Quercetin-3-O-beta-D-glucopyranoside was isolated from the ethylacetate soluble fraction of the ethanol extract of the fresh leaves of Azadirachta indica (Family: Meliaceae). The crude extract of hexane, ethylacetate and butanol soluble fractions of this ethanol extract were subjected to antimicrobial screening and brine shrimp lethality bioassay. The ethylacetate crude extract exhibited moderate antimicrobial activity against most of the test organisms and also showed significant cytotoxicity having LC50 0.61 µg/ml.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10328Dhaka Univ. J. Sci. 60(1): 11-14, 2012 (January)

Three known compounds were isolated from the n-hexane extract of the rihzomes of Sansevieria hyacinthoides, they were two steriods; β-sitosterol (1) and daucosterol (2), and a flavonoid; isokaemferide (3). The structures of the compounds were elucidated on the basis of NMR spectral analysis as well as comparison with available data in the literature. All extracts and the three pure compounds were evaluated for their antimicrobial activity. The compounds showed moderate activity against Bacillus subtilis, Stapylococcus aureus, Salmonella typhi and Candida albicans.

The pollution due to minerals and anions in surface water and their settlement tendency on sediment of the Turag river has been studied. Higher concentration of potassium and phosphate ion in surface water and similar deposition on sediment has been recorded. The observed average concentration of Na, K, Cl-, PO4 3- in surface water and in surface sediment was 22.10, 13.20, 108.50, 17.80 mg/L and 1359.07, 2526.10, 37.50, 31.76 mg/kg, respectively. This high concentration of minerals and anions in surface water and sediments indicates that hidro-environment of the Turag river is badly affected.The minerals and ions are strongly correlated (r = 0.99) which implies that they come from similar sources and forcefully added to the river in a regular basis. Principal component analysis reveals that only one principal component is covering more than 99 % of cumulative variance. There are very few variations of parameters in the principal component to indicate that all parameters exert similar effect on hydro-environment and are contributing to deteriorate the ecological balance.These are supported by dendrogram analysis.Bangladesh J. Sci. Ind. Res.53(3), 161-168, 2018

The study was conducted to assess the concentration level of heavy metals in water of the Turag river during the months from January to March, 2014. The level of Pb, Cd, Cr, Cu, Hg and Fe ranged from 0.002-0.005 ppm, BDL (Below Detection Level)-0.03 ppm, 0.007-0.024 ppm, 0.03-0.15 ppm, BDL (Below Detection Level)-0.00024 and 0.78-6.33 ppm, respectively. The concentration level of heavy metals in water did not exceed the permissible limit except Fe. This result was obtained because of river water is always flowing and metals cannot be accumulated in flowing water. For this reason a little amount of analyzed heavy metals were traced in water samples. But heavy metals have toxic properties, leading to adverse effects on human and ecosystem health even in small doses. So, the Turag river water is not safe for using different purposes and steps should be undertaken to improve the water quality of the river.

The comprehensive study was found out to evaluate the concentration of different water qualities of the Karnaphuli river. Samples were collected from ten points (Bhandor Ghat to Bhakoliya Khal Ghat) in three seasons (winter, rainy, and spring) during the Hydrological Year 2014-2015 for continuous monitoring. Collected samples were analyzed for finding of some physicochemical parameters Temperature, pH, Alkalinity, Acidity, Total hardness, Sulfate, Chloride, Total Dissolved Solids (TDS), and CO 2 . The investigated parameters were compared to the national and international standards. The mean values of water Temperature, pH, Alkalinity, Acidity, Total hardness, Phosphorus, Sulfate, Chloride, TDS, and free CO 2 were found to be 28. 36° C, 6.25, 275.63ppm, 19.75ppm, 259.29ppm, 0.904ppm, 70.74ppm, 534.63ppm, 778.83ppm & 18.03ppm, respectively. Water Quality Index (WQI), Langelier Saturation Index (LSI) and Ryznar Stability Index (RSI) values were found to be 99.92, −3.06 & 12.36, respectively, which indicate that the water quality is not good.