Promotion by phloroglucinol of micropropagation of Minuartia valentina, an endangered and endemic Spanish plant

Tissue culture techniques for the propagation and conservation of endemic or threatened plants can be used to complement the methods usually applied in ex situ conservation. Thus, Minuartia valentina (Caryophyllaceae), an endangered plant species endemic to the Valencia Community (Eastern Spain), was successfully regenerated through shoot proliferation from wild plants growing in their natural area. Nodal segments, 10~mm long, were cut from rametes of adult material, sterilised and established in vitro. Equally successful shoot multiplication was achieved on Murashige and Skoog (MS) medium with 80 mg l-1 phloroglucinol in combination with either 1 mg l-1 6-benzylaminopurine or 1 mg l-1 kinetin. Excised shoots were rooted in MS medium supplemented with an auxin (indole acetic acid, indole-3-butyric acid, or napththalene acetic acid). Shoots rooted well (96–100%) within three weeks in all auxin treatments. However, the use of napththalene acetic acid was discarded because this auxin delayed root differentiation, and induced adventitious root malformation. Rooted plantlets were transferred to pots and 85% of them acclimatized successfully four weeks after transfer to greenhouse conditions, where they exhibited normal morphology and growth.     

Neue phloroglucin-derivate aus Leontonyx-arten sowie weitere verbindungen aus vertretern der tribus inuleae

The investigation of several South African species of the tribe Inuleae afforded in addition to known compounds 16 new constituents. From Leontonyx a group of 9 new phloroglucinol derivatives, from Stoebe species two new p-hydroxyacetophenone, two thymol and two coumaric acid derivatives and from Relhania a new euparine-derivative were isolated. The structures are elucidated mainly by spectroscopic methods. The chemotaxonomic aspects are discussed briefly. The phloroglucinol derivatives, which in part are derived from geraniol, seem to be especially characteristic.     

A phloroglucinol derivative from the brown alga Zonaria tournefortii

The major lipid component of the brown seaweed Zonaria tournefortii was identified as the acylphlorogluconol (all Z)-2′-icosa-5,8,11,14,17-pentae     

The Reaction Mechanism of Rat Liver Glyoxalase I and Its Inhibition by MS-3

Glyoxalase I from rat liver was purified about 25-fold by acetone fractionation and ion-exchange chromatography on CM-Sephadex and DEAE-cellulose columns. The kinetic study of the enzymatic reaction supported the one-substrate mechanism : the hemimercaptal adduct produced nonenzymatically from methylglyoxal and glutathione is the substrate. The Km value determined was 0.1 mm and similar to that of porcine erythrocytes enzyme but differed significantly from that of yeast enzyme. It was inhibited by free glutathione competitively (Ki 1.2 mm). Kinetic studies on inhibition of glyoxalase I by MS–3 which was obtained from a cultured mushroom, Stereum hirsutum, indicated the inhibition type was competitive with the hemimercaptal adduct (Ki 4.6 × 10^?6 m). By the graphical study of the multiple inhibition kinetics free glutathione and MS–3 were shown to bind at the same sites of the enzyme.     

Qualitative analysis and HPLC isolation and identification of procyanidins from Vicia faba

The soluble proanthocyanidins of the coloured seed coats of Vicia faba L. were isolated and separated by solvent partition. The chemical characteristics of the proanthocyanidins were elucidated by total oxidation and partial degradation in the presence of phloroglucinol followed by HPLC analysis. The native extract of proanthocyanidins contained (+)-gallocatechin, (-)-epigallocatechin, (+)-catechin and (-)-epicatechin units. Oligomeric procyanidins were purified by chromatography on Sephadex LH-20 and the accessible compounds were isolated by RP-HPLC using a Licrospher Li 100 Column. The structures of the purified oligomeric procyanidins were elucidated using a procedure involving TLC, UV spectroscopy, ESI-MS and HPLC analysis of the products from the phloroglucinol reaction. The major condensed tannins of Vicia faba comprise six compounds identified as two A-type procyanidin dimers, the procyanidin dimers B1, B2 and B3, and a procyanidin trimer.     

Conversion of diacetyl-C-(beta-D-glucopyranosyl)phloroglucinol to spiroketal compounds

Diacetyl-C-(beta-D-glucopyranosyl)phloroglucinol was converted by refluxing in water to spiro(benzofuran-[2H]furan) a new compound, along with spiro(benzofuran-[2H]pyran). The stereochemistry of the quaternary carbon of both spiro compounds had an S-configuration.     

Cytoprotective effect of phloroglucinol on oxidative stress induced cell damage via catalase activation

We investigated the cytoprotective effect of phloroglucinol, which was isolated from Ecklonia cava (brown alga), against oxidative stress induced cell damage in Chinese hamster lung fibroblast (V79-4) cells. Phloroglucinol was found to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydrogen peroxide (H(2)O(2)), hydroxy radical, intracellular reactive oxygen species (ROS), and thus prevented lipid peroxidation. As a result, phloroglucinol reduced H(2)O(2) induced apoptotic cells formation in V79-4 cells. In addition, phloroglucinol inhibited cell damage induced by serum starvation and radiation through scavenging ROS. Phloroglucinol increased the catalase activity and its protein expression. In addition, catalase inhibitor abolished the protective effect of phloroglucinol from H(2)O(2) induced cell damage. Furthermore, phloroglucinol increased phosphorylation of extracellular signal regulated kinase (ERK). Taken together, the results suggest that phloroglucinol protects V79-4 cells against oxidative damage by enhancing the cellular catalase activity and modulating ERK signal pathway.     

Screening for Tannin Degradation by Rumen and Faecal Samples of Wild and Domestic Animals in Ethiopia

Summary Tannins limit the use of fodder trees as feed for ruminants. Removal of the effects of tannins would thus improve the nutritional quality of these trees. This prompted the study to evaluate the effect of rumen or faecal mixed cultures from different animals on tannin degradation. Tannin extracts, tannic acid and gallic acid were used to enrich media to assess if rumen or faecal mixed cultures could degrade the phenolic compounds. Rumen fluid of Acacia-adapted sheep, sheep fed on wheat bran, bush duikers (Sylvicapra grimmia) and goats fed on Leucaena pallida and Sesbania goetzei were separately inoculated into Growth Study Medium (GSM) and incubated for 5-15 days. Faecal samples from dikdik (Madoqua guentheri), camel (Camelus dromedarius), zebra (Equus quagga), Grant’s gazelle (Gazella granti) and hartebeest (Alcelaphus buselaphus) were also separately inoculated into GSM media and incubated from 3-5 days. TLC results showed that mixed cultures from rumen fluids of Acacia-adapted sheep, sheep on wheat bran, goats on Leucaena pallida and Sesbania goetzei partially hydrolysed tannic acid to pyrogallol. Complete degradation of the heterocyclic ring in tannic acid and gallic acid was achieved by the mixed cultures from the faecal samples of dikdik and this was confirmed by HPLC. Mixed cultures from faecal samples of camel hydrolysed gallic acid to phloroglucinol. This study has demonstrated that faecal microorganisms of Ethiopian dikdik could completely degrade hydrolysable tannin.     

The biosynthesis of flavonoid pigments: On the incorporation of phloroglucinol and phloroglucinyl cinnamate into rutin in Fagopyrum esculentum

The problem of whether phloroglucinol is a direct biosynthetic precursor of flavonoids was reinvestigated. Phloroglucinol-2,4,6-¹⁴C was found to be incorporated into rutin in Buckwheat (Fagopyrum esculentum) but most of the activity was found in the sugar moiety, the remainder being approximately equally distributed among the A- and B-rings of the aglycone, quercetin. This indicates extensive degradation of the added phloroglucinol prior to its utilization in the biosynthesis of the flavonoid. The hypothesis of a bio-Fries rearrangement of phloroglucinyl cinnamate to a chalcone, and hence to flavonoids, was also eliminated by comparing the efficiency of incorporation of ¹⁴C-labelled phloroglucinyl cinnamate and those of labelled phloroglucinol and cinnamic acid.     

Polycyclic phloroglucinols as PTP1B inhibitors from Hypericum longistylum: Structures,PTP1B inhibitory activities,and interactions with PTP1B

Protein tyrosine phosphatase 1B (PTP1B) has been regarded as a target for the research and development of new drugs to treat type II diabetes and PTP1B inhibitors are potential lead compounds for this type of new drugs. A phytochemical investigation to obtain new PTP1B inhibitors resulted in the isolation of four new phloroglucinols, longistyliones A–D (1–4) from the aerial parts of Hypericum longistylum. The structures of 1–4 were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of these compounds were established by comparing their experimental electronic circular dichroism (ECD) spectra with those calculated by the time-dependent density functional theory method. Compounds 1–4 possess a rare polycyclic phloroglucinol skeleton. The following biological evaluation revealed that all of the compounds showed PTP1B inhibitory effects. The further molecular docking studies indicated the strong interactions between these bioactive compounds with the PTP1B protein, which revealed the possible mechanism of PTP1B inhibition of bioactive compounds. All of the results implied that these compounds are potentially useful for the treatment of type II diabetes.