Imbricatin

Identification of phenanthrene derivatives in Aerides rosea (Orchidaceae) using the combined systems HPLC-ESI-HRMS/MS and HPLC-DAD-MS-SPE-UV-NMR.[Pubmed:25130411]

Phytochem Anal. 2015 Jan-Feb;26(1):34-9.

INTRODUCTION: In our continued efforts to contribute to the general knowledge on the chemical diversity of orchids, we have decided to focus our investigations on the Aeridinae subtribe. Following our previous phytochemical study of Vanda coerulea, which has led to the identification of phenanthrene derivatives, a closely related species, Aerides rosea Lodd. ex Lindl. & Paxton, was chosen for investigation. OBJECTIVE: To identify new secondary metabolites, and to avoid isolation of those already known, by means of the combined systems HPLC-DAD(diode-array detector) with high-resolution tandem mass spectrometry (HRMS/MS) and HPLC-DAD-MS-SPE(solid-phase extraction)-UV-NMR. METHODS: A dereplication strategy was developed using a HPLC-DAD-HRMS/MS targeted method and applied to fractions from A. rosea stem extract. Characterisation of unknown minor compounds was then performed using the combined HPLC-DAD-MS-SPE-UV-NMR system. RESULTS: The dereplication method allowed the characterisation of four compounds (gigantol, Imbricatin, methoxycoelonin and coelonin), previously isolated from Vanda coerulea stem extract. The analyses of two fractions permitted the identification of five additional minor constituents including one phenanthropyran, two phenanthrene and two dihydrophenanthrene derivatives. The full set of NMR data of each compound was obtained from microgram quantities. CONCLUSION: Nine secondary metabolites were characterised in A. rosea stems, utilising HPLC systems combined with high-resolution analytical systems. Two of them are newly described phenanthrene derivatives: aerosanthrene (5-methoxyphenanthrene-2,3,7-triol) and aerosin (3-methoxy-9,10-dihydro-2,5,7-phenanthrenetriol).

Inhibitory activities on nitric oxide production of stilbenoids from Pholidota yunnanensis.[Pubmed:24205813]

J Asian Nat Prod Res. 2013;15(12):1256-64.

Three new stilbenoids, 1-(4'-hydroxybenzyl)-Imbricatin, (E)-4'-hydroxy-2',3,3',5-tetramethoxystilbene, and (E)-3,4'-dihydroxy-2,6-bis(4-hydroxybenzyl)-2',3',5-trimethoxystilbene, together with 15 known stilbene derivatives, were isolated from Pholidota yunnanensis. Their structures were elucidated by spectroscopic methods and by comparison of their NMR data with those of related compounds. Furthermore, the inhibitory activities on nitric oxide (NO) production of the isolated compounds were examined in murine macrophages (RAW 264.7) activated by lipopolysaccharide. The cytotoxicity of 18 compounds was determined by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetr azolium assay. Among the tested compounds, eight stilbenoids, including three dihydrophenanthrenes, three stilbenes, and one bibenzyl derivative showed inhibitory effects on NO production without cytotoxicity with IC(5)(0) values ranging from 4.07 to 7.77 muM, as compared to MG-132, which was used as a positive control (IC(5)(0) of 0.10 muM). One dihydrophenanthrene, phoyunnanin C, showed cytotoxic effects at the test concentrations.

[Action of an extract of Vanda coerulea on the senescence of skin fibroblasts].[Pubmed:21570542]

Ann Pharm Fr. 2011 May;69(3):177-81.

The family of the orchids to date is poorly studied as a potential source of molecules with biological activity. The phytochemical analysis of extracts of Vanda coerulea stems (Orchidaceae), the isolation and the purification of the secondary metabolites realized by CLHP followed with high-resolution mass spectrometry and mono and two-dimensional nuclear magnetic resonance made it possible to identify the joint presence in an orchid of three stilbenoids i.e, Imbricatin, methoxycoelonin and gigantol. By flow cytometry, it is shown that the replicative senescence of human normal skin fibroblasts involves a reduction in the number of cells in phase S. A proteins chips technology dedicated to cell cycle proteins makes it possible to correlate this decrease of the number of cells in phase S to a decrease in cyclin E and cyclin dependant kinase 2, cdk2. The treatment by an ethanolic extract of stems of Vanda coerulea titrated in the three stilbenoids restores the percentage at an equivalent rate to that of young cells and the rate of cyclin E and, cdk2, thus bringing a beginning of explanation of their mechanism. These activities let predict an interesting potential as active ingredients to fight against the visible signs of cutaneous ageing.

