Germacranolides,calbertolides A,B and C,from Calea berteriana

The isolation and structure elucidation of two germacranolides, calbertolides A and B, and a heliangolide, calbertolide C, from Calea berteriana are reported. The structures of the new compounds were established by spectroscopic methods.     

Sesquiterpene lactones of Calea zacatechichi and C. urticifolia

Calea zacatechichi yielded the sesquiterpene lactone zexbrevin and a new analog, several analogs of neurolenin B including calein A, two analogs of budlein A and the flavones acacetin and O-methylacacetin. Calea urticifolia contained additional analogs of neurolenin B as well as a series of epoxidation products. Structures were established by spectrometric techniques. The results are contrasted with previous findings.     

Sesquiterpene lactones,flavonoids and anthraquinones from Asphodeline globifera and Asphodeline Damascena

The known compounds chrysoeriol, apigenin, luteolin, acacetin, scutellarein, 6-methoxyluteolin, apigenin 7-glucoside, luteolin 7-glucoside, esculetin, chrysophanol, asphodeline, mircocarpin, sitosterol, 1-β-acetoxyeudesman-4(15),7(11)dien-2α,12-olide and 1-β-acetoxy-8β-hydroxyeudesman-4(15),7(11)-dien-8α,12-olide were isolated from Asphodeline globifera and A. damascena. A new sesquiterpene lactone 1-β-acetoxy-8β-ethoxyeudesman-4(15),7(11)dien-8α, 12-olide was also characterized. These are the first reports of sesquiterpene lactones in Asphodeline and in the Liliaceae.     

Flavonoid glycosides of the black locust tree, Robinia pseudoacacia (Leguminosae)

Four flavone glycosides isolated from extracts of the leaves of Robinia pseudoacacia (Leguminosae) were characterised by spectroscopic and chemical methods as the 7-O-β-d-glucuronopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranosides of acacetin (5,7-dihydroxy-4′-methoxyflavone), apigenin (5,7,4′-trihydroxyflavone), diosmetin (5,7,3′-trihydroxy-4′-methoxyflavone) and luteolin (5,7,3′,4′-tetrahydroxyflavone). Assignment of glycosidic ¹H and ¹³C resonances in their NMR spectra was facilitated by ²J_HC correlations detected using the H2BC (heteronuclear two-bond correlation) pulse sequence. Spectroscopic analysis of two known triglycosides, acacetin 7-O-β-d-glucopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside (previously unrecorded from this species) and acacetin 7-O-β-d-xylopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside (‘acacetin trioside’), enabled inconsistencies in the literature relating to these structures to be resolved. Comparison of the flavonoid chemistry of leaves and flowers of R. pseudoacacia using LC-UV and LC-MS showed that flavone 7-O-glycosides, particularly of acacetin, predominated in the former, whereas the latter comprised mainly flavonol 3,7-di-O-glycosides, including several examples new to this species. Tissue dependent differences in flavonoid chemistry were also evident from the glycosylation patterns of the compounds.     

Changeover in flavonoid pattern accompanying reproductive structure formation in a bryophyte

Sexual reproduction in Marchantia berteroana is accompanied by a dramatic change in flavonoid pattern of the plant. During the sexual reproductive phase, acacetin production ceases and the predominant flavonoids are the previously absent 8-hydroxyapigenin and 8-hydroxyluteolin glycosiduronic acids. In contrast, acacetin levels reach their peak during the asexual reproductive phase. The chemotaxonomic significance of these results is discussed.     

Syntheses of 3-fluoro-, 3-epi-3-fluoro-, and 3,3-difluoro-3-de(methoxy)sporaricin A

3-Fluoro- (4), 3-epi-3-fluoro- (3), and 3,3-difluoro-3-de(methoxy)sporaricin A (5) have been prepared by reaction of diethylaminosulfur trifluoride with the corresponding precursors: 1,2′,6′-tris(N-benzyloxycarbonyl)-4-N, 5-O-carbonyl-3-de(O-methyl)sporaricin B (6), its 3-epi-3-hydroxy isomer (10), and the 3-oxo derivative (9). The structures of 3,4, and 5 were determined by ¹H-, ¹³C-, and ¹⁹F-n.m.r. spectroscopy.     

