Acanthostyles buniifolius

Acanthostyles buniifolius (Hook. ex Arn.) R.M.King & H.Rob.

(syn. Eupatorium buniifolium

– common name: “chilca” or “chirca”)

is currently the only species recognized in the genus Acanthostyles (Grossi et al., 2011; King and Robinson, 1987; Matzenbacher, 1979).

It is a 0.60–1.80 m tall shrub native to southern Bolivia and Southern Brazil, Paraguay, Uruguay, and Northern and Central Argentina. There is abundant literature on this species. VOs obtained from our sample of A. buniifolius contained 9.8% α- pinene, the major compound in the monoterpene fraction. The main compounds in the sesquiterpene fraction were β- caryophyllene (7.1%) and germacrene D (22.4%), which are common to many other species of Eupatorieae analyzed by our group. In addition to these substances, germacrene A (8.3%) and its Cope rearrangement product, β- elemene (4.7%), were found. A compound with a guaiane nucleus, trans -β- guaiene (22.0%), was also found in large amounts. VOs obtained from other samples from Argentina have been reported, whose major compounds were α- pinene (39.1%), sabinene (6.42%), limonene (8.02%), and (E)-β- ocimene (10.42%) (Cecati et al., 2018). A very similar composition has been reported for other samples collected from Argentina containing α- pinene (41.48–51.81%), sabinene (5.37–8.44%), (E)-β- ocimene (8.09–11.09%), and limonene (6.95–9.53%) (Guerreiro et al., 2018), which were tested against the coleopteran Tribolium castaneum, exerting repellence and lethality against this species of beetle (Lancelle and Giordano, 2009). Another sample dominated by α- pinene (68.8%), δ-2-carene (5.3%), and limonene (5.1%), was assayed on bees against Varroa desctructor (Ruffinengo et al., 2005). In Uruguay, a different composition was reported, which was more similar to our samples with and α- pinene (14.7%) and sesquiterpenes β- elemene (12.2%) and germacrene D (11.5%) as main compounds (Lorenzo et al., 2005). In a different report from the same country, samples composed of β- guaiene (10%), germacrene D (7.8%), β- elemene (6.7%), and α- pinene (22%) exhibited insecticidal and fungicidal activities toward tomato pests (Umpi´errez et al, 2012, 2013, 2017). In RS, Brazil, a different sample was previously reported with α- thujene (26.01–28.1%), γ- muurolene (15.2–1.17%), sabinene (8.54–9.42%), α- humulene (0.6–7.8%), and limonene (5.34–6.8%) observed in the summer and winter samples, respectively (Stüker, 2007). The presence of either β- elemene or germacrene A in the sample could be an artifact of the injection temperature of the GC–MS analysis, resulting in the presence of β- elemene in the samples injected at high temperature or germacrene A in the samples injected at low temperature. Considering this, the samples reported with either germacrene A or β- elemene may belong to the same chemotype. This way the Uruguayan samples were more similar to ours. This species has been reported to be a host plant for the butterfly Actinote surima, similar to other closely related Eupatorieae (Grazielia intermedia, Symphyopappus reticulatus, and S. casarettoi) (Penz and Francini, 1996), A. carycina, A. pyrrha, Rothschildia jacobaeae (Saturniidae), and Pericopis sacrifica (Pericopidae) in Uruguay (Biezanko et al., 1974). It is also a host for the vineyard Basidiomycota pathogen Arambarria sp. (Pildain et al., 2017) and the aphid Uroleucon garnicai (Delfino, 1991). From plants collected in Argentina, ent-labdane diterpenes have been previously isolated (Carreras et al., 1998), as well as two flavones and one coumarin with anti-inflammatory activity (Muschietti et al., 2001). Its extracts were evaluated for antiviral (Varicellovirus pseudorabies virus strain RC/79) (Zanon et al., 1999), antifungal (Mino ˜et al., 2005), and trypanocidal (Trypanosoma cruzi) (Sülsen et al., 2006) activity. Inhibition of the neutrophil function (Paya´ et al., 1996), antinociception in acetic acid-induced pain test (Mino ˜ et al., 2005), in vivo CNS-depression (Mino ˜et al., 2007), in vitro anticholinesterasic (Carpinella et al., 2010), and anti-arsenite-induced peroxidation (Soria et al., 2008) activities were also demonstrated. The antipoliovirus benzofuran euparin was isolated from the extracts of aerial parts and characterized (Visintini Jaime et al., 2013).

Legend

a Retention Index in a DB5 column b aerial parts

c leaves

d inflorescences

e twigs

f Aliphatics

g Hydrocarbon Monoterpenes

h Oxygenated Monoterpenes

i Hydrocarbon Sesquiterpenes

j Oxygenated Sesquiterpenes

k traces.

Despite the abundance of literature data for this species reflecting its geographical dispersion in Southern South America, popular use, and several biological activities, only tests against Varroa destructor, Tribolium castaneum, Trialeurodes spp., Botrytis cinerea, Alternaria spp., and Fusarium spp. were directly performed using the VOs. Some of them were reported from the Uruguayan samples similar to the samples described herein, which were characterized by higher amounts of trans - β- guaiene.