Sci Pharm. 2008; 76: 269 277 doi:10.3797/scipharm.0803-14 269 Österreichische Apotheker-Verlagsgesellschaft m. b. H., Vienna, Austria Reproduction is permitted for non-commercial purposes. Preservative Evaluation of Novel 2,4-Hexadienoic Acid Derivatives in Aluminium Hydroxide Gel USP Vikramjeet JUDGE 1, Balasubramanian NARASIMHAN * 1, Rakesh NARANG 1, Ruchita OHLAN 2, Sucheta OHLAN 2 1 Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Hisar-125 001, Haryana 2 Hindu College of Pharmacy, Sonepat-131001, Haryana Abstract The potential derivatives of sorbic acid (2,4-hexadienoic acid) from our previous study were subjected to preservative efficacy testing. Aluminium Hydroxide Gel USP was used as a pharmaceutical product and Staphylococcus aureus MTCC 2901, Bacillus subtilis MTCC 2063, Escherichia coli MTCC 1652, Candida albicans MTCC 227 and Aspergillus niger MTCC 8189 were used as representative challenging microorganisms for antimicrobial effectiveness testing as per USP 2004. The hexadienoic acid derivative, m-nitrosorbanilide has better preservative efficacy than sorbic acid as well as the standard preservatives, methyl paraben and propyl paraben. Keywords Sorbic acid m-nitrosorbanilide 8-Quinolinyl sorbate Preservative Log CFU/mL Introduction Non-sterile pharmaceutical products with a high degree of water availability may be contaminated with microorganisms. The contaminating microorganisms may cause spoilage of the product with loss of therapeutic properties and, if they are pathogenic, serious infections can arise [1]. During past 20 years, the frequency of systemic infection has increased dramatically along with the number of invasive, * Corresponding author: Tel.: +91-1662-263162; Fax: +91-1662-267240. E-mail: naru2000us@yahoo.com (B. Narasimhan).
270 V. Judge et al.: mostly opportunistic, fungal species carrying infectious diseases. Fungal infections are important cause of morbidity and mortality in hospitalized patients: candidiasis is the fourth most common blood culture isolates at US hospitals, pulmonary aspergillosis is the leading cause of death in bone marrow transplant recipients, and Pneumocystis carinii pneumonia is the leading cause of death in AIDS patients in North America and Europe [2]. To inhibit the growth of contaminating microorganisms, antimicrobial preservatives are introduced into the product during manufacturing process for safety of products throughout its use by consumers [3]. In view of above, in the present study we have decided to search for some better preservatives among potential antimicrobial compounds from a series of sorbic acid (2,4-hexadienoic acid) derivatives recently reported by us [4]. Experimental Materials Nutrient agar, nutrient broth, sabouraud dextrose agar and sabouraud dextrose broth were obtained from Himedia, Mumbai. Mannitol, methyl and propyl paraben were obtained from CDH, Mumbai. Methods Aluminium Hydroxide Gel USP was used as the pharmaceutical product for evaluation of preservative efficacy testing. Preparation of Aluminum Hydroxide Gel-USP [5] Formula Aluminium hydroxide gel 36 g; Mannitol 7 g; Methyl paraben 0.2 g; Propyl paraben g; Saccharin g; Peppermint oil 5 ml; Alcohol 1 ml; Purified water q.s. 100 ml The weighed quantity of aluminum hydroxide gel and mannitol were triturated with 50 ml of water in a mortar. Methyl paraben, propyl paraben, saccharin and peppermint oil were dissolved in alcohol and added to above mixture and triturated well. The volume was made up to 100 ml with purified water.
