Phytotoxicity of Antofine from Invasive Swallow-Worts

Abstract

Pale swallow-wort (Vincetoxicum rossicum) and black swallow-wort (V. nigrum) are two emerging invasive plant species in the northeastern United States and southeastern Canada that have shown rapid population expansion over the past 20 years. Using bioassay-guided fractionation, the known phytochemical phenanthroindolizidine alkaloid, (-)-antofine, was identified as a potent phytotoxin in roots, leaves, and seeds of both swallow-wort species. In seedling bioassays, (-)-antofine, at μM concentrations, resulted in greatly reduced root growth of Asclepias tuberosa, A. syriaca, and Apocynum cannabinum, three related, native plant species typically found in habitats where large stands of swallow-wort are present. In contrast, antofine exhibited moderate activity against lettuce, and it had little effect on germination and root growth of either black or pale swallow-wort. In disk diffusion assays, antifungal activity was observed at 10 μg and 100 μg, while antibacterial activity was seen only at the higher level. Although both swallow-wort species display multiple growth and reproductive characteristics that may play an important role in their invasiveness, the presence of the highly bioactive phytochemical (-)-antofine in root and seed tissues indicates a potential allelopathic role in swallow-worts' invasiveness.

Phytochemical composition and antifeedant activity of five Vincetoxicum taxa against Spodoptera littoralis and Leptinotarsa decemlineata

“…[12] also showed that V. pumilum contained antofine and antofine N-oxide. Furthermore, antofine was found in V. nigrum and V. rossicum in different studies by some authors [8,13,30].…”

“…Barb., V. stocksii and V. hirundinaria species including antibacterial and antifungal [8], antidiarrheal, antispazmodic [9], antileishmanial, antimalarial [5], cytotoxic [10], antifeedant and growth inhibition [7] effects in the literature. Phytochemical investigations revealed the presence of phenanthroindolizidine alkaloids [8,[10][11][12][13], steroidal glycosides [7,14,15], triterpenoids [15,16], flavonoids, saponins, phenolics [7,9], steroids [6,15], volatile compounds, acetophenone [6] and alkanols [15] in Vincetoxicum species. In these phytochemical constituents, phenanthroindolizidine alkaloids are characteristic secondary metabolites of some Asclepiadaceae and Moraceae genera including Cynanchum L., Vincetoxicum, Tylophora R.…”

Evaluation of antimicrobial activity of five Vincetoxicum taxa growing in Turkey

“…Barb. and V. nigrum [21,22]; antifungal, antibacterial [12,23], antileishmanial and antimalarial activities of V. stocksii [12] and antioxidant activity of V. lutea L. [11] have been determined. Furthermore, cytotoxic [24,25], antifeedant and growth inhibition [26][27][28] effects of the genus were also reported.…”

“…Phytochemical investigations revealed the presence of triterpenoids [13,15], phenanthroindolizidine alkaloids [21,22,25], steroids [15] and sugars [27,29] in whole parts of the Vincetoxicum species. Moreover, acetophenone, volatile compounds [13], starch [27] and saponins [27,30] were detected from the roots, and alkanols [15] and tannins [28] were detected from the aerial parts.…”

Invasion by Two Plant Species Affects Fungal Root Colonizers

“…Dog-strangling vine has the ability to establish dense monocultures in invaded sites due to advantageous properties that include a polyembryony, tolerance of a wide range of environmental conditions, unique phytochemistry providing antifeedant/pathogenic protection, as well as the ability to be preferentially colonized by beneficial AMF relative to local native plants (Greipsson and DiTommaso 2006, Mogg et al 2008, Blanchard et al 2010, Douglass et al 2011, Gibson and Krasnoff 2011, Bongard et al 2013. Dog-strangling vine has the ability to establish dense monocultures in invaded sites due to advantageous properties that include a polyembryony, tolerance of a wide range of environmental conditions, unique phytochemistry providing antifeedant/pathogenic protection, as well as the ability to be preferentially colonized by beneficial AMF relative to local native plants (Greipsson and DiTommaso 2006, Mogg et al 2008, Blanchard et al 2010, Douglass et al 2011, Gibson and Krasnoff 2011, Bongard et al 2013.…”