INTRODUCTION:

Aspirin is a acetylic salicylate has widely used as analgesic, anti-inflammatory (1) agent also used in treatment of articular and musculo skeletal disorders (2) because it is rapidly absorbed and hydrolyzed to acetic acid and salicylate in tissues and blood (3). Low dosage of aspirin for long term use is associated with lower incidence of colon cancer (4). It is irreversibly blocks the enzyme cycloxenase COX (prostaglandin PG synthase) which catalyzes (5) the conversion of platelet aggregation and work as effective antithrombotic (6) medicine. Aspirin is a non-steroidal COX inhibitor acting on both COX 1 & 2 isozymes. It has been observed that use of Aspirin cause irritation to digestive tract. Zn-Aspirin a Zinc coordination complex of acetyl salicylate used as a more active anti-thinner agent for Stroke.

Zn (II) plays a very important role in biological system; they are involved in several biochemical reactions. Deficiency of this metals cause disease like Zn deficiency cause growth retardation in children. The bioinorganic pharmacological and medicinal importance of metal drug complexes are well established (7). In continuation to the work done on the study of electrochemical bioinorganic and microbial study of some metal drug complexes (8), the present paper deals with the said studies on the Zn(II)- Aspirin complex.

MATERIAL AND METHODS:

All the chemicals used were of Anala R /BDH grade. The drug Aspirin (C₉H₈O₄) was purchased from Alfa Aesar Heysham, England. Doubly distilled water and absolute ethanol (55:45 v/v) are used as solvent.

Polarographic Study:

Polarographic experiments were performed on software connected Ω metrotism 757VA computrace (ion analyzer). The polarographic cell consisted of a three-electrode assembly and a stirrer having a dropping mercury electrode (DME) as a working electrode, a platinum wire as an auxiliary electrode and saturated calomel electrode as a reference electrode. The nitrogen gas was bubbled for 15 minutes. A systronics digital pH meter model- 361 was used for pH measurements.

Experimental sets were prepared by keeping overall zinc (metal ion) and Ammonium Chloride (supporting electrolyte) concentration fixed at 1.0mM and 1.0M respectively. The ligand concentration was varied from 0.5 to 5mM. The pH of the test solution was adjusted to 8.0±0.2 using NaOH/HCl.

Amperometric Determination:

The Amperometric titrations were performed on a manually operated set up, equipped with a polyﬂex galvanometer (sensitivity 8.1×10−9amp./div.) and an AJCO vernier potentiometer. The capillary characteristic of the DME had a m^2/3, t^1/6 values of 2.5 mg^2/3 s^−1/2 at 60 cm ef height of mercury column. The pH of the test solution was measured on a systronics digital pH meter model- 361

Synthesis of solid drug metal complex:

Zinc Chloride and 2-Acetoxy benzoic acid solution were prepared separately in distilled water and ethyl alcohol (55:45v/v) and were mixed in 1:2 molar ratio. The mixture was then refluxed in a round bottom flask for 2 and half h. the residue was filtered and washed thoroughly to remove any unreacted material. The complex was dried at low temperature and stored over P₄O₁₀.

The elemental C, H, N and O analysis of the complex was done on a coleman Elemental Analyser model -29/33 at CDRI Lucknow, India whereas gravimetric method was used for the estimation of zinc in the complex (9).

IR spectrometry:

The IR spectrum of solid complex was recorded using KBr pellets on a BRUKER Alpha ATR FTIR spectrophotometer of Sagar Institute of research Technology- Pharmacy, Bhopal, equipped with a Spectra-Tech Diffuse Reflectance Accessory (DRA). The spectrometer is equipped with the following: an air-cooled DTGS detector, a KBrbeamsplitter with a spectral range of 4000 to 650 cm^-1. The instrument was run under vacuum during spectral acquisition. Spectra were recorded at a resolution of 4 cm^-1, with the co-addition of 128 scans and a Blackman-Harris 3-Term apodisation function was applied. Prior to analysis the samples were mixed, and lightly ground, with finely ground spectroscopic grade KBr. The spectra were then recorded using the Kubelka83 Munk mathematical function in the OPUS software to convert the spectra from reflectance into absorbance.

Microbial screening:

Disc diffusion method (10) was applies for the microbial screening of Zn(II)-Aspirin complex against various pathogenic organisms i.e. Staphylococusaureus, Bacillus pumilus, Proteus mirabillis and Escherichia coli.

RESULTS:

Polarographic behavior of Aspirin with Zn (II):

In0.1 M Ammonia-Ammonium chloride buffer at pH 8.0±0.2Zn (II) and E. The reduction was found to be reversibly reduced involving two electrons. Which was evidenced by the plots of log i/ (id-i) Vs E. The reduction was found to be diffusion controlled, which was evidenced by the plots of id VsÖhcr.

