Iridoids from Symphoricarpos albus

Abstract

Twelve compounds including secologanin, loganin, the aglycon of loganin, and a new iridoid called glucologanin were isolated from fruit of common snowberry Symphoricarpos albus (L.) Blake. The structure of glucologanin was confirmed using PMR and mass spectroscopy and chemical transformations. 2′,3′,4′,6′,3′,4′, Common snowberry Symphoricarpos L. (Caprifoliaceae, honeysuckle) is a bush up to 1.5 m in height and is widely used as a decorative plant. In nature it is found mainly in North America and in the northern strip of European Russia. In Ukraine, white common snowberry Syphoricarpos albus (L.) Blake is most common.The phytochemistry of common snowberry is insufficiently studied. The contents in fruit of S. albus of phenolic acids [1], carbohydrates [2], and iridoids [3, 4] have been reported.We studied fruit of white common snowberry (S. albus) collected in October-November 2005 in the Botanical Garden of Karazin Kharkov National University (Ukraine). Fruit contains a large amount (85-87%) of water, which we took into account during its processing.Freshly collected berries were ground and extracted with n-butanol. The extract was divided into three fractions by polarity and chromatographed over columns using mixtures of CHCl 3 and CH 3 OH of increasing polarity for elution (see Experimental).A total of 12 pure compounds was isolated. Three of the isolated compounds were iridoids and were identified as secologanin (1), loganin (2), and loganigenin (3) [3, 5, 6]. A fourth glycoside (4) was new. The structures of 1, 2, and 3 were confirmed by PMR and mass spectrometry.Compound 1 was found to be highly unstable during its isolation. The compound was quickly oxidized in solutions by oxygen in air. The product of auto-oxidation was presumably cyclized to form lactone 8. The carboxyl and vinyl (ethylene) groups were involved in the cyclization. The product of auto-oxidation 8 was isolated during additional purification of 1 by column chromatography. Compound 8 contained two C=O groups according to IR spectra, one of which was an ester conjugated to a C=C bond (absorption band at 1696 cm −1 ); the second, a carbonyl of a seven-membered lactone ring (absorption band at 1655 cm −1 ).The PMR spectrum of 8 exhibited a characteristic resonance for the C-3 proton at 7.3 ppm, for the anomeric C-1′ proton at 4.5 ppm; a characteristic multiplet for the ester OCH 3 group at 3.7 ppm; and for protons H-5 and H-11 at 2.7 ppm. There was no resonance for an aldehyde.The mass spectrum of the lactone was consistent with the proposed structure of 8 (see Experimental). Compound 2 can exist as cyclic dimer 5. The C-7 OH group and ester carbonyl form two intermolecular H-bonds. The mass spectrum of the loganin dimer was consistent with the proposed structure of 5.

Differences in performance and transcriptome‐wide gene expression associated with Rhagoletis (Diptera: Tephritidae) larvae feeding in alternate host fruit environments

“…; Szaufer‐Hajdrych & Zgorka ; Makarevich et al . ), implying that the two fruits impose very different chemical challenges on feeding fly larvae. Overall, the plastic changes in transcription that we observed in R. zephyria would seem to allow relatively high survival to pupation on apple, albeit with a cost of slower development rate.…”

“…Both fruits contain numerous phenolic compounds and glycosides. However, the lists of compounds found in extracts of apples and snowberries are largely distinct (Schieber et al 2001;Szaufer-Hajdrych & Zgorka 2003;Makarevich et al 2009), implying that the two fruits impose very different chemical challenges on feeding fly larvae. Overall, the plastic changes in transcription that we observed in R. zephyria would seem to allow relatively high survival to pupation on apple, albeit with a cost of slower development rate.…”

“…; Szaufer‐Hajdrych & Zgorka ; Makarevich et al . ), compounds with well‐known toxic effects on herbivorous insects (Despres et al . ).…”

“…Apple-infesting R. pomonella flies have become abundant in the Pacific Northwest since initial detection in the 1970s (Yee et al 2012), and infested apple trees are often microsympatric with infested snowberry plants (both taxa are caught on the same sticky traps) (Yee et al 2009). The fruit environment experienced by larvae is quite distinct, as the apple and snowberry host plants are members of different families (Rosaceae and Caprifoliaceae, respectively) whose fruits contain different complements of phenolic and glycosidic secondary metabolites (Schieber et al 2001;Szaufer-Hajdrych & Zgorka 2003;Makarevich et al 2009), compounds with well-known toxic effects on herbivorous insects (Despres et al 2007). In contrast to these pronounced differences in larval feeding environment, host plant differences in seasonal timing are limited because snowberry bushes fruit over a broad seasonal window (early summer to early fall) that overlaps the fruiting time of apples (Schwarz 2004).…”

The scaffold-forming steps of plant alkaloid biosynthesis

“…These seco-iridoids are found in multiple plants where alkaloids are absent. 125,126 In C. roseus (Gentianales), secologanin is the precursor to all monoterpene indole alkaloids (MIAs). It is also a precursor to the ipecac .…”