NMR Shielding and S-NICS Investigation for Imipenem,Penicillin G, Ticarcillin, Ampicillin and Clavulanic Acid in Viewpoint of Bio-Nanotechnology

Ampicillin, Clavulanic acid, Imipenem, Penicillin G and Ticarcillin properties for the drug delivery in viewpoint of NMR shielding and S-NICS investigation have been studied.Phenoxy-acetic acid for Penicillin V or Penicillin and its alteration Penicillin G are used for large scale production. Various Penicillins and the other cells-wall inhibitor are mainly specific against Gram(+) bacteria due to highest percentage of peptidoglycan” in the cells-wall of those organisms. Ampicillin which is belongs to the penicillin groups of beta lactam-antibiotics is capable to penetrate Gram(+) and some Gram(-) bacteria. Imipenem or Primaxine is an intravenous-b-lactamantibiotic discovered by William Leanza, Kenneth Wildonger and Burton Christensen from Merck scientists in 1980. It was the first part of the carbapenem kinds of antibiotics. Based on our previous works82 we have design and simulated a drug delivery system of those antibiotics. In this study, we have discussed a statistical approach via computing of nucleus-independent chemical shifts (S-NICS) in view point of probes motions in a sphere of de-shielding and shielding spaces of antibiotic rings. In the related work82, it has been exhibited that S-NICS method is a suitable method for evaluting the aromaticity in the non-benzene rings such as those antibiotics which are important compounds for organic chemical synthesize and reactions. keyword: Ampicillin, Clavulanic acid, Imipenem, Penicillin G, Ticarcillin, NMR and S-NICS


INTRODUCTION
Antibiotics are molecules that stop or kill the growth of, microorganisms, including both bacteria and fungus. Antibiotic that block the growth of bacteria is called bacteriostatic" andantibiotic that kill bacteria is called "bactericidal.
Antibioticis specific chemical substance produced (or derived) by living organisms that are capableof inhibiting the life processes of other organisms 1-10. A test, resulting in the classification of bacteria, has developed by "Hans Christian Gram" Antibiotics are special chemical substances isolated or produced from by living organisms that are able for inhibiting the life activities of other organisms. The first antibiotics were derivedfrom micro-organisms" but currently some are obtained through higher plants and animals. Over 3,000 antibiotics have been synthesized and classified butonly a few dozen are used as medicine.
As an example penicillins which has been discovered by Alexander Fleming in 1928, is a kind of antibiotic that has been used inthe treatment towards bacteria invasion. Fleming whoworks at St. Mary's Hospital London 6-10 , left for his holidays therefor left the culture of the microbe near the window of his lab thenafter he came back, he found an unusual phenomenon of theculture (of microbe) that he had left [1][2][3][4][5][6][7][8][9][10] .
However, sorption can be overcome by investigating either separated natural soil constituents such as "humic" acid or polymers from well-defined "phenolic" compounds, representing specific site and functionality of "humic" substances that can serve as a model to elucidate mode of binding. "Phenolic" compoundis a major building block of "humic" polymer and was found to polymerize to humus-like substance [5][6][7][8][9][10] .
Penicillin attaches such as penicillin binding protein and interfere with the last step of bacterial cell-wall synthesis which is trans-peptidation or cross linkage by inhibition of transpeptidase and production of autolysin leads to bactericidal action. The mechanism of action for various antibiotics is different. In view point of bacterial spectrum several points are important such as in effective against organism devoid of peptidoglycan can such as mycobacteria,effective against active organism which synthesizes peptidoglycan cell wall,fungi, viruses and protozoa. Gram positive organisms have cell wall easily traversed by penicillins and therefore theyare susceptible to penicillins, several Gram negative organisms have "porin" permit transmembrane entry of penicillin and so they are susceptible organisms. Staphylococci developed resistance to natural Dicloxacillin,penicillin Gand Methicillin which are penicillinase resistance preparations are effective against staphylococci.Combination of penicillins and aminoglycosides has synergistic effect while in view point of absorption; most of them are poorly absorbed after oral administration except amoxicillin and ampicillin. Penicillinase resistant preparation should be given one hour before meals because their absorptionsare delayed by presence of food [10][11][12][13][14][15][16][17][18][19][20] .
Van der Waals forcesand multiple weak H-bonds between zeolites and antibiotics are responsible for the ir-reversible extraction from water of all the examined drugs. Lastly, the most stable tautomer form of each antibiotics adsorbed into the zeolites were identified.
The hypersensitivities reaction, consisting of fever and non-urticarial rash, usually developseven up to fourteen days after the medication initiation. The term "sulfa" refers to a derivative of an antimicrobial agent, "sulfanilamide".
Penicillin was the first antibiotic discovered from naturalproducts (Penicillium). It is a "beta-lactamantibiotic" that is a part of the amino-penicillin" family and is hastily equivalent to successor,amoxicillin in its spectrum and level of activity which is produced by Penicilliumchrysogenum 10-12 . Phenylacetic acid for PenicillinG or phenoxyacetic" acid for PenicillinVis used for the larger scale production. Otherpenicillins are produced semi-synthetically". Penicillinis primarilyspecific against Gram(+) bacteria because of its higher percentage of peptidoglycan in the cell wall ofthat organism.
Ampicillin belongs to the penicillin group of b-lactamantibiotics, ampicillinsare able to penetrate Gram(+) and some Gram(-) bacteria. Ampicillinsare semi synthetic penicillins with an extera amino-chain synthesized into the penicillin molecules.
Based on previous works we have modeled and simulated drug delivery systems of those antibiotics  .In this work we have exhibited the especial properties of Ampicillin, Clavulanic acid, Imipenem, Penicillin G and Ticarcillin in view point of NMR shielding and S-NICS methods for delivering in cell body via QM/MM and Abinitio methods.

