Impacts of COVID-19 lockdown on ambient air quality: Statistical analyses of available data on urban West Bengal (India)

Majumder, Rajib Techno-Press 2021 Advances in environmental research Vol.10 No.2

COVID-19 pandemic and consequent unavoidable lockdown left an unprecedented shock on social and economic life. Present study aimed to evaluate the impacts of COVID-19 lockdown on the ambient air quality of urban areas of eastern Indian state West Bengal. During lockdown period, Air Quality Index (AQI) was mostly found in 'Good' or 'Satisfactory' and sometimes, in 'Moderate' categories, and rarely, in 'poor' category. AQI was in 'Good' category for most of the lockdown span at Siliguri (67%) followed by Kolkata (44%), Howrah (38%) and Asansol (25%). Based on average AQI ranges: lockdown period (48.68- 62.12) < same period before 1 year (75.09-89.81) < Period 3 months before lockdown (175-206), it can be stated that AQI category was better during lockdown compared to the other two at all study areas. In Kolkata overall air pollutant levels except ozone (p>0.05) decreased significantly during lockdown. Similarly, PM_2.5, PM₁₀ and NO₂ level reduced in Howrah. Beside, no significant changes observed for NH₃ and SO₂ concentration in Howrah compared to one year before. Apart from PM_2.5, NO₂, NH₃ and SO₂ level of previous year, mean concentration of PM₁₀, CO, O₃ showed significant drop at Siliguri during lockdown. Ambient air quality parameters except SO₂ showed remarkable decline in Asansol also during lockdown. It can be concluded that COVID-19 lockdown exerted positive effects from environmental health perspective. It improved overall ambient air quality parameters of urban areas of West Bengal. Proper planning and policy making should be given utmost priority to control air pollution in the present 'new normal' COVID-19 scenario.

<i>Piper betle</i> extracts exhibit antitumor activity by augmenting antioxidant potential

ALAM, BADRUL,MAJUMDER, RAJIB,AKTER, SHAHINA,LEE, SANG-HAN D.A. Spandidos 2015 Oncology letters Vol.9 No.2

<P>The present study was conducted to evaluate the methanolic extract of <I>Piper betle</I> leaves (MPBL) and its organic fractions with regard to antitumor activity against Ehrlich ascites carcinoma (EAC) in Swiss albino mice and to confirm their antioxidant activities. At 24 h post-intraperitoneal inoculation of tumor cells into mice, extracts were administered at 25, 50 and 100 mg/kg body weight for nine consecutive days. The antitumor effects of the extracts were then assessed according to tumor volume, packed cell count, viable and non-viable tumor cell count, median survival time and increase in life span of EAC-bearing mice. Next, hematological profiles and serum biochemical parameters were calculated, and antioxidant properties were assessed by estimating lipid peroxidation, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) levels. MPBL and the ethylacetate fraction (EPBL) at a dose of 100 mg/kg induced a significant decrease in tumor volume, packed cell volume and viable cell count and increased the life span of the EAC-bearing mice (P<0.05). Hematological and serum biochemical profiles were restored to normal levels in the extract-treated mice compared with the EAC control mice. MPBL and EPBL treatment significantly decreased lipid peroxidation (P<0.05) and restored GSH, SOD and CAT levels towards normal compared with the EAC control. Taken together, the results of the present study demonstrated that <I>Piper betle</I> extracts exhibit significant antitumor activity, which may be attributed to the augmentation of endogenous antioxidant potential.</P>

In situ Reversible Aggregation of Extracellular Cellobiase in the Filamentous Fungus Termitomyces clypeatus

Samudra Prosad Banik,Swagata Pal,Shakuntala Ghorai,Sudeshna Chowdhury,Rajib Majumder,Soumya Mukherjee,Suman Khowala 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.5

Cellobiase (E.C. 3.2.1.21), is a widely exploited industrial glycosidase with a major role in biofuel industry. Its stability and shelf life are major bottlenecks in achieving a superior formulation for industry. In the filamentous fungus Termitomyces clypeatus, the enzyme is secreted in a co-aggregated form with sucrase; the separation of this co-aggregation results in substantial loss of the enzyme’s activity. The aim of the present study was to examine the mode of aggregation of the secreted cellobiase-sucrase coaggregate and its role in the stabilization of cellobiase. Transmission electron microscopy and dynamic light scattering of purified co-aggregates revealed reversible, concentration driven self-aggregation of the extracellular enzymes to form larger entities. However, the intracellular enzyme aggregates were rigid,non-interacting, and possessed a higher percentage of disulphide bonds. Circular dichroic spectra of the two coaggregates indicated no significant difference in secondary structures. Self-association increased the stability of extracellular aggregates towards heat by 1.5 fold, SDS by 4 ~ 7 fold, and chaotropic agents, by 1.5 ~ 2 fold, than the intracellular counterpart. The Km of extracellular aggregate varied between 0.29 and 0.45 mM as a result of spontaneous aggregation and disaggregation, whereas that of intracellular aggregate was 0.22 mM irrespective of its concentration status. In situ detection of cellobiase in native PAGE revealed two activity bands of the extracellular enzyme, which indicated a minimum of two active dissociated aggregate species, as compared to a single band for the intracellular enzyme. These studies are believed to improve the understanding of aggregation of the fungal glycosidases, which remains to be a blackbox, to increase the efficacy of these enzymes. Cellobiase (E.C. 3.2.1.21), is a widely exploited industrial glycosidase with a major role in biofuel industry. Its stability and shelf life are major bottlenecks in achieving a superior formulation for industry. In the filamentous fungus Termitomyces clypeatus, the enzyme is secreted in a co-aggregated form with sucrase; the separation of this co-aggregation results in substantial loss of the enzyme’s activity. The aim of the present study was to examine the mode of aggregation of the secreted cellobiase-sucrase coaggregate and its role in the stabilization of cellobiase. Transmission electron microscopy and dynamic light scattering of purified co-aggregates revealed reversible, concentration driven self-aggregation of the extracellular enzymes to form larger entities. However, the intracellular enzyme aggregates were rigid,non-interacting, and possessed a higher percentage of disulphide bonds. Circular dichroic spectra of the two coaggregates indicated no significant difference in secondary structures. Self-association increased the stability of extracellular aggregates towards heat by 1.5 fold, SDS by 4 ~ 7 fold, and chaotropic agents, by 1.5 ~ 2 fold, than the intracellular counterpart. The Km of extracellular aggregate varied between 0.29 and 0.45 mM as a result of spontaneous aggregation and disaggregation, whereas that of intracellular aggregate was 0.22 mM irrespective of its concentration status. In situ detection of cellobiase in native PAGE revealed two activity bands of the extracellular enzyme, which indicated a minimum of two active dissociated aggregate species, as compared to a single band for the intracellular enzyme. These studies are believed to improve the understanding of aggregation of the fungal glycosidases, which remains to be a blackbox, to increase the efficacy of these enzymes.