Seasonal and Diurnal Variation in Leaf Phenolics of Three Medicinal Mediterranean Wild Species: What Is the Best Harvesting Moment to Obtain the Richest and the Most Antioxidant Extracts?

• Main Authors: Antonella Gori, Luana Beatriz Nascimento, Francesco Ferrini, Mauro Centritto, Cecilia Brunetti
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Molecules
• Subjects: antioxidant capacity; <i>cistus incanus</i>; dpph; environmental factors; flavonoids; <i>phyllirea latifolia</i>; <i>pistacia lentiscus</i>; polyphenols; seasonality; tannins
• Online Access: https://www.mdpi.com/1420-3049/25/4/956

Mediterranean plants biosynthesize high amounts of polyphenols, which are important health-promoting compounds. Leaf polyphenolic composition changes according to environmental conditions. Therefore, it is crucial to know the temporal variation in their production. This study aimed to: i) evaluate the monthly and daily changes in polyphenols of <i>Phyllirea latifolia</i>, <i>Cistus incanus</i>, and <i>Pistacia lentiscus</i> to identify their best harvesting moment, ii) verify the possible correlations between phenolic production and temperature and irradiation, iii) evaluate their antioxidant capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical (OH)scavenging assays. The extracts of leaves harvested at 8:00, 13:00 and 18:00, in May, July, and October for two years were analysed by HPLC-DAD. Both &#8220;month&#8221; and &#8220;time of the day&#8221; affected the polyphenolic content in all species. July at 13:00 was the best harvesting moment for all polyphenolic classes of <i>P. latifolia</i> and only for some classes of <i>C. incanus</i> and <i>P. lentiscus</i>. Environmental parameters positively correlated with the polyphenols of <i>C. incanus</i> and <i>P. latifolia</i>, while the antioxidant capacity only varied in this last species, reaching the highest value in July. Results of the study allow to determine the balsamic time for each species. Moreover, the relationship between polyphenols and environmental data can be useful for the cultivation of these plants under controlled conditions.