Fruits of Sonneratia caseolaris Linn. have many therapeutic applications in folklore medicine. However, chemical examination and biological activity of its fruit are less studied. During the work on ...identification of antidiabetic principles from Indian mangrove flora, we noticed moderate intestinal ? -glucosidase inhibitory activity of the methanolic extract of its fruits. Three compounds namely oleanolic acid, ? -sistosterol- ? -D-glucopyranoside and luteolin were isolated and identified from the bioactive methanolic extract. In vitro pre-incubation of crude rat intestinal ? -glucosidase with oleanolic acid showed potent ? -glucosidase inhibitory (IC50 = 15 ? M) activity, however, its inhibitory potential decreased drastically when oleanolic acid was pre-incubated with substrate. In in vivo studies also, pretreatment of rats with oleanolic acid displayed significant (p<0.05) antihyperglycemic activity in starch tolerance test however, administration of starch fortified with oleanolic acid to the rats could not exhibit antihyperglycemic activity. This is the first report identifying oleanolic acid in S. caseolaris fruits in substantial yield and assigning its intestinal ?-glucosidase inhibitory and antihyperglycemic activities. This study also highlights the fact that the mode of incubation in in vitro experiments and administration of active principles isolated from natural medicinal plants in in vivo studies play important role in revealing various facets of their biological activities and therapeutic implications.
Background: The uneven distribution of recombination across the length of chromosomes results in inaccurate estimates of genetic to physical distances. In wheat (Triticum aestivum L.) chromosome 3B, ...it has been estimated that 90% of the cross over events occur in distal sub-telomeric regions representing 40% of the chromosome. Radiation hybrid (RH) mapping which does not rely on recombination is a strategy to map genomes and has been widely employed in animal species and more recently in some plants. RH maps have been proposed to provide i) higher and ii) more uniform resolution than genetic maps, and iii) to be independent of the distribution patterns observed for meiotic recombination. An in vivo RH panel was generated for mapping chromosome 3B of wheat in an attempt to provide a complete scaffold for this similar to 1 Gb segment of the genome and compare the resolution to previous genetic maps. Results: A high density RH map with 541 marker loci anchored to chromosome 3B spanning a total distance of 1871.9 cR was generated. Detailed comparisons with a genetic map of similar quality confirmed that i) the overall resolution of the RH map was 10.5 fold higher and ii) six fold more uniform. A significant interaction (r = 0.879 at p = 0.01) was observed between the DNA repair mechanism and the distribution of crossing-over events. This observation could be explained by accepting the possibility that the DNA repair mechanism in somatic cells is affected by the chromatin state in a way similar to the effect that chromatin state has on recombination frequencies in gametic cells. Conclusions: The RH data presented here support for the first time in vivo the hypothesis of non-casual interaction between recombination hot-spots and DNA repair. Further, two major hypotheses are presented on how chromatin compactness could affect the DNA repair mechanism. Since the initial RH application 37 years ago, we were able to show for the first time that the iii) third hypothesis of RH mapping might not be entirely correct.
Background: The uneven distribution of recombination across the length of chromosomes results in inaccurate estimates of genetic to physical distances. In wheat (Triticum aestivum L.) chromosome 3B, ...it has been estimated that 90% of the cross over events occur in distal sub-telomeric regions representing 40% of the chromosome. Radiation hybrid (RH) mapping which does not rely on recombination is a strategy to map genomes and has been widely employed in animal species and more recently in some plants. RH maps have been proposed to provide i) higher and ii) more uniform resolution than genetic maps, and iii) to be independent of the distribution patterns observed for meiotic recombination. An in vivo RH panel was generated for mapping chromosome 3B of wheat in an attempt to provide a complete scaffold for this similar to 1 Gb segment of the genome and compare the resolution to previous genetic maps. Results: A high density RH map with 541 marker loci anchored to chromosome 3B spanning a total distance of 1871.9 cR was generated. Detailed comparisons with a genetic map of similar quality confirmed that i) the overall resolution of the RH map was 10.5 fold higher and ii) six fold more uniform. A significant interaction (r = 0.879 at p = 0.01) was observed between the DNA repair mechanism and the distribution of crossing-over events. This observation could be explained by accepting the possibility that the DNA repair mechanism in somatic cells is affected by the chromatin state in a way similar to the effect that chromatin state has on recombination frequencies in gametic cells. Conclusions: The RH data presented here support for the first time in vivo the hypothesis of non-casual interaction between recombination hot-spots and DNA repair. Further, two major hypotheses are presented on how chromatin compactness could affect the DNA repair mechanism. Since the initial RH application 37 years ago, we were able to show for the first time that the iii) third hypothesis of RH mapping might not be entirely correct.
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