Inclusion complexes of rifampicin (RP) were prepared with hydroxypropyl-β-cyclodextrin (HPβCD). The aqueous solubility of RP increased linearly with cyclodextrin concentration in all rangeof the solubility diagram. The data was analyzed using the framework of Higuchi and Connors. The stability constant (K) values for RP/HPβCD complex at pH 6.9 were 18 and 120-125 M -1 for ionic strength 0.01 and 0.18M, respectively. The analysis of the chemical shift data of 1 H and 15 N for free RP and RP/HPβCD inclusion complex reveal that only peaks of the side chain related to the piperazine ring of RP change substantially, probably due to interaction of this region of RP molecule with the hydrophobic core of HPβCD. We also postulated the optimized structure of RP/ HPβCD inclusion complex using molecular modelling study. We found that the postulated structure was in agreement with 1 H and 13 C-NMR and 15 N-NMR spectra.
Gelatinization of the starch obtained from fruit seed such as mango and cumbaru was investigated applying an analytic methodology developed in the polymer nuclear magnetic resonance (NMR) laboratory at IMA=UFRJ, employing high resolution nuclear magnetic resonance spectroscopy in the solid state for hydrogen nucleus, using 1 H HR-MAS pulse sequence. The results showed that NMR can be used instead of some techniques normally applied to study the gelatinization process, because 1 H HR-MAS and relaxation time allow the evaluation of this process at the molecular level. NMR was also able to indicate the best gelatinization conditions. To start this study the glass transition (Tg) determination was a first step, because the Tg of seed starches are different than the Tg of starches derived from cereal, for example. The 1 H HR-MAS NMR showed some useful information on the fruit seed starches gelatinization process. X-ray measurements were also used to support the data obtained from NMR technique. It was verified, 1135 from X-ray, that mango starch exhibits crystallinity in the A form and cumbaru showed a predominant amorphous phase. The use of 1 H HR-MAS was shown to be a new, powerful method to follow the gelatinization process, because this process can be understood at the molecular level.
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