Minor iridoids from Scutellaria albida ssp. albida. Inhibitory potencies on lipoxygenase,linoleic acid lipid peroxidation and antioxidant activity of iridoids from Scutellaria sp.

A new iridoid glycoside, 6′-O-E-caffeoyl-mussaenosidic acid, in addition to one known aglycon, four known triterpenes and one known flavonoid, were isolated from the aerial parts of Scutellaria albida subsp. albida. Furthermore, 12 iridoids with similar structures isolated from Scutellaria sp., were examined for their inhibitory potency on lipoxygenase and lipid peroxidation, as well as their antioxidant activity, in comparison to known antioxidants e.g. caffeic acid, nordihydroguaretic acid (NDGA) and trolox. AAPH, DPPH and soybean lipoxygenase (LOX) assays were used for the tests. This investigation led to interesting observations considering the Structure-Activity Relationship. According to our results, the presence of a p-coumaroyl group optimized and even dramatically changed the biological responses of the investigated iridoids.     

Secondary metabolites from Scutellaria albida L. ssp. velenovskyi (Rech. f.) Greuter & Burdet

Fourteen compounds (Fig.1) were isolated from the aerial parts of Scutellaria albida L. ssp. velenovskyi (Rech. f.) Greuter & Burdet, including four iridoids (1–4) catalpol, macfadienoside, mussaenosidic acid, albidoside; four flavonoids (5–8) hispidulin 7-Ο-β-D-glucuronide, scutellarin, xanthomicrol, eriodictyol; four phenylethanoid glycosides (9–12) verbascoside, leucosceptoside A, martynoside, 2-(3-hydroxy-4-methoxy-phenyl)-ethyl-1-Ο-β-D-glucopyranoside; the sugar ester 6′-β-D-glucopyranosyl-E-p-coumarate (13), as well as the acetogenic glucoside (Z)-3-hexenyl-1-O-β-D-glucopyranosyl-(1 → 2)-β-D-glucopyranoside (14). The structures of the isolates were established by means of NMR and HRMS spectral analyses. This is the first phytochemical study on S. velenovskyi and the first report of an acetogenic glycoside in the genus Scutellaria L. A chemical review on the isolated secondary metabolites in this study has been carried out. The chemotaxonomic value of the isolates is also discussed. Based on the literature data, the analysis revealed that the chemical profile of S. velenovskyi is close to that of the taxa belonging to the S. albida group.     

Iridoids from Kigelia pinnata DC. fruits

From the fruits of Kigelia pinnata DC., a new furanone derivative formulated as 3-(2'-hydroxyethyl)-5-(2"-hydroxypropyl)-dihydrofuran-2(3H)-one (1), and four new iridoids named; 7-hydroxy viteoid II (2), 7-hydroxy eucommic acid (3), 7-hydroxy-10-deoxyeucommiol (4) and 10-deoxyeucommiol (5) have been isolated together with seven known iridoids, jiofuran (6), jioglutolide (7), 1-dehydroxy-3,4-dihydroaucubigenin (8), des-p-hydroxybenzoyl kisasagenol B (9), ajugol (10), verminoside (11) and 6-trans-caffeoyl ajugol (12). The structures of the isolated compounds were characterized by different spectroscopic methods.     

Differentiation patterns in the Scutellaria albida group (Lamiaceae) in the Aegean area

An experimental investigation of the mainly white-flowered Scutellaria albida group in the Aegean area was carried out. Eight populations representing maximum morphological variation as well as geographic separation were chosen for crosses between populations. Strong sterility barriers were observed in the Cretean endemic species, S. sieberi Benth., which also deviated morphologically and is probably an ancient relic. Strong crossing barriers were also found in plants from Euboea, and, in spite of little morphological differentiation from S. albida L. s. str., they are treated as a separate species, S. goulimyi Rech. fil. Crossing barriers of intermediate strength were present in morphologically distinct material from N Sporades, which is also treated as a separate species, S. sporadum Bothmer sp. nov. All other populations showed high compatibility in crosses among themselves, viz. populations from Bulgaria, Thrace, Andros, Naxos, and Rodhos. These were treated as the same species, S. albida , having large local as well as clinal variation. Three subspecies are retained: ssp. albida in the north; ssp. perhispida (Bornm.) Bothmer in E Macedonia, Thrace and on the islands; and the mainly purple-flowered, ssp. vacillans (Rech. fil.) Bothmer, endemic to the peninsula of Athos. Evolutionary pathways and phytogeographical patterns are discussed.
S. sporadum is mainly inbreeding and, in S. sieberi , indications of a self-incompatibility system were found. The other taxa have a more versatile system.     

