Aldo Tava

The protein quality control system manages plant defence compound synthesis

Jasmonates are ubiquitous oxylipin-derived phytohormones that are essential in the regulation of many development, growth and defence processes. Across the plant kingdom, jasmonates act as elicitors of the production of bioactive secondary metabolites that serve in defence against attackers. Knowledge of the conserved jasmonate perception and early signalling machineries is increasing, but the downstream mechanisms that regulate defence metabolism remain largely unknown. Here we show that, in the legume Medicago truncatula, jasmonate recruits the endoplasmic-reticulum-associated degradation (ERAD) quality control system to manage the production of triterpene saponins, widespread bioactive compounds that share a biogenic origin with sterols. An ERAD-type RING membrane-anchor E3 ubiquitin ligase is co-expressed with saponin synthesis enzymes to control the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the rate-limiting enzyme in the supply of the ubiquitous terpene precursor isopentenyl diphosphate. Thus, unrestrained bioactive saponin accumulation is prevented and plant development and integrity secured. This control apparatus is equivalent to the ERAD system that regulates sterol synthesis in yeasts and mammals but that uses distinct E3 ubiquitin ligases, of the HMGR degradation 1 (HRD1) type, to direct destruction of HMGR. Hence, the general principles for the management of sterol and triterpene saponin biosynthesis are conserved across eukaryotes but can be controlled by divergent regulatory cues.

Flavonoids from Pinus sylvestris needles and their variation in trees of different origin grown for nearly a century at the same area

Abstract Flavonoids in needles of Scots pine planted in 1912–1914 in Poland from seeds originating from different parts of Europe, were isolated, chemically characterised and analysed by HPLC. It was shown that flavonoid profiles were similar in all tested populations and were different from those previously reported for Scots pine seedlings. They included taxifolin, taxifolin 3′- O -glucoside, quercetin as well as quercetin 3- O -glucoside and 3′- O -glucoside. The quercetin 3- O -glucoside could be found only in a trace amount in all samples and quercetin 3′- O -glucoside appeared in all samples regardless their origin. The relative concentration of taxifolin 3′- O -glucoside, quercetin, taxifolin and total flavonoids showed dependence on the origin of seeds; needles from high latitude populations contained smaller amounts of these compounds. Presented data clearly indicate that Scots pine contain glycosidases specific for glycosylation at C-3′ rather than at C-3. Besides, they indicate that long lasting influence of similar environmental factors is not able to change genetic regulatory systems responsible for flavonoid biosynthesis.

The major Boswellia serrata active 3-acetyl-11-keto-β-boswellic acid strengthens interleukin-1α upregulation of matrix metalloproteinase-9 via JNK MAP kinase activation

BACKGROUNDnBoswellia serrata gum resin has attracted pharmacological interest as an alternative antinflammatory.nnnPURPOSEnWe studied the application of an ethanolic extract of the resin and its main active 3-O-acetyl-11-keto-β-boswellic acid (AKBA) against inflammatory degeneration of skin extracellular matrix.nnnSTUDY DESIGNnWe compared the effects of the extract and AKBA on the activity of MMP-2 and MMP-9 (72-kDa and 92-kDa type IV collagenases) in HaCaT keratinocytes exposed to interleukin-1α (IL-1α) as a skin inflammation model.nnnMETHODSnMMP activity in cell conditioned medium was assayed by gelatin zymography, while NF-kB and MAP kinase activations were evaluated by Western blotting.nnnRESULTSnIL-1α (10u202fng/ml) upregulated MMP-9 but not MMP-2 in HaCaT cells. The extract, used at 2.3, 4.6 and 9.3u202fµg/ml, had no effect, but in combination with IL-1α showed MMP-9 inhibition at the lowest dose and increased upregulation at the highest one. AKBA alone, at the same concentrations (corresponding to 5, 10, and 20u202fµM), did not stimulate MMP-9, but together with IL-1α induced an increased upregulation at the lowest dose that progressively disappeared at higher doses. WB analysis showed that IL-1α induced phosphorylation of NF-κB p65, while AKBA abolished this effect at 20u202fµM, but conversely increased it at 5u202fµM. Screening of MAP kinase phosphorylation showed a combined activation of IL-1α/AKBA on JNK, while the JNK inhibitor SP600125 abolished MMP-9 upregulation induced by IL-1α/AKBA.nnnCONCLUSIONnThe enhancing effect of IL-1α/AKBA on MMP-9 at low AKBA concentration seems to involve the activation of JNK-mediated NF-κB pathway. Conversely, the extract inhibits the IL-1α effect at low doses, but not at higher ones, where AKBA and possibly other β-boswellic acids reach concentrations that potentiate the effect of IL-1α. The extract at low doses could protect the skin against degenerative processes of extracellular matrix, while keto-β-boswellic acids seem unsuitable for this purpose.

