Grazielia gaudichaudeana (DC.)

de Souza, Tiago J. T., S, Bordignon, ergio A. L., Apel, Miriam A. & Henriques, Amelia T., 2021, Volatile constituents of Eupatorieae (Asteraceae). Compositional multivariate analysis of volatile oils from Southern Brazilian species in the subtribe Disynaphiinae, Phytochemistry (112734) 186, pp. 1-23 : 2

Grazielia gaudichaudeana (DC.) R.M.King & H.Rob

(= Eupatorium gaudichaudianum , Dimorpholepis gaudichaudeana )

were collected in Canela and Paraíso do Sul, which exhibited VOs with very similar chemical compositions in terms of the monoterpene fraction. The major compounds in this fraction were α- pinene (12.4–15.5%), β- pinene (9.2–28.9%), and limonene (18.3–37.2%). The sample from Canela/05 also showed a large percentage of α- thujene (10.1%). In the sesquiterpene fraction, the VOs presented large quantitative differences. The VOs obtained from a region of higher altitude (Canela) were characterized by the presence of sesquiterpene hydrocarbon compounds with a germacrane nucleus, namely germacrene D and bicyclogermacrene (11.3 and 7.6%), these compounds did not reach 2% of the VOs obtained from the Paraíso do Sul/06 sample. In the VOs from the samples obtained from the lower central region, this fraction was characterized by the predominance of an oxygenated compound with an aromadendrane nucleus, spathulenol (20.5 and 9.4% in the leaves and inflorescences, respectively). The transformation of bicyclogermacrene and germacrene D into spathulenol has already been reported ( Toyota et al., 1996; Venturi et al., 2015). Previously, several diterpenes bearing an ent-caurane nucleus have been isolated from this species collected in S˜ao Paulo state ( Taleb et al., 1999) and from a sample collected in Parana ´state, a cytotoxic 18-nor-ent-labdane furan was isolated together with sterols, triterpenes, and flavonols ( Balbinot et al., 2019). The yield of the VOs has already been reported to be 1.09–1.29% (in dry and fresh inflorescences, respectively), which was in the same range as our samples, but the chemical composition has not been previously reported ( Souza, 2015). In Southeastern Brazil, this species has been reported to be associated with Cecidomyiidae stem gall inducers ( Coelho et al., 2013) and an unknown lepidopteran leaf gall inducer whose galls were occupied by coleopterans ( Maia and Mascarenhas, 2017). In addition, its flower heads have been reported to be a feeding site for adults of the very endangered endemic Nymphalidae butterfly Actinote zikani ( Francini et al., 2005) , the threatened Pierideae butterfly Charonias theano ( Freitas et al., 2011) , and the Ithomiiniae Placidula euryanassa (which also feeds on other Eupatorieae , such as Chromolaena laevigata and Barrosoa betoniciiformis ) ( Freitas, 1993). The role of VOs in the interactions between plants and insects, gall inducers, leaf-suckers, and leaf-eaters has been previously studied ( Jiang et al., 2018; Rost´as et al., 2013; Tooker et al., 2008; Tooker and De Moraes, 2008). For instance, Malacosoma disstria caterpillars induce a germacrene D synthase in Populus trichocarpa × deltoides by feeding on that species, possibly implying a role for this compound in attracting the caterpillar’ s natural enemies in a tri-trophic interaction ( Arimura et al., 2004). On the other hand, the moth Heliothis virescens (Noctuidae) is attracted by ()-germacrene D in tobacco, enhancing oviposition in the plant ( Mozuraitis et al., 2002; Røstelien et al., 2000). Limonene exhibits insect repellent activity ( Hebeish et al., 2008; Tripathi et al., 2003), while β- pinene has also been shown to be neurotoxic to the coleopteran Tribolium castaneum by inducing the overexpression of the histamine-gated chloride channel 2 (Hiscl2), GABA-gated ion channel (Grd), and acetylcholinesterase (Ace1) Ace1 genes ( Pajaro-Castro et al., 2017). The role of the VOs produced by G. gaudichaudieana during the interaction of this species with insects remains to be established.