title: Carotenoid stabilized gold and silver nanoparticles derived from the Actinomycete Gordonia amicalis HS-11 as effective free radical scavengers.
abstract: The Actinomycete Gordonia amicalis HS-11 produced orange pigments when cultivated on n-hexadecane as the sole carbon source. When cells of this pigmented bacterium were incubated with 1mM chloroauric acid (HAuCl4) or silver nitrate (AgNO3), pH 9.0, at 25°C, gold and silver nanoparticles, respectively, were obtained in a cell associated manner. It was hypothesized that the pigments present in the cells may be mediating metal reduction reactions. After solvent extraction and High Performance Liquid Chromatography, two major pigments displaying UV-vis spectra characteristic of carotenoids were isolated. These were identified on the basis of Atmospheric Pressure Chemical Ionization Mass Spectrometry (APCI-MS) in the positive mode as 1'-OH-4-keto-γ-carotene (Carotenoid K) and 1'-OH-γ-carotene (Carotenoid B). The hydroxyl groups present in the carotenoids were eliminated under alkaline conditions and provided the reducing equivalents necessary for synthesizing nanoparticles. Cell associated and carotenoid stabilized nanoparticles were characterized by different analytical techniques. In vitro free radical scavenging activities of cells (control, gold and silver nanoparticle loaded), purified carotenoids and carotenoid stabilized gold and silver nanoparticles were evaluated. Silver nanoparticle loaded cells and carotenoid stabilized silver nanoparticles exhibited improved nitric oxide (NO) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activities compared to their control and gold counterparts. This paper thus reports cell associated nanoparticle synthesis by G. amicalis, describes for the first time the role of carotenoid pigments in metal reduction processes and demonstrates enhanced free radical scavenging activities of the carotenoid stabilized nanoparticles.
authors.affiliation: Department of Chemistry, Biochemistry Division, Savitribai Phule Pune University, Pune, 411007 India.
authors.forename: Harshada
authors.initials: H
authors.lastname: Sowani
authors.affiliation: Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University, Pune 411007 India, India.
authors.forename: Pallavi
authors.initials: P
authors.lastname: Mohite
authors.affiliation: Shimadzu Analytical (India) Pvt. Ltd, Andheri East, Mumbai 400059, India.
authors.forename: Shailesh
authors.initials: S
authors.lastname: Damale
authors.affiliation: Department of Chemistry, Biochemistry Division, Savitribai Phule Pune University, Pune, 411007 India. Electronic address: kulmv@chem.unipune.ac.in.
authors.forename: Mohan
authors.initials: M
authors.lastname: Kulkarni
authors.affiliation: Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University, Pune 411007 India, India; Department of Microbiology, Savitribai Phule Pune University, Pune, 411007 India. Electronic address: smita@unipune.ac.in.
authors.forename: Smita
authors.initials: S
authors.lastname: Zinjarde
mesh_terms: D002338:Carotenoids / Q000737:chemistry / Q000378:metabolism; D004355:Drug Stability; D016166:Free Radical Scavengers / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D006046:Gold / Q000737:chemistry* / Q000494:pharmacology*; D033601:Gordonia Bacterium / Q000378:metabolism*; D055772:Green Chemistry Technology; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D016166:Free Radical Scavengers; D002338:Carotenoids; D012834:Silver; D006046:Gold
keywords: Carotenoid; Free radical scavenging activity; Gordonia amicalis; Nanoparticle