Theoretical back ground NMR Shielding and S-NICS method
There are not theoreticallyor mathematically reports for the statistical approaches in NMR shielding and nucleus-independent-chemical-shift (S-NICS), Since the asymmetry(η)and skew(К) parameters have fluctuated in a short distances and in contrast are alternative in long distances.
In the item of axially-symmetric tensor, the s 22 is the same value of s11 or s 33 ,and then skew is К=±1. Through changing the asymmetry between 0≤η≤+1 skewis changed between -1≤К≤+1 , and the parameter "К" is zero when s 22 = s iso .
The total chemical-shielding-tensors{r}are non-symmetric tensors that can be decomposed into 3 independent tensors as:(1) a traceless symmetric component, (2) an isotropic component, and (3) The traceless component (anti-symmetric). In a spherical representation of tensor, Haeberlenhas pointed a fundamental level tensoris better represented in the spherical presentation, so a general secondorder property of "s" may be written as s= s iso(o) + s anti(1) + s sym (2) ... (5), where the number in brackets indicates to tensor ranks. Spherical tensoris involved in considering the effects of tensor quantities in the density matrix , so using of thoserepresentations are inevitable for such study. It is notable that: The component of the shielding tensors have symmetric tensor elements with r ij = r ji . These tensorsare responsible for a relaxation (CSA) most often illustrated in the literature and can be diagonalizedthroughthe rotation onto the shielding tensorsof the principal coordinate system.
With a statistical calculation it has beenexhibited that a time independent average of (Ω*) can be remodeledfor all above sum of antisymmetric, asymmetric,and the scalar term, which are rank tensors equal 1, 2 and zero respectively. These methodsare based on of a probe with random motions in the de-shielding and shielding spaces of the aromatic rings and anti-aromatic molecules. The magneticsmedia of spin are seldom isotropic. Therefore, are represented through of span tensor: ( Ω) = s 33 -s 11 ... (8) and k = 3(s iso -s 22 / Ω) ... (9). In the notation of Herzfeld-Berger, tensors have explained with3 parameters, which they are a combination of the major components in this standard notation. These are including, (Ω), which indicates of a maximum width, (Ω≥ 0), and (κ) tensors which are a magnitude of this value.
The accurate formulation of (Ω), including the factor of (1-s ref ) have been described by Moreover the orientation of a-symmetry tensorsare given by (κ = 3a/ Ω )and the skew is κ= 3(s iso -s 22 / Ω) ;(-1≤ κ≤+1) and dependentto the position of s 22 with consideration of s iso , the sign of κ is either negative or positive.
In the items of the axially symmetric tensors, s 22 equals either s 11 or s 33 and κ= ±1 thereforea = Ω/3, and then parameter "a" and "κ" are equal to zero when s 22 = s iso and the parameter "m" used with the Herzfeld-Berger is dependent to the span of a )] ... (13) Where t r,1 and t r,2 correspond to the correlation times for isotropic tumbling and small-step molecular rotation, respectively and in the case of axial symmetry or for isotropic t r,1 =3t r,2 .

