Seasonal variation and gender pattern of phenolic and flavonoid contents in Pistacia chinensis Bunge inflorescences and leaves

Beyond the Nut: Pistacia Leaves as Natural Food Preservatives

The pistachio tree (Pistacia vera) is globally renowned for its nutritious nuts, while its leaves remain an underutilized source of chemicals with significant potential value as food preservatives. Similar value may be found in the leaves of other wild Pistacia species common in Central Asia, the Levant, and around the Mediterranean. Some species' leaves have been used as natural preservatives, demonstrating their effectiveness and highlighting their rich bioactive components. This review investigates the antioxidant and antimicrobial properties of Pistacia leaves, comparing both cultivated and wild species. A comprehensive search was performed across several scientific databases, including PubMed, Scopus, Web of Science, and Google Scholar, utilizing a combination of keywords related to Pistacia species and their bioactive compounds. The inclusion criteria focused on articles published in English from 2017 till the end of June 2024, analyzing the antioxidant and antimicrobial activities of Pistacia leaves and employing relevant extraction methods. A total of 71 literature sources were included, covering species such as P. vera, P. atlantica, P. terebinthus, and others sourced from countries such as Iran, Turkey, and Italy. This review found that Pistacia leaves are rich in polyphenolic compounds and exhibit robust antioxidant and antimicrobial properties, with certain wild species outperforming P. vera, suggesting species-specific traits that enhance their preservative potential. The major findings indicate that extracts from wild species exhibit superior bioactivity, which could be harnessed for food preservation. These insights underscore the promising role of Pistacia leaves as natural food preservatives, with further research needed to address challenges in extraction and application. Exploring their synergistic effects with other preservatives could lead to innovative solutions in food preservation while fostering local economic growth.

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?

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 Phyllirea latifolia, Cistus incanus, and Pistacia lentiscus 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 "month" and "time of the day" affected the polyphenolic content in all species. July at 13:00 was the best harvesting moment for all polyphenolic classes of P. latifolia and only for some classes of C. incanus and P. lentiscus. Environmental parameters positively correlated with the polyphenols of C. incanus and P. latifolia, 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.

Comparative metabolomics of Tilia platyphyllos Scop. bracts during phenological development

The medicinal plant drug "Tiliae flos" consists of the botanical flowers and bracts of Tilia sp., gathered almost exclusively during flowering. In this study, we examined the changes in the metabolome of specialized products in the bracts of Tilia platyphyllos from the appearance of the organ till the onset of senescence by LC-ESI-MS and data mining. A set of 504 natural products were detected, 241 of which showed significant seasonal variation (p < 9.92E-5). Seven compounds were quantified and an additional 45 were putatively identified. These included flavonoid glycosides, catechins, procyanidins, quinic acid derivatives (including chlorogenic acid) and coumarins. Compared to bracts during flowering, young tissues were characterized by a relatively high diversity of polyphenolic substances. Higher amounts of flavonol glycosides (quercetin, kaempferol), catechins and derivatives have been observed. Deoxyhexosides were almost exclusive to this phenological stage. Changes of about one order of magnitude were not uncommon. For some substances, 5-fold differences were observed (calibration with authentic standards). Some compounds (e.g. the coumarin fraxin) were more prominent at the late fruit growth stage. It was shown that bracts gathered before or after flowering could potentially be therapeutically useful. Changes are rapid during the early phase of bract development: three different groups of compounds presented their maxima during the first 32 days. Considering seasonal variation is of extreme importance during bioactivity tests and screening candidate sources for bioactive natural products. In the case of T. platyphyllos, young and old bracts can be of interest because of their high diversity of distinct specialized metabolites.

Nitrogen availability alters flavonoid accumulation in Cyclocarya paliurus via the effects on the internal carbon/nitrogen balance

Cyclocarya paliurus has traditionally been used in medicines and nutraceutical foods. The aims of this study were to determine whether flavonoid accumulation in C. paliurus is dependent on nitrogen (N) availability and to investigate the internal C (carbon)/N balance under controlled conditions. One-year-old seedlings were grown under five increasing available N level treatments (N1-5) and were harvested throughout the 15-d experimental period. The greatest total chlorophyll amount and photosynthetic rate were achieved during the intermediate N treatments (N3 and N4). The greatest starch level was detected in N3. The total C level was relatively stable, but the total N and free amino acid levels increased, which resulted in a decreased C:N ratio. The flavonoid contents in roots and stalks decreased, while leaves showed a different pattern (peaking in N3). The flavonoid level was closely correlated with flavanone-3-hydroxylase activity, which displayed a similar variation pattern, and their levels were significantly positively correlated with those of total C and starch. Thus, the partitioning of C among primary and secondary metabolisms could be responsible for flavonoid biosynthesis and provide the basis for maintaining high yields, which increases the nutritional values of crops and medicinal plants.

Effects of nitrogen availability on mineral nutrient balance and flavonoid accumulation in Cyclocarya paliurus

Cyclocarya paliurus has traditionally been used as medicine or nutraceutical foods. This study aims at investigating flavonoid accumulation in C. paliurus dependent on nitrogen availability and the following internal mineral nutrient balance under controlled condition. The 1-year-old seedlings of C. paliurus were grown in five different nitrogen levels. Along with the N gradient, C/N was significantly decreased, and the concentrations of phosphorus, potassium, calcium and magnesium were changed within plant. In the leaves, the main accumulation organ in C. paliurus, the highest flavonoid accumulation was achieved in intermediate N level (N3), which was closely related to flavanone-3-hydroxylase (FHT) activity as they had the similar variation patterns. Correlation analysis suggested that internal mineral nutrient balance can significantly affect flavonoid accumulation, especially for Mg within plant. These data revealed that nitrogen availability and the following altered internal mineral balance can significantly affect flavonoid accumulation. This study can provide the basis for developing new agricultural practices to maintain high yield while still keeping the nutritional value of crop or medicinal plants.