Chemical composition of essential oil from female cones of Cupressus arizonica Greene

Abstract The hydrodistilled volatile essential oils extracted from the female cones of Cupressus arizonica Greene that harvested in winter and spring seasons were analysed for their chemical composition by using gas chromatography-mass spectrometry (GC/MS). Twenty-four and seventeen components were identified, accounting for winter (95.5%) and spring (96.9%) of the total oils volume, respectively. Monoterpenoids (winter 93.7% and spring 95.0%) dominated the identified components in the essential oils, followed by a small portion of sesquiterpenoids (winter 1.8% and spring 1.9%). Monoterpene hydrocarbons (MH) (winter 90.9% and spring 94.9%) were the principal subclasses of components with α-pinene (winter 42% and spring 72%), β-myrcene (winter 18.5% and spring 7.7%), δ-3-carene (winter 11.3% and spring 5.1%), limonene (9.4% for winter), and β-pinene (5.3% for spring) as main constituents. Limonene (9.4%), camphor (0.2%), exo-methylcamphenilol (0.2%), terpinene-4-ol (0.6%), β-citronellol (0.9%), and bornyl acetate (0.3%) were representative of the monoterpene hydrocarbon and oxygen-containing monoterpenoids (OM) in winter essential oil. Graphical Abstract

The Arizona cypress is a medium-sized evergreen coniferous tree with 15 to 18 m tall and 38 to 76 cm in diameter. It has blue-green foliage to scaly reddish brown bark and is naturally grown in Arizona and southwest USA (Little and Skolmen 1989;Mozaffarian 2004;Swearingen and Bargeron 2016). This beautiful tree was introduced into Iran in 1954 and cultivated in various parts of the country as an ornamental tree and for reforestation purposes (Sabeti 1966). Essential oils are generally derived from one or more plant parts such as flowers, leaves, stems, bark, wood, roots, seeds, fruits, rhizomes, and gums or oleoresin exudations (Handa et al. 2008) and essential oils play an important role in plants when act as antibacterials, antivirals, antifungals, insecticides, and protect plants against herbivores (Cascaes et al. 2021). The essential oil of C. arizonica has a potential effect on malaria vector (Sedaghat et al. 2011) with a remarkable inhibition on bacteria growth tested (Bouksaim et al. 2018). The yield of plant material, essential oil content, and quantitative composition of plants can be influenced by harvest time, ecological, and climatical conditions (Putievsky and Basker 1977;Cabo et al. 1987). Essential oil is also affected by soil types varies (Gouyon et al. 1986) and seasonally (Putievsky et al. 1986;_ Inan et al. 2011;Verma et al. 2015;Rathore et al. 2022;Stefanakis et al. 2022). Milos et al. (2002) analyzed the essential oil from fresh leaves of Cupressus sempervirens L. by GC/MS in order to determine seasonal variation in their chemical composition. They found that there were notable differences in the amounts of several compounds. M€ uller-Riebau et al. (1997) reported that the amount of essential oils and their concentrations of the phenolic constituents were the lowest in spring and the highest in June/July when the full blooming period.
C. arizonica Greene is an aromatic evergreen coniferous plant with great importance in urban horticulture and in the pharmaceutical and fragrance industries (Hassanpouraghdam 2011).
There is no previous report on the chemical analysis of C. arizonica volatile oil in winter and spring harvesting seasons from central Alborz province of Iran. Therefore, this study attempts to identify the volatile oil components of female cones harvested in winter and spring seasons from C. arizonica cultivated in central Alborz province of Iran for the first time.

