The complex world of polysaccharides edited by Desiree Nedra Karunaratne

 

The Complex World of Polysaccharides 

608 

In general way, results demonstrated that three chemicals (fluoxetine, vitamins B2 and B12) 

are transferred to microenvironment generated by weakly acidic solution of chitosan but in 

different proportions, due to the structural feature and solubility of each. Table 1 describes 

the relative increase of the fluorescence and absorption intensities of the chemicals when 

chitosan concentration ranges from zero to 1.0 g.L

-1

. 

Both vitamins belong to the class of hydro soluble vitamins (Sun et al., 2007), while the 

fluoxetine drug is slightly soluble in water (Darwish, 2005). The low solubility promotes 

some molecules of fluoxetine to migrate from aqueous environment to the more rigid 

environment generated by chitosan (the higher the concentration) causing a proportionately 

greater increase of absorbance and fluorescence intensities. However, the fluorescence 

intensities of vitamin B12 also increase in the same proportion and the absorbance 

intensities in proportion even higher, despite the hydro soluble nature of this vitamin. 

 

 

 

 

Figure 2.

 Absorption spectra and chemical structures of vitamin B12 (A), vitamin B2 (B)  

and fluoxetine (C). 

---

The Chitosan as Dietary Fiber: An in vitro Comparative  

Study of Interactions with Drug and Nutritional Substances  609 

These results demonstrate that the transfer process of chemicals from aqueous environment 

to the chitosan aggregates is influenced by solubility of the molecules in water and/or by the 

molecular structure. Particularly, the structure molecular of vitamin B12 seems to have an 

interesting effect in this case. Vitamin B12 belong to the cobalamins, a class of octahedral 

Co(III) complexes which contain a planar framework called a corrin, with the metal center 

coordinated in the equatorial position by the four corrin nitrogens. Her energies of excited 

states are sensitive to the nature of the ligands of center coordinated and are influenced by 

water content of the surrounding environment (Solheim et al., 2011). These characteristics 

may be the reason for the more significant increase of the spectral properties of the vitamin 

B12, with increasing concentration of chitosan (lower water content), compared with the 

vitamin B2. 

In fact, some molecules of fluoxetine or vitamins B2 or B12, are transferred to 

microenvironment generated by weakly acidic solution of chitosan. Among the three, the 

vitamin B2 is transferred in a smaller proportion. However, for all of them is expected that 

its loss in the diet, caused by administration of chitosan, is not so significant. 

From our observations, possible risks to the patient should be considered when prolonged 

treatment with chitosan is prescribed and perhaps extra care should be taken when 

chitosan and fluoxetine are prescribed together in slimming diets. In the case of vitamins, 

essential for many physiological functions, there must be some precautions to minimize 

the impacts generated by this therapeutic, as the replacement of nutrients in the diet of 

patient. 

 

Figure 3.

 Fluorescence spectra of fluoxetine in acid aqueous solution of chitosan.  

Chitosan concentrations: 0.00; 0.050; 0.60 and 1.0 (from the base to the top). 

---

 

The Complex World of Polysaccharides 

610 

 

 

 

Figure 4.

 Fluorescence spectra of vitamin B12 in acid aqueous solution of chitosan. Chitosan 

concentrations: 0.00; 0.050; 0.60 and 1.0 (from the base to the top). 

 

 

Figure 5.

 Fluorescence spectra of vitamin B2 in acid aqueous solution of chitosan. Chitosan 

concentrations: 0.00; 0.050; 0.60 and 1.0 (from the base to the top). 

---

The Chitosan as Dietary Fiber: An in vitro Comparative  

Study of Interactions with Drug and Nutritional Substances  611 

 

Figure 6.

 Behavior of absorption intensities of fluoxetine, vitamin B12 and B2. 

Chemicals

I

ABS

Vitamin B12 

107 % 

80 % 

Vitamin B2 

30 % 

14 % 

fluoxetine 

109 % 

40 % 

Table 1.

 Relative increase on the fluorescence (I) and absorption (ABS) intensities of the fluoxetine, 

vitamins B2 and B12 when chitosan concentration ranges from zero to 1.0 g.L

-1

. 

This paper seeks to warn to possible problems connected with the excessive loss of vitamins 

and other nutrients by the body during prolonged treatment with chitosan, as well as due 

the concomitant use of chitosan and fluoxetine. 

4. Conclusions 

Innumerous studies have described the formation of aggregates in naturals (Kim et al., 2000; 

Pelletier et al., 2000; Zhbankov et al., 2003), as chitosan ((Rodrigues, 2005; Hennen, 2005; 

Rodrigues et al., 2008) and synthetic (Kalyanasundaram, 1987; Neumann & Rodrigues, 1994; 

Neumann et al., 1995; Gomes et al., 2006; Gomes et al., 2007; Sur, 2010) polymers solutions 

and these molecular structures occur due to intra- and intermolecular interactions. 

Chitosan is a polysaccharide precursor of materials suitable to release and/or dissolve drugs 

into the human body (Hennen, 2005), among other uses. However, the study of spectral 

properties of chemicals, fluoxetine, vitamins B2 and B12, demonstrated that the 

microenvironment generated by weakly acidic solution of chitosan also is able to sequester 

some B2, B12 and fluoxetine molecules, despite the hydro soluble nature of vitamins. 

---