07–27.9% v/v). For C. jejuni, complete inhibition of growth was observed at extract concentrations of 0.78%. These results indicate potential for the use of manuka in the rehabilitation of microbial contaminated sites.

An in vitro high‐throughput assay for screening reproductive and toxic effects of anticancer compounds

An in vitro assay was developed that simultaneously tested the effects of anticancer drug candidates on cytotoxicity, hormone synthesis, and gonadotrophin responsiveness using the choriocarcinoma JAr cell line. JAr culture conditions were optimized and then cells were exposed to a marine mollusc extract in the presence and absence of hCG. The intra- and interassay coefficients of variation of the optimized 1 H thiazolyl blue tetrazolium bromide assay were 11.3% and 10.9%, respectively. hCG (1,000 mIU/mL) increased progesterone (P4) synthesis after 24 H (P<0.05). The mollusc extract significantly decreased cell viability, with the IC50 affected by incubation time, but not hCG. P4 synthesis was inhibited at low concentrations of the anticancer extract, but stimulated at the highest concentration, and complex interactions of P4 were also found with hCG. In conclusion, the optimized assay is useful to characterize the effects of novel drugs on cytotoxicity, basal, and gonadotrophin-stimulated P4 synthesis in vitro, and can be used to inform subsequent in vivo studies.

Role of Challenger pesticide and plant extracts on some physiological parameters of the cotton leafworm, Spodoptera littoralis (Boisd.)

Fourth instar larvae of cotton leafworm, Spodoptera littoralis (Boisd.), fed on castor bean leaves treated with sub-lethal concentrations of both alcohol and hexane extracts of Egyptian conyza and Challenger 36% SC insecticide as well to study their effects on mortality, food consumption and utilisation of food. The tested insecticides exhibited relatively high mortality in alcoholic extract of Egyptian conyza (5.0% concentration) followed by Challenger (1.0% concentration). Results showed a slight reduction in the consumption index for larvae treated with both alcoholic extract and Challenger at low concentrations, while hexane extract (5%) recorded significant increase. The approximate digestibility (AD) was reduced in all treatments of alcoholic extract and the relative growth rate insignificantly decreased at 5% concentration, whereas AD increased for larvae fed on Challenger 0.25% concentration. The lower concentration of alcoholic extract of conyza and all treatments of Challenger pesticides induced insignificant decrease in the efficiency of conversion of the ingested food, while hexane extract exhibited insignificant increase. Challenger at all tested concentrations achieved insignificant decrease in the efficiency of the conversion of digested food with respect to the control.

Bioconversion of xylose, hexoses and biomass to ethanol by a new isolate of the white rot basidiomycete Trametes versicolor

Second-generation bioethanol production requires the development of economically feasible and sustainable processes that use renewable lignocellulosic biomass as a starting material. However, the microbial fermentation of xylose, which is the principal pentose sugar in hemicellulose, is a limiting factor in developing such processes. Here, a strain of the white rot basidiomycete Trametes versicolor that was capable of efficiently fermenting xylose was newly isolated and characterized. This strain, designated KT9427, was capable of assimilating and converting xylose to ethanol under anaerobic conditions with a yield of 0.44 g ethanol per 1 g of sugar consumed. In culture medium containing low yeast extract concentrations, xylose consumption and ethanol productivity were enhanced. Adjusting the initial pH between 3.0 and 5.0 did not markedly influence xylose fermentation. T. versicolor KT9427 also produced ethanol from glucose, mannose, fructose, cellobiose and maltose at yields ranging from 0.45 to 0.49 g ethanol per 1 g of sugar consumed. In addition, strain KT9427 exhibited favourable conversion of non-pretreated starch, cellulose, xylan, wheat bran and rice straw into ethanol compared to common recombinant yeast strains. Taken together, the present findings suggest that T. versicolor KT9427 is a promising candidate for environmentally friendly ethanol production directly from lignocellulosic biomass.

