Tag Archives: TLC

Thin layer chromatographic compatibility study in preformulation of new transdermal therapeutic systems

DOI: 10.2478/amma-2020-0004

Objective: The compatibility of four binary active substances combinations adapalene – levofloxacin (ADP-LFX), adapalene – miconazole nitrate (ADP-MCZ), levofloxacin – meloxicam (LFX-MLX) and levofloxacin – miconazole nitrate (LFX-MCZ) was analysed to be comprised in new transdermal therapeutic systems. Also, the compatibility of selected active substances and four polymeric excipients (hydroxypropyl methylcellulose – HPMC 15000, hydroxypropyl methylcellulose – HPMC E5, ethyl cellulose – EC 10, and hydroxyethyl cellulose – HEC) was studied.
Methods: Thin layer chromatographic method (TLC) and four selected mobile phases were used. On the plate (in situ) were obtained the binary combinations (active substances and active substance-polymer).
Results: A good compatibility of ADP-LFX was found using ammonia : methanol : acetonitrile : methylene chloride 2:4:1:4 mobile phase. Using chloroform : acetone : glacial acetic acid 34:4:3 on the chromatogram of ADP-MCZ, only ADP spots appeared but without changes in the shape of the spots and Rf values. Any modifications of LFX and MLX spots (from LFX-MLX mixture) had been observed using toluene : glacial acetic acid : methanol 11:1:0.5 mobile phase, although LFX spots have remained on the baseline. Only LFX spots were visible from LFX-MLX and LFX-MCZ mixtures (ammonia : methanol : acetonitrile : methylene chloride 2:4:1:4 mobile phase). Distinctive spots were observed for ADP, LFX and MLX with variable results from no chemical interactions to limited chemical interactions when the compatibility with polymers was verified.
Conclusions: ADP-LFX and LFX-MLX mixtures were found to be compatible. ADP with HPMC polymers and LFX with HPMC E5 and HEC had presented excellent compatibility; for the other binary combinations, different analytical methods will be necessary.

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The Analysis of Flavonoids from Inula helenium L. Flowers and Leaves

Objective: In this study we investigated the flavonoids in the leaves and flowers of Inula helenium L..
Material and method: Flowers and leaves were harvested from the Medicinal Plant Garden of the University of Medicine and Pharmacy of Tîrgu Mureș. Dried vegetable product was extracted with methanol and in order to investigate aglycones we prepared hydrolised extracts. We screened the vegetable product for flavonoids using a TLC method, then we determined the total flavonoid content by a spectrophotometric method. HPLC-MS and HPLC-UV methods were used to determine polyphenols in methanolic and hydrolised extracts.
Results: Flavonoid content varies from 1.83% in leaves to 1.43% in flowers, equivalent in hyperoside. We identified the flavonols quercetin and kaempferol and the glycosides isoquercitrin, quercitrin and rutoside. Isoquercitrin is the major compound, in a concentration of 0.898 mg/g dry vegetable product.
Conclusions: Our study shows that the leaves and flowers of Inula helenium L. contain a high percentage of flavonoids with pharmacological activities.

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