The chemical composition of essential oil from Seseli tortuosum subsp. tortuosum and S. tortuosum subsp. maritimum (Apiaceae) aerial parts growing in Sicily (Italy)

Abstract Seseli L. genus, belonging to the Apiaceae family, includes more than eighty taxa, mainly growing in Europe and Asia. Due to the several biological properties, species of this genus have been largely investigated, showing to be a rich source of coumarins, as well as, of essential oils with anti-inflammatory, antiviral, antifungal, cytotoxic, etc. properties. In the present study, the chemical composition of the essential oils from aerial parts of Sicilian accessions of Seseli tortuosum subsp. tortuosum and S. tortuosum subsp. maritimum were analysed by GC-MS. No one report has been previously published on the subsp. maritimum. The results showed the presence, in both oils, of large quantity of monoterpene hydrocarbons. Main metabolites were β-pinene (15.81-19.84%), α-pinene (14.63–18.52%), sylvestrene (11.18–17.45%) and 3-carene (14.58%), the last one being absent in the oil of subsp. maritimum. Chemotaxonomic considerations with respect to other oils of Seseli taxa were carried out. Graphical Abstract


Introduction
Seseli L. is a large genus belonging to the Apiaceae family, distributed in Asia besides Europe, Africa, North America and Australia (Cinar et al. 2020) with 34 species reported for Europe in the Flora Europaea (Tutin et al. 1968).
Consequently, in the frame of our ongoing researches on Mediterranean plant essential oil (Bruno et al. 2019;Rosselli et al. 2020;Sut et al. 2020;Badalamenti et al. 2021;D'Agostino et al. 2021;Gagliano Candela et al. 2021) and on chemotaxonomic differences (Catinella et al. 2021;, we decided to investigate the composition of the essential oil of S. tortuosum L. subsp. tortuosum and S. tortuosum subsp. maritimum., collected in Sicily. For botanical description: see Supplementary Material section. The traditional uses of S. tortuosum have been largely reported. In fact, its fruits were used in Spain and Turkey as emmenagogue and in digestive diseases (Baytop 1999;Carretero Accame et al. 2011) and in the 13th century AD in Saudi Arabia as a contraceptive (Kaya et al. 2003). In Iranian traditional medicine, S. tortuosum, known with the vernacular name 'Sisalius', has been used as herbal remedies to treat epilepsy (Sahranavard et al. 2014).
Recently, a high antioxidant activity, determined by using the LPO assay, has been shown for the AcOEt and MeOH extracts (at 5 mg/mL) of S. tortuosum, collected in Turkey ). Both extracts were also shown to possess anti-inflammatory and antinociceptive properties (K€ upeli et al. 2006).
The essential oil of the fruits, rich in (E)-sesquilavandulol (37.0%) and sabinene (19.0%), of a Turkish accession of S. tortuosum showed antibacterial activity against Paenibacillus larvae ( € Ozkı rı m et al. 2012), whereas the essential oils of S. tortuosum, collected in Portugal, demonstrated excellent antiproliferative activity, in both 2D and 3D models, with very low IC 50 values (Beeby et al. 2020) as well as antifungal and cytotoxic activities (Gonc¸alves et al. 2012).
On the other hands, no one research has been carried out on S. tortuosum subsp. maritimum.
Comparison of Stt and Stm with the essential oils of the other Seseli taxa allowed us to carry out some interesting comments. In fact, b-pinene and a-pinene were shown to be present in good amount in the aerial parts of all the other accessions and subspecies of S. tortuosum studied so far (Bader et al., 2003;Habibi et al. 2003;Kaya et al., 2003;Beeby et al 2020), and in several other taxa, namely S. bocconi ssp. praecox (Marongiu et al. 2006 Despite to be one of the principal constituent in both oils (Stt and Stm), p-cymene has been found, in moderate quantity, only in aerial parts of the Portuguese accessions of S. tortuosum (Beeby et al 2020), of S. tortuosum ssp. kiabii (Habibi et al. 2003), of S. bocconi ssp. praecox (Marongiu et al. 2006), and of S. libanotis ssp. armeniacum (Masoudi et al. 2006). On the other hands, sylvestrene was detected in good amount only in S. bocconi from Sicily (Badalamenti, Vaglica, et al. 2022a) and 3-carene have been never previously identified among the significant metabolites (>3%) of all the Seseli taxa studied so far.

Experimental
See Supplementary material.

Conclusions
Comparison of the chemical compositions of the essential oils shows that in many cases they can be used as chemotaxonomic markers to support taxonomic decisions related to the establishment of separate critical taxa. In our study, the GC analysis of S. tortuosum L. subsp. tortuosum EO showed a chemical profile rich in monoterpenic hydrocarbons, similar to that of S. tortuosum subsp. maritimum EO but somewhat different, due to the presence of some peculiar components. In fact, 3-carene occurs only in Stt, and sabinene is present in Stt in major quantity (7.42%) than Stm (1.01), on the contrary the monoterpene sylvestrene is more abundant in Stm.
On the bases of our investigation and in agreement with the botanical description we can confirm, as stated by Brullo et al. (2011), the occurrence of two different subspecies.

Disclosure statement
No potential conflict of interest was reported by the authors.

Funding
The author(s) reported there is no funding associated with the work featured in this article.