Emad A. Shalaby

Allelopathic Effects of Water Hyacinth [Eichhornia crassipes]

Eichhornia crassipes (Mart) Solms is an invasive weed known to out-compete native plants and negatively affect microbes including phytoplankton. The spread and population density of E. crassipes will be favored by global warming. The aim here was to identify compounds that underlie the effects on microbes. The entire plant of E. crassipes was collected from El Zomor canal, River Nile (Egypt), washed clean, then air dried. Plant tissue was extracted three times with methanol and fractionated by thin layer chromatography (TLC). The crude methanolic extract and five fractions from TLC (A–E) were tested for antimicrobial (bacteria and fungal) and anti-algal activities (green microalgae and cyanobacteria) using paper disc diffusion bioassay. The crude extract as well as all five TLC fractions exhibited antibacterial activities against both the Gram positive bacteria; Bacillus subtilis and Streptococcus faecalis; and the Gram negative bacteria; Escherichia coli and Staphylococcus aureus. Growth of Aspergillus flavus and Aspergillus niger were not inhibited by either E. crassipes crude extract nor its five fractions. In contrast, Candida albicans (yeast) was inhibited by all. Some antialgal activity of the crude extract and its fractions was manifest against the green microalgae; Chlorella vulgaris and Dictyochloropsis splendida as well as the cyanobacteria; Spirulina platensis and Nostoc piscinale. High antialgal activity was only recorded against Chlorella vulgaris. Identifications of the active antimicrobial and antialgal compounds of the crude extract as well as the five TLC fractions were carried out using gas chromatography combined with mass spectroscopy. The analyses showed the presence of an alkaloid (fraction A) and four phthalate derivatives (Fractions B–E) that exhibited the antimicrobial and antialgal activities.

Bioremoval capacity of three heavy metals by some microalgae species (Egyptian Isolates).

Three fresh water microalgal isolates [Phormidium ambiguum (Cyanobacterium), Pseudochlorococcum typicum and Scenedesmus quadricauda var quadrispina (Chlorophyta)] were tested for tolerance and removal of mercury (Hg2+), lead (Pb2+) and cadmium (Cd2+) in aqueous solutions as a single metal species at conc. 5–100 mg / L under controled laboratory conditions. The obtained results showed that Hg2+ was the most toxic of the three metal ions to the test algae even at low concentration (

Algae as promising organisms for environment and health.

Algae like other plants produce a variety of remarkable compounds collectivity refereed to as secondary metabolites they are synthesized by these organisms at the end of the growth phase and/or due to metabolic alterations induced by environmental stress conditions. Carotenoids, phenolic compounds, phycobiliprotein pigments, polysaccharides and unsaturated fatty acids are same of the algal natural products which were reported to have variable biological activities, including antioxidant activity, anticancer activity, antimicroabial activity against bacteria-virus-algae-fungi, organic fertilizer and bioremediation potentials.

Acaricidal activity of different extracts from Syzygium cumini L. Skeels (Pomposia) against Tetranychus urticae Koch

OBJECTIVE To investigate the acaricidal activity of different extracts from Syzygium cumini (S. cumini) (Pomposia) againsst Tetranychus urticae Koch (T. urticae) and the biochemical changes in antioxidants enzymes. METHODS Six extracts of S. cumini (Pomposia) at concentrations of 75, 150 and 300µg/mL were used to control T. urticae (Koch). RESULTS The ethanol extract showed the most efficient acaricidal activity agent against T. urticae (98.5%) followed by hexane extract (94.0%), ether and ethyl acetate extract (90.0%). The LC50 values of the promising extract were 85.0, 101.0, 102.0 and 98.0µg/mL, respectively. The activities of enzymes including ascorbate peroxidase (APX), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) in susceptible mites were increased. The activities of all antioxidant enzymes reach the maximum value in mites at LC50 with ethanol and ethyl acetate extracts, respectively. CONCLUSIONS The extract of S. cumini has acaricidal acivity against T. urticae, and the ethanol extract is the most efficient.

Eichhornia crassipes (Mart) solms: From water parasite to potential medicinal remedy

Water hyacinth, Eichhornia crassipes (Mart) Solms, originating in the amazonian basin, is a warm water aquatic plant. Water hyacinth is considered one of the most productive plants on earth and, accordingly, is considered one of the top 10 world’s worst weeds. Water hyacinth spread to other tropical and subtropical regions by humans. It invaded about 62 countries in Africa, Asia and North America, and propagated extremely serious ecological, economical and social problems in the region between 40 degrees north and 45 degrees south. The dense weed of water hyacinth forms dense monocultures that can threaten local native species diversity and change the physical and chemical aquatic environment, thus altering ecosystem structure and function by disrupting food chains and nutrient cycling. We have separated and identified nine active fractions from water hyacinth and showed their promising therapeutic activities. Several compounds (alkaloid, phthalate derivatives, propanoid and phenyl derivatives) were identified in the extract of water hyacinth.

