Inhibition of Bacterial Efflux Pumps by Crude Extracts and Essential Oil from Myristica fragrans Houtt. (Nutmeg) Seeds against Methicillin-Resistant Staphylococcus aureus

Myristicafragrans Houtt. (Nutmeg) is a widely known folk medicine across several parts of Asia, particularly used in antimicrobial treatment. Bacterial resistance involves the expression of efflux pump systems (chromosomal norA and mepA) in methicillin-resistant Staphylococcus aureus (MRSA). Crude extract (CE) and essential oil (EO) obtained from nutmeg were applied as efflux pump inhibitors (EPIs), thereby enhancing the antimicrobial activity of the drugs they were used in. The major substances in CE and EO, which function as EPIs, in a descending order of % peak area include elemicin, myristicin, methoxyeugenol, myristicin, and asarone. Here, we investigated whether the low amount of CE and EO used as EPIs was sufficient to sensitize MRSA killing using the antibiotic ciprofloxacin, which acts as an efflux system. Interestingly, synergy between ciprofloxacin and CE or EO revealed the most significant viability of MRSA, depending on norA and mepA, the latter being responsible for EPI function of EO. Therefore, CE and EO obtained from nutmeg can act as EPIs in combination with substances that act as efflux systems, thereby ensuring that the MRSA strain is susceptible to antibiotic treatment.     

Myristigranol,a new diarylpropane derivative from the wood of Myristica fragrans

Myristigranol, a new diarylpropane derivative, was isolated from the methanol extract of Myristica fragrans wood along with one diarylpropanoid and three stilbenoids. The isolated constituents were exhaustingly identified using the analyses of 1D and 2D NMR spectroscopic techniques and comparison of the literatures reported as well. The antioxidant activity was also determined.

     

On the contribution of A. C. Hurley to theoretical chemistry

Andrew Crowther Hurley was born in Melbourne, Australia, on 11 July 1926 and received his early education at Melbourne Church of England Grammar School. He graduated from the University of Melbourne with high honors in mathematics and natural philosophy and, in 1949, was awarded his M.A. with first class honors in the school of mathematics for his thesis “The Irreducible Crystal Classes in Four Dimensions,” his supervisor being Dr. Hans Schwerdtfeger. From 1950–1952 he was a member of Trinity College, Cambridge, and was awarded a Ph.D. for his research in theoretical chemistry under Sir John Lennard-Jones. In 1953 he returned to Melbourne and joined what was to become the Division of Chemical Physics of the Commonwealth Scientific and Industrial Research Organization (CSIRO). The award of a fellowship by Trinity College enabled him to spend two more years, 1954–1956, in the Theoretical Chemistry Department of the University of Cambridge, and this was followed by a year with Professor J.C. Slater's solid state and molecular theory group at the Massachusetts Institute of Technology. In 1957 Andrew again returned to the Division of Chemical Physics in Melbourne, where he has remained, except for the academic year 1962–1963, when he was Visiting Professor in Theoretical Chemistry at Iowa State University.     

中草药肉豆蔻挥发油研究

肉豆蔻Myristica fragrans Houtt.为肉豆蔻科植物,高大常绿乔木,其果实(包括假种皮和种仁)用作药材.肉豆蔻原产印度尼西亚的加鲁古群岛,始载于唐<本草拾遗>,谓:"肉豆蔻生胡国,……中国则无之".现马来西亚、斯里兰卡等热带国家有栽培.我国云南、台湾也有引种,但药材多以进口为主.肉豆蔻的果实除用作药品外,还可用作可作香料、化妆品.后传入欧洲,成为著名的香料和调味品.国外多用其假种皮,即肉豆蔻衣(mace),俗称玉果花.     