Newbouldia Laevis ( Seem ) as an Entomocide against Sitophilus Oryzae and Sitophilus Zeamais Infesting Maize Grain

This study was conducted under laboratory conditions at temperature of 28±2 o C and relative humidity 75±5% to investigate the entomocidal flurry of Newbouldia laevis against Sitophilus oryzae and Sitophilus zeamais infesting maize grain in storage. The powders of stem and root of N. laevis were prepared at 0.1, 0.2, 0.3, 0.4 and 0.5g dosages, while their extracts were prepared at 1, 2, 3, 4 and 5% concentrations. The control experiments were also set up. None of the powders of stem and root of this plant was able to achieve complete mortality of the two insects within 96h of application, except for the root powder which was able to achieve 100% mortality of S. oryzae at 0.5g dosage only. Only the root extract at 4% was able to achieve complete weevils mortality within 96h and its effect was significantly different (p<0.05) from the extracts of the stem except at 4 and 5% concentration of stem extract. The fiducial limits showed that a lower concentration of root extract was needed to cause 50% mortality in S. zeamais (0.00-1.64 %) when compared to the concentration needed for S. oryzae (0.10-1.72 %). Both the stem and root extracts of the plant were more effective than their powders. The powders and the extracts of this plant either reduced or prevented the emergence of adult weevils and inhibit the developmental period of the insects. The powders and the extracts of N. laevis also reduced or prevented the weight loss of the treated maize grains. Therefore, with the result obtained in this research, both the powder and extract of N. laevis root and stem could go a long way in the quest of providing alternative wherewithal to the use of chemical insecticides for protecting maize grain in storage. Root extract of N. laevis could, however, offer more protection against S. oryzae and S. zeamais infesting maize grain than its stem extracts.

Parasiticidal effects of Morus alba root bark extracts against Ichthyophthirius multifiliis infecting grass carp

Ichthyophthirius multifiliis (Ich), an important fish parasite, can cause significant losses in aquaculture. To find efficacious drugs to control Ich, the root bark of white mulberry Morus alba was evaluated for its antiprotozoal activity. Bark was powdered and extracted with 1 of 5 organic solvents: petroleum ether, chloroform, ethyl acetate, acetone, or methanol. The extracts were concentrated, dissolved in 0.1% (v/v) DMSO, and used for anti-Ich trials. Acetone and ethyl acetate extracts significantly reduced the survival of Ich tomonts and theronts. In vitro, acetone extract at 25 mg l-1 killed all non-encysted tomonts, at 50 mg l-1 eradicated all encysted tomonts, and at 8 mg l-1 caused mortality of all theronts. Ethyl acetate extract at 50 mg l-1 eliminated all non-encysted tomonts, at 100 mg l-1 killed all encysted tomonts and terminated tomont reproduction, and at 8 mg l-1 killed all theronts. Low concentrations (2 and 4 mg l-1) of acetone and ethyl acetate extracts could not kill all theronts after 4 h exposure, but a significant decrease in theront infectivity was observed following 30 min of pretreatment with the extracts. The 96 h LC(50) values of acetone and ethyl acetate extracts to grass carp were 79.46 and 361.05 mg l-1, i.e. much higher than effective doses for killing Ich theronts (8 mg l-1 for both extracts) and non-encysted tomonts (12.5 and 25 mg l-1, respectively). Thus M. alba extract may be a potential new, safe, and efficacious drug to control Ich.

Medicinal plant extracts can variously modify biofilm formation in Escherichia coli

Low concentrations of black tea and water extracts from medicinal plants Arctostaphylos uva-ursi, Vaccinium vitis-idaea, Tilia cordata, Betula pendula and Zea mays stimulated biofilm formation in Escherichia coli BW25113 up to three times. Similar effect was observed for tannic acid and low concentrations of quercetin. In contrast, the extract from Urtica dioica reduced biofilm production. Pretreatment with plant extracts variously modified antibiotic effects on specific biofilm formation (SBF). Extract from V. vitis-idaea increased SBF, while the extracts from Achillea millefolium, Laminaria japonica and U. dioica considerably decreased SBF in the presence of ciprofloxacin, streptomycin and cefotaxime. Stimulatory effect of the extracts and pure polyphenols on biofilm formation was probably related to their prooxidant properties. The rpoS deletion did not affect SBF significantly, but stimulation of biofilm formation by the compounds tested was accompanied by inhibition of rpoS expression, suggesting that a RpoS-independent signal transduction pathway was apparently used.

