Antimicrobial and Cytotoxicity Properties of 2,3-Dihydroxy-9,10-Anthraquinone Isolated from Streptomyces galbus (ERINLG-127)

Streptomyces galbus ERINLG-127 was isolated from the soil samples of the Marapalam forest, Nilgiris, India. The ethyl acetate extract was subjected to activity-guided fractionation by column chromatography over silica gel. This led to the isolation of 2,3-dihydroxy-9,10-anthraquinone as the active principle. The compound showed good antimicrobial activity against tested bacteria and fungi. The minimum inhibitory concentration values of isolated compound were 12.5 μg/mL against Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhimurium, K. pneumoniae (ESBL-3971), K. pneumoniae (ESBL-3894) and Staphylococcus aureus (MRSA). The compound showed prominent cytotoxic activity in vitro against A549 lung adenocarcinoma cancer cell line. It showed 75.1 % activity at the dose of 100 μg/mL with IC₅₀ value of 60 μg/mL. The isolated compound was subjected to molecular docking studies for the inhibition of TtgR and Topoisomerase IV enzymes which are targets for antimicrobials. Docking studies of the compound showed low docking energy indicating its usefulness as antimicrobial agent.     

An efficient approach for the synthesis of functionalized selenoethers and selenacalix[4]thiophenes, {2,5-(μ-Se)(3,4-dialkoxythiophene)}4

An efficient method for the synthesis of selenoethers and selenacalix[4]thiophene utilizing SeCl₂ is described. Reactions of phenols with SeCl₂ produce the corresponding selenoethers in moderate to good yields. The selenacalix[4]thiophenes, [–Se-3,4-(C₄(OR)₂S)]₄ (R = CH₃, C₆H₁₃) were synthesized by convenient one-pot electrophilic aromatic substitution reaction of dialkoxy thiophene with SeCl₂ in good yield.     

Smoothing of likelihood ratio statistic for equiprobable multinomial goodness-of-fit

The likelihood ratio chi-square criterion for testing goodness-of-fit in k cell multinomials is known to overestimate significance for small and moderate sample sizes (see, e.g., Larntz (1978)). Therefore, the usual chi-square approximation to the upper tail of the likelihood ratio statistic G ², is not satisfactory. Several authors have derived adjustments (e.g., Williams (1976), Smith et al. (1981), Hosmane (1987b)), so that the asymptotic mean of G ² matches the mean of the asymptotic chi-square distribution in the hope that the distribution of G ² would improve. In this paper, a new adjustment to G ² is determined on the basis of the n ^-1-order term (n being the total number) of the Edgeworth expansion of the distribution of smoothed G ². Monte Carlo results indicate that the modified G ² outperforms the unadjusted G ².     

Studies on the effects of energy gap anisotropy in magnetically doped superconductors

The ultrasonic longitudinal sound wave attenuation coefficient and nuclear spin relaxation rate have been calculated for an anisotropic superconductor containing paramagnetic impurities with local states within the gap. The local states within the gap is shown to be anisotropic.     

Synthesis and characterization of Ru/Au,Pd/Au,Pd/2Au,Pt/2Au and Cu/2Au heterometallic complexes of cyclodiphosphazane cis-{(o-MeOC6H4O)P(μ-NBu)}2

Mononuclear complexes of cyclodiphosphazane with an uncoordinated phosphorus centre [RuCl₂(η⁶-cymene){l-κP}] (1a) (L = cis-{(o-MeOC₆H₄O)P(μ-N^tBu)}₂) and [PdCl₂(PEt₃){l-κP}] (1b) react with 1 equiv. of [AuCl(SMe₂)] to afford Ru^II/Au^I and Pd^II/Au^I heterodinuclear complexes [RuCl₂(η⁶-cymene){μ-l-κP,κP}AuCl] (2) and [PdCl₂(PEt₃){μ-l-κP,κP}AuCl] (3), respectively. Heterotrinuclear complexes [PdCl₂{μ-l-κP,κP}₂(AuCl)₂] (4), [PtCl₂{μ-l-κP,κP}₂(AuCl)₂] (5) and [CuI{μ-l-κP,κP}₂(AuCl)₂] (6) containing Pd^II/2Au^I, Pt^II/2Au^I and Cu^I/2Au^I metal centers have been synthesized from the reactions of trans-[PdCl₂{l-κP}₂] (1c), cis-[PtCl₂{l-κP}₂] (1d) and [CuI{{l-κP}₂] (1f) respectively, with 2 equiv. of [AuCl(SMe₂)]. Molecular structures of complexes 2, 3 and 4 were established by single crystal X-ray diffraction studies.     