A contribution to 1-azapentadienylmetal chemistry: Si, Sn(II), Fe(II) and Co(II) complexes

Complexes of three related 1-azapentadienyl ligands [N(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R]⁻, abbreviated as L (R = Bu^t, R¹ = Me), L′ (R = Me = R¹), and L″ (R = Bu^t = R¹), are described. The crystalline compounds Sn(L)₂ (1), Sn(L′)₂ (2), [Sn(L′)(μ-Cl)]₂ (3) and [Sn(L″)(μ-Cl)]₂ (4) were prepared from SnCl₂ and 2 K(L), 2 K(L′), K(L′) and K(L″), respectively, in thf. Treatment of the appropriate lithium 1-azapentadienyl with Si(Cl)Me₃ yielded the yellow crystalline Me₃Si(L) (5) and the volatile liquid Me₃Si(L′) (6) and Me₃Si(L″) (7), each being an N,N,C-trisilyldieneamine. The red, crystalline Fe(L)₂ (8) and Co(L′)₂ (9) were obtained from thf solutions of FeCl₂ with 2 Li(L)(tmeda) and CoCl₂ with 2 K(L′), respectively. Each of 1-9 gave satisfactory C, H, N analyses; 6 and 7 (GC-MS) and 1, 2, 8 and 9 (MS) showed molecular cations and appropriate fragments (also 3 and 4). The ¹H, ¹³C and ¹¹⁹Sn NMR (1-4) and IR spectra support the assignment of 1-4 as containing Sn-N(SiMe₂R¹)-C(Bu^t)(CH)₃SiMe₂R moieties and 5-7 as N(SiMe₃)(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R molecules; for 1-4 this is confirmed by their X-ray structures. The magnetic moments for 8 (5.56 μ_B) and 9 (2.75 μ_B) are remarkably close to the appropriate Fe and Co complex [M{η³-N(SiMe₃)C(Bu^t)C(H)SiMe₃}₂]; hence it is proposed that 8 and 9 have similar metal-centred, centrosymmetric, distorted octahedral structures.     

Dieter Cremer's contribution to the field of theoretical chemistry

This legacy article reviews the contributions of Dieter Cremer (1944-2017) to the field of theoretical chemistry, highlighting his major accomplishments in method development and applied quantum chemistry, which has led to many advances in the field. His work reflects an extraordinary breadth and deep understanding of theory, which is needed to solve complex chemical problems. His passion for science has inspired many colleagues in the past and will do so in the future.     

Gas-phase chemistry of bare and oxo-ligated protactinium ions: a contribution to a systematic understanding of actinide chemistry

Gas-phase chemistry of bare and oxo-ligated protactinium ions has been studied for the first time. Comparisons were made with thorium, uranium, and neptunium ion chemistry to further the systematic understanding of 5f elements. The rates of oxidation of Pa(+) and PaO(+) by ethylene oxide compared with those of the homologous uranium ions indicate that the first and second bond dissociation energies, BDE[Pa(+)-O] and BDE[OPa(+)-O], are approximately 800 kJ mol(-1). The relatively facile fluorination of Pa(+) to PaF(4)(+) by SF(6) is consistent with the high stability of the pentavalent oxidation state of Pa. Reactions with ethene, propene, 1-butene, and iso-butene revealed that Pa(+) is a very reactive metal ion. In analogy with U(+) chemistry, ethene was trimerized by Pa(+) to give PaC(6)H(6)(+). Reactions of Pa(+) with larger alkenes resulted in secondary and tertiary products not observed for U(+) or Np(+). The bare protactinium ion is significantly more reactive with organic substrates than are heavier actinide ions. The greatest difference between Pa and heavier actinide congeners was the exceptional dehydrogenation activity of PaO(+) with alkenes; UO(+) and NpO(+) were comparatively inert. The striking reactivity of PaO(+) is attributed to the distinctive electronic structure at the metal center in this oxide, which is considered to reflect the greater availability of the 5f electrons for participation in bonding, either directly or by promotion/hybridization with higher-energy valence orbitals.     

