Interest in plant extracts as a natural source of antioxidants has grown significantly in recent years. The tree species Koelreuteria paniculata deserves attention due to its wide distribution, good adaptability, and growth to the degree of invasiveness in a number of European countries. The purpose of the present study was to analyze flavonoids and phenolic acids of the ethanol extracts from aerial parts of K. paniculata and to screen their antioxidant and DNA-protective activity. HPLC profiling revealed the presence of five flavonoids, with rutin (4.23 mg/g DW), hesperidin (2.97 mg/g DW), and quercetin (2.66 mg/g DW) as the major ones in the leaves, and (−)-epicatechin (2.69 mg/g DW) in the flower buds. Among the nine phenolic acids identified, rosmarinic, p-coumaric, salicylic, vanillic, and gallic acids were the best represented. All the extracts tested showed in vitro antioxidant activity that was determined by DPPH, ABTS, FRAP, and CUPRAC assays. The highest activity was recorded in the flower parts (in the range from 1133 to 4308 mmol TE/g DW). The DNA-protective capacity of the flower and stem bark extracts from the in vitro nicking assay performed, as well as the main diagnostic microscopic features of the plant substances, are given for the first time. According to the results obtained, the aerial parts of K. paniculata could be valuable sources of natural antioxidants.

Methylxanthines, purine alkaloids found in plants, are found in beverages (coffee, tea, cocoa) and foods (chocolate and other cocoa-containing foods) commonly consumed worldwide. Members of this family include caffeine, theophylline and theobromine. Methylxanthines have a variety of pharmacological effects, and caffeine and theophylline are used as pharmaceuticals. Methylxanthines are metabolized in the liver predominantly by the enzyme CYP1A2. Their co-administration with CYP1A2 inhibitors may lead to pharmacokinetic interactions. Little is known about the possible drug interactions between caffeine and substrates of other CYP450 enzymes. In our study, methylxanthine fractions inhibited CYP3A4 in a concentration-dependent manner. Concomitant consumption of green tea with CYP3A4 substrates could increase the possibility of interactions, and this requires further clarification. The inhibition of CYP3A4 is not only due to the presence of catechin derivatives but methylxanthines may also contribute to this effect.

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Background: Lycium barbarum has gained immense popularity over the past decade because of its antioxidant properties. There are many reports of observed health benefits of juice consumption, including prophylaxis in neoplastic disease and treatment of tumors. Materials and methods: In this study, we isolated three fractions of Lycium barbarum fruits – total water, pectin-free and polysaccharide, and determined their antioxidant activity by ORAC and HORAC assays. We investigated the antiproliferative effects of Lycium barbarum’s pectin-free and polysaccharide fraction on three different breast cell lines - MCF-10A (non-tumorigenic epithelial breast cell line), MCF-7 (breast cancer cell line, estrogen, progesterone receptors +, HER2-), and MDA-MB-231 (breast cancer cell line, triple negative), by the MTT dye reduction assay. Results: The Lycium barbarum’s pectin-free fraction showed concentration-dependent growth inhibition on the three cell lines, moreover, on cancer cells (MCF- 7 and MDA-MB-231) it was significantly more pronounced. The polysaccharide fraction showed negligible activity on the three cell lines, only the highest concentration (1000 μg/mL), suppressed the proliferation of MCF-7 cells. The combination of pectin-free and polysaccharide fraction on MCF-7 did not show the expected synergistic effect. Conclusion: We found a relative correlation between the polyphenolic content of the extracts and the observed effects. The pectin-free extract had the highest content of polyphenols with the best antioxidant and antineoplastic activity against breast cancer cells. Addition of polysaccharide to the pectin-free fraction contributes to its pharmacological activity.