Efficient Antioxidant Formulations for Use in Biodiesel

Biodiesel has a lipid origin; thus, antioxidants commonly used in oils and fats have been adopted for the improvement of the oxidative stability of biodiesel. However, these antioxidants have not shown the same efficiency when they are applied to biodiesel. This fact points out the need to investigate additives that warrant the oxidative stability of biodiesel, especially during long storage periods. In this paper, antioxidant formulations were developed for application in biodiesel, from blends including the synthetic antioxidants butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), the chelating agent citric acid, and organic rosemary extracts. The antioxidants were applied at different concentrations and combinations and were evaluated by the Rancimat method, EN 14112, and by the pressurized PetroOXY method. The results showed that for ethanol soybean biodiesel, the antioxidant compositions formed by TBHQ (2000 mg kg–1) and citric acid (500 mg kg–1) and by the chloroform rosemary extract (2000 mg kg–1) and citric acid (500 mg kg–1) were the most effective in delaying the oxidative process, in a manner independent of the evaluation method. For the methanol cottonseed oil biodiesel, the best result was obtained using the combination of 1500 mg of TBHQ with 1500 mg of ethanol rosemary extract. However, the formulations using low concentrations of rosemary ethanol extract and citric acid induction periods of >6 h were obtained, reaching the limit specified by European Standard EN 14214.

Chemical Composition of Celandine (&lt;i&gt;Chelidonium majus&lt;/i&gt; L.) Extract and its Effects on &lt;i&gt;Botrytis tulipae&lt;/i&gt; (Lib.) Lind Fungus and the Tulip

In this study, the content of chelidonine and berberine alkaloids, and sterols and phenols in the Chelidonium majus plant extract were analyzed. Subsequently, the effects of the extract on the germination and growth of Botrytis tulipae fungus on nutritive medium were compared to the effects of fluconazole. The plant extract was used at the minimum inhibitory concentration on B. tulipae developed in tulip leaves and the in vivo effects were investigated. The influence of different concentrations of C. majus extract on the physiological processes of the tulip (gas exchange parameters, photosynthetic light use efficiency, and induced chlorophyll fluorescence) were also tested to assess the applicability of the extract for the protection of ornamental plants against fungal infection. Our results demonstrated that 2% celandine extract does not significantly change the gas exchange parameters (transpiration rate, carbon dioxide uptake, and stomatal conductivity) of leaves exposed for 2 h, and does not interfere with the photochemical processes in the leaves. However, in higher concentrations, it increases the transpiration rate and net carbon dioxide influx. At concentrations of 15% and 20%, the extract lowers the potential quantum yield efficiency of photosystem II and the vitality index of the photosynthetic apparatus. Therefore we recommend the use of lower concentrations (≤6%) of celandine extract for the biological protection of tulips against gray mold.

Phytotoxicity evaluation of six fast-growing tree species in South Africa

Vachellia sieberiana, Albizia adianthifolia, Buddleja saligna, Combretum kraussii, Halleria lucida and Rapanea melanophloeos are fast-growing, indigenous tree species in South Africa. They are usually found growing alongside other plants in agricultural systems. In this study, the comparative phytotoxic activity of aqueous leaf extracts of these tree species at different concentrations was investigated using lettuce seeds (Lactuca sativa L.) in a laboratory bioassay. To simulate natural situations, seeds were germinated under 16h light/8h darkness in a growth chamber using distilled water as control. The results showed that germination, chlorophyll accumulation and growth indices (plumule and radicle lengths) were significantly inhibited with increasing concentration of plant extracts. The treated lettuce seedlings experienced lipid peroxidation at high extract concentrations (1.0% and 2.0%) as evidenced by increased concentration of malondialdehyde (MDA). In response to this, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) increased at low extract concentration but significantly dropped as concentration increased. These results suggest that aqueous extracts of the studied tree species may produce growth inhibitory substances. Thus, our study revealed that these trees possess phytotoxic activity which could be exploited in the management of weeds in agroforestry systems.

