Identification of Indole Diterpenes in Ipomoea asarifolia and Ipomoea muelleri, Plants Tremorgenic to Livestock

Abstract

Ipomoea asarifolia has been associated with a tremorgenic syndrome in livestock in Brazil and was recently reported to contain tremorgenic indole diterpenes. Ipomoea muelleri has been reported to cause a similar tremorgenic syndrome in livestock in Australia. Ipomoea asarifolia and I. muelleri were investigated by high-performance liquid chromatography-high-resolution mass spectometry (HPLC-HRMS) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for indole diterpene composition. The high-resolution mass spectrometric data in combination with MS/MS fragmentation mass spectral data provided valuable information for indole diterpene characterization. The previous report of indole diterpenes in I. asarifolia was confirmed and expanded; and the presence of indole diterpenes in I. muelleri is reported for the first time. Two new indole diterpenes were isolated and their structures determined by 1D and 2D NMR spectroscopy and given the names 11-hydroxy-12,13-epoxyterpendole K and 6,7-dehydroterpendole A. The presence of terpendole K and terpendole E in I. asarifolia is unequivocally demonstrated for the first time. This is the first detailed MS analysis of known indole diterpenes and possible isomers in I. asarifolia and I. muelleri.

Tremorgenic and neurotoxic paspaline-derived indole-diterpenes: biosynthetic diversity, threats and applications

“…These two fungi form IDTs with the C11(12) epoxide, giving rise to terpendoles and the more elaborate lolitrems. Meanwhile, Periglandula ipomoeae strains, symbionts of morning glory, also produce terpendole analogues such as terpendoles C, K, and E (Schardl et al 2013; Lee et al 2017; Gardner et al 2018). Fungi in two other hypocrealean families also produce paspaline-derived IDTs.…”

“…This toxicosis is also associated with the presence of IDTs (Lee et al 2017), produced by seed-transmitted endophytic fungi, most likely P. ipomoeae (Schardl et al 2013; Lee et al 2017). The main IDT congeners isolated from endophyte-infected I. asarifolia and I. muelleri are terpendole K, 11-hydroxy-12,13-epoxyterpendole K and 6,7-dehydroterpendole A (Lee et al 2017). …”

“…Co-regulation of aflatrem production with sclerotia development has been demonstrated in A. flavus (Ehrlich and Mack 2014), while a wide spectrum of environmental conditions including temperature, light, various carbon and nitrogen sources were shown to influence penitrem production in P. crustosum (Kalinina et al 2017). Nevertheless, a deeper understanding of mycotoxin production, including the regulation of the biosynthesis of tremorgenic IDTs will be crucial to combat the agricultural threats posed by these fungi (Uhlig et al 2009; Moyano et al 2010; Lee et al 2017). Moreover, further studies are necessary to estimate the real dimensions of the risks posed by these fungi and their harmful metabolites to consumers of agricultural products (Moldes-Anaya et al 2012; Eriksen et al 2013).…”

Bioactive Alkaloids from Plants Poisonous to Livestock in North America

“…Four classes of bioactive alkaloids, ergot alkaloids (ergovaline), lolines, indole‐diterpenes (paspaline) and peramine, may be produced in different combinations among the host and the respective endophyte (Figure ) ,. Some plant species in the morning glory family ( Convolvulaceae ) also form symbioses with endophytic fungi of the Clavicipitaceae that produce ergot alkaloids and indole‐diterpenes . The ergot alkaloids and indole diterpenes are both harmful toxins to livestock species …”

“…Some plant species in the morning glory family ( Convolvulaceae ) also form symbioses with endophytic fungi of the Clavicipitaceae that produce ergot alkaloids and indole‐diterpenes . The ergot alkaloids and indole diterpenes are both harmful toxins to livestock species …”