Qualitative Phytochemical Screening, Anti-Bacterial Activity and TLC Profiling of Different Parts of Three Medicinal Plants

The aim of this study was to carry out phytochemical screening Anti-bacterial activity and TLC profiling of sequentially extracted petroleum ether, dichloromethane, ethyl acetate and methanol extracts of leaf and barks of the Nerium oleander, Leaf, bark and seeds of Cascabela thevetia and Cerbera odollum. The phytochemical analysis of the extracts obtained from different solvents was carried and Ant-bacterial activity was carried out for all the extractions at 25 mg/ml and 50 mg/ml test concentration against E.coli and S.aureus bacteria by well diffusion method. All the tested extractions showed low activity against both bacteria at 25mg/ml compared with 50mg/ml. Results were subjected to one way (ANOVA) and followed by Tukey’s test (P < 0.05). All the extractions of all plant materials showed in bioactivity against E.coli and S.aureus bacteria at 50 mg/ml among them. The statistical analysis revealed that anti-bacterial activity of the ethyl acetate extracts of C.thevetia leaves and N.oleander barks against E.coli bacteria and Methanol extract of Nerium oleander leaves and ethyl acetate extracts of C.thevetia bark against S.aureus bacteria were comparable with the positive control Amoxicillin. TLC profiling was carried out using a various solvent system of varying polarity for all sequential extractions and obtained different retention factor (Rf) values of different phytochemicals. KEYWORDS: Phytochemical analysis, Antibacterial activity, Thin-layer chromatographic profiling, Sequential extractions, Cascabela thevetia and Cerbera odollu

A Study on Hydrogen Peroxide Scavenging Activity and Ferric Reducing Ability of Simple Coumarins

Coumarin compounds are δ-lactones where α-pyrone ring is fused with benzene ring. Coumarins are widely distributed in the plant kingdom as well as they are very important in synthetic organic chemistry. Coumarins have great interest because of their abundance in nature and diverse pharmacological activities including antibacterial, antiviral, antipyretic, and anticoagulant, antioxidant, anti-inflammatory and anticancer. This study focused on synthesizing different simple Coumarins and studying their antioxidant activity. Four simple Coumarins (Coumarin (C1), 4-hydroxy coumarin (C2), 7-hydroxy coumarin (C3) and 7-hydoxy-4-methyl coumarin (C4)) were synthesized by using standard methods and were characterized by using UV, IR, 1H and 13C NMR spectra. Antioxidant activity of the simple Coumarins was studied by using standard FRAP assay and Hydrogen peroxide assay and expressed as FRAP value (mmol Fe2+/g) and IC50 value (mg/dm-3) respectively. Ascorbic acid was used as standard. All synthesized simple Coumarins showed both antioxidant activities. Hydroxyl Coumarins (C2, C3 and C4) showed higher activities in both cases than C1. Among the hydroxyl Coumarins C3 showed highest hydrogen peroxide scavenging activity and Ferric reducing capacity too. Antioxidant power of the tested simple Coumarins in decreasing order was C3, C2, C4 and C1 in both cases. But the hydrogen peroxide scavenging activity and Ferric reducing capacity of the all synthesized simple Coumarins were lower when compared to standard ascorbic acid

Green Synthesis of Silver Nanoparticles from the Extracts of Fruit Peel of Citrus tangerina, Citrus sinensis, and Citrus limon for Antibacterial Activities

Wide application of nanoparticles motivates the need for synthesising them. Here, a nontoxic, eco-friendly, and cost-effective method has been established for the synthesis of silver nanoparticles using extracts of lemon peel (Citrus limon), green orange peel (Citrus sinensis), and orange peel (Citrus tangerina). The synthesised nanoparticles have been characterised using UV-visible absorptionspectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy (TEM). The UV-visible absorption spectrum of these synthesised silver nanoparticles shows an absorption peak at around 440 nm. TEM images show different shaped particles with various sizes. Furthermore, the antibacterial activity of silver nanoparticles was appraised by a well-diffusion method and it was observed that the green synthesised silver nanoparticles have an effective antibacterial activity against Escherichia coli and Staphylococcus aureus. The outcome of this study could be beneficial for nanotechnology-based biomedical applications

Multiscale analysis of land use and land cover changes in Sri Lanka by remote sensing: the impacts of post-war infrastructure development in the last 20 Years (2002-2022)

International audienceOn a worldwide scale, land use and land cover changes (LULCC) is a major driver of global change and biodiversity erosion. This study aims to monitor at the scale of Sri Lanka, LULCC and vegetation dynamics, to identify the main changes and their drivers. It places emphasis on multiscale geospatial monitoring with satellite data but also mobilises the interdisciplinary knowledge of a research programme. First, national scale data allows the identification of major changes with the MODIS NDVI dataset using Mann-Kendall tests and time profile analysis. A second local scale was mobilised with a systematic diachronic visual interpretation of high-resolution images on Google Earth. The third step, a macro-regional scale focus on the South and East coasts, used LANDSAT imagery (Stacked K-means) verified by field studies (botanical and vegetation analysis, and interviews). About 92.5% of the island of Sri Lanka is stable or presents no significant trends in the vegetation cover. 5% show a significant positive (greening) trend between 2000 and 2020 around the Puttalam lagoon, west of the Samanalawewa Reservoir, in the Udawalawe National Park, east and north of Ella, and the Nuwaragala Forest Reserve. Only about 2.5% (165,000 ha) of the Island shows a negative significant trend mainly in the periphery of Colombo and Trincomalee. The first driver is a set of national planning decisions in terms of infrastructure development (including urban growth, housing programmes and agricultural fields, and the management of protected areas). The second driver comes under rural dynamics with increasing tree density in rural landscapes over the Uva Province. Infrastructure development initiated by the state, creates both underlying conditions for other activities and negative impacts on coastal ecosystems, such as degradation of wetlands (including protected areas)