FTIR analysis of molecular composition changes in hazel pollen from unpolluted and urbanized areas

The prevalence of respiratory allergic diseases is increasing every year, especially in developed countries (Verlato et al. 2003 ; ECRHS 1996 ; ISAAC 1998 ; Sozańska et al. 2015 ; Timm et al. 2016 ). Pollen grains are recognized as important agents causing allergies in susceptible subjects, and hazel pollen is one of the most common allergen (D’Amato et al. 2007 ; Yalcin et al. 2013 ; Asam et al. 2015 ). As an aeroallergen, it can cause conjunctivitis, allergic rhinitis, or even asthma in sensitized individuals. In early spring, hazel pollen has been shown to be an important cause of pollinosis in Switzerland (Frei and Gassner 2008 ), France (Thibaudon 2003 ), Germany (Levy and Bircher 1994 ), Romania (Popescu et al. 1985 ), Poland (Grewling et al. 2014 ) and Italy (Cecchi et al. 2013 ). High or relatively high airborne pollen concentrations have been recorded during February–March in Italy (Longo and Sauli 2010 ), England (Emberlin et al. 2007 ), Croatia (Sikora et al. 2013 ) and in Poland (Nowosad et al. 2014 , Kruczek et al. 2015 ). This period coincides with the heating season in Central Europe, when increased levels of contaminants such as SO 2 , NO 2 , CO 2 and O 3 are observed. Numerous studies correlating the increase in number of people suffering from allergy with morphological and biochemical changes within the pollen grain caused by air pollutants have been conducted (Emberlin et al. 1993 ; D’Amato 2000 ; Ackaert et al. 2014 ; Lázaro et al. 2014 ; Todea et al. 2013 ). These changes can cause a more frequent occurrence of inhalant allergies or more severe allergic reactions (Pasqualini et al. 2015 ; Tedeschini et al. 2015 ). The morphological modifications of the pollen grains can be analyzed by microscopy, which however does not provide any information about structural and biochemical changes. An alternative are molecular biology techniques, which give information about the mutation in nucleic acid of the pollen grains leading to mutations in proteins. These mutations could be responsible for structural and functional changes in peptides (Friedberg 2010 ; Li et al. 2010 ). Unfortunately molecular biology techniques are very expensive and do not provide information about biochemical and structural changes in proteins. Yet, information about structural and biochemical changes in chemical compounds building the pollen grains can be obtained by Fourier Transform Infrared (FTIR) spectroscopy. This technique, in combination with curve-fitting analysis of amide I profile, is becoming more and more common for studying biological samples. FTIR spectroscopy is fast, simple, requires small quantities of measured material, is economic and does not destroy the sample. The energy of the electromagnetic wave in the infrared range is large enough to cause vibrations of functional groups belonging to nucleic acids, proteins, polysaccharides, lipids and water, through a change in the dipole moment of bonds (Scotter 1997 ; Van de Voort and Sedman 1993 ). The FTIR technique therefore seems to be an ideal tool for measuring the chemical compounds of plant pollen of different species. The fingerprint region of FTIR spectra allows for unambiguous identification of the substances. Therefore, the FTIR technique is often used to identify the pollen species (Suphioglu et al. 1992 ). Indeed, there are studies, in which the authors apply spectroscopic methods for the identification of pollen and thus create spectroscopic libraries of plants and pollen (Zimmermann and Kohler 2014 ; Gottardini et al. 2009 ; Guedes et al. 2014 ).