Evaluation of anti–resistant activity of Auklandia(Saussurea lappa) root against some human pathogens

ObjectiveThe antimicrobial activity of the ethanol extract of the Auklandia (Saussurea lappa)root plant was investigated to verify its medicinal use in the treatment of microbial infections. MethodsThe antimicrobial activity of the ethanol extract was tested against clinical isolates of some multidrug-resistant bacteria using the agar well diffusion method. Commercial antibiotics were used as positive reference standards to determine the sensitivity of the clinical isolates. ResultsThe extracts showed significant inhibitory activity against clinical isolates of methicillin resistant Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia, Extended Spectrum Beta-Lactemase, Acinetobacter baumannii. The minimum inhibitory concentration values obtained using the agar dilution test ranged from 2.0 μg/μL-12.0 μg/μL. In the contrary the water extract showed no activity at all against the tested isolates. Furthermore, the results obtained by examining anti-resistant activity of the plant ethanolic extract showed that at higher concentration of the plant extract (12 μg) all tested bacteria isolates were inhibited with variable inhibition zones similar to those obtained when we applied lower extract concentration using the well diffusion assay. ConclusionThe results demonstrated that the crude ethanolic extract of the Auklandia (Saussurea lappa) root plant has a wide spectrum of activity suggesting that it may be useful in the treatment of infections caused by the above clinical isolates (human pathogens).

Achillea fragrantissima extract exerts its anticancer effect via induction of differentiation, cell cycle arrest and apoptosis in chronic myeloid leukemia (CML) cell line K562

The advantages of herbs in cancer therapy/prevention are attributed to their broad inhibitory activity against multiple aberrant cancer specific pathways and non-toxic nature. Achillea fragrantissima (Af) is a traditional herb used to treat viral fever and chronic diseases such as arthritis and diabetes. However, the anticancer potential of Af has not been studied yet. Anticancer properties of extract from Af leaves were studied using human chronic myeloid leukemia (CML) (K562), T cell lymphoma (Jurkat) and hepatocellular carcinoma (HepG2) cell lines. Af extract induced morphological changes were studied using inverted light microscope and its effect on viability of cells was measured by trypan blue assay. Af extract altered the morphology of K562 and Jurkat cells from spherical to spindle shape. This shape change was considered indicative of initiation of differentiation and occurred at a low concentration of the extract (0.5 mg/ml) in K562 cells and at this concentration viability of K562 cells was not significantly affected. At higher (≥1 mg/ml) concentrations, Af extract induced elongation of K562 cells, which was considered indicative of cell cycle arrest. Increasing concentration of Af extract also caused plasma membrane rupture in a higher proportion of K562 cells resulting in reduced viability. Af extract reduced the viability of K562 cells in a time and dose dependent manner. Results from our study indicated Af extract as a potent inducer of differentiation, cell cycle arrest and apoptosis in K562 and Jurkat cells. Af extract activated these anticancer mechanisms in a concentration dependent manner. Anticancer activity of Af extract on K562 and Jurkat cells, mediated by multiple independent mechanisms, suggests its potential use in the treatment of drug resistant leukemia and other cancers. Key words: Chronic myeloid leukemia, chronic myeloid leukemia (CML), differentiation therapy, K562, Achillea fragrantissima, Jurkat, hepatocellular carcinoma (HepG2), cell cycle arrest, apoptosis.

