Diterpenoids and phenolics from pseudopanax simplex

An ethanolic extract of Pseudopanax simplex yielded kaempferol-3,7-di-O-rhamnopyranoside, chlorogenic acid, maltol glucoside, ent-kaur-16-en-18-acid, and 4R,5S,9R,10S,13S-ent-pimara-7,15-dien-19-oic acid. Full NMR data for the last compound are reported for the first time

Evolution and function of red pigmentation in land plants

Background Land plants commonly produce red pigmentation as a response to environmental stressors, both abiotic and biotic. The type of pigment produced varies among different land plant lineages. In the majority of species they are flavonoids, a large branch of the phenylpropanoid pathway. Flavonoids that can confer red colours include 3-hydroxyanthocyanins, 3-deoxyanthocyanins, sphagnorubins and auronidins, which are the predominant red pigments in flowering plants, ferns, mosses and liverworts, respectively. However, some flowering plants have lost the capacity for anthocyanin biosynthesis and produce nitrogen-containing betalain pigments instead. Some terrestrial algal species also produce red pigmentation as an abiotic stress response, and these include both carotenoid and phenolic pigments. Scope In this review, we examine: which environmental triggers induce red pigmentation in non-reproductive tissues; theories on the functions of stress-induced pigmentation; the evolution of the biosynthetic pathways; and structure-function aspects of different pigment types. We also compare data on stress-induced pigmentation in land plants with those for terrestrial algae, and discuss possible explanations for the lack of red pigmentation in the hornwort lineage of land plants. Conclusions The evidence suggests that pigment biosynthetic pathways have evolved numerous times in land plants to provide compounds that have red colour to screen damaging photosynthetically active radiation but that also have secondary functions that provide specific benefits to the particular land plant lineage

Alkaloid Variation in New Zealand Kōwhai, \u3cem\u3eSophora\u3c/em\u3e Species

Alkaloid contents of leaf and seed samples of eight species of Sophora native to New Zealand, plus Sophora cassioides from Chile are reported. Fifty-six leaf and forty-two seed samples were analysed for alkaloid content by proton nuclear magnetic resonance spectroscopy, which showed major alkaloids as cytisine, N-methyl cytisine and matrine. GC analyses quantified these and identified further alkaloid components. The alkaloids identified were cytisine, sparteine, and matrine-types common to Sophora from other regions of the world. Cytisine, N-methyl cytisine, and matrine were generally the most abundant alkaloids across all species with seeds containing the highest concentrations of alkaloids. However, there was no clear taxonomic grouping based on alkaloid composition. A quantitative analysis of various parts of two Sophora microphylla trees showed that the seeds were the richest source of alkaloids (total 0.4–0.5% DM), followed by leaf and twig (0.1–0.3%) and then bark (0.04–0.06%), with only low amounts (Sophora species to date and presents data for three species of Sophora for which no prior chemistry has been reported

