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Browsing Faculty of Science by Subject "Chemistry"
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- ItemA preliminary study on bioactivities of Agave Vera - Cruz leaf extract(University of Peradeniya, 2011-11-24) Karunaratne, K. U; Ranawana, K. B; Wickramasinghe, AAgave vera-cruz is a perennial plant with large, spine-tipped leaves and short thick stems. It belongs to the family Agavaceae. It appears to be well established in Badulla, Nuwara Eliya and Kandy districts. Fibre obtained from this plant is used to make ropes, baskets and cloths. Freshly ground leaves of Agave vera-cruz are currently used as a piscicidal agent in fishing by remote farmers in the Knuckles region. The present study is an attempt to evaluate bioactive properties of Agave vera-cruz. Antioxidant, cytotoxic and phytotoxic properties were investigated. Plant materials were collected from Wattappola in Paranapattiya area. Freeze- dried plant materials were ground into a powder and extracted into methanol (MeOH). Concentrated crude extract was subjected to bioassay. Phytotoxic activity against Lactuca sativa, cytotoxic activity against Artemia salina and antioxidant activity were evaluated. Fractionation involved the use of VLC chromatography using Merck 9385 (40-63 Jim) silica gel, gravity column chromatography using 7734 Merck silica gel (63-200 ,urn) and analytical thin layer chromatography. LD50 value for cytotoxic bioassay was 675 ppm for the MeOH extract. IC50 value for the DPPH radical assay was 62.0 ppm. IC50 value for shoot inhibition was 1000 ppm and that for root inhibition was 1800 ppm. These results show that there are some allelopathic compounds present in Agave vera-cruz.
- ItemA preliminary study on bioactivities of Agave Vera - cruz leaf extract(University of Peradeniya, 2024-11-24) Karunaratne, K. U; Ranawana, K. B; Wickramasinghe, AAgave vera-cruz is a perennial plant with large, spine-tipped leaves and short thick stems. It belongs to the family Agavaceae. It appears to be well established in Badulla, Nuwara Eliya and Kandy districts. Fibre obtained from this plant is used to make ropes, baskets and cloths. Freshly ground leaves of Agave vera-cruz are currently used as a piscicidal agent in fishing by remote farmers in the Knuckles region. The present study is an attempt to evaluate bioactive properties of Agave vera-cruz. Antioxidant, cytotoxic and phytotoxic properties were investigated. Plant materials were collected from Wattappola in Paranapattiya area. Freeze- dried plant materials were ground into a powder and extracted into methanol (MeOH). Concentrated crude extract was subjected to bioassay. Phytotoxic activity against Lactuca sativa, cytotoxic activity against Artemia salina and antioxidant activity were evaluated. Fractionation involved the use of VLC chromatography using Merck 9385 (40-63 Jim) silica gel, gravity column chromatography using 7734 Merck silica gel (63-200 ,urn) and analytical thin layer chromatography. LD50 value for cytotoxic bioassay was 675 ppm for the MeOH extract. IC50 value for the DPPH radical assay was 62.0 ppm. IC50 value for shoot inhibition was 1000 ppm and that for root inhibition was 1800 ppm. These results show that there are some allelopathic compounds present in Agave vera-cruz.