Iridoids from Desfostainia Spinosa

The leaves of Desfontainia spinosa were found to contain the known iridoid glucosides loganin and loganic acid. Loganetin, the aglucone of loganin was also isolated. This compound has not previously been reported as occurring naturally.     

Iridoids from Dunnia sinensis

A plumieride type iridoid glucoside, dunnisinoside, and a non-glucosidic iridoid, dunnisinin, were isolated from the leaves of Dunnia sinensis. Their structures were established by 1D and 2D NMR and FABMS experiments.     

Iridoids from Galium mollugo

From Galium mollugo, two new iridoids, gardenosidic acid and 10-hydroxymorroniside as well as 10-hydroxyloganin have been isolated, along with seven known iridoids, secogalioside, asperuloside, asperulosidic acid, daphylloside, monotropein, scandoside and scandoside methyl ester. 10-Hydroxyloganin, a compound which was previously considered to be the key biosynthetic intermediate of secoiridoids, was obtained for the first time from a natural source.     

Iridoids from Scrophularia genus

We report here an updated summary about iridoid composition of a series from the genus Scrophularia which have been investigated until now from a phytochemistry point of view. In addition a list is included about iridoids isolated in our laboratory from different plant parts of Scrophularia scorodonia L., which are compared with iridoids from some species of the Scrophularia genus. The present study may serve as a current information to researchers working on phytochemistry and pharmacological aspects from the Scrophularia genus and possibly to serve as a new starting point for future investigations.     

Iridoids from Avicennia marina

Three new iridoid glucosides, 10-O-[(E)-cinnamoyl]-geniposidic acid, 10-O-[(E)-p-coumaroyl]-geniposidic acid, 10-O-[(E)-caffeoyl]-geniposidic acid and the known iridoid glucoside, 2'-O-[(E)-cinnamoyl]-mussaenosidic acid have been isolated from Avicennia marina. The structures were determined primarily by NMR spectroscopy. The assignment of NMR signals was performed by means of 1H-1H COSY, HMQC and HMBC experiments.     

Iridoids from Globularia dumulosa

Two new iridoids, 10-O-benzoylglobularigenin (1) and dumuloside (2) were isolated from the aerial parts of Globularia dumulosa together with seven known iridoid glucosides, davisioside (3), aucubin (4), melampyroside (5), catalpol (6), 10-O-benzoylcatalpol (7), alpinoside (8) and deacetylalpinoside (9). Three phenylethanoid glycosides, verbascoside, decaffeoyl-verbascoside, leucosceptoside A and three flavone glucosides, pectolinarigenin 7-O-beta-D-glucopyranoside, nepetin 7-O-B-D-glucopyranoside, demethoxycentaureidin 7-O-beta-D-glucopyranoside were also isolated and characterized. The structure elucidation of the isolated compounds was performed by spectroscopic (UV, IR, HR-MALDIMS, 1D- and 2D NMR) methods.     

Iridoids from Caryopteris x clandonensis

In continuation of our phytochemical studies on Caryopteris x clandonensis (Lamiaceae), three further iridoids were isolated from the methanolic extract of the stems. Their structures were established by 1D and 2D NMR and MS analysis as a C-6 epimer of 8-O-acetylharpagide (6-epi-8-O-acetylharpagide), a derivative of harpagide which contained the unusual feature of a 3',4' seco-glycopyranosyl moiety (clandonoside II) and a methyl cetal of 8-O-acetylharpagide aglucone hydrate named clandonensine.     

Two new pyrrolizidine alkaloids from Crotalaria albida

Two new pyrrolizidine alkaloids, namely, neocroalbidine and neocroalbidinone, were isolated from the herbs of Crotalaria albida. Their structures were established using a combination of NMR spectroscopy and mass spectrometry techniques. The absolute stereochemistry of the two alkaloids presented herein was determined by single-crystal X-ray diffraction analysis.     

Production of L-serine by Sarcina albida.

Conditions for the production of microbial L-serine hydroxymethyltransferase and for the conversion of glycine to L-serine were studied. A number of microorganisms were screened for their abilities to form and accululate L-serine from glycine, and Sarcina albida was selected as the best organism. Enzyme activity in this organism as high as 0.12 U/ml could be produced in shaken cultures at 30 degrees C in a medium containing glucose, ammonium sulfate, glycine, yeast extract, and inorganic salts. L-Serine was produced most efficiently by shaking cells at 30 degrees C in a reaction mixture containing 20% glycine, 5 X 10(-3) M formaldehyde, and 3 X 10(-4) M pyridoxal phosphate in yields of 22 mg of broth in 5 days. L-Serine was easily isolated in 84% yields by ion-exchange resin.     

