The aim of the research is the determination of the total antioxidant activity and the content of phenolic compounds of the leaves of 12 species of non-traditional plants, namely,
Fruits constitute is a large group of functional food, whose consumption delivers several health benefits, but very limited studies about the leaves of plants especially lesser-known and non-traditional plants, among which fruit plants. Biological activity in plants present in leaves has attracted much attention to their beneficial health effects (
The leaves
The leaves of
The results of this study will provide new knowledge and useful information about the content of phenolic compounds in some selected non-traditional plants leaves and the antioxidant activity of their extracts, which will give a wide range of possibilities to employing these plants as the sources of phenolic compounds.
Objects of this study were leaves of 12 species of non-traditional plants, namely,
Leaves of non-traditional plants. Note: 1 –
The collected samples were packed in cotton bags and air-dried for several days. The air-dried samples were finely powdered using laboratory blender and kept in zip-locked bags until further analysis. Duplicate specimens were collected for the herbarium preparation.
All the chemicals used were of analytical grade and were purchased from Sigma-Aldrich (St. Louis, MO, USA) and CentralChem (Slovakia).
The dry non-traditional plants leaves were used for the detection of total phenolic content and total flavonoid content. An amount of 0.25 g of each sample was extracted with 20 mL of 80% ethanol for 24 h. Then, the sample in 80% ethanol was centrifuged at 4605 RCF (Rotofix 32 A, Hettich, Germany) for 10 min and the supernatant was used for measurement with the DPPH and molybdenum reducing antioxidant power methods.
The total polyphenol content (TPC) was measured by the method of
The total flavonoid content (TFC) was determined by the modified method described by
Total phenolic acid (TPA) content was determined using the method of
Free radical scavenging activity of samples was measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) (
Molybdenum reducing (MRP) antioxidant power of samples was determined by the method of
Basic statistical analyses were performed using PAST 2.17. Data were analyzed with ANOVA test and differences between means compared through the Tukey-Kramer test (α = 0.05). The variability of all these parameters was evaluated using descriptive statistics. Correlation coefficients were calculated by CORR analysis.
The main classes of natural antioxidant compounds such as flavonoids and phenolic acids often show a high correlation with antioxidant activity and have been identified in following non-traditional plants species:
Phenolic compounds have been proven to have a particularly strong antioxidant effect (
The amount of total phenolic acid content varied with the plant species (Figure
Total phenolic acid content in leaves of non-traditional plants.
Note: different superscripts in each column indicate the significant differences in the mean at
Comparing the works of literature,
The biological effects of many plant species depend on flavonoids; therefore, studies on the variation in their content are important and relevant (
In the present work,
Total flavonoid content in leaves of non-traditional plants.
Note: different superscripts in each column indicate the significant differences in the mean at
According to
Natural plant antioxidants include main classes such as phenolic compounds, vitamins, carotenoids, etc. Phenolic compounds are a large group of antioxidants that can have structures from simple molecules to polyphenols (like flavonoids). Moreover, polyphenol compounds characterized by numerous activities that can be useful in human life such as antimicrobial, antifungal, anti-inflammatory, etc. (
The concentrations of total polyphenols content in non-traditional plant leaves are presented in Figure
Total polyphenol content in leaves of non-traditional plants.
Note: different superscripts in each column indicate the significant differences in the mean at
The highest total polyphenol content was obtained from
After studying the total phenolic compounds content it is important to examine and assess the antioxidant activity in the extracts of non-traditional plant species leaves. The results obtained during studies will be useful for the assessment and standardization of the quality of plant raw materials and will allow predicting an antioxidant effect of leaves non-traditional plants species.
The DPPH radical scavenging activities of non-traditional plant leaves at different stages of growth are shown in Figure
Antioxidant activity in leaves of non-traditional plants evaluated by the DPPH method.
Note: different superscripts in each column indicate the significant differences in the mean at
The DPPH radical scavenging activity of the distilled water and 80% ethanol extracts of samples
Antioxidant activity by molybdenum reducing antioxidant power method ranged from 109.43 (
Antioxidant activity in leaves of non-traditional plants evaluated by the molybdenum reducing antioxidant power (different superscripts in each column indicate the significant differences in the mean at
Comparison analyses of obtained data with results of other reviews often difficult to use in a similar study because of using different methods of determination of antioxidant parameters, especially it is concerning standards that used and units.
The Pearson correlation coefficients between antioxidant activities and TPC, TPA, and TFC were depicted in Figure
Correlation between antioxidant activity and TPC (1), TPA (2), and TFC (3) of non-traditional plants leaves extract.
The result revealed the existence of a positive and negative correlation between tested antioxidant assays. TPC was significantly correlated with DPPH and phosphomolybdate assays (r = 0.609 – 0.718,
In conclusion, the results of this study will provide new knowledge and useful information about the content of phenolic compounds in some selected non-traditional plants leaves and the antioxidant activity of their extracts, which will give a wide range of possibilities to employing these plants as the source of phenolic compounds. The highest total amounts of polyphenols and flavonoids were determined in the
The publication was prepared with the active participation of researchers in International Network AgroBio