الفهرس 
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Abstract
In recent years, the increasing of prevalence of multi-antibiotics resistant bacteria may be opened to search for alternative approaches for exploring of new drugs from various sources such as actinomycetes. Thus, the search for actinobacterial extracts may offer a unique potential for the development of novel agents to treat infections. Secondary metabolites (natural products) from bacteria such as Actinobacteria serve as lead compounds for the development of pharmaceutical drugs widely used to fight bacterial, viral and fungal infections, as well as cancer and immune system disorders.
Different chromatographic methods such as classical column chromatography (with different mobile and stationary phases), preparative HPLC were used to isolate the active compounds from each extract. Various spectroscopic methods such as ultraviolet spectroscopy (UV), infrared spectroscopy (IR), mass spectroscopy (MS) and nuclear magnetic resonance (1D and 2D NMR) and physical methods such as melting point were used for the structure determination of the isolated compounds.
Antimicrobial activity was investigated by using agar diffision method against Gram-positive bacteria: S. pyogenes and S. aureus, Gram–negative bacteria: S. typhi, K. pneumonia and P. aeruginosa and against fungi: C. albicans suggesting that this strain is a promising producer of an antimicrobial compound. Besides this, the minimum inhibitory concentration of the active isolated compound against S. aureus was 30µg/ml and was evaluated by agar diffision method.
The chemical investigation of S. bikinensis strain ess_amA-1 in the current study resulted in isolation and identification of one active compound may be belong to novel isoflavonoid glycosides and was identified as 6-hydroxygenistein 6-O-glucoside and was subjected to antimicrobial tests.
The isolated S. bikiniensis strain ess_amA-1 has the inherent potential to produce more stabilized, bioefficacious, and ecofriendly SeNrs or AgNPs than physico-chemically synthesized SNMs or AgNPs, and can be exploited for mass-scale production. The biosynthesized SeNrs and AgNPs showed anticancer activity against Hep-G2 and MCF-7 cells under in vitro conditions and additionally their antimicrobial activity.
The strain was grown aerobically with selenium dioxide and produced stable SeNrs with average particle size of 17 nm and incubation of silver nitrate with filtrate of strain ess_amA-1 at the same condition produced stable AgNPs in the size range 3 nm to 70 nm. The optical, structural, morphological, elemental, and functional characterizations of the SeNrs were carried out using techniques such as UV-vis spectrophotometry; transmission electron microscopy, energy dis¬persive X-ray spectrometry, and Fourier transform infrared spectrophotometry, respectively. The bioassay of AgNPs and SeNrs as antibacterial and antifungal was occurred by disc diffusion agar technique.
The results showed that silver nanoparticles as antibacterial agents are significantly more than selenium nanorods; and the other affected on Gram positive bacteria more than Gram negative bacteria. The present study showed that both AgNPs and SeNrs have ability to inhibit growth of C. albicans.
The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed that the biosynthesized SeNrs and AgNPs induces cell death of Hep-G2 and MCF-7 human cancer cells. The lethal dose (LD50%) of SeNrs on Hep-G2 and MCF-7 cells was recorded at 75.96 μg/mL and 61.86 μg/mL, and in case of AgNPs were 253.6 μg/mL and 119.9 μg/mL respectively.