Sophora microphylla Aiton

<i>2.4. Alkaloid distribution in S. microphylla plant parts</i> <p>Our comparison of the leaf and seed alkaloid compositions across kōwhai (see above) showed that leaf samples contained greater relative amounts of biosynthetic intermediates (A, DHM, and L), versus seed, which generally contained higher amounts of biosynthetic end products: C, NMC, and M (Table 1 and Fig. 1). These findings are consistent with reports of quinolizidine alkaloid biosynthesis beginning from lysine, occurring in leaf, and metabolic transformation to biosynthetic end-points taking place in seed (Wink, 1992).</p> <p> We examined this further by analysing alkaloids from the root, bark, twig, leaf and seed from two individual <i>S. microphylla</i> trees (samples m15 and m19). Integration of the GC-FID alkaloid absolute peak area allowed reasonable approximation of total alkaloid quantities. This was a viable approach because the mass of plant material extracted was within ±0.5% across all samples and the extraction method was consistent for all samples as verified by check, control, and blank samples. The results of the relative alkaloid quantity comparison by plant part are presented in Table 4 for two trees that were found to contain among the highest alkaloid content in the leaves of the 56 leaf extracts studied. In general, seeds contained the highest concentration of alkaloids (supportive of Section 2.3, above). Leaves and twig samples had the next highest concentration of alkaloids followed by bark, with the root samples having the lowest amounts of total alkaloids. The findings presented here reinforce reports in the literature that alkaloids are predominantly concentrated in seed (Connor, 1977; Burrows and Tyrl, 2001). Compositional analysis of the <i>S. microphylla</i> plant parts showed that the alkaloids differentially accumulated in the various plant parts (Table 4). A MANOVA confirmed the significant (<i>P</i> <0.01) differences in plant parts alkaloid composition, with a univariate ANOVA test for each alkaloid showing significant differences in the amounts of anagyrine, ammodendrine, cytisine, dehydrolupanine, lupanine and <i>N</i> -methyl cytisine. A canonical discriminate analysis on this data showed clear groups (Fig. 2) and the contribution of each alkaloid to the dataset variation. The first canonical variable explained 60% of the variation; the second canonical variable explained 32% of the variation. The canonical structure coefficients (as indicated by the arrows on Fig. 2) show that the variations in anagyrine and lupanine have the highest impact on the first canonical variable, followed by dehydrolupanine and matrine. For the second canonical variable <i>N</i> -methylcytisine and cytisine have the highest contributions, followed by dehydrolupanine and then matrine.</p> <p>The quantitative analysis of total alkaloid content across all plant parts demonstrates that alkaloids are concentrated in the seeds, with minimal amounts in the root and bark, and intermediate quantities in the twig and leaf (Table 4). Plants that produce quinolizidine alkaloids as allelochemicals in their leaves and seeds tend to preferentially produce antifeedant and antifungal phenolics (flavonoids, isoflavonoids, anthocyanins, etc.) in their roots to deter insect herbivores (Wink, 1992). A complementary phytochemical investigation of phenolics produced by kōwhai is underway. This may validate the prediction that the roots produce allelochemicals equivalent to, or in excess of, those produced in the leaf and seed.</p> <p> A = ammodendrine, AN = anagyrine, C = cytisine, DHL = dehydrolupanine, L = lupanine, M = matrine, NMC = <i>N</i> -methyl cytisine, S = sparteine; # including tentative and unidentified.</p> <p>*</p> <p>Relative to cytisine.</p> <p> Since many of the nicotinic alkaloids are known to be toxic (Schep et al., 2009), the amount of alkaloids in <i>Sophora</i> species has potential health concerns in term of intentional or accidental ingestion. Cytisine, for example, has a lethal (LD 50) oral dose of 101 mg /kg in rats (Barlow and McLeod, 1969), and reports of fatal human poisoning (see (Musshoff and Madea, 2009) and references therein) corresponding to about 50 mg of cytisine, but the lethal dose in humans is unknown. However, since the seeds have a very hard outer casing, it has been recognised that they would need to be crushed or soaked to poison, otherwise they would pass though the gastrointestinal tract without causing toxicity (Slaughter et al., 2012).</p>Published as part of <i>McDougal, Owen M., Heenan, Peter B., Jaksons, Peter, Sansom, Catherine E., Smallfield, Bruce M., Perry, Nigel B. & van Klink, John W., 2015, Alkaloid variation in New Zealand kōwhai, Sophora species, pp. 9-16 in Phytochemistry 118</i> on pages 13-14, DOI: 10.1016/j.phytochem.2015.07.019, <a href="http://zenodo.org/record/10488908">http://zenodo.org/record/10488908</a&gt

Fast Phenotyping of LFS-Silenced (Tearless) Onions by Desorption Electrospray Ionization Mass Spectrometry (DESI-MS)

Fast MS techniques have been applied to the analysis of sulfur volatiles in Allium species and varieties to distinguish phenotypes. Headspace sampling by proton transfer reaction (PTR) MS and surface sampling by desorption electrospray ionization (DESI) MS were used to distinguish lachrymatory factor synthase (LFS)-silenced (tearless; LFS−) onions from normal, LFS-active (tear-inducing; LFS+), onions. PTR-MS showed lower concentrations of the lachrymatory factor (LF, <b>3</b>) and dipropyl disulfide <b>12</b> from tearless onions. DESI-MS of the tearless onions confirmed the decreased LF <b>3</b> and revealed much higher concentrations of the sulfenic acid condensates. Using DESI-MS with MS² could distinguish zwiebelane ions from thiosulfinate ions. DESI-MS gave reliable fast phenotyping of LFS+ versus LFS– onions by simply scratching leaves and recording the extractable ions for <0.5 min. DESI-MS leaf compound profiles also allowed the rapid distinction of a variety of <i>Allium</i> cultivars to aid plant breeding selections

Red leaf margins indicate increased polygodial content and function as visual signals to reduce herbivory in Pseudowintera colorata

Summary • Red-pigmented leaf margins are common, but their functional significance is unknown. We hypothesized that red leaf margins reduce leaf herbivory by signalling to herbivorous insects the presence of increased chemical defences. • Leaves were collected from a natural population of Pseudowintera colorata. Margin size, herbivory damage, anthocyanin content and concentrations of polygodial, a sesquiterpene dialdehyde with antifeedant properties, were quantified. Feeding trials involving larvae of Ctenopseustis obliquana, a generalist herbivore, were conducted on red-and green-margined P. colorata leaves in darkness, or under white, green or red light. • Leaves with wider red margins contained higher concentrations of polygodial and anthocyanins, and incurred less natural herbivory. In trials under white light, C. obliquana consumed disproportionately more green-than red-margined leaf laminae. Larvae exhibited no feeding preference when light was manipulated such that leaf colour discrimination was impaired. • Red leaf margins provide a reliable and effective visual signal of chemical defence in P. colorata. Ctenopseustis obliquana larvae perceive and respond to the colour of the leaf margins, rather than to olfactory signals. Our study provides direct experimental evidence for aposematic coloration in red leaves