A contribution to the structural chemistry of A-type rare earth sesquioxides

La₂O₃ and Nd₂O₃ have been annealed at temperatures between 1000 and 1600°C for decontamination. Only products annealed at least at these temperatures appeared to be monophasic. Both X-ray powder and electron single-crystal diffraction revealed the A-type sesquioxide structure. No difference could be found in samples either quenched or slowly cooled to room temperature. Two space groups, $\text{P}\text{3}\text{m1}$ and $\text{P6}{}_3\text{mmc}$, are reported for the A-type structure. X-Ray powder studies seemed to support the latter on the evidence of extinctions. Electron diffraction from single crystals, however, indicated the space group $\text{P}\text{3}\text{m1}$, confirming the so-called Pauling structure, while $\text{P6}{}_3\text{mmc}$ can now be excluded unequivocally.     

Assessment of chemically characterised Myristica fragrans essential oil against fungi contaminating stored scented rice and its mode of action as novel aflatoxin inhibitor

Abstract

The study reports chemically characterised Myristica fragrans essential oil (MFEO) as plant based food preservative against fungal and aflatoxin B₁ (AFB₁) contamination of scented rice varieties. The chemical profile of MFEO revealed elemicin (27.08%), myristicine (21.29%) and thujanol (18.55%) as major components. The minimum inhibitory and minimum aflatoxin inhibitory concentrations of MFEO were 2.75 and 1.5?mg/ml, respectively. The MFEO was efficacious against a broad spectrum of food deteriorating fungi. MFEO caused decrease in ergosterol content of fungal plasma membrane and enhanced leakage of cellular ions, depicting plasma membrane as the site of action. The MFEO caused reduction in cellular methylglyoxal content, the aflatoxin inducer. This is the first report on MFEO as aflatoxin suppressor. The essential oil may be recommended as plant based food preservative after large scale trials and reduction in methylglyoxal suggests its application for development of aflatoxin resistant varieties through green transgenics.     

10 years after rio-concepts on the contribution of chemistry to a sustainable development

The principles of the United Nations Conference on Environment and Development (UNCED), held in June 1992 in Rio de Janeiro, and Agenda 21, the comprehensive plan of action for the 21st century, adopted 10 years ago by more than 170 governments, address the pressing problems of today and also aim at preparing the world for the challenges of this century. The conservation and management of resources for development are the main focus of interest, to which the sciences will have to make a considerable contribution. Natural, economic, and social sciences will have to be integrated in order to achieve this aim. In their future programs, the associations of the chemical industries in Europe, Japan, and the USA have explicitly accepted their obligation to foster a sustainable development.In this review we investigate innovations in chemistry exemplarily for such a development with regard to their ecological, economical, and social dimensions from an integrated and interdisciplinary perspective. Since base chemicals are produced in large quantities and important product lines are synthesized from them, their resource-saving production is especially important for a sustainable development. This concept has been shown, amongst others, by the example of the syntheses of propylene oxide and adipic acid. In the long run, renewable resources that are catalytically processed could replace fossil raw materials. Separation methods existing today must be improved considerably to lower material and energy consumption. Chemistry might become the pioneer of an innovative energy technique.The design of chemical products should make possible a sustainable processing and recycling and should prevent their bio-accumulation. Methods and criteria to assess their contribution to a sustainable development are necessary. The time taken to introduce the new more sustainable processes and products has to be diminished by linking their development with operational innovation management and with efficient environmental-political control procedures.     

Organoplatinum(II) complexes as a color biomarker in solid-phase peptide chemistry and screening

[reaction: see text] A novel organoplatinum(II) biomarker is introduced to facilitate the solid-phase screening of combinatorial libraries for substrates and inhibitors of enzymes and receptors. The robust organoplatinum(II) biomarker can be incorporated, on amine functions, in peptides using standard peptide coupling techniques. The chemistry, stability, and (reversible) coloration process with KI(3) of the organoplatinum(II) biomarker was investigated.     