Comparative chemical composition of Agastache mexicana subsp. mexicana and A. mexicana subsp. xolocotziana

A comparative chemical analysis of Agastache mexicana subsp. mexicana and A. mexicana subsp. xolocotziana reveals that their methanol extracts constituents were very similar, with acacetin and (2-acetyl)-7-O-glucosyl acacetin being the most abundant compounds obtained. These results are consistent with the information reported for other species of Agastache. However, GS-MS analyses showed that methyl chavicol, limonene and linalool were the main constituents of the essential oils of A. mexicana subsp. mexicana, while pulegone, menthone and isopulegone were the major constituents found in A. mexicana subsp. xolocotziana. Furthermore, a different composition was found in their respective hexane extracts. These chemical composition dissimilarities between the two taxa support their recognition as distinct subspecies.     

Epi-α-bisabolol 6-deoxy-β-d-gulopyranoside from the glandular trichome exudate of Brillantaisia owariensis

A new sesquiterpene glycoside, (?)-epi-α-bisabolol 6-deoxy-β-d-gulopyranodide (1), has been isolated from the glandular trichome exudate of Brillantaisia owariensis (Acanthaceae). The structure of compound 1 was determined by spectroscopic analysis as well as acidic hydrolysis of 1 leading to (?)-epi-α-bisabolol (2) and 6-deoxy-d-gulose (3). This is the first study to analyze secondary metabolites from glandular trichome exudates of plants belonging to the Acanthaceae family. 6-Deoxygulopyranoside is the first example of an epi-α-bisabolol glycoside of plant origin.     

A new flavone glycoside from the leaves of Agastache rugosa (Fisch. & C.A.Mey.) Kuntze

Agastache rugosa (Fisch. & C.A.Mey.) Kuntze has been widely used as a food spice and a remedy for colds in Korea, China and Japan. In this study, one new flavone glycoside (1) along with six flavonoids (2–7), nine phenyl glycosides (8–16) and three megastigmane glycosides (17–19) were isolated from the leaves of A. rugosa. By extensive spectroscopic methods including 1D and 2D NMR, and MS data, the structure of the new compound (1) was elucidated as acacetin 7-O-β-(6″-(E)-crotonylglucopyranoside). From present investigation, compound 1 and 7–19 were isolated for the first time from the genus Agastache and 1, 16, 18 and 19 in the Lamiaceae family.     

Acacetin enhances glucose uptake through insulin-independent GLUT4 translocation in L6 myotubes

BackgroundLowering blood glucose levels by increasing glucose uptake in insulin target tissues, such as skeletal muscle and adipose tissue, is one strategy to discover and develop antidiabetic drugs from natural products used as traditional medicines.PurposeOur goal was to reveal the mechanism and activity of acacetin (5,7-dihydroxy-4′-methoxyflavone), one of the major compounds in Agastache rugose, in stimulating glucose uptake in muscle cells.MethodsTo determine whether acacetin promotes GLUT4-dependent glucose uptake in cultured L6 skeletal muscle cells, we performed a [¹⁴C] 2-deoxy-_D-glucose (2-DG) uptake assay after treating differentiated L6-GLUT4myc cells with acacetin.ResultsAcacetin dose-dependently increased 2-DG uptake by enhancing GLUT4 translocation to the plasma membrane. Our results revealed that acacetin activated the CaMKII-AMPK pathway by increasing intracellular calcium concentrations. We also found that aPKCλ/ζ phosphorylation and intracellular reactive oxygen species (ROS) production were involved in acacetin-induced GLUT4 translocation. Moreover, acacetin-activated AMPK inhibited intracellular lipid accumulation and increased 2-DG uptake in HepG2 cells.ConclusionTaken together, these results suggest that acacetin might be useful as an antidiabetic functional ingredient. Subsequent experiments using disease model animals are needed to verify our results.     