- ItemAllelopathic activity studies of Sri Lankan flora and chemical investigation of endophytic fungi and terrestrial STREPTOMYCES species(University of Peradeniya, 2011) Piyasena, K. G. N. P.he first part of the present investigation is focused on the search for the allelopathic active compounds from Sri Lankan plants, with the hope of using them as herbicides. In order to trace allelopathic activity, seed germination inhibition bioassay was employed, using lettuce (Lactuca sativa) and barnyard grass (Echinochloa crus-gall) seeds. Out of 60 plant extracts tested, 14 plant extracts significantly reduced radicle growth of lettuce seeds and bamyard grass seeds. Considering preliminary activity results, the ariel parts of Mikania scandens and the bark of Canarium zeylanicum were selected for further chemical and biological investigation, with the aim of isolating allelochemicals, which are responsible for the above activity. Activity guided fractionation of the M. scandens extract led to the isolation of highly active compound mikanolide which showed lettuce seed inhibition activity at MIC 25.0 pg/mL. Activity guided fractionation of the C. zeylanicum bark extract led to the isolation of two compounds 13- hydroxy-12-methoxy-8, 1 1,13-podocarpatrien-3-one and 38-OAc,28-COOH acetyl aleuritolic acid. As M_ scandens is a highly abundant invasive plant in Sri Lanka, either this plant in crude form or as mikanolide in pure form could be developed as an environmental friendly herbicides in Sri Lanka. The second part of the present study was focused on chemical investigation of endophytic microorganisms, especially fungi and terrestrial Streptomyces, with the aim of isolating biologically active compounds. In this process, isolated fungi were cultivated, extracted, and tested for biological activities. According to the chemical and biological screening nine endophytic fungal strains and three terrestrial Streptomyces strains were selected for further chemical investigation. From these strains, seventy compounds were isolated using chromatographic techniques. Of them seven compounds were found to be new. They are hydroxy-2-isocyanatebenzoic acid, 2-isocyanate-3-methoxy-benzoic acid, 5,6-dimethyl-2, 3- dihydro-phthalazine-1,4-dione, tectariamide, 1,3,5,7-tetraaza-tricyclo[6.6.1.0*4,15*]pentade ca- 2,4 (15),5,7-tetraene, 2-phenyl-2H-pyrazolo[3,4-d] pyrimidine and N-(chloro-1, 3, 4, 5, 6- pentahydroxyl-hexyl)acetamide. Structural elucidation of the new compounds and other isolates were carried out with the help spectroscopic analysis, x-ray analysis, comparison with literature data and the help of AntiBase data base. Antibacterial activity of above compounds was tested against five control strains FE. coli (ATCC25922), Pseudomonas aeruginosa (ATCC27853), Enterococci faecalis (ATCC 29212), Bacillus subtilis (ATCC6051), Streptomyces viridochromogenes (Ti 57) and Staphylococcus aureus (ATCC29213) using a disk diffusion method (40 yg/disk). Of them, cercosporamide, beauvericin and altertoxin I showed the highest activity against Bacillus subtilis and E. coli. Antifungal activity of isolates were tested against strains of human pathogenic fungus Candida albicans and plant pathogenic fungi Rhizoctonia solani and Pythium ultimum, using disk diffusion method. Glaucanic acid and beauvericin showed the highest activity against Candida albicans. Algaecide activity of isolates was tested against strains of three microalgae; Chlorellavulgaris, Chlorella sorokiniana, and Scenedesmus subspicatus were used in this study. Of them, only julichrome Q3,3 showed activity against Chlorella vulgaris.
- ItemDiscovery of a Novel Ferrielectric subphase of Five-Laye Periodicity in Binary Mixtures of Chiral Smetic Reversed Phase Sequence(University of Pearadeniya, 2011) Chandani, A. D. L.; Fukuda, Atsuo; Kumar, S.; Jagdish, K. VijIn a binary mixture system of ferroelectric and antiferroelectric liquid crystals whose major component shows an unusual reversed phase sequence of SmC∗A(1/2)−SmC∗, a new phase with ferrielectric order of five layers has been discovered by the electric field-induced birefringence (EFIB) measurements. The EFIB was measured using a photo-elastic modulator (PEM) set-up and by applying an in-plane electric field to a homeotropic aligned cell filled with the binary mixtures of compounds with ferroelectric and antiferroelectric compounds. The contours of constant birefringence in the electric field–temperature (E–T) phase diagrams clearly indicate a distinct region corresponding to a new phase bordering the four-layer SmC∗(1/2) on the low temperature side and SmC∗α on the high temperature side. This new phase is unambiguously assigned to SmC∗(3/5) whose structure has been calculated by Osipov and Gorkunov.