Modulation of the Immune and Inflammatory Responses by Plasmodium falciparum Schizont Extracts: Role of Myeloid Dendritic Cells in Effector and Regulatory Functions of CD4 + Lymphocytes

The optimal immune response to malaria infection comprises rapid induction of inflammatory responses promptly counteracted by regulatory mechanisms to prevent immunopathology. To evaluate the role of dendritic cells (DC) in the balance of parasite-induced inflammatory/anti-inflammatory mechanisms, we studied the activity of monocyte-derived dendritic cells (MDDC), previously exposed to soluble extracts of Plasmodium falciparum-infected red blood cells (PfSE), in the differentiation of CD4 cells isolated from donors never exposed to malaria infection. We show that MDDC exposed to PfSE are extremely efficient to induce a contemporary differentiation of TH1 effector cells and T regulatory (Treg) cells in CD4 T cells even when exposed to low concentrations of parasitic extracts. Treg cells induced by MDDC infected with PfSE (MDDC-PfSE) produce transforming growth factor beta (TGF-β) and interleukin 10 (IL-10) and are endowed with strong suppressive properties. They also show phenotypical and functional peculiarities, such as the contemporary expression of markers of Treg and TH1 differentiation and higher sensitivity to TLR4 ligands both inducing an increasing production of suppressive cytokines. On the whole, our data indicate that MDDC exposed to PfSE orchestrate a well-balanced immune response with timely differentiation of TH1 and Treg cells in CD4 cells from nonimmune donors and suggest that, during the infection, the role of MDCC could be particularly relevant in low-parasitemia conditions.

Cyanobacteria can allelopathically inhibit submerged macrophytes: Effects of Microcystis aeruginosa extracts and exudates on Potamogeton malaianus

Submerged macrophytes are known for their positive effects on water clarity, especially in shallow lake ecosystems. Eutrophication of these systems, however, has often resulted in a decline of submerged vegetation and a dominance of cyanobacteria, producing and releasing allelopathically active substances. Whether and how these allelochemicals affect submerged macrophytes is, however, largely unknown. We tested the effect of exudates and extracts of one of the most common cyanobacteria species, Microcystis aeruginosa, on seed germination and seedling growth and photosynthesis of the submerged macrophyte Potamogeton malaianus, a common species in Chinese shallow lakes. We found that: (1) low and high exudate concentrations significantly promoted or inhibited P. malaianus seed germination, respectively, while extracts had no effect; (2) low exudate and medium extract concentrations significantly increased, whereas high concentrations decreased the biomass of P. malaianus seedlings; (3) chlorophyll content and maximum quantum yield of PS II (Fv/Fm) of the seedlings were decreased by all levels of exudates; (4) of the various responses tested, seedling leaf Fv/Fm showed the greatest sensitivity to M. aeruginosa allelochemicals; (5) the allelopathic effects of M. aeruginosa exudates were stronger than those of extracts. Our results indicate that cyanobacteria exudates can allelopathically inhibit submerged macrophytes. The early growth of seedlings rather than seed germination seems to be a sensitive phase for the impact of cyanobacterial allelochemicals.

Integrated Analysis of COX-2 and iNOS Derived Inflammatory Mediators in LPS-Stimulated RAW Macrophages Pre-Exposed to Echium plantagineum L. Bee Pollen Extract

Oxidative stress and inflammation play important roles in disease development. This study intended to evaluate the anti-inflammatory and antioxidant potential of Echium plantagineum L. bee pollen to support its claimed health beneficial effects. The hydromethanol extract efficiently scavenged nitric oxide (•NO) although against superoxide (O2 •−) it behaved as antioxidant at lower concentrations and as pro-oxidant at higher concentrations. The anti-inflammatory potential was evaluated in LPS-stimulated macrophages. The levels of •NO and L-citrulline decreased for all extract concentrations tested, while the levels of prostaglandins, their metabolites and isoprostanes, evaluated by UPLC-MS, decreased with low extract concentrations. So, E. plantagineum bee pollen extract can exert anti-inflammatory activity by reducing •NO and prostaglandins. The extract is able to scavenge the reactive species •NO and O2 •− and reduce markers of oxidative stress in cells at low concentrations.