Neelma Munir

Evaluation of antifungal and antioxidant potential of two medicinal plants: Aconitum heterophyllum and Polygonum bistorta

ABSTRACT Objective To focus on the evaluation of antimicrobial and antioxidant activity of two endangered medicinal plants Aconitum heterophyllum (A. heterophyllum) and Polygonum bistorta (P. bistorta). Materials Plant extracts were obtained by using microwave assisted extraction method. The in vitro antifungal activity of A. heterophyllum and P. bistorta extracts were determined by measuring diameters of inhibitory zones of these extracts against Aspergillus niger and Alternalia solani. Results Methanolic extract of A. heterophyllum showed significant (P≤0.05) antifungal activity against both the tested organisms. It was also observed that ethanolic extracts of P. bistorta also had good antifungal activity against the tested fungal strains as compared to the methanolic extracts. It showed significant antifungal activity (P≤0.05) against both the tested strains. Antioxidant activity of methanolic and ethanolic extracts of A. heterophyllum and P. bistorta were also measured using a radical scavenging method. Ascorbic acid was used as a standard. Conclusions It was observed that A. heterophyllum and P. bistorta have significant antioxidant activity. Higher antioxidant activity was recorded in methanolic extract of A. heterophyllum as compared to its ethanolic extract. However, in case of P. bistorta ethanolic extract of the plant exhibited higher antioxidant potential than methanolic extracts. Hence both of these plants have significant antimicrobial as well as antioxidant potential.

Molecular characterisation of Bacillus chitinase for bioconversion of chitin waste

In this work chitin was extracted chemically from shrimp shells. Seventeen Bacillus isolates were screened for chitinolytic activity. The chitinolytic strains of Bt. were screened at different temperatures and pHs for their hydrolytic potentials. By using a pair of specific primers, endochitinase gene was amplified from SBS Bt-5 strain through PCR, and then cloned into pTZ57 TA cloning vector and transferred in Escherichia coli DH5α strain. The sequenced gene (GenBank Accession No: HE995800) consists of 2031 nucleotides capable of encoding 676 residues. The protein consisted of three functional domains with a calculated molecular mass of 74.53 kDa and a pI value of 5.83. The amino acid sequence of chi gene showed 99% similarity to the genes of Bt MR11 endochitinase, Bt serovar kurstaki chitinase (kchi), Bt strain MR21 endochitinase and Bacillus cereus B4264.

Mass cultivation of various algal species and their evaluation as a potential candidate for lipid production

Microalgae have been proposed as a promising source for biodiesel production. Focusing on algal strains for biodiesel production, efforts should be made to search new strains. Experiments were carried out to investigate the effects of growth parameters (nutrients, pH, light, aeration and temperature) and the oil percentage of eight algal strains (Chlorella sp., Cladophora sp., Hydrodictylium sp., Oedogonium sp., Oscillatoria sp., Spirogyra sp., Stigeocolonium sp., Ulothrix sp.). Results show that 6.5–7.5 is the optimum pH for the growth of all algal species. Temperature showed a greater variation (25°40°C). Ulothrix sp. gave more biomass productivity and is the most suitable strain for biodiesel production due to higher oil percentage (62%). Least biomass production was observed for Stigeocolonium sp. and least oil content was obtained from Hydrodictylium sp. It was observed that among these eight algal strains for biodiesel production, Ulothrix and Chlorella are the most promising algae species.

In vitro evaluation of mutagenicity and genotoxicity of sitagliptin alone and in combination with artificial sweeteners

Purpose: To determine the in vitro genotoxicity and mutagenicity of sitagliptin alone and in combination with three commonly used artificial sweeteners (saccharin, aspartame and acesulfame-k). Methods: The in vitro genotoxicity and mutagenicity of Sitagliptin alone and in combination with three popular artificial sweeteners (saccharin, aspartame and acesulfame-k) were evaluated by Comet and Ames assays, respectively. Results: Sitagliptin demonstrated mutagenic potential only to TA 98 with S9 mix at a concentration of 3040 μg/plate. The mutagenicity of sitagliptin was enhanced when tested in combination with the artificial sweeteners. Furthermore, sitagliptin also caused pronounced DNA fragmentation at higher doses compared with negative control. Conclusion: At higher doses, sitagliptin showed both mutagenicity and genotoxicity. Thus, long-term use of artificial sweeteners with sitagliptin may lead to increase in both mutagenicity and genotoxicity. Keywords: Sitagliptin, Artificial sweeteners, Comet assay, DNA damage, Ames assay, Genotoxicity, Mutagenicity

Origin of Algae and Their Plastids

Abstract Algae are of central importance in marine and freshwater ecosystems; however, their origin has remained an enigma. Recent molecular sequence analyses show that algae are of polyphyletic origins, and that their evolution is best explained by tracing the endosymbiotic events, which resulted in the origins of their plastids. Plastid is a major double-membrane cytoplasmic semiautonomous organelles, it synthesize or store various types of organic compounds. Plastids are derived from endosymbiotic event through a complex mix of movement, loss and replacement, non-photosynthetic plastids are being found in many non-photosynthetic lineages. In other cases, photosynthetic lineages have evolved from ancestors with a plastid of different origin, so an ancestral plastid has been replaced with a new one. On the basis of origin of algae and their plastids, the four distinct groups of algae include prokaryotes—the cyanobacteria; chloroplast-containing eukaryotic algae with one membrane of chloroplast endoplasmic reticulum (ER); chloroplast-containing eukaryotic algae that are surrounded by two membranes of chloroplast ER; and chloroplast-containing eukaryotic algae that are surrounded by two membranes of the chloroplast envelope. Fatty acids, heme, amino acids, and aromatic isoprenoids are some of the significant compounds synthesized by algal plastids through photosynthetic and biochemical pathways.