Preservative Evaluation of Novel 2,4-Hexadienoic Acid Derivatives 271 For preservative efficacy testing, the aluminium hydroxide gel was prepared using the preservatives mentioned in Table 1 by replacing methyl paraben and propyl paraben from the above formula. The equimolar amount of selected preservatives (Table 1) were calculated with reference to the amount of methyl paraben (13 mol) and added into the pharmaceutical products. Tab. 1. Amount of selected preservatives added in the pharmaceutical products Code Preservative Amount (% w/w) P 1 Sorbic acid 0.15 P 2 8-Quinolinylsorbate 0.31 P 3 m-nitrosorbanilide 0.30 Preservative efficacy testing in pharmaceutical products [6] Aluminum hydroxide gel prepared with different preservatives was sterilized in autoclave at 120 0 C for 15 minutes. The products were then inoculated separately with 2 x 10 4 CFU/mL of Staphylococcus aureus MTCC 2901, Bacillus subtilis MTCC 2063, Escherichia coli MTCC 1652, Candida albicans MTCC 227 and Aspergillus niger MTCC 8189 and stored at room temperature (25 0 C). The CFU/mL of the product was determined at an interval of 0, 7, 14, 21 and 28 days. The experiment was performed in triplicate. The log values of number of colonies of microorganisms per ml along with their log standard deviation values (Table 2 Table 6) in aluminium hydroxide gel was calculated and compared as per the guidelines of USP 2004. Results and Discussion For B. Subtilis: The log results are shown in Table 2. The parent compound sorbic acid was effective upto the limit prescribed by USP on 14 th day ( ) but it could not pass the limit on 28 th day ( ). The derivatives m-nitrosorbanilide and 8- Quinolinylsorbate were found to be effective on 14 th day (,
272 V. Judge et al.: respectively) and 28 th day (, respectively) as the log results were found to be in accordance with limit prescribed in the USP. The standard preservative was active on 14 th day ( ) but fails to meet the required limit on 28 th day ( ). Tab. 2. Bacterial count (CFU/mL) of B. subtilis in Aluminium Hydroxide Gel USP Compound Sorbic acid (P 1 ) 8-Quinolinyl sorbate (P 2 ) m-nitrosorbanilide (P 3 ) Methyl and Propyl paraben Control 1.110 ± 0.845 ± For S. aureus: As per the results given in Table 3 sorbic acid was found to be active against S. aureus on 14 th ( ) as well as 28 th ( ) day. The derivatives m-nitrosorbanilide (, ) and 8-Quinolinyl sorbate (, ) showed results better than sorbic acid and are within the pharmacopoeial limits. The standard methyl paraben (, ) also passes the prescribed limits.
Preservative Evaluation of Novel 2,4-Hexadienoic Acid Derivatives 273 For E. coli: Sorbic acid ( (14 th day), (28 th day)) meets the pharmacopoeial limits and m-nitrosorbanilide ( (14 th day), (28 th day)) showed results better than sorbic acid and meets the required limits. 8-Quinolinyl sorbate exceeds the pharmacopoeial limits on 14 th day ( ) by marginal difference but passes the limit on 28 th day ( ) as complete microbial inhibition was seen at that period. The standard ( (14 th day), (28 th day)) fails to meet the limits. The results are shown in Table 4. Tab. 3. Bacterial count (CFU/mL) of S. aureus in Aluminium Hydroxide Gel USP Comp. Sorbic acid (P 1 ) 8-Quinolinyl sorbate (P 2 ) m-nitrosorbanilide (P 3 ) Methyl and Propyl paraben 0301 ± Control 0.903 ± For C. albicans: Sorbic acid ( (14 th day), (28 th day)) passes the limit of preservative efficacy test and the derivatives m-nitrosorbanilide ( (14 th day), (28 th day)) and 8-Quinolinyl sorbate ( (14 th day),
274 V. Judge et al.: (28 th day)) were found to be active in accordance with USP. The standard ( (14 th day), (28 th day)) also meets the limits and the test compounds showed results better than standard. The results are presented in Table 5. Tab. 4. Bacterial count (CFU/mL) of E. coli in Aluminium Hydroxide Gel USP Comp. Sorbic acid (P 1 ) 8-Quinolinyl sorbate (P 2 ) m-nitrosorbanilide (P 3 ) Methyl and Propyl paraben Control 0.845 ± 0.954 ± 1.041 ± For A. niger: Sorbic acid (0.903 ± (14 th day), (28 th day)), m-nitrosorbanilide ( (14 th day), (28 th day)) and 8- Quinolinylsorbate ( (14 th day), (28 th day)) were found to be active against the fungus. The test compounds m-nitrosorbanilide and 8-Quinolinyl sorbate were more active than sorbic acid and comparable to standard methyl paraben ( (14 th day), (28 th day)). The results are presented in Table 6.
Preservative Evaluation of Novel 2,4-Hexadienoic Acid Derivatives 275 Tab. 5. Fungal count (CFU/mL) of C. albicans in Aluminium Hydroxide Gel USP Comp. Sorbic acid (P 1 ) 8-Quinolinyl sorbate (P 2 ) m-nitrosorbanilide (P 3 ) Methyl and Propyl paraben Control 0.845 ± 0.845 ± 0.903 ± Tab. 6. Fungal count (CFU/mL) of A. niger in Aluminium Hydroxide Gel USP Comp. Sorbic acid (P 1 ) 0.903 ± 8-Quinolinyl sorbate (P 2 ) m-nitrosorbanilide (P 3 ) Methyl and Propyl Paraben Control 1.079 ± 0.954 ± 1.000 ± 1.079 ± 0.01
276 V. Judge et al.: The test compound m-nitrosorbanilide (P 3 ) was active against all the tested microbial strains under the standard test conditions as per USP NF 2004. It has shown potential to be chosen as a pharmaceutical preservative. 8-Quinolinyl sorbate also had shown good results except against E. coli against which it was active only in later period of testing interval. Conclusion The derivatives selected for preservative efficacy testing have shown promising results. The test compound m-nitrosorbanilide (P 3 ) was active against all the tested microbial strains under the prescribed test conditions as per the criteria of USP 2004 i.e for antacid made with an aqueous base, preservative effectiveness are met if there is no increase from initial calculated count at 14 th and 28 th days in case of bacteria, yeast and moulds. Where no increase is defined as not more than 0.5 log 10 higher than previous value measured. The above fact was supported by the log CFU/mL values of m-nitrosorbanilide (P 3 ) for 0 28 days viz. 0.301 0.447 (S. aureus), 0.602 0.301 (B. subtilis), 0.699 0.301 (E. coli), 0 0 (C. albicans), 0.301 0 (A. niger) which were according to the prescribed USP criteria. The results of preservative efficacy testing indicated that m-nitrosorbanilide (P 3 ) has the potential to be chosen as a pharmaceutical preservative. References [1] Zani F, Minutello A, Maggi L, Santi P, Mazza P. Evaluation of preservative effectiveness in pharmaceutical products: the use of a wild strain of Pseudomonas cepacia. J Appl Microbiol. 1997; 83: 322 326. [doi:10.1046/j.1365-2672.1997.00231.x] [2] Garcia-Domenech R, Rios-Santamariana I, Catala A, Calabuig C, Castillo LD, Galvez J. Application of molecular topology to the prediction of antifungal activity for a set of dication-substituted carbazoles, furans and benzimidazoles. J Mol Str. 2003; 624: 97 107. [doi:10.1016/s0166-1280(02)00740-6]
Preservative Evaluation of Novel 2,4-Hexadienoic Acid Derivatives 277 [3] Denyer SP, King RO. In Microbial Quality Assurance in Pharmaceuticals, Cosmetics and Toiletries Ed. Bloomfield SF, Baird R, Leak RE, Leech R, Chichester: Ellis Horwood: 1988: 156 170. [4] Narasimhan B, Judge V, Narang R, Ohlan R, Ohlan S. Quantitative Structure Activity Relationship Studies For Prediction of Antimicrobial Activity of Synthesized 2,4-Hexadienoic Acid Derivatives. Bioorg Med Chem Lett. 2007; 21: 5836 5845. [doi:10.1016/j.bmcl.2007.08.037] [5] Lachman L, Lieberman HA, Kanig JL. In: The Theory and Practice of Industrial Pharmacy 3 rd Ed., Vargheese Publishing House, Bombay, 1987: 498 499. [6] The United States Pharmacopoeia. United States Pharmacopoeial Convention, Inc, Rockville, 2004: 2148 2150. Received March 18 th, 2008 Accepted (after revision) May 6 th, 2008 Available online at www.scipharm.at May 22 nd, 2008