Flavonoid glycosides of Artemisia monosperma and A. herba-alba

Ten flavonoid glycosides were isolated and identified from Artemisia monosperma: vicenin-2, lucenin-2, acacetin 7-glucoside, acacetin 7-rutinoside, the 3-glucosides and 3-rutinosides of quercetin and patuletin, and the 5-glucosides of quercetin and isorhamnetin. From Artemisia herba-alba eight flavonoid glycosides were isolated and identified: isovitexin, vicenin-2, schaftoside, isoschaftoside and the 3-glucosides and 3-rutinosides of quercetin and patuletin.     

Acacetin 7-O-β-d-galactopyranoside from Chrysanthemum indicum

From the yellow flowers of Chrysanthemum indicum, a new flavone glycoside, acacetin 7-O-β-d-galactopyranoside was isolated and its structure established from spectral evidence and synthesis.     

Diterpenoids from Sideritis arborescens subsp. Paulii

Several ent-labda-13(16),14-dienes, ent-13-epi-manoyl oxides and the new natural products ent-6α,8α-dihydroxylabda-13(16),14-diene, ent-18-hydroxy-15(16)peroxylabd-13-ene,ent-16,18-dihydroxymanoyl oxide, ent-13-epi-16,18-dihydroxymanoyl oxide and ent-6α16,18-trihydroxymanoyl oxide have been isolated from Sideritis arborescens subsp. paulii. The structures of these compounds have been established by spectroscopic means and chemical correlations.     

Metabolism of [14C]cholesterol in Manduca sexta pupae: Isolation and identification of sterol sulfates,free ecdysteroids,and ecdysteroid acids

[¹⁴C]Cholesterol was injected into fifth-instar larvae of Manduca sexta, and the metabolites were isolated and identified from 8-day-old male and female pupae. A major portion of the metabolized cholesterol was esterified either with a sulfate group or with fatty acids. The predominant ecdysteroid metabolites were 20-hydroxyecdysone, 20,26-dihydroxyecdysone, 20-hydroxyecdysonoic acid, and 3-epi-20-hydroxyecdysonoic acid. Smaller amounts of ecdysteroids were identified as conjugates of 26-hydroxyecdysone, 3-epi-20-hydroxyecdysone, 20,26-dihydroxyecdysone, and its 3α-epimer. The metabolic profiles were similar for both male and female pupae. The two ecdysteroid acids were identified by nuclear magnetic resonance spectroscopy and chemical ionization mass spectrometry and by mass spectral analyses of their methyl esters. Detection of 3-epi-20-hydroxyecdysonoic acid as a major metabolite is significant, as its occurrence has been scarcely reported. 3-Epiecdysteroid acid formation is discussed as a possible ecdysteroid-inactivating pathway that may be operating specifically in lepidopterous insects or in particular developmental stages such as eggs or pupae.     

Alkaloids and styryllactones from the leaves of Goniothalamus tamirensis

Three new compounds, goniotamirine (1), goniotamiric acid (2), and 3,5-demethoxypiperolide (3) were isolated from the leaves of Goniothalamus tamirensis (Annonaceae), together with sixteen known compounds, (?)-N-nornuciferine (4), (?)-norisocorydine (5), (?)-isocorydine (6), (?)-3-hydroxynornuceferine (7), (?)-O-methylisopiline (8), (?)-anonaine (9), (?)-roemerine (10), (?)-roemeroline (11), (?)-boldine (12), glaunine (13), liriodenine (14), 9-deoxygoniopypyrone (15), 8-epi-9-deoxygoniopypyrone (16), 8-epi-9-deoxygoniopypyrone acetate (17), goniodiol (18) and goniothalamin (19). The structures were established from spectral analysis, including mass spectrometry and 2D-NMR. The absolute configuration of 1 was determined from analysis of its MTPA amide derivatives. The cytotoxicity of all isolates was evaluated against KB cells. Only compound 4 (N-nornuciferine) showed a moderate activity with an IC₅₀ value of 12 μg/mL.     