Results and discussion
Hydrodistillation of C. arizonica gave dark-yellow oil with a yield of 1 mL/100 g, based on the wet weight of fruit.
Figures S1 and S2 (Supplementary material) shows the chromatograms of the essential oil of C. arizonica female cones obtained by using two different times and stations and analyzed in the HP-5MS column.
The identified constituents were presented in Tables S1 and S2 (Supplementary material), where all compounds are listed in order of their elution from the HP-5MS column. Twenty-four and seventeen compounds were identified (Supplementary material, Tables S1 and S2), representing 95.5 and 96.9% of the oil volume in January 2020 (winter) and April 2022 (spring) test materials, respectively. Among the groups, monoterpene hydrocarbons were predominant (90.9 and 94.9%, respectively), followed by oxygenated monoterpenes (2.9 and 0.2%, respectively), sesquiterpene hydrocarbons (1.5 and 1.4%, respectively), and oxygenated sesquiterpene (0.2 and 0.6%, respectively). Among the monoterpene hydrocarbons, a-pinene (42 and 72%, respectively) was the major compound, and among the sesquiterpene hydrocarbons, a-cubebene (0.4%) in January 2020 and a-humulene (0.5%) in April 2022 test samples were main components. While, in C. arizonica oil extracted from the fruits harvested in the campus of Ferdowsi University of Mashhad, Mashhad, Khorasan Razavi province, northeast of Iran, at height of 933 m, monoterpene hydrocarbons (85.6%) and oxygen-containing monoterpenes (11.6%) were the main parts of the essential oil, where a-pinene (61.9%), myrcene (12.6%), and limonene (5.0%) were the main monoterpene hydrocarbons, but trans-sabinene hydrate (6.8%) was the main oxygen-containing monoterpene (Emami et al. 2010). According to Hassanpouraghdam (2011) in related to female cones of cultivated C. arizonica from northwest of Iran (Tabriz) that harvested in July 2009. Monoterpenoids (91.9%) were the main class of volatile components, followed by a minor share of sesquiterpenoids (4.2%). Monoterpene hydrocarbons (87.9%) were quantified as the principal subclass of components and beyond them were placed the oxygenated monoterpenes (4%). Sesquiterpenoids (4.2%) had a minor share in the volatile oil percentage. Hydrocarbonic mono and sesquiterpenoids (91.1%) were the highlighted components of volatile oil. In contrast, oxygen-containing components (5%) had only a small portion among total identified components.
The researcher studies has shown that the monoterpene fraction, in particular hydrocarbon fraction (a-pinene, sabinene, and d-3-carene), generally remains the majority for most of the studied species and for all the essential oils from the fruits (cones) of Cupressus sempervirens L. (Kassem et al. 1991;Riaz et al. 1996). Afsharypuor and Tavakoli (2005) revealed that the major components of the fruit oil were a-pinene (57.6%), camphene (10.1%), b-pinene (7.2%), sabinene (3.7%), and p-cymene (3.7%); but, in the present study, a-pinene, b-Myrcene, and d-3-carene were identified as 42 and 72%; 18.5 and 7.7%; 11.3 and 5.1% in the female cones harvested in winter and spring with bolded numbers in the Tables S1 and S2 (Supplementary material), respectively. The environmental and genetic factors which govern and influence the composition of the essential oils have been studied by various researchers (Hanover 1966;Hickok and Anway 1972;Rhoades et al. 1976;Vokou et al. 1993). As early as 1966, Hanover stated that the environmental variation of a plant chemical may be attributed to a number of possible sources including climatic factors. Nutritional status, time of sampling, tissue sampled, position in the plant, maternal effects, and environmental error. It seems that in the winter season, the growth conditions of trees is unsuitable than the spring. For this reason, the number of compounds in the winter was higher than the spring; but, the quality of compounds in the spring was higher than the winter. According to the above mentioned result, researchers were found considerable seasonal variation in the berry (female cone) oils of Juniperus excelsa M. Bieb. trees from Iran, in contrast with the foliage oils. The oil yields in berries increased to 162% from spring to autumn as the berries matured. During the summer, the content of a-pinene in the foliage oil decreased, while the content of this compound increased in the berry oil. Seasonal variation in the berry oil was much greater than the foliage oil. A comparison of oils from fresh vs. dried foliage and berries revealed changes in the amounts of several constituents. a-Pinene decreased after drying, whereas the amounts of several other constituents in the foliage and berry oils increased. They studies illustrates that for the industrial utilization of J. excelsa berry oils, the harvesting period is a critical factor (Salehi Shanjani et al. 2010).

Conclusions
The identification of chemical composition of C. arizonica female cones essential oil harvested in two different times from central Alborz province of Iran showed the presence of a-pinene, b-myrcene, d-3-carene, and limonene in higher amounts in winter season and a-pinene, b-myrcene, b-pinene, and d-3-carene in higher amounts in spring season. In order to increasing the effectiveness of essential oils, it can be suggested that different seasons and times of harvesting from different parts of medicinal herbs such as C. arizonica can be examined and compared.