Antioxidant and DNA-Protective Potentials, Main Phenolic Compounds, and Microscopic Features of Koelreuteria paniculata Aerial Parts

Abstract

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.

Phenolic Profile, Antioxidant and DNA-Protective Capacity, and Microscopic Characters of Ailanthus altissima Aerial Substances

“…Plant substances (crushed, fresh) used for the DNA analysis were extracted with 96% ethanol for 10 days. The methodology and apparatus used to prepare the dried (vacuum) extracts are according to the previously described procedure of Andonova et al [ 42 ].…”

“…HPLC analysis was conducted according to the method described by Krasteva and Andonova et al [ 42 , 43 ] using HPLC system Waters 1525 (Binary HPLC pump) and UV-VIS Waters 2487 (Dual Absorbance Detector). Separation of the compounds was performed by a SUPELCO Analytical Discovery HS C18 column (25 cm × 4.6 mm, 5 µm) under gradient conditions with a mobile phase consisting of 1% ( v / v ) acetic acid in water (Mobile phase A) and methanol (Mobile phase B) at a flow rate of 1 mL per minute.…”

“…The DNA protective effect of the extracts was assessed using pUC19 plasmid DNA purified from E. coli strain Neb10 according to Andonova et al and Rajiv et al [ 42 , 49 ]. Serial dilutions of plant extracts, starting from 0.6 μg/mL up to 10.0 μg/mL, were tested.…”

Bioavailability and Bioactivity of Plant Antioxidants

“…Andonova et al [ 14 ] conducted research on the composition and concentration of phenolic compounds, antioxidant activity (tests: DPPH, ABTS, FRAP, CUPRAC), and the ability to protect DNA against the reactive oxygen species (ROS) of ethanol extracts from the aerial parts of the Koelreuteria paniculata tree, such as the flowers, the flower buds, leaves, and stem bark. Five flavonoids (rutin, hesperidin, quercetin, (-)-epicatechin and only in stem bark extract: (+)-catechin) and nine phenolic acids (rosmarinic, p -coumaric, salicylic, vanillic, protocatehuic, caffeic, syringic, only in stem bark extract: ferulic and only in leaf extract: gallic) were identified in the extracts).…”

“…Five flavonoids (rutin, hesperidin, quercetin, (-)-epicatechin and only in stem bark extract: (+)-catechin) and nine phenolic acids (rosmarinic, p -coumaric, salicylic, vanillic, protocatehuic, caffeic, syringic, only in stem bark extract: ferulic and only in leaf extract: gallic) were identified in the extracts). All of the tested extracts showed antioxidant and DNA-protective potential, most visible in the case of extracts from flower parts and leaves [ 14 ].…”