Essential Oil Composition of Roots of Heracleum candicans Wall. Cultivated in Nursery

Abstract Heracleum candicans Wall. (Apiaceae) is one of the important endangered aromatic species within the genus Heracleum. Owing to multiple uses, high market demand and endangered status of species, a wild strain was domesticated at Pothivasa (2200 m asl). Roots were dug out during senescence stage in November and essential oil was extracted. Twenty constituents composed of 93.52 % of the total volatile part could identify by using GC-FID and GC-MS analysis. The major portion of the volatile was α-and β-pinene. The study reveals interesting information about the H. candicans that major component of the essential oil varied between underground and leaf parts. Other important constituents were myrcene, germacrene D, dill apiole, limonene, Z-β-ocimene, cyclosativene, sabinene. The characterization of volatile part from cultivated roots opens new avenues for research on medicinal, aromatic and industrial use of H. candicans.

Artefact formation during acid hydrolysis of saponins from Medicago spp.

Artefact compounds obtained during acid hydrolysis of saponins from Medicago spp. (Fabaceae), have been monitored and evaluated by GC-FID. Their identification has been performed by GC-MS and 1H and 13C NMR. Saponins with different substituents on the triterpenic pentacyclic aglycones were considered, and their hydrolysis products were detected and quantified during 10xa0h of time course reaction. From soyasapogenol B glycoside the well known soyasapogenols B, C, D and F were obtained together with a previously undescribed sapogenol artefact identified as 3β,22β,24-trihydroxyolean-18(19)-en and named soyasapogenol H. From a zanhic acid saponin two major artefact compounds identified as 2β,3β,16α-trihydroxyolean-13(18)-en-23,28-dioic acid and 2β,3β,16α-trihydroxyolean-28,13β-olide-23-oic acid were obtained, together with some zanhic acid. Other compounds, detected in very small amount in the reaction mixture, were also tentatively identified based on their GC-MS and UV spectra. The other most characteristic saponins in Medicago spp., hederagenin, bayogenin and medicagenic acid glycosides, under acidic condition of hydrolysis, released instead the correspondent aglycones and generated a negligible amount of artefacts. Nature of artefacts and mechanism of their formation, involving a stable tertiary carbocation, is here proposed and discussed for the first time.

Volatile Composition of Underground Parts of Angelica glauca Edgew. from Two Distant Populations of India

Abstract Angelica glauca (Apiceae) is one of the important medicinal and aromatic plant species (MAPs) of the Himalaya. Medicinal and aromatic properties of this species are well described in literature elsewhere. Samples were collected during the month of September from two distant populations i.e. Sissu (Himachal Pradesh) and Panwali Kantha (Uttarakhand), India. Essential oil was extracted from chopped underground parts using Clevenger-type apparatus and analyzed. Variations exist in quantitative as well as qualitative parameters of the essential oil samples between selected populations. Samples collected from Panwali Kantha showed highest percentage of Z-ligustilide. Variations in the composition of essential oil indicate that genetic variability exists among different populations of A. glauca.

Isoflavone Content in Subterranean Clover Germplasm from Sardinia

Subterranean clover (Trifolium subterraneum) is an important pasture legume, and Sardinia is known as a major centre of diversification of this species. As other legumes, this clover produces biologically active flavonoids including the subclass of isoflavones that are natural phytoestrogens with positive health effects. Present sources of isoflavones for medical/nutraceutical treatments are red clover (Trifolium pratense) and soybean (Glycine max). This study assessed the content and composition of flavonoids in 14 subterranean clover genotypes from Sardinia, grown ex‐situ in comparison with two red clover ecotypes, to acquire information on the potential of the species as an alternative source of isoflavones for possible exploitation. Twenty compounds were tentatively identified across the two clovers after HPLC and LC/ESI‐MS analyses, including clovamide, four flavonols, and 15 isoflavones. Most compounds were present as glucosides or glucosyl malonates. Subterranean clover extracts mainly comprised of derivatives of the isoflavones genistein, biochanin A, and formononetin. Compared to red clover, subterranean clover had higher content of total isoflavones and lower concentration of total flavonols. The isoflavone concentration in subterranean clover was higher than literature data for soybean or red clover. The existing genotypic variation warrants the possibility of selecting varieties with high isoflavone concentration for nutraceutical or pharmaceutical purposes.