Apport de la biochimie flavonique à la systematique du genre Lycopodium

A systematic study of Lycopodium s.l. shows that only flavones occur in the four genera Huperzia, Lepidotis, Lycopodium s.s. and Diphasium. The arrangement of these taxa is discussed on the basis of the distribution of tricin, selgin, chrysoeriol, luteolin and apigenin. The evolutionary significance of these results and the uniqueness of Lycopodium phenolic metabolism are outlined.     

Apigenin 7-glucoside diacetates in ligulate flowers of Matricaria chamomilla

From ligulate flowers of Matricaria chamomilla was isolated a mixture of apigenin 7-O-β-glucoside diacetates, which was shown to be based on (2″, 3″)- and (3″, 4″)-diacetates.     

Different substitution tendencies of leaf flavones in theVeronica hederifolia group (Scrophulariaceae)

Flavonoid patterns of several provenances ofVeronica triloba, V. sublobata, andV. hederifolia s. str. have been investigated. 7-0-glucuronides of apigenin and luteolin as well as of 6-substituted (6-hydroxyluteolin and hispidulin) and 3′-methylated (chrysoeriol) derivatives represent characteristic accumulation tendencies in theV. hederifolia group. The three species show slightly different flavonoid profiles.V. hederifolia exhibits a cumulative pattern of all compounds occurring either inV. triloba orV. sublobata, thus supporting the hypothesis of an allopolyploid origin ofV. hederifolia.     

Altered Glycoflavone expression in induced Autotetraploids of Phlox drummondii

The effects of colchicine induced autotetraploidy on non-anthocyanin flavonoid expression were determine for 15 cultivars of Phlox drummondii and for the naturally occuring P. drummondii ssp. mcallisteri. Collectively, the taxa express a total of nine glycoflavonoid derivatives (C, O-diglycosides or di-C-glycosides) of either apigenin or luteolin. The autotetraploids of 14 cultivars and those of the natural subspecies exhibit altered glycoflavone profiles relative to their respective diploid sources. The qualitative alternations in the cultivars may be grouped into three phenotypic categories: (1) the expression of novel glycoflavones, (2) the absence of diploid glycoflavones, and (3) the deregulation of tissue-specific glycoflavone production. Alterations in mcallisteri autotetraploids include only the latter two categories. Each of the novel compounds is otherwise expressed among other diploid cultivars or in other wild P. drummondii subspecies. Quantitatively, the phenolic content of most autotetraploid flowers is significantly greater than in respective diploid flowers. However, on a dry weight basis, phenolic titre in comparable 4n and 2n floral or leaf tissues is not significantly different. Floral tissues express from 5 to 10 times the phenolic titre of leaves. The results are discussed in terms of the possible origins of novel flavonoids in natural polyploid Phlox species.     

Anti-inflammatory activity of flavonoids from Chrozophora tinctoria

Chemical investigation of Chrozophora tinctoria (L.) A. Juss. growing in Saudi Arabia revealed the isolation of two new acylated flavonoids identified as acacetin-7-O-β-d-[α-l-rhamnosyl(1 → 6)]3″-E-p-coumaroyl glucopyranoside (4) and apigenin-7-O-(6″-Z-p-coumaroyl)-β-d-glucopyranoside (5), in addition to amentoflavone (1), apigenin-7-O-β-d-glucopyranoside (2), apigenin-7-O-6″-E-p-coumaroyl-β-d-glucopyranoside (3) and rutin (6). The structures of isolated compounds were established by 1D, 2D NMR and HRESIMS spectral data, in addition to comparison with literature data. The anti-inflammatory activities of isolated compounds were assessed by measuring the levels of IL-1β, IL-6, TNF-α and PGE₂ in the supernatant media of human peripheral blood mononuclear cells (PBMCs) stimulated by phytohaemagglutinin (PHA). At a concentration of 100 μM, compounds 1, 2, 4 and 6 significantly decreased Il-1β, Il-6 and PGE₂ to nearly normal values. All tested compounds caused a dose-dependent decrease in TNF-α level but failed to reach that of the control values.     

Geographic variation of flavonoids in Phlox carolina

Non-anthocyanin flavonoid expression was determined among 64 continuous range and nine disjunct range populations of Phlox carolina. The species contains four flavone nuclei and a total of 25 derivatives, most of which are $\text{C-}\text{glycosides}$. Nearly all populations express unique flavone patterns. Using a qualitative similarity index of minimum biosynthetic step distance (MBSD), the average population contains only ca. 50% of the overall substitutional diversity. The separate ranges are distinctive in the % occurrence of most compounds but only weakly divergent in comparative mean MBSD. Proximity and MBSD are significantly correlated overall but local variability is extensive and no discrete racism is apparent. Within the continuous range 18 compounds are distributed in independent but overlapping gradients and 13 of these extend consistently through the disjunct range. The patch-work continuum of flavone variation is the apparent consequence of dissection and contraction of a historically more widespread distribution. Other general aspects of the variation patterns are discussed.     

HuR-positive stress granules: Potential targets for age-related osteoporosis

Aging impairs osteoblast function and bone turnover, resulting in age-related bone degeneration. Stress granules (SGs) are membrane-less organelles that assemble in response to stress via the recruitment of RNA-binding proteins (RBPs), and have emerged as a novel mechanism in age-related diseases. Here, we identified HuR as a bone-related RBP that aggregated into SGs and facilitated osteogenesis during aging. HuR-positive SG formation increased during osteoblast differentiation, and HuR overexpression mitigated the reduction in SG formation observed in senescent osteoblasts. Moreover, HuR positively regulated the mRNA stability and expression of its target β-catenin by binding and recruiting β-catenin into SGs. As a potential therapeutic target, HuR activator apigenin (API) enhanced its expression and thus aided osteoblasts differentiation. API treatment increased HuR nuclear export, enhanced the recruitment of β-catenin into HuR-positive SGs, facilitated β-catenin nuclear translocation, and contributed osteogenesis. Our findings highlight the roles of HuR and its SGs in promoting osteogenesis during skeletal aging and lay the groundwork for novel therapeutic strategies against age-related skeletal disorders.     

Three flavonoids targeting the beta-hydroxyacyl-acyl carrier protein dehydratase from Helicobacter pylori: crystal structure characterization with enzymatic inhibition assay

Flavonoids are the major functional components of many herbal and insect preparations and demonstrate varied pharmacological functions including antibacterial activity. Here by enzymatic assay and crystal structure analysis, we studied the inhibition of three flavonoids (quercetin, apigenin, and (S)-sakuranetin) against the beta-hydroxyacyl-acyl carrier protein dehydratase from Helicobacter pylori (HpFabZ). These three flavonoids are all competitive inhibitors against HpFabZ by either binding to the entrance of substrate tunnel B (binding model A) or plugging into the tunnel C near the catalytic residues (binding model B) mainly by hydrophobic interaction and hydrogen-bond pattern. Surrounded by hydrophobic residues of HpFabZ at both positions of models A and B, the methoxy group at C-7 of (S)-sakuranetin seems to play an important role for the inhibitor's binding to HpFabZ, partly responsible for the higher inhibitory activity of (S)-sakuranetin than those of quercetin and apigenin against HpFabZ (IC(50) in microM: (S)-sakuranetin, 2.0 +/- 0.1; quercetin: 39.3 +/- 2.7; apigenin, 11.0 +/- 2.5). Our work is expected to supply useful information for understanding the potential antibacterial mechanism of flavonoids.