From dereplication and anti-inflammatory screening of Clusiaceae and Calophyllaceae species to novel immunomodulatory coumarins from Mesua lepidota

Vascular endothelium plays a central role in the development of inflammatory and immune processes, which are involved in graft rejection1. Many Clusiaceae/Calophyllaceae species (pantropical plants) biosynthesize original polyphenolic compounds exhibiting antioxidant and anti-inflammatory properties2-3. Bark, leaves and occasionally fruits from thirteen Malaysian plants belonging to the genus Calophyllum, Mesua (Calophyllaceae), Garcinia (Clusiaceae) were extracted using DCM and MeOH as the solvents. Each extract was then submitted to a HPLC-PDA-MSn dereplication analysis and its anti-inflammatory potential was evaluated on Human Umbilical Vein Endothelial Cells (HUVECs). This allowed to select the bioactive fruits DCM extract of Mesua lepidota T. Anderson for an advanced phytochemical study, which led to the identification of several new coumarin derivatives. A flow cytometry study revealed that the major component of this extract, namely lepidotol A (1), significantly inhibited the VCAM-1, HLA-II and HLA-E expression of HUVECs previously activated by TNF-α or IFN-γ cytokines.   References   1.     P. T. Clesca, Int. Congr. Ser., 2002, 1237, 181-191. 2.     F. V. Cechinel, C. Meyre-Silva, and R. Niero, Chem. Biodivers., 2009, 6, 313-327. 3.     J. González-Gallego, M. V. García-Mediavilla, S. Sánchez-Campos and M. J. Tuñón, Br. J. Nutr., 2010, 104, S15-S2

Effets anti-inflammatoire et immunomodulateur de composés polyphénoliques isolés de Clusiaceae et de Calophyllaceae

L’endothélium vasculaire joue un rôle central dans le développement des réponses inflammatoires et immunitaires conduisant notamment au phénomène de rejet de greffe1. Les Clusiaceae et Calophyllaceae, plantes des régions pantropicales, biosynthétisent des dérivés polyphénoliques originaux présentant des activités anti-inflammatoires intéressantes2-3. Divers polyphénols isolés de ces plantes ont été sélectionnés, afin d’évaluer in vitro leur potentiel anti-inflammatoire et immunomodulateur sur des cellules endothéliales humaines. Plusieurs coumarines et une benzophénone se sont alors révélées inhibitrices de l’expression de marqueurs de l’inflammation et de l’immunité. Parallèlement à cette étude, les extraits dichlorométhaniques (DCM) et méthanoliques d’un panel de plantes issues des genres Garcinia (Clusiaceae), Calophyllum et Mesua (Calophyllaceae), originaires de Malaisie, ont été analysés par déréplication (HPLC-PDA-MSn). Deux extraits contenant des pharmacophores d’intérêt ont ainsi été sélectionnés pour une étude phytochimique approfondie : l’extrait DCM de fruits de Mesua lepidota, duquel ont été identifiés sept phénylcoumarines originales, que nous avons baptisées lépidotols et lépidotines, et l’extrait DCM de feuille de Calophyllum tetrapterum, ce dernier riche en benzophénones polyprénylées. Références : 1.         Brick C, Atouf O, Benseffaj N, et al. Rejet de la greffe rénale : mécanisme et prévention. Nephrol Ther 2011;7:18-26. 2.         Ali M, Arfan M, Ahmad M, et al. Anti-inflammatory xanthones from the twigs of Hypericum oblongifolium Wall. Planta Med 2011;77:2013-2018. 3.         Santa-Cecilia FV, Freitas LAS, Vilela FC, et al. Antinociceptive and anti-inflammatory properties of 7-epiclusianone, a prenylated benzophenone from Garcinia brasiliensis. Eur J Pharmacol 2011;670:280-285

Chemically engineered extracts of St John’s wort as sources of polyprenylated acylphloroglucinols to prevent endothelial dysfunction

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Lepidotols and lepidotins: new phenylcoumarins from Mesua lepidota as promising inhibitors of endothelial immune responses and dysfunction

During organ transplantation, graft endothelium is the first barrier encountered by immune cells of the recipient. Endothelial cells surface presents inflammatory and immune proteins which are over-expressed after activation by pro-inflammatory cytokines, Damage Associated Molecular Patterns (DAMPs) or Advanced Glycation End Products (AGEs) [1]. Among natural products, several polyprenylated polyphenols have shown anti-inflammatory, immunomodulatory and anti-AGEs properties [2 – 3]. Such secondary metabolites are biosynthesized by Calophyllaceae species such as Calophyllum or Mesua species. In order to identify natural products able to prevent endothelial dysfunction, a dereplication analysis was conducted on various extracts from Calophyllum and Mesua species native to Malaysia. It appeared that the fruits of Mesua lepidota T. Anderson are a rich source of original phenylcoumarins named as lepidotols and lepidotins. The main compound, lepidotol A, was evaluated for its anti-inflammatory, immunomodulatory and anti-AGEs potential. Beside a potent inhibitory effