Free Standard AU & NZ Shipping For All Book Orders Over $80!
Register      Login
Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
Shopping Cart: ( empty )
You are here: Home > Journals > CH > CH12457
RESEARCH ARTICLE
Contents Vol 66(5)

Effect of pH, Buffer, and Viscosity on the Photolysis of Formylmethylflavin: A Kinetic Study

Iqbal Ahmad A , Tania Mirza A , Kefi Iqbal B , Sofia Ahmed A , Muhammad Ali Sheraz A D and Faiyaz H. M. Vaid C
+ Author Affiliations
- Author Affiliations

A Institute of Pharmaceutical Sciences, Baqai Medical University, Toll Plaza, Super Highway, Gadap Road, Karachi-74600, Pakistan.

B Department of Material Science, Baqai Dental College, Baqai Medical University, Toll Plaza, Super Highway, Gadap Road, Karachi-74600, Pakistan.

C Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Karachi, Karachi-75270, Pakistan.

D Corresponding author. Email: ali_sheraz80@hotmail.com

Australian Journal of Chemistry 66(5) 579-585 https://doi.org/10.1071/CH12457
Submitted: 7 October 2012  Accepted: 29 January 2013   Published: 22 February 2013

Abstract

The kinetics of the photolysis of formylmethylflavin, a major intermediate product in the aerobic and anaerobic photolysis of riboflavin, was studied in the pH range 2.0–11.0. Formylmethylflavin and its photoproducts, lumichrome and lumiflavin, were determined in degraded solutions using a specific multicomponent spectrophotometric method. The photolysis of formylmethylflavin in alkaline medium takes place by first-order kinetics and the rate constants (kobs) at pH 7.5–11.0 range from 0.27 × 10–4 to 3.88 × 10–4 and 0.36 × 10–4 to 5.63 × 10–4 s–1 under aerobic and anaerobic conditions respectively. In acid medium, the photolysis involves a second-order mechanism and the rate constants at pH 2.0–7.0 range from 1.37 to 2.11 and 2.03 to 2.94 M–1 s–1 under aerobic and anaerobic conditions respectively. The rate–pH profiles for the photolysis reactions indicate the highest rate of formylmethylflavin degradation is at ~pH 4 and above pH 10. In the alkaline region, the increase in rate with pH is due to higher reactivity of the flavin triplet state. The photolysis of formylmethylflavin is catalyzed by phosphate ions and is affected by the solvent viscosity.


References

[1]  E. C. Smith, D. E. Metzler, J. Am. Chem. Soc. 1963, 85, 3285.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF3sXkslKgsrg%3D&md5=f3e4877c9ead05ef987a1e5c61794861CAS |

[2]  P. S. Song, E. C. Smith, D. E. Metzler, J. Am. Chem. Soc. 1965, 87, 4181.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF2MXkslSqu7k%3D&md5=2af42568a75a9ab3bc337a48b9cb9b9fCAS |

[3]  I. Ahmad, H. D. C. Rapson, P. F. Heelis, G. O. Phillips, J. Org. Chem. 1980, 45, 731.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL3cXptlGqsg%3D%3D&md5=0e4b304851c3014bcb93593431c7aaffCAS |

[4]  I. Ahmad, F. H. M. Vaid, J. Chem. Soc. Pak. 2008, 30, 688.
         | 1:CAS:528:DC%2BD1cXhtF2gsb%2FL&md5=99e569bd5d315bc97a0d7595de38f571CAS |

[5]  P. S. Song, D. E. Metzler, Photochem. Photobiol. 1967, 6, 691.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF2sXltFekurw%3D&md5=c0f11c372ee08f1e6bf2e601af54f3bfCAS |

[6]  G. E. Treadwell, W. L. Cairns, D. E. Metzler, J. Chromatogr. A 1968, 35, 376.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF1cXksV2htb0%3D&md5=b467805592324e88dc5542b2c950c746CAS |

[7]  D. E. Metzler, W. L. Cairns, J. Am. Chem. Soc. 1971, 93, 2772.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE3MXksV2nur0%3D&md5=8d4ec059d9375ccc9cba34daaf2e513bCAS |

[8]  P. F. Heelis, G. O. Phillips, I. Ahmad, H. D. C. Rapson, Photobiochem. Photobiophys. 1980, 1, 125.
         | 1:CAS:528:DyaL3MXmtVarsA%3D%3D&md5=f3060c9d41964a36880c5374099b46e7CAS |

[9]  I. Ahmad, H. D. C. Rapson, J. Pharm. Biomed. Anal. 1990, 8, 217.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3cXlsFyktbo%3D&md5=22bea32d1b16d798b8e295e03657a89cCAS |

[10]  I. Ahmad, Q. Fasihullah, Pak. J. Pharm. Sci. 1991, 4, 21.
         | 1:CAS:528:DyaK3MXlvFOnsb4%3D&md5=0c61291b7a46135446c0c6433228dfe1CAS |

[11]  I. Ahmad, Q. Fasihullah, F. H. M. Vaid, Photochem. Photobiol. Sci. 2006, 5, 680.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XmsFOntrg%3D&md5=35c4631309e0b779e0d84c5771d7bfc0CAS |

[12]  M. M. McBride, D. E. Metzler, Photochem. Photobiol. 1967, 6, 113.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF2sXptFOrtg%3D%3D&md5=d8506a813f1a42ca91565631194f81c7CAS |

[13]  W. M. Moore, R. C. Ireton, Photochem. Photobiol. 1977, 25, 347.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE2sXltVWls7g%3D&md5=6dc952a3601ffd9183c02f392c87f95dCAS |

[14]  W. Holzer, J. Zirak, A. Penzkofer, P. Hegemann, R. Deutzmann, E. Hochmuth, Chem. Phys. 2005, 308, 69.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXpslOjsrk%3D&md5=d91954547cd40fecb1a5f5f024cc2cedCAS |

[15]  I. Ahmad, Q. Fasihullah, F. H. M. Vaid, J. Photochem. Photobiol. B 2004, 75, 13.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXlsFOku70%3D&md5=49f5e25db757a149c32be4063681a807CAS |

[16]  I. Ahmad, Q. Fasihullah, A. Noor, I. A. Ansari, Q. N. M. Ali, Int. J. Pharm. 2004, 280, 199.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXlslGhsLs%3D&md5=41eef72e1d279689bb38b8fa55640431CAS |

[17]  I. Ahmad, Q. Fasihullah, F. H. M. Vaid, J. Photochem. Photobiol. B 2005, 78, 229.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXhtlaisrg%3D&md5=6708782007bd96b8e73e2914805e7e43CAS |

[18]  I. Ahmad, Q. Fasihullah, F. H. M. Vaid, J. Photochem. Photobiol. B 2006, 82, 21.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXht12qt7bK&md5=eb206fcc68921615d339e6a4f234c9e5CAS |

[19]  I. Ahmad, S. Ahmed, M. A. Sheraz, F. H. M. Vaid, J. Photochem. Photobiol. B 2008, 93, 82.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXhtlaqsbfM&md5=854e448e8693f6eab82ca1ef368cbea1CAS |

[20]  I. Ahmad, S. Ahmed, M. A. Sheraz, M. Aminuddin, F. H. M. Vaid, Chem. Pharm. Bull. 2009, 57, 1363.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhsVOrt7w%3D&md5=9dbf76bb90bff707d27661cb86a21e51CAS |

[21]  I. Ahmad, S. Ahmed, M. A. Sheraz, F. H. M. Vaid, I. A. Ansari, Int. J. Pharm. 2010, 390, 174.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXksFSht78%3D&md5=4f4b51f25ed60a951461d1b00ea5d915CAS |

[22]  W. M. Moore, J. T. Spence, F. A. Raymond, S. D. Colson, J. Am. Chem. Soc. 1963, 85, 3367.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF3sXkslKgsrc%3D&md5=d82aadef24ade326e491ced14d110276CAS |

[23]  G. R. Penzer, G. K. Radda, Methods Enzymol. 1971, 18, 479.
         | Crossref | GoogleScholarGoogle Scholar |

[24]  P. F. Heelis, Chem. Soc. Rev. 1982, 11, 15.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL38XkvFajsr8%3D&md5=7cb8034806540abaa512d7bfb186cc74CAS |

[25]  P. F. Heelis, in Chemistry and Biochemistry of Flavoenzymes (Ed. F. Muller) 1991, Vol. 1, pp. 171–193 (CRC Press: Boca Raton, FL).