...(27).
In all calculations the default gaugesincluding atomic orbital (GIAO) orbitals were used to obtain molecular magnetic susceptibilities, NMR shielding with Gaussian program.

Table3: Charge (ESP), isotropy, anisotropy, span and aromaticity of Clavulanic acid in gas phase and solvent media
Imipenem in gas phase Imipenem in water atom charge siso saniso η ∆d Ω atom charge siso saniso

Computational details
Calculations were accomplished using Gaussian and GAMESS-US packages. The ONIOM methodcontainingthree levels from high (H), medium (M), and low (L)calculations have been accomplished in this study. The "advanced DFT" methods are used for high layer of the model and semi-empirical method of Pm6" including pseudo=lanl2 and Pm3MM" are used for the low and medium layers, respectively. There are various situations of noncovalent interaction in this system between hydrogen diffused. In this study, we have mainly focused on getting the optimized results for each item from "advanced DFT" methods including the "m06" and "m06-L". The "m062x", "m06-L", and "m06-HF" are a novel Meta hybrid DFT functional with a good correspondence in non-bonded calculations.
The charge calculation based on molecularelectrostatic-potential or MESP fitting are not wellsuited for treating larger systems whereas some of the innermost atoms are located far away from the points at which the MESP is computed.The MESP charge was also calculated using the Merz-Kollman-Singh chelpG [92][93][94][95][96] .
The representative atomic charges should be computed as expection values over several molecular positions. The electron densities have been calculated, values of orbital wave-functions, electron spin densities, electrostatic potentials from nuclear / atomic charges, electron localization functions (ELF), localized orbital locators, total electrostatic potentials (ESP) and the exchangecorrelation densities, correlation hole and correlation factors, Average local ionization energiesusing Multifunctional Wave-function analyzer [89][90][91] .
The contour line map has drawn via Multiwfnsoftware [89][90][91] . The relief map has used to present the height value at every point. The graphsare shown on interactive interface.Shaded surface mapand shaded surface map with projection are used in our representation of height value at each situation [89][90][91] .

RESULT and DISCUSSIONS
Three steps have been investigated in this study, first (1), set up a molecule with appropriate starting geometries andsecond (2) choose a calculation method and its associated choices. Third (3) choose the types of calculations with the relevant options. The Monte Carlo simulations always detect the so-called "important-phase-space" regions which are of low energyies.
In this work, difference in force field has illustrated by comparing the energies calculated by using force fields, Amber,MM+, and OPLS. Also, we have investigated polar solvent and the temperature effects on the stability of antibiotics to CFA (or CGA) in various solvents. The quantum mechanics (QM) calculations were carried out with the HyperChem 8.0 program. This study mainly focuses on the electron density Ampicillin, Clavulanic acid, Imipenem, Penicillin G and Ticarcillinin viewpoint of S-NICS method. The models and situation of molecular structures and binding interaction are shown in figs1-7. As it is indicated in tables 1-3, the NMR parameters including isotropy, anisotropy, asymmetry, span and S-NICS value have been simulated.
The fermi hole is a six-dimension function and as a result, it is difficult to be studied visually. Based those equations, Becke and Edgecombe noted that the Fermi hole is a spherical average of the spin which is in good agreementwith our results in tables and Figs.
According to the equations 16-22 the largest electron localization is located onatoms which are bonded to nanotubes wherethe electron motion is more likely to be confined within that region. If electrons are completely localized in those atoms, they can be distinguished from the ones outside. As shown the large density is close to the bonded atoms. The regions with large electron localization need to have large magnitudes of Fermi-hole integration which would leadthose atoms towards superparamagnetic.

CONCLUSION
Once a compound that fulfills all of these requirements has been identified, it will begin the process of drug development prior to clinical trials. Modern drug discovery involves the identification of screening hits, medicinal chemistry and optimization of those hits to increase some properties. One or more of these steps may involve computer-aided drug design. A fascinating result of the theoretical analysis of antibiotics-S-NICS methods were the stable model for drug delivery.