On gradual increase of the Aspirin concentration the half wave potential and peak potential (E_1/2 and Ep) of Zn(II)metal ion shifted to more electronegative value and the diffusion current also decreased, thereby showing complex formation between Zn(II) with Aspirin drug. The metals and its complexes with the ligand understudy were found to be reversibly reduced involving two and three electrons. Which was evidenced by the plots of log i/(id-i) versus Potential (E). The shift in half wave potentials towards a more negative value a with increasing concentration of ligand and decrease in diffusion current indicated complex formation between bio metal ions to be used i.e Fe(III) with drug Aspirin. The curves are shown in Figures 1.

To study the composition and formation constant of the complex, plots DE_1/2(shift in the E_1/2) i.e. DE_1/2 = (E_1/2)s against log C_x(logarithm of the concentration of the ligand) were drawn. The plots were linear lines showing the formation of single complex species in solution. Lingane treatment (11) of the observed polarographic data reveals 1:2 metal (Zn): ligand (Aspirin) complex formation with formation constant log β =4.5.

Amperometric determination of Aspirin- Fe(III) complex:

Zn (II) gives a well-defined polarographic wave in 0.1M KCl and 0.001% gelatin at pH 7.0±0.1, the half wave potential (E_1/2) -1.2 V versus SCE. The diffusion current was found proportional to the concentration of Zn(II). The aspirin drug does not produce any wave under the said experimental conditions. The plateau potential for the polarographic wave of Zn (II) was -1.3 V versus Hg pool was applied for carrying out titration. On performing the amperometric titration of aspirin solution with standard solution of Zn (II), the current volume plots resulted in “L” shaped curve. The end point is determined by graphical method revealed metal to drug ratio of 1:2. The result is shown in Figure 1.

Characterization of Zn (II)-Aspirin Complex:

Elemental Analysis:

The results of elemental analysis of the drug and its complex with Zn(II) revealed 1:2 metal:drug ratio in this complex (Table-1) which supports authors finding using polarographic and amperometric methods.

Figure 1: Amperometric titration of Aspirin (2mM/10 ml)and Zn(II) (1mM/10 ml) solution

Table 1 Analytical data of Aspirin and its complex with Zn(II) Analysis/Calculated/(Found)

Element	Aspirin	Zn-Aspirin Complex
Zn	-	15.2(15.3)
C	60.0(60.2)	50.8(51.0)
H	4.44(4.45)	3.29(3.28)
O	35.5(30.1)	30.11(30.10)

DISCUSSION:

IR Spectra:

The significant IR spectral bands investigated of metal complex are show that acetylsalicylic acid behaves in a bidentate manner, coordinating via the two oxygen atoms of the acidic group with the displacement of a hydrogen atom. This mode of coordination is supported by the disappearance of carboxylic group (v COOH) and the appearance of band at ~ 1315cm^-1 assigning to v(C-O), v (C=O) shift to lower frequency, indicating participation of this group in coordination(). New band appearance assigned to band at ~ 420cm^-1 is indicated that two chlorides are coordinated to zinc metal (12). A tentative structure of Zn-Aspirin complex is shown as-

Zn-Aspirin Complex:

Antimicrobial activity of Aspirin-Zn(II) complex:

The results of antimicrobial activity of the Zn-Aspirin complex is presented in Table 2. A perusal of the data in table clearly shows that Zn(II)-Aspirin complex is found to be more toxic as compared to pure drug against various pathogenic bacteria and fungi understudy.

Table 2 Antimicrobial study of Zn(II)- Aspirin Complex

S. No	Test Organism	Inhibition zone (mm) Con. of complex 2mM/10ml (B)	Control Zn(II) metal (A) 1.0mM/10ml	% Change (A-B/A) ×100	Control (Y) Aspirin drug 1.0 mM/10ml	% Change (Y-B/Y) ×100
1	Staphylo-cocusaureus	09	14	36	11	18
2	Bacillus pumilus	04	10	60	05	-20
3	Proteus mirabillis	41	53	23	42	-43
4	Escherichia coli	29	88	66	25	-16

CONCLUSION:

In this research paper, metal complex of Aspirin with Zn bio metal has been synthesized and characterized by electrochemical methods i. e Polarography, Amperometry and IR spectroscopy. This work confirms the environmentally synthesis of metal complex with the use of non-toxic solvent alcohol and water. Microbial studies prove that prepared complex is more potent as compared to its parent drug. The objective of this research is also a recommendation of Polarographic methods which give a valuable information about this complex like metal ligand ratio, formation constant, stability complexes etc. The used Polarographic methods are accurate, fast, sensitive, oligo determination, species sensitive, economic method, these capabilities make superior by other methods prevalent in this field.

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Received on 08.09.2021 Modified on 07.11.2021

Research J. Pharm. and Tech 2022; 15(10):4416-4418.

DOI: 10.52711/0974-360X.2022.00740