Srabanti Basu

Hypoglycemic activity of the antioxidant saponarin, characterized as α-glucosidase inhibitor present in Tinospora cordifolia

Tinospora cordifolia, used in anti-diabetic herbal drug preparations, was reported [12] to contain an α-glucosidase inhibitor, characterized as saponarin (apigenin-6-C-glucosyl-7-O-glucoside). The leaf extract had appreciable antioxidant and hydroxyl radical scavenging activities and contained the flavonoid in the range of 32.1 ± 1.5–45.5 ± 3.5 mg/g of dry solid. Saponarin showed mixed competitive inhibition on activities of α-glucosidase and sucrase of different origins. IC50, Ki and ki′ values determined were 48 μM, 8 μM and 19.5 μM respectively for intestinal maltase and 35 μM, 6 μM and 13 μM respectively for intestinal sucrase. When given orally to maltose-fed rat, saponarin showed hypoglycemic activity in the range of 20–80 mg/kg compared to 100–200 mg/kg for acarbose as reported [27].

Removal of mercury from its aqueous solution using charcoal-immobilized papain (CIP).

In the present work mercury has been eradicated from its aqueous solution using papain, immobilized on activated charcoal by physical adsorption method. Operating parameters for adsorption of papain on activated charcoal like pH, amount of activated charcoal, initial concentration of papain in solution have been varied in a suitable manner for standardization of operating conditions for obtaining the best immobilized papain sample based on their specific enzymatic activity. The immobilized papain sample obtained at initial papain concentration 40.0 g/L, activated charcoal amount 0.5 g and pH 7 shows the best specific enzymatic activity. This sample has been designated as charcoal-immobilized papain (CIP) and used for further studies of mercury removal. Adsorption equilibrium data fit most satisfactorily with the Langmuir isotherm model for adsorption of papain on activated charcoal. Physicochemical characterization of CIP has been done. The removal of mercury from its simulated solution of mercuric chloride using CIP has been studied in a lab-scale batch contactor. The operating parameters viz., the initial concentration of mercury in solution, amount of CIP and pH have been varied in a prescribed manner. Maximum removal achieved in the batch study was about 99.4% at pH 7, when initial metal concentration and weight of CIP were 20.0mg/L and 0.03 g respectively. Finally, the study of desorption of mercury has been performed at different pH values for assessment of recovery process of mercury. The results thus obtained have been found to be satisfactory.

Removal of mercury (II) from aqueous solution using papain immobilized on alginate bead: Optimization of immobilization condition and modeling of removal study

Papain having the characteristics of metal binding ability is immobilized on alginate bead. Design Expert Software (Version 7.1.6) uses Response Surface Methodology (RSM) for statistical designing of operating condition for immobilization of papain on alginate bead considering concentration of papain, concentration of sodium alginate, concentration of calcium chloride and pH as numeric factors and Specific Enzymatic Activity (SEA) of immobilized papain sample as response. Immobilization using 25.96 g/L papain, 20 g/L sodium alginate and 20 g/L calcium chloride at pH 7 gives the desired product as indicated by ANOVA (Analysis of Variance). Three parameters viz., initial concentration of mercury (II), amount of AIP and pH are varied in a systematic manner. Maximum 98.88% removal of mercury (II) has been achieved within 8 min when simulated aqueous solution of mercury (II) with initial concentration of 10mg/L has been contacted with 5 g of AIP at pH 9 and at 35 degrees C in a batch contactor. A mathematical model has been developed and the value of equilibrium constant for binding of mercury (II) with AIP has been found to be 126797.3.

Performance Study of Chromium (VI) Removal in Presence of Phenol in a Continuous Packed Bed Reactor by Escherichia coli Isolated from East Calcutta Wetlands

Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI) in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI) from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI)-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI) in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7.

