Sanaa M. M. Shanab

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 (

Enteromorpha compressa Exhibits Potent Antioxidant Activity

The green macroalgae, Enteromorpha compressa (Linnaeus) Nees, Ulva lactuca, and E. linza, were seasonally collected from Abu Qir bay at Alexandria (Mediterranean Sea) This work aimed to investigate the seasonal environmental conditions, controlling the green algal growth, predominance, or disappearance and determining antioxidant activity. The freshly collected selected alga (E. compressa) was subjected to pigment analysis (chlorophyll and carotenoids) essential oil and antioxidant enzyme determination (ascorbate oxidase and catalase). The air-dried ground alga was extracted with ethanol (crude extract) then sequentially fractionated by organic solvents of increasing polarity (petroleum ether, chloroform, ethyl acetate, and water). Antioxidant activity of all extracts was assayed using different methods (total antioxidant, DPPH [2, 2 diphenyl-1-picrylhydrazyl], ABTS [2, 2 azino-bis ethylbenzthiazoline-6-sulfonic acid], and reducing power, and β-carotene linoleic acid bleaching methods). The results indicated that the antioxidant activity was concentration and time dependent. Ethyl acetate fraction demonstrated higher antioxidant activity against DPPH method (82.80%) compared to the synthetic standard butylated hydroxyl toluene (BHT, 88.5%). However, the crude ethanolic extract, pet ether, chloroform fractions recorded lower to moderate antioxidant activities (49.0, 66.0, and 78.0%, resp.). Using chromatographic and spectroscopic analyses, an active compound was separated and identified from the promising ethyl acetate fraction.

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..

A review on algae and plants as potential source of arachidonic acid

Graphical abstract

The First Record of Biological Activities of the Egyptian Red Algal Species Compsopogon helwanii

Compsopogon helwanii is a new Egyptian species of the genus compsopogon, collected (in 1999) from Ain Helwan Spring. It dominated all over the year. Neither this new red alga species, nor the other known eight compsopogon species were subjected to any physiological or biochemical studies. This is the first investigation concerning the biological activities of this new algal species. Methanolic extract of this alga was tested for antimicrobial (G+ve, G-ve bacteria, yeast, fungi), antialgal (green and cyanobacteria) , antioxidant (DPPH and ABTS assays) and anticancer (EACC) activities. The obtained results correlated the biological activities to the contents of phycobilin pigments, spermine derivatives (GC/MS) and other active constituents in this algal extract.

Suggested mechanism for the effect of sweeteners on radical scavenging activity of phenolic compounds in black and green tea

ABSTRACT The present work aims to evaluate the relation between the antioxidant activities and phenolic compound contents of two tea samples (green and black) mixed with or without sweeteners (sucrose or aspartame). The aqueous extracts were screened for total polyphenol and flavonoids contents. Antioxidant activities of extracts were tested using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical method and 2, 2′-azino-bis [ethylbenzthiazoline-6-sulfonic acid] (ABTS) methods using butylated hydroxyl anisole as standard compound. In addition, we identified polyphenols compounds using high performance liquid chromatography (HPLC). The results indicated that the antioxidant activity was higher against ABTS radical more than DPPH radical. Also, there is positive correlation between the antioxidant activity and phenolic compounds content presented in water extracts of tea samples. The results also indicated that addition of table sugar to green tea significantly decreased the antioxidant activity (from 95.8% to 90.6% with 4.0% sucrose). However, the same table sugar in black tea increased the antioxidant activity (from 87.0% to 91.9% with 4.0% sucrose). The analysis using HPLC showed that caffeine was the most predominant individual compounds in green and black tea without and with 1.0% sucrose (6081.8, 8772.1, 6474 and 3755 µg/100g, respectively). However, cinnamic acid showed the lowest content in the same tea samples (0.21, 0.25, 0.19 and 0.18 µg/100g respectively). Pyrogallol, catechol, epicatechin, ellagic, protocatchuic were significantly higher in green tea than in black tea.