Antioxidant Activity of Phenolic Compounds from Different Grape Wastes

Winery pomace (from red and white grapes) was extracted under various conditions using different solvents. The antioxidant activity of solvent extracts was investigated by DPPH radical scavenging method. Ethanol extract exhibited the highest antioxidant activity compared to the other solvent (BuOH, EtOAc, Me2Cl2 and pet.ether). There was a correlation between antioxidant activity and total phenol content. HPLC analysis of the extracts showed that gallic and cinnamic acid was the major phenolic compounds in winery pomace. Various phenolic compounds such as catechin, rutin, rosmarinic, chlorogenic, caffeic, vanillic, coumaric acids were also identified.

Antiradical and Antioxidant Activities of Different Spirulina platensis Extracts against DPPH and ABTS Radical Assays

Antiradical and Antioxidant Activities of Different Spirulina platensis Extracts against DPPH and ABTS Radical Assays The aim of the present research was to evaluate and compare the antiradical and antioxidant activities of extracts from Spirulina platensis. In the present study, Three extracts (Water, absolute methanol and 50% methanol in water) were analyzed for the total Phenolic compounds, phycobiliprotein content: Antiradical and antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging methods..

Antioxidant Mechanism of Active Ingredients Separated from Eucalyptus globulus

The present study aimed to evaluate the antioxidant activity of petroleum ether, methanolic extracts and active ingredients separated from Eucalyptus globulus using three different antioxidant assays: 2,2 diphenyl picryl hydrazyl (DPPH), 2,2’- azino-bis [ethylbenzthiazoline-6-sulfonic acid] (ABTS) and β-carotene bleaching assay and identify the mode of action. The results revealed that, crude methanolic extract showed higher antioxidant activity against both DPPH and ABTS radicals than petroleum ether extract. The promising methanol soluble fraction of Eucalyptus globulus wood was fractionated on a silica gel column, using hexane, chloroform and ethyl acetate as the mobile phase to give three fractions (C1, C2 and C3), and both the antioxidant activity and chemical composition for raw and fractions were determined. One of the fractions isolated (C2) showed a remarkable antioxidant activity (EC 50 of 64.4 µg/ml, in comparison with 52.74 µg/ml for crude extracts) against ABTS radical method, and the chemical structures of separated active ingredients were identified using different spectroscopic methods such as 17-pentatricontene (C1), N,N-diphenyllauramide (C2) and O-benzyl-N-tert-butoxycarbonyl-D-serine (C3). Also, the mode of action of the promising fraction was determined.

Biological Activities and Application of Marine Polysaccharides

Late blight and wilt caused by the oomycete, Phytophthora infestans, and the fungus, Fusarium solani f. sp. eumartii, respectively, are severe diseases in Solanaceae crops worldwide. Although traditional approaches to control plant diseases have mainly relied on toxic chemical compounds, current studies are focused to identify more sustainable options. Finding alternatives, a low molecular weight chitosan (LMWCh) obtained from biomass of Argentine Sea’s crustaceans was assayed. In an attempt to characterize the action of LMWCh alone or in combination with the synthetic fungicide Mancozeb, the antimicrobial properties of LMWCh were assayed. In a side-by-side comparison with the SYTOX Green nucleic acid stain and the nitric oxide–specific probe, diaminofluorescein-FM diacetate (DAF-FM DA), yielded a similar tendency, revealing LMWChmediated cell death. The efficacy of LMWCh, Mancozeb, and the mixture LMWCh– Mancozeb was in turn tested. A synergistic effect in the reduction of F. eumartii spore germination was measured in the presence of subinhibitory dosis of 0.025 mg ml−1 LMWCh and 0.008 mg ml−1 Mancozeb. This mixture was efficient to increase the effectiveness of the single treatments in protecting against biotic stress judged by a drastic reduction of lesion area in P. infestans–inoculated tissues and activation of the potato defense responses.

Screening of Microalgae for Antioxidant Activities, Carotenoids and Phenolic Contents

Ten different microalgal species were screened for their antioxidant activity using 2,2 ́-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay, both total phenolic and carotenoid contents were determined. The ethanolic extract of Oscillatoria sp. showed the highest antioxidant activity (69.1 %), while the green Chlorella sp. showed higher phenolic content (39.1 mg GAE g-1 dry wt.) and Scenedesmus obliquus recorded higher carotenoid content (3.73 mg L-1), than cyanobacterial species Microalgal biomass plays a great role as a potential source of natural antioxidants, not only due to the carotenoids but also the phenolic compounds.