Iridoids from Catalpa bignonioides

Five new iridoids and related glucosides have been isolated from the methanol extract of Catalpa bignonioides root, along with a new phenylethanoid diglycoside. In addition, known iridoid glucosides, catalposide, amphicoside, 6-O-veratryl catalposide and minecoside were identified.     

Iridoids from Gentiana loureirii

Iridoid glycosides, 2′,3′,6′-tri-O-acetyl-4′-O-trans-p-(O-β-d-glucopyranosyl)coumaroyl-7-ketologanin (1), 2′-O-caffeoylloganic acid (2), 2′-O-p-hydroxybenzoylloganic acid (3), 2′-O-trans-p-coumaroylloganic acid (4), and 2′-O-cis-p-coumaroylloganic acid (5), were isolated from whole plants of Gentiana loureirii along with six known iridoids, 7-ketologanin (6), loganin (7), loganic acid (8), sweroside, boonein, and isoboonein, and three other known compounds. Their structures were elucidated by spectroscopic means and chemical correlations. The isolated iridoids were evaluated for antibacterial and antioxidant activities, but were either inactive or very weakly active.     

Iridoids from Viburnum betulifolium

Two iridoid glycosides have been isolated from Viburnum betulifolium. Viburnalloside, the major leaf glycoside, is composed of an iridoid aglucone acylated at C-1 with isovaleric acid and with a di-O-acetyl-β-D-allopyranosyl moiety attached through a glycosidic bond to C-11. Decapetaloside (10-hydroxyiridodial glucoside) has been isolated from the bark. The structure and absolute configuration of viburnalloside have been established by spectroscopic means, and those of decapetaloside by chemical correlation with adoxoside.     

In vitro anti-leukemic activity of the ethno-pharmacological plant Scutellaria orientalis ssp. carica endemic to western Turkey

Aim of this studyWithin the genus Scutellaria various species are used in different folk medicines throughout Asia. Traditional Chinese Medicine (TCM) uses S. baicalensis (Labiatae) to treat various inflammatory conditions. The root shows strong anticancer properties in vitro and was suggested for clinical trials against multiple myeloma. Further, S. barbata was successfully tested against metastatic breast cancer in a phase I/II trial. Therefore, we investigated the anti-cancer properties of S. orientalis L. ssp. carica Edmondson, an endemic subspecies from the traditional medicinal plant S. orientalis L. in Turkey, which is used to promote wound healing and to stop haemorrhage.Materials and methodsFreeze-dried plant material was extracted with petroleum ether, dichloromethane, ethyl acetate, and methanol and the bioactivity of these extracts was analysed by proliferation assay, cell death determination, and by investigating protein expression profiles specific for cell cycle arrest and apoptosis.ResultsThe strongest anti-leukemic activity was shown by the methanol extract, which contained apigenin, baicalein, chrysin, luteolin and wogonin, with an IpC50 of 43 μg/ml (corresponding to 1.3 mg/ml of dried plant material) which correlated with cyclin D1- and Cdc25A suppression and p21 induction. At 132 μg/ml (=4 mg/ml of the drug) this extract caused genotoxic stress indicated by substantial phosphorylation of the core histone H2AX (γ-H2AX) followed by activation of caspase 3 and signature-type cleavage of PARP resulting in a 55% apoptosis rate after 48 hours of treatment.ConclusionsHere, we report for the first time that S. orientalis L. ssp. carica Edmondson exhibited potent anti-leukaemic properties likely through the anti-proliferative effect of baicalein and the genotoxic property of wogonin.     

Production of L-serine by Sarcina albida.

Conditions for the production of microbial L-serine hydroxymethyltransferase and for the conversion of glycine to L-serine were studied. A number of microorganisms were screened for their abilities to form and accululate L-serine from glycine, and Sarcina albida was selected as the best organism. Enzyme activity in this organism as high as 0.12 U/ml could be produced in shaken cultures at 30 degrees C in a medium containing glucose, ammonium sulfate, glycine, yeast extract, and inorganic salts. L-Serine was produced most efficiently by shaking cells at 30 degrees C in a reaction mixture containing 20% glycine, 5 X 10(-3) M formaldehyde, and 3 X 10(-4) M pyridoxal phosphate in yields of 22 mg of broth in 5 days. L-Serine was easily isolated in 84% yields by ion-exchange resin.