Pot marigold (Calendula officinalis L.) contains various bioactive compounds such as flavonoids, tannins, saponosides, carotenoids, triterpene alcohols, polysaccharides, amino acids, and essential oil. The extract of pot marigold flower has a benefit to the skin due to the presence of flavonoids that possess the anti-inflammatory, astringent, antifungal, and antiseptic effects. The aim of this study was to apply the ultrasound-assisted extraction as an advanced extraction technique and to investigate the impact of extraction time (5-35 min), ethanol concentration (20-80%, v/v), and extraction temperature (30-70 °C) on the total flavonoid content of pot marigold flower at the liquid-to-solid ratio of 20 cm 3 g -1 . The total flavonoids content of the extracts was determined spectrophotometrically with aluminium (III) chloride. The modeling of ultrasound-assisted extraction was carried out using a Box-Behnken design. Thus found optimal extraction conditions were the extraction time of 29 min, 39.6% (v/v) ethanol, and extraction temperature of 64.2 °C. The experimental value (220.2 mg 100 g -1 d.w.) of the total flavonoid content under optimal conditions was in a good agreement with the predicted value (221.5 mg 100 g -1 d.w.). According to the results of statistical analysis, the proposed second-order polynomial equation can be used to describe the extraction of flavonoids and to predict the total flavonoid content. The extraction procedure can be accepted from the point of the pharmaceutical application due to the use of ethanol as a representative of green solvents. The extraction time was shorter compared with other conventional extraction techniques.

In this study, the modified stability-indicating RP-HPLC method was validated for quantitative analysis of amlodipine besylate in the presence of its impurity D (3-ethyl 5-methyl 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-6-methylpyridine-3,5-dicarboxylate). The method was applied for the determination of an analyte in the tablets and irradiated samples packed in the primary packaging (Alu/PVC/PVDC blister packaging). The efficient chromatographic separation was achieved using a ZORBAX Eclipse XDB-C18 column (4.6×250 mm, 5 mm) with isocratic elution of mobile phase which consisted of acetonitrile:methanol:triethylamine solution (15:35:50, v/v/v) (pH 3.0). The flow rate of the mobile phase was 1 mL min-1, while the detection of amlodipine besylate was carried out at 273 nm. Amlodipine besylate and its impurity D were identified at the retention times of 16.529 min and 2.575 min, respectively. The linearity of the method with the coefficient of determination of 0.999 was confirmed in the concentration range of 10 - 75 µg mL-1 for amlodipine besylate. The limit of detection was 0.2 µg mL-1, while the limit of quantification was 0.66 µg mL-1. After UV and Vis radiation of the tablets packed in the primary packaging, the content of amlodipine besylate was reduced by 22.38% and 19.89%, respectively. The presence of new degradation products was not detected under the given chromatographic conditions. The photodegradation of amlodipine besylate followed pseudo-first-order kinetics. Based on the half-life of amlodipine besylate (38.4 days for UV radiation and 43.3 days for Vis radiation), it was concluded that amlodipine besylate in the tablets has satisfactory photostability after its packing in the Alu/PVC/PVDC blister packaging.

Pot marigold flower extract (Calendula officinalis L.) has pharmacological properties due to the presence of various bioactive compounds. It is known that the extract has antioxidant, anti-inflammatory, antitumor, antibacterial, antifungal, antiviral, antimutagenic, antidermatitis properties, etc. The aim of this study was to improve the quality of the selected topical formulation by adding the ethanolic extract of pot marigold flower, as well as to monitor its stability. The topical formulation was water-in-oil emulsion prepared using the hot/hot emulsification process with an oil phase consisting of Vaseline, lanolin, and almond oil. The extract, prepared by ultrasound-assisted extraction, had an antioxidants content of 3.512 g gallic acid equivalent per 100 g-1 of dry weight and the half-maximal inhibitory concentration of 0.14 mg mL-1 determined by the DPPH assay. Chemical stability studies have shown that daylight has no significant effect on the stability of antioxidants in the extract, while an increase in temperature leads to their degradation. The shelf-life of the extract is about 8 months at 4 °C and 3 months at 22 °C (room temperature). The prepared uncategorized topical formulations containing 1% and 2% (w/w) pot marigold extract were stable at different temperatures during the storage. The uncategorized formulations showed antioxidant activity, but the activity of the extract in the formulations decreased with increasing storage temperature. Pot marigold flower extract and the developed uncategorized formulations showed an inhibitory effect on Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae), as well as on Candida albicans. The uncategorized formulations with this activity can be used in the treatment of skin infection.