Titanium tetrachloride mediated reductive ring opening of C-aryl pseudoglycals

A facile reductive ring opening of C-aryl pseudoglycals is reported for the first time. The combination of titanium tetrachloride (Lewis acid) and triethylsilane (reducing agent) at −78 °C in dichloromethane is a mild and efficient reagent system for this transformation. The reagent system was successfully tested on various C-aryl pseudoglycal substrates to yield the corresponding ring opened products containing two asymmetric hydroxyls and a cis-double bond.     

Novel octanuclear copper(I) metallomacrocycles and their transformation into hexanuclear 2-dimensional grids of copper(i) coordination polymers containing cyclodiphosphazanes, [(micro-NtBuP)2(NC4H8X)2] (X = NMe, O)

Novel octanuclear copper(I) macrocyclic complexes and hexanuclear 2-dimensional grid-like polymers containing [P(micro-NR)](2) scaffold in which the anionic moieties are trapped inside the cationic macrocyclic cavities are reported.     

Sterically Demanding Novel Triazole Based Tertiary Phosphines: Synthesis,Transition Metal Chemistry and Catalytic Applications

Sterically demanding 2,6-dibenzhydryl-4-methylphenyl and 1,2,3-triazole based tertiary phosphines, [Ar*{1,2,3-N₃C(Ph)C(PR₂)}] (R=Ph, 3 ; R=ⁱPr, 4 ) were obtained by the temperature-controlled lithiation of 1-(2,6-dibenzydryl-4-methyl)-5-iodo-4-phenyl-1H-1,2,3-triazole ( 2 ) followed by the reaction with R₂PCl (R=Ph, ⁱPr). Treatment of 3 with H₂O₂, elemental sulfur and selenium yielded chalcogenides [Ar*{1,2,3-N₃C(Ph)C(P(E)Ph₂)}] (E=O, 5 ; E=S, 6 ; E=Se, 7 ). The reaction of 3 with [Pd(COD)Cl₂] in 1 : 1 molar ratio, afforded dimeric complex [Pd(μ₂-Cl)Cl{Ar*{1,2,3-N₃C(Ph)C(PPh₂)}-κ¹-P}]₂ ( 8 ), whereas the reactions of 3 and 4 with [Pd(η³-C₃H₅)Cl]₂ in 2 : 1 molar ratios produced complexes [Pd(η³-C₃H₅)Cl{Ar*{1,2,3-N₃C(Ph)C(PR₂)}-κ¹-P}] (R=Ph, 9 ; R=ⁱPr, 10 ). Treatment of 3 with [Pd(OAc)₂] in 1 : 1 molar ratio afforded a rare trinuclear complex [{Pd₃(OAc)₄}{Ar*{1,2,3-N₃C(C₆H₄)C(PPh₂)}-κ²-C,P}₂] ( 11 ). Treatment of 3 and 4 with [AuCl(SMe₂)] resulted in [AuCl{Ar*{1,2,3-N₃C(Ph)C(PR₂)}-κ¹-P}] (R=Ph, 12 ; R=ⁱPr, 13 ). Bulky phosphine 4 was very effective in Suzuki-Miyaura coupling and amination reactions with very low catalyst loading. Molecular structures of 3 – 5 , and 8 – 13 were confirmed by single-crystal X-ray diffraction studies.     

Methylene insertion into the exocyclic P-N bonds of bis(amido)cyclodiphosphazane, cis-[Bu(H)NP(μ-BuN)]2

The 1:2 and 1:1 reactions of cis-[^tBu(H)NP(μ-^tBuN)]₂ (1) with paraformaldehyde afforded α-aminophosphonates, cis-[^tBu(H)NCH₂(O)P(μ-^tBuN)]₂ (2) and cis-[^tBu(H)NP(μ-^tBuN)₂P(O)CH₂N(H)^tBu] (3), respectively, through the insertion of a methylene moiety into the P-N bonds. The X-ray crystal structure of 2 reveals that the insertion reaction occurs selectively at the exocyclic P-N bonds of bis(amido)cyclodiphosphazane.