Antioxidant biomarkers from Vanda coerulea stems reduce irradiated HaCaT PGE-2 production as a result of COX-2 inhibition.[Pubmed:21060890]

PLoS One. 2010 Oct 28;5(10):e13713.

BACKGROUND: In our investigations towards the isolation of potentially biologically active constituents from Orchidaceae, we carried out phytochemical and biological analyses of Vanda species. A preliminary biological screening revealed that Vanda coerulea (Griff. ex. Lindl) crude hydro-alcoholic stem extract displayed the best DPPH /(*)OH radical scavenging activity and in vitro inhibition of type 2 prostaglandin (PGE-2) release from UV(B) (60 mJ/cm(2)) irradiated HaCaT keratinocytes. PRINCIPAL FINDINGS: Bio-guided fractionation and phytochemical analysis led to the isolation of five stilbenoids: Imbricatin (1) methoxycoelonin (2) gigantol (3) flavidin (4) and coelonin (5). Stilbenoids (1-3) were the most concentrated in crude hydro-alcoholic stem extract and were considered as Vanda coerulea stem biomarkers. Dihydro-phenanthropyran (1) and dihydro-phenanthrene (2) displayed the best DPPH/(*)OH radical scavenging activities as well as HaCaT intracellular antioxidant properties (using DCFH-DA probe: IC(50) 8.8 microM and 9.4 microM, respectively) compared to bibenzyle (3) (IC(50) 20.6 microM). In turn, the latter showed a constant inhibition of PGE-2 production, stronger than stilbenoids (1) and (2) (IC(50) 12.2 microM and 19.3 microM, respectively). Western blot analysis revealed that stilbenoids (1-3) inhibited COX-2 expression at 23 microM. Interestingly, stilbenoids (1) and (2) but not (3) were able to inhibit human recombinant COX-2 activity. CONCLUSIONS: Major antioxidant stilbenoids (1-3) from Vanda coerulea stems displayed an inhibition of UV(B)-induced COX-2 expression. Imbricatin (1) and methoxycoelonin (2) were also able to inhibit COX-2 activity in a concentration-dependent manner thereby reducing PGE-2 production from irradiated HaCaT cells. Our studies suggest that stilbenoids (1-3) could be potentially used for skin protection against the damage caused by UV(B) exposure.

9, 10-Dihydrophenanthrene derivatives from Pholidota yunnanensis and scavenging activity on DPPH free radical.[Pubmed:17454314]

J Asian Nat Prod Res. 2007 Mar;9(2):165-74.

Three new 9,10-dihydrophenanthrene derivatives named phoyunnanins A-C, together with six known 9,10-dihydrophenanthrene constituents, 4,4',7,7'-tetrahydroxy-2,2'-dimethoxy-9,9',10,10'-tetrahydro-1,1'-biphenanthrene (4), lusianthridin (5), eulophiol (6), 2,4,7-trihydroxy-9,10-dihydrophenanthrene (7) and Imbricatin (8), were isolated from the 60% ethanolic extract of air-dried whole plant of Pholidota yunnanensis Rolfe. The structures of phoyunnanins A-C were established as 6-[2'-(3',3''-dihydroxy-5'-methoxybibenzy)]-4,7-dihydroxy-2-methoxy-9,10-dihydrop henanthrene (1), 6-[6'-(trans-3',3''-dihydroxy-5'-methoxystilbeny)]-4,7-dihydroxy-2-methoxy-9,10-d ihydrophenanthrene (2) and 4,4',7,7'-tetrahydroxy-2,2'-dimethoxy-9,9',10,10'-tetrahydro-1,6'-biphenanthrene (3), respectively, on the basis of the spectroscopic analysis. All eight compounds (1-8) were found to show the DPPH free radical scavenging activity with EC(50) from 8.8 to 55.9 microM.