[26]  I. Ahmad, F. H. M. Vaid, in Flavins: Photochemistry and Photobiology (Eds E. Silva, A. M. Edwards) 2006, pp. 13–40 (Royal Society of Chemistry: Cambridge, UK).

[27]  I. Ahmad, G. Tollin, Biochemistry 1981, 20, 5925.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL3MXlt1yhtbo%3D&md5=46e2f32ab4bd65cb5bf65b8b252a42a2CAS |

[28]  I. Ahmad, Ph.D. thesis: A Study of the Degradation of Riboflavin and Related Compounds 1968, University of London.

[29]  M. Insinska-Rak, A. Golczak, M. Sikorski, J. Phys. Chem. A 2012, 116, 1199.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XivVejug%3D%3D&md5=717454be3278a13e0e9d9aa19312561bCAS |

[30]  M. J. O’Neil, The Merck Index 2001, 13th edn, electronic version (CD-ROM) (Merck & Co. Inc.: Rahway, NJ).

[31]  C. H. Suelter, D. E. Metzler, Biochim. Biophys. Acta 1960, 44, 23.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF3MXkvV2qsg%3D%3D&md5=a234928694250e395039e63f7f647a5bCAS |

[32]  P. J. Sinko, Martin’s Physical Pharmacy and Pharmaceutical Sciences 2006, 5th edn, pp. 270–277 (Lippincott Williams & Wilkins: Baltimore, MD).

[33]  E. Knobloch, Methods Enzymol. 1971, 18, 305.
         | Crossref | GoogleScholarGoogle Scholar |

[34]  B. Holmstrom, G. Oster, J. Am. Chem. Soc. 1961, 83, 1867.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaF3MXhtVensb4%3D&md5=60e7c4d5741dad5f56d416831700a4b1CAS |

[35]  E. S. Amis, J. F. Hinton, Solvent Effects on Chemical Phenomena 1973 (Academic Press: New York, NY).

[36]  C. Reichardt, Solvents and Solvent Effects in Organic Chemistry, 1988, 2nd edn (VCH Publishers: New York, NY).

[37]  E. Buncel, R. A. Stairs, H. Wilson, The Role of the Solvent in Chemical Reactions 2003 (Oxford University Press: New York, NY).

[38]  N. J. Turro, V. Ramamurthy, J. C. Scaiano, Modern Molecular Photochemistry of Organic Compounds 2010, pp. 469–474 (University Science Books: Sausalito, CA).

[39]  I. Ahmad, M. A. Sheraz, S. Ahmed, R. H. Shaikh, F. M. H. Vaid, S. R. Khattak, S. A. Ansari, AAPS PharmSciTech 2011, 12, 917.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhtFWks7nP&md5=3a5e6ea1188d4ae9f6af25c414400471CAS |

[40]  I. Ahmad, R. Bano, M. A. Sheraz, S. Ahmad, T. Mirza, S. A. Ansari, Acta Pharm. in press.

[41]  H. H. Fall, H. G. Petering, J. Am. Chem. Soc. 1956, 78, 377.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaG28XmvFCmtg%3D%3D&md5=c2e02376443eed9fcd50b6f25310146dCAS |

[42]  C. Fukumachi, Y. Sakurai, Vitamins 1954, 7, 939.(Kyoto)
         | 1:CAS:528:DyaG2sXpvFGisA%3D%3D&md5=f8607dfbeda6b49316d8f8a3a1cb1a26CAS |

[43]  Hatchard  C. G.Parker  C. A.Proc. R. Soc. 1956 , A235 , 518.