ABSTRACT
Cirsiliol is a flavone found in many Lamiaceae species with high cytotoxic activity against tumor cell lines. Although cirsiliol is being used in cancer therapy, its pharmacological potential is limited by its low solubility and bioavailability. In this paper, a cirsiliol-ß-cyclodextrin inclusion complex was developed in order to increase its solubility and bioavailability. The formation of inclusion complex was proved by scanning electron microscopy, Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) and solubility increment was verified through the ultraviolet-visible (UV-Vis) method. The cytotoxic effect against tumor cells (PC3, HCT-116 and HL-60 human cell lines, and S-180 murine cell line) and the antitumor activity in mice bearing sarcoma S-180 were also investigated. The inclusion complex was obtained with 71.45% of total recovery and solubility 2.1 times higher compared to the compound in its free form. This increment in solubility was responsible by a tumor growth inhibition potentiation (1.5 times greater compared to compound in its free form). In addition, this study showed that cirsiliol and its inclusion complex in ß-cyclodextrin have strong antitumor potential at low doses without promoting side effects commonly observed for conventional drugs as doxorubicin.
ABSTRACT
UNLABELLED: Abstract Context: Benznidazole (BNZ) is an antiparasitic with trypanocidal properties for the etiological treatment of Chagas disease since 1973. Monitoring the stability of this drug is one of the most effective methods of assessment, forecasting and prevention of problems related to quality product. OBJECTIVE: To investigate the direct and indirect photodegradation of BNZ and to evaluate the interference of the excipients used in the forms dosage solid as well as to shed light on the chemical structure of the degradation products obtained. MATERIALS AND METHODS: To perform this work we adopted the "ICH Harmonised Tripartite Guideline: Photostability Testing of New Drug Substances and Products Q1B" (Guideline Q1B). We used benzonidazole (BNZ) (N-benzil-2-(2-nitroimidazol-1-il) acetamide) (LAFEPE®, Recife, Brazil) and various excipients; beyond high-performance liquid chromatography (HPLC), differential scanning calorimetry (DSC), infrared spectroscopy (IR) and mass spectrometry/mass spectrometry (MS/MS). The indirect photodegradation of BNZ was carried out using physical mixtures with 13 pharmaceutical excipients commonly used in the preparation of solid dosage forms. RESULTS: HPLC and MS/MS techniques were selected for the identification of two photoproducts (PPs) and photoreactions found in direct and indirect tests with the microcrystalline cellulose, considered a critical excipient. DISCUSSION: Despite variations in the infrared spectrometry, differential scanning calorimetry and differential thermogravimetry curves, these techniques are not conclusive since the study of photodegradation of the drug caused decay of 30%, according to the ICH. CONCLUSIONS: The results show that BNZ only undergoes direct photodegradation, since no new PPs were found for a combination of the drug and excipients.
