Stability tests are essential to assuring herbal derivative quality, especially because of the complexity of the herbal matrix. To monitor the stability of Sambucus nigra L. flower tincture, a practical liquid chromatography (LC)-UV method was developed and validated. Rutin, the flower's pharmacopeial marker, in addition to other markers, isoquercitrin and quercetin, were quantified. The last two represent the degradation products of glycosylated flavonoids. In addition, other chromatographic peaks exhibiting typical flavonoid UV absorption profiles (total flavonoids) were also quantified and expressed in rutin equivalents. The method was developed with a reverse phase C 18 column, using a gradient mobile phase at 0.7 mL min-1 at 30°C. The herbal drug and tincture obtained by percolation at 60 °C with ethanol 25% (v/v) were submitted to accelerated (40°C/75% RH, 2 months) and long duration (15-30°C, 6 months) studies. The LC-UV method was linear in the ranges of 1-200 µg mL-1 (rutin) and 1-100 µg mL-1 (isoquercitrin and quercetin), without interference of herbal matrix, and was precise (RSD ≤ 2.0% for intra and interday precision), selective, and robust (changes in mobile phase flow, pH and temperature). The tincture revealed the presence of quercetin, which was absent in the herbal drug, likely due to the hydrolysis process. After 2 months under accelerated study, the total flavonoids in the tincture decreased by approximately 20%, and after 6 months at room temperature, they decreased by approximately 30%. These results indicate the thermolability of the S. nigra tincture and the importance of monitoring phytomedicine stability.
Although traditional use of elderberry flowers is recognized by Medical Agencies, there are not suitable products on the Brazilian market. To overcome poor stability of tinctures of Sambucus nigra flowers, we aimed to develop spray dried microparticles. Statistical experimental design was applied taking inlet temperature and maltodextrin% at five different levels. Next, we applied a stability study for 60 days under accelerated conditions (40 C/75% RH) and 180 days at room temperature (15-30 C). We monitored flavonoid content as markers. The best drying condition was 188 C and 65% of carrier and enabled microparticles with more than 90% of markers recovery. After 180 days, the dried extract remained with 90.8% at room temperature. The markers were released from microparticles in two minutes. In conclusion, the spray drying process and formulation enabled elderberry flowers to be easier to apply in solid pharmaceutical forms.
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