Removal of Chromium (VI) by Bacillus subtilis Isolated from East Calcutta Wetlands, West Bengal, India

Chromium (VI), one of the major pollutants released from tanneries, dye and textile industries, is highly toxic and carcinogenic in nature. Chemical methods for bulk treatment of industrial effluents often fail to reduce the level to meet the environmental regulations. For end of the pipe treatment, bioremediation is considered a better alternative. East Calcutta Wetlands, the major sewage treatment site of Kolkata (previously known as Calcutta), has been reported to be contaminated with several heavy metals including chromium (VI). Therefore, there is a possibility that bacterial population of this region can tolerate chromium (VI) and would be useful for bioremediation of chromium (VI). A strain of Bacillus subtilis isolated from this region was grown in presence of chromium (VI) (2.5 g/L–7.5 5 g/L). There were 97% and 90% reduction of residual chromium concentration in growth media after 24 hours with initial concentrations of 2.5 g/L and 5 g/L respectively. Best removal was observed at 30C. Growth of the Bacillus strain in presence of chromium (VI) was found to be best fit for Tessier model by non-linear regression analysis using MATLAB® 7.4. The Bacillus strain has the potential for the end of the pipe treatment removal of chromium (VI).

Studies on removal of lead(II) by Alginate Immobilized Bromelain (AIB)

AbstractThe work is based on augmentation of active sites of calcium alginate bead by immobilizing bromelain to remove lead(II) from simulated solution. The optimum immobilization condition as specified by response surface methodology is as follows: initial concentration of sodium alginate, bromelain, and calcium chloride are 20, 21.09, and 20 g/L, respectively, at pH 7 and 35°C and the sample, thus prepared, is termed as alginate immobilized bromelain (AIB). Maximum 99.5% lead(II) has been removed when 30 mL lead(II) solution having initial concentration of 0.0048 mmol L−1 has been treated with 5 g of AIB at pH 7 and 35°C. 77.9% lead(II) has been recovered when 1 g of spent adsorbent is stirred in 100 mL of solution having pH 2 for 30 min. The removal of lead(II) using AIB and, thereby, simultaneous inhibition of enzyme have been modeled both statistically and empirically.

Biochemical degradation of Methylene Blue using a continuous reactor packed with solid waste by E. coli and Bacillus subtilis isolated from wetland soil

AbstractEffluent from textile industries contain various azo dyes. Methylene Blue is one of the most predominant one which is hazardous for the environment and has to be degraded chemically or biochemically. A pure culture of Bacillus subtilis and E. coli cells which were already acclimatized to phenol as the sole carbon source were taken for the purpose of the present work. The rate of degradation of MB for E. coli had increased at a much slower rate than that of B. subtilis over the entire degradation period. Hence, in the batch process, overall removal efficiency of Methylene Blue by B. subtilis is higher than that of E. coli. Thus, B. subtilis was taken for further biodegradation of Methylene Blue studies in a continuous process in a counter current packed bed reactor packed with clay chips. In addition to a packing material, the clay chips also act as a whole cell immobilizing matrix for the Bacillus cells. The effect of Methylene Blue flow rate and air flow rate on percentage Methylene Blue removal ...

Process Optimization for Preparation of an Antibacterial Agent Using a Combined Extract of Tulsi and Marigold Leaves

Medicinal plants and herbs contain substances known to modern and ancient civilizations for their healing properties. India is rich in biodiversity and many of its plants are known to have medicinal properties. This paper highlights two tropical and subtropical important plants -Ocimum sanctum (tulsi) and Targetes erecta (marigold) due to their easy availability and antimicrobial effectiveness. Several studies have been done on the antimicrobial properties of the individual extracts; however, few attempts have been made to study their antimicrobial properties in combination. The present work attempts to prepare an antimicrobial agent possessing the maximum efficiency, with a combination of leaf extracts from tulsi and marigold prepared in the most suitable solvent. Objective of the present work is to optimize the preparation method of the antimicrobial product and to check the properties of the product. Propylene glycol was found to be the most suitable extraction solvent. Process for preparation of the antimicrobial agent was then optimized by Response Surface Methodology using Design Expert Software 10. The extract retained its 72% and 62% of its antibacterial activity after 35 days when preserved at 4C against E.coli and S. aureus respectively.