Browsing by Author "Sathyadevi, Palanisamy"

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Assessment of a diketopiperazine, cyclo(Trp-Phe) from Streptomyces griseoplanus SAI-25 against cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)
(2016-02-01)
Sathya, Arumugam
;
Vijayabharathi, Rajendran
;
Kumari, Bhimineni Ratna
;
Srinivas, Vadlamudi
;
Sharma, Hari C.
Microorganisms produce a range of metabolites with varying pest control properties. With this concept, we earlier identified 15 Streptomyces spp. strains with insecticidal activity against Helicoverpa armigera (Hubner), Spodoptera litura (Fabricius), and Chilo partellus (Swinhoe). In recent studies, we evaluated an insecticidal compound purified from the extracellular extract of S. griseoplanus SAI-25 by bioactivity-guided fractionation against H. armigera. Spectral studies by infrared (IR), nuclear magnetic resonance (NMR), and electron spray ionization mass spectroscopy (ESI-MS) confirmed that the purified compound was cyclo(Trp-Phe) of the diketopiperazines class. Cyclo(Trp-Phe) exhibited antifeedant (70 %), larvicidal (67 %), and pupicidal (59 %) action against H. armigera in a dose-dependent manner. The lethal dose for 50 % of the group (LD50) and LD90 values for larvicidal effect were 619 and 2750 ppm, respectively. In addition, the purified compound prolonged larval (10.3-11.1 days) and pupal (10.9-11.8 days) periods compared with the untreated control (larval duration 9.8 days, pupal duration 10.6 days). This is the first report on the presence and biological activity of cyclo(Trp-Phe) isolated from the genus Streptomyces.
Reaction-based epoxide fluorescent probe for in vivo visualization of hydrogen sulfide
(2015-06-15)
Sathyadevi, Palanisamy
;
Chen, Yu-Jen
;
Wu, Shou-Cheng
;
Chen, Yen-Hao
;
Wang, Yun-Ming
Hydrogen sulfide (H2S) has emerged as the most important biosynthetic gasotransmitters along with nitric oxide (NO) and carbon monoxide (CO). In this study, we report the design and the synthesis of a new epoxide fluorescent probe 7-glycidyloxy-9-(2-glycidyloxycarbonylphenyl)-2-xanthone (FEPO) for use in in vivo visualization of hydrogen sulfide. The probe employs a fluorescein as a fluorophore, and is equipped with an operating epoxide unit. FEPO functions via epoxide ring opening upon nucleophilic attack of H2S. This ring opening strategy may open a new avenue for the development of various H2S fluorescent sensors. FEPO showed high selectivity and high sensitivity for H2S. FEPO\'s cytotoxicity was tested using MTT (2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide) assay. Furthermore, the use of confocal imaging of H2S and in vivo imaging in live zebra fish demonstrated FEPO\'s potential biological applications. We anticipate that, owing to their ideal properties, probes of this type will find great uses in exploring the role of H2S in biology. (C) 2015 Elsevier B.V. All rights reserved.