Germacrane and eudesmane derivatives from Calea reticulata

Calea reticulata afforded in addition to known compounds two new sesquiterpenes. These were germacrane and eudesmane derivatives, identified as germacra-4(15),5,10(14)-trien-1-one and 6-epi-β-verbesinol coumarate, respectively.     

16-epi-19-S-vindolinine,an indoline alkaloid from Catharanthus roseus

Studies on the alkaloids of Catharanthus roseus have resulted in the isolation of a new alkaloid, to which the structure of 16-epi-19-S-vindolinine has been assigned.     

α-Glucosidase inhibitory constituents from Chrozophora plicata

Five new secondary metabolites have been isolated from Chrozophora plicata including an acacetin derivative (1), three pyrrole alkaloids plicatanins A–C (2–4, resp.) and the bilactone plicatanone (5). Together with these compounds, the known compounds, β-sitosterol (6), methyl p-coumarate (7), 4-hydroxyphenylacetic acid (8), succinic acid (9), speranberculatine A (10), β-sitosterol-3-O-β-d-glucopyranoside (11) and apigenin-5-O-β-d-glucopyranoside (12) have also been isolated. The structures of isolates 1–12 were established by 1D (¹H, ¹³C) and 2D NMR (HMQC, HMBC, COSY) spectroscopy and mass spectrometry (EIMS, HREIMS, FABMS, HRFABMS). The structure of plicatanin A (3) was further confirmed through single crystal X-ray technique. Compounds 1–12 were evaluated for their inhibitory activity against the enzyme yeast α-glucosidase. The compound 4 was found to be most potent with IC₅₀ value 27.8 μM.     

Three homologous genes encoding functional ∆8-sphingolipid desaturase in Populus tomentosa

?⁸-sphingolipid desaturase is characterized by its ability to catalyze desaturation at the C8 position of the long-chain base of sphingolipids in plants. No previous studies have been conducted on genes encoding Δ⁸-sphingolipid desaturases in the woody plant Populus tomentosa. In this study, three genes that encode Δ⁸-sphingolipid desaturase were isolated from P. tomentosa. Among these genes, PtD8A and PtD8B showed high sequence similarity; whereas PtD8C exhibited large sequence divergence. RT-PCR results showed that PtD8A and PtD8B were expressed in all tissues detected, whereas PtD8C was not expressed in roots. Heterologous expression in yeast revealed that PtD8A/B/C were functional Δ⁸-sphingolipid desaturases, and can catalyze the C18-phytosphingenine desaturation to produce 8(Z)- and 8(E)-C18-phytosphingenine. However, the conversion rate and ratios of the two products differed. Compared with control cells, transgenic yeasts expressing PtD8A/B/C exhibited enhanced aluminum tolerance. Our findings further elucidated the biochemical functions and evolutionary history of Δ⁸-sphingolipid desaturases in plants. Candidate genes for breeding new poplar germplasm resources with enhanced tolerance ability to aluminium were also provided.     

Chemical constituents from Striga asiatica and its chemotaxonomic study

Six flavonoids, diosmetin (1), apigenin (2), luteolin (3), chrysoeriol (4), apigenin-7-O-glucuronide (5) and acacetin (6), two caffeic acid sugar esters, verbascoside (7) and isoverbascoside (8), as well as one norsesquiterpene, blumenol A (9) were isolated or detected from the EtOAc and n-BuOH extract of the whole plants of Striga asiatica. Their structures were identified by ¹H & ¹³C NMR, HR-LC-TOF-MS and co-injection with the reference standards. Among them, blumenol A (9) was firstly found from the Scrophulariaceae. Diosmetin (1) and isoverbascoside (8) were firstly reported from the genus Striga, while verbascoside (7) was reported from this plant for the first time. Based on our chemotaxonomic studies and the previous phytochemical studies on Scrophulariaceae, Striga could be tentatively treated as a member of the family Scrophulariaceae instead of Orobanchaceae.