Abstract:Silver nanoparticles, endowed with powerful antimicrobial property, are the most widely used nanomaterial in consumer products, with associated risk of their easy access to environment and freshwater ecosystems by surface runoff. Although toxic effects of nanosilver on bacterial, fungal and mammalian cells have been documented, its impact on algal growth remains unknown. Pithophora oedogonia and Chara vulgaris are predominant members of photosynthetic eukaryotic algae, which form major component of global aquatic ecosystem. Here we report for the first time that nanosilver has significant adverse effects on growth and morphology of these filamentous green algae in a dose-dependent manner. Exposure of algal thalli to increasing concentrations of silver nanoparticles resulted in progressive depletion in algal chlorophyll content, chromosome instability and mitotic disturbance, associated with morphological malformations in algal filaments. SEM micrographs revealed dramatic alterations in cell wall in nanoparticle-treated algae, characterized with cell wall rupture and degradation in Pithophora. Although these observations underscore severe deleterious effects of nanosilver on aquatic environment, the information can also be exploited as a bioengineering strategy to control unwanted and persistent growth of noxious algal weeds that clog the municipal water supply and water channels and produce fouling of water bodies.

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Gymnema sylvestre Wild R.Br (family: Asclepidaceae) is a valuable medicinal plant used in folk medicine to treat diabetes, obesity, asthma etc. in India for antiquity. Diabetes mellitus is a syndrome characterized immunologically by lymphocyte apoptosis and reduced cell-mediated and humoral immunity. Modulation of immune responses to alleviate diseases has been of interest, and traditional herbal medicines may play an important role in this regard. In this study, we aim to evaluate the immunomodulatory potential of methanolic extract of G. sylvestre leaf using rat model. HPLC analysis of leaf extract was carried out for gymnemic acid. The method involves the initial hydrolysis of gymnemic acids, the active ingredients, to a common aglycone followed by the quantitative estimation of gymnemagenin, using gymnemagenin as reference standard. Gymnemic acid content was 2.40% (w/w) in G. sylvestre leaf extract. In vitro immunomodulatory activity of the methanolic extract of G. sylvestre leaf (1–200μg/ml) was evaluated by gauging its effects on nitroblue tetrazolium reduction and nitrite release in rat peritoneal macrophages and on mitogen (ConA, PHA and LPS) induced splenic lymphocyte proliferation. G. sylvestre leaf extract showed significant (<0.05) enhancement in NO and ROS generation in macrophages and in proliferation of lymphocytes in dose dependent manner. EC50 value was 3.10, 3.75 and 2.68μg/ml for NBT reduction, nitrite release and lymphoproliferation, respectively. Potential effect was observed at 100 μg/ml in NO and ROS generation in macrophages and 20 μg/ml in lymphocyte proliferation. G. sylvestre leaf extract stimulates macrophage reactivity, increasing the level of activity even higher when combined with PMA or LPS. These findings suggest the presence of active compounds, gymnemic acid, in methanolic extract of G. sylvestre leaf that stimulates both myeloid and lymphoid components of immune system, and therefore can restore the innate immune function. Through this study, the traditional knowledge of anti-diabetic property of G. sylvestre is scientifically supplemented with its immunomodulatory properties.

Schizomeris leibleinii KUTZ was collected from Debra Dun as well as from Varanasi and the observations on its morphology, asexual reproduction and cytology were made by using material from nature and in culture .

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