Contribution to the crystal chemistry of tetrametaphosphates (I)

Crystal structures of K₄P₄O₁₂ · 2H₂O and of two polymorphs of Na₂K₂P₄O₁₂ · 2H₂O are reported. K₄P₄O₁₂ · 2H₂O is triclinic P1 with a = 8.153(4), b = 8.222(4), c = 11.154(8) Å, α = 97.33(5), β = 95.46(5), γ = 88.92(5)°, and Z = 2. R = 0.021 for 2898 reflections. Na₂K₂P₄O₁₂ · 2H₂O has two crystalline forms: a triclinic one ($\text{P}\text{1}$) with a = 11.366(8), b = 7.908(5), c = 7.929(5) Å, α = 90.07(5), β = 106.85(5), γ = 95.66(5)°, and Z = 2, and a tetragonal one (P4₁) with a = 7.928(5), c = 21.66(2), and Z = 4. The crystal structures of the first and second crystalline forms have been solved with final R values of 0.022 for 2505 reflections and 0.036 for 1347 reflections, respectively. Crystal data and chemical preparations are given for Na₂(NH₄)₂P₄O₁₂ · 2H₂O and Na₂Rb₂P₄O₁₂ · 2H₂O, both isotypic with the triclinic form of Na₂K₂P₄O₁₂ · 2H₂O. Unit-cell dimensions are, respectively, a = 11.547(8), b = 8.012(5), c = 8.044(5) Å, α = 89.76(5), β = 106.22(5), and γ = 94.78(5)°, for the ammonium salt, and a = 11.577(8), b = 8.006(5), c = 8.032(5) Å, α = 89.79(5), β = 106.58(5), and γ = 95.19(5)° for the rubidium salt. In addition the crystal structures of the two crystalline forms of Na₄P₄O₁₂ · 4H₂O were reexamined in order to localize the hydrogen atoms and refine their positions.     

Contribution to the crystal chemistry of tetrametaphosphates(II)

Chemical preparations and crystal structures of two hydrated forms of CsNa₃P₄O₁₂ are described. CsNa₃P₄O₁₂ · 4H₂O with a = 14.50(2), b = 7.804(3), c = 7.006(3)Å crystallizes in space group Imm2, Z = 2. The crystal structure has been determined using 745 independent reflexions with a final R value of 0.028 (R = 0.040 with the 934 collected reflexions), CsNa₃P₄O₁₂ · 3H₂O with a = 11.39(1), b = 10.92(1), c = 11.81(1)Å, β = 95.24(5)° in $\text{P2}{}_1\text{c}\text{, Z = 4}$. The crystal structure has been solved with 2975 independent reflexions with a final R-value of 0.018 (R = 0.057 with all the 6531 collected reflexions). In both structures there are four-membered rings built up with corner-sharing phosphate tetrahedron. For the tetrahydrate, the ring symmetry is mm whereas in the trihydrate, one observes two independent ring anions of symmetry $\text{1}$. In both cases hydrogen atoms have been located and refined.     

Click chemistry as a route to cyclic tetrapeptide analogues: synthesis of cyclo-[Pro-Val-psi(triazole)-Pro-Tyr

[STRUCTURE: SEE TEXT] Despite the plethora of techniques to cyclize small peptides, a synthesis of cyclo-[(L)Pro-(L)Tyr-(L)Pro-(L)Val], a potent tyrosinase inhibitor, remains elusive because of the unfavorable transition state leading to the cyclic product. Herein, we report the successful synthesis of its triazole analogue, cyclo-[(L)Pro-(L)Val-psi(triazole)-(L)Pro-(L)Tyr]. Attempted cyclization via peptide bond formation at room temperature fails to provide the desired product, but Cu(I)-catalyzed alkyne-azide coupling at 110 degrees C affords the triazole tetrapeptide in 70% yield, demonstrating the utility of "click" chemistry.