Assessment of the phytochemical constituents and antioxidant activity of a bloom forming microalgae Euglena tuba

BACKGROUND: Unstable generation of free radicals in the body are responsible for many degenerative diseases. A bloom forming algae Euglena tuba growing abundantly in the aquatic habitats of Cachar district in the state of Assam in North-East India was analysed for its phytochemical contents, antioxidant activity as well as free radical scavenging potentials. RESULTS: Based on the ability of the extract in ABTS•+ radical cation inhibition and Fe3+ reducing power, the obtained results revealed the prominent antioxidant activity of the algae, with high correlation coefficient of its TEAC values to the respective phenolic and flavonoid contents. The extract had shown its scavenging activity for different free radicals and 41.89 ± 0.41 µg/ml, 5.83 ± 0.07 µg/ml, 278.46 ± 15.02 µg/ml and 223.25 ± 4.19 µg/ml were determined as the IC50 values for hydroxyl, superoxide, nitric oxide and hypochlorous acid respectively, which are lower than that of the corresponding reference standards. The phytochemical analysis also revealed that the phenolics, flavonoids, alkaloids, tannins and carbohydrates are present in adequate amount in the extract which was confirmed by HPLC analysis. CONCLUSIONS: The results showed that 70% methanol extract of the algae possesses excellent antioxidant and free radical scavenging properties.

Euglenoid blooms in the floodplain wetlands of Barak Valley, Assam, North eastern India.

Red blooms of Euglena sp. in the floodplain wetland ecosystems of Barak Valley, Assam, India, were found to be induced by high concentrations of NH3-N, NO3, Fe, Mg and to some extent, PO4, Cu and Zn in their water. The trace elements were rapidly accumulated by the bloom organisms to high levels, whereby their concentrations in the water declined, leading to a collapse of the bloom, which tended to reappear as decomposition again led to the release of the nutrients. The bloom also harboured fairly high density of certain other algae and zooplankton, thereby acting as a sub-system within the wetland ecosystem. The bloom is non-toxic and is exploited as a fish food by the fish-farmers who artificially induce a bloom for augmenting the growth of surface-feeding species of fishes.

Recent progress in understanding the temporal behavior of unicellular organisms

This survey summarizes the findings concerning endogenous oscillations of three unicellular organisms: the dinophyte Gonyaulax polyedra, the ciliate Tetrahymena thermophila and the euglenophyte Euglena gracilis. All of them behave rhythmically and show the common features of zeitgeber action, differential sensitivity and temperature compensation; however, they exhibit some species-specific peculiarities that make each of them suitable for addressing particular chronobiological questions. Although ultradian rhythms have been described for Tetrahymena thermophila and Euglena gracilis, they appear under different conditions: in the first case, a modulation of the period in relation to the concentration of nutrients is observed, whereas Euglena oscillates in an ultradian and circadian fashion simultaneously. Transitions between periodic and aperiodic states can be induced in Euglena gracilis and Gonyaulax polyedra: Euglena gracilis can enter an aperiodic state after repeated exposure to short light pulses (up to I 0 sec) given at intervals of 40 min or less, whereas in Gonyaulax polyedra the circadian oscillator is arrested at temperatures below 12 degrees Celsius. In the arrhythmic state, the oscillator might be driven into singularity within the phase space of a limit cycle attractor; re-initiation from the holding point occurs by transition to a relatively precisely defined new phase. Photoperiodism as another important chronobiological phenomenon can be studied in Gonyaulax polyedra: cells enter the dormant stage of an asexual cyst under short days and a temperature below 16 degrees Celsius. This response can be mimicked by 5-methoxylated indoleamines such as melatonin and 5-methoxytryptamine, which are synthesized by this organism. Melatonin concentration exhibits an endogenous circadian rhythm characterized by a rapid increase shortly after the onset of darkness. Encystment, as induced by indoleamines, is associated with stimulations of bioluminescence. The coupling of the two processes involves, as a common element, the release of protons from an acidic vacuole.

Estudo comparativo da flora Euglenaceae pigmentadas (euglenophyceae) de lagos do Parque Estadual das Fontes do Ipiranga. Säo Paulo, SP

Estudos de Euglenaceae pigmentadas relacionados a aspectos taxonômicos, ecológicos e sanitários foram realizados em Lagos do Parque Estadual das Fontes do Ipiranga, situado na cidade e Estado de Säo Paulo. Procurou-se comparar um ambiente que recebe grande quantidade de matéria orgânica (localizado no Parque Zoológico) com outro mais protegido (localizado no Jardim Botânico). Identificaram-se 53 táxons infragenéricos, que foram classificados em cinco gêneros (Euglena, Lepocinclis, Phacus, Strombomonas e Trachelomonas). No estudo ecológico procurou-se caracterizar o ambiente onde vive este grupo de organismos e, consequentemente, permitir o maior aproveitamento de sua potencialidade como indicadores biológicos de poluiçäo orgânica carbona da água. Constatou-se que os principais fatores físicos e químicos que interferem na proliferaçäo de Euglenaceae pigmentadas nas estaçöes 1 e 2 foram, ao que tudo indica, a temperatura da água, o pH, a amônia, o oxigênio dissolvido e a matéria orgânica carbonada, pois observou-se maior proliferaçäo dos organismos quando os valores dessas variáveis foram respectivamente, 21,5 a 23,0-C, 6,2 a 6,3, 1,7 a 1,9mg/l, 1,86 a 1,98mg e 7,3 a 11,0mg/l. Os dados obtidos do estudo sanitário foram discutidos e comparados com os da literatura, procurando-se classificar os organismos estudados em vários dos sistemas sapróbicos vigentes. Assim, sugere-se o uso eventual de Euglena communis Gojdics, Euglena polymorpha Dangeard e de Strombomonas ovalis (Playfair) Deflandre como indicadores biológicos de poluiçäo orgânica da água, desde que os valores da análise qualitativa estejam ao redor de 600org./ml.10-4