Chemical profile, antioxidant and antimicrobial activity of Pinus heldreichii Christ. distributed in Bulgaria

Authors: SEMERDJIEVA, IVANKA - Agricultural University Plovdiv; Cantrell, Charles; ZHELJAZKOV, VALTCHO - Oregon State University; RADOUKOVA, TZENKA - Plovdiv University; KOLEVA-VALKOVA, LYUBKA - Agricultural University Plovdiv; ASTATKIE, TESS - Dalhousie University; KACANIOVA, MIROSLAVA - Slovak University Of Agriculture; BORISOVA, DANIELA - Vrachanski Balkan

Submitted to: Heliyon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2023
Publication Date: 12/10/2023
Citation: Semerdjieva, I.; Cantrell, C. L.; Zheljazkov, V. D.; Radoukova, T.; Koleva-Valkova, L. H.; Astatkie, T.; Kacániová, M.; Borisova, D. Chemical profile, antioxidant and antimicrobial activity of Pinus heldreichii Christ. distributed in Bulgaria. Heliyon 10 (2024) e22967 https://doi.org/10.1016/j.heliyon.2023.e22967.
DOI: https://doi.org/10.1016/j.heliyon.2023.e22967

Interpretive Summary: Pinaceae Lindl. species are a rich source of secondary metabolites, including monoterpenes, sesquiterpenes, diterpenes, phenolic compounds, and flavonoids. Some Pinus species' essential oils (EO) and products have been used in folk medicines and phytotherapy due to their various therapeutic activities. Exploring the phytochemical composition of plants has always been an area of interest for researchers and pharmacologists, particularly regarding the diversity of secondary metabolites in plants. The phytochemical composition of endemic plants with limited distribution provides a potential source for discovering new molecules and understanding the interaction between the plant and its environment. Pinus h'ldreichii (Bosnian pine), a survivor plant from the Tertiary era and a Balkan sub-endemic, is now mainly restricted to high altitude areas in the mountains of the Balkan Peninsula and is listed as the least concern species in 2016 by the IUCN Red List of Threatened Species. Given the limited distribution of P. heldreichii, research on its phytochemical composition of EO is mostly from Serbia, Greece, Bulgaria, Bosna, and Herzegovina. The objective of this study was to determine the variability of the EO composition, antimicrobial and antioxidant activities, and phenolic and flavonoid content of different parts of P. heldreichii in Bulgarian populations. The EO compositions were found to have significant diversity in terms of quantity and quality, with limonene and germacrene D being the most frequently reported major constituents of P. heldreichii EO. This is the first study that to identify several chemotypes and the total polyphenol, flavonoid content, and radical scavenging activity of annual wood, biennial wood, leaf, male cones, and the top of a twig.

Technical Abstract: Pinus h'ldreichii (Bosnian pine) Pinaceae is a Balkan sub-endemic, a Tertiary relict. There are no previous comprehensive studies on the essential oils (EO) profile and bioactivity of P. heldreichii plant parts; leaves, twigs, wood, cones (Male (M) and Femal (F)). The samples were collected from three different populations (mountains) in Bulgaria, and three of trees were sampled from each population. Therefore, the objective of the study was to determine the variability of the EOs composition, and antimicrobial, and antioxidant activities in Bulgarian populations of P. heldreichii plant parts. The EOs yield from different plant parts (wood of one-two-year-old twigs, leaves, the top of twigs, cones (M, F), and whole twigs (wood, leaves, the top of twigs) ranged from 0.085% (leaves) to 0.74% (wood). The monoterpenes was the predominant class in most of the samples of P. heldreichii EO, while in some of the leaf samples the sesquiterpenes was prevailing class. Limonene, ß-caryophyllene, a-pinene, ß-pinene, ß-myrcene, and germacrene D were found in all analyzed trees from the three populations but not in all plant parts. For example, limonene varied from 1.9% (grinded leaves, Slavyanka, tree #1) to 81.1% (M) cones, Slavyanka, tree #3) while germacrene D from 0.0% (M, cones, Slavyanka, tree #3) to 43.11% (grinded leaves, Vitosha). Similar variations were observed for a-pinene, ß-pinene, and ß-caryophyllene, respectively. Four chemical groups were identified for leaves and three for twigs based on the percent ratio of the main EO constituents of P. heldreichii. This study is the first one that has detailed analysis of the endemic plant P. heldreichii that identified several chemotypes and the total polyphenol, flavonoid content and radical scavenging activity of annual wood, biennial wood, leaf, M cones, and top of a twig. The leaves have the highest values in terms of polyphenols (31.65 mg g-1) and flavonoids (11.20 mg g-1), and higher ABTS radical scavenging activity (77.03% inhibition). The highest antimicrobial activity against Staphylococcus aureus subsp. aureus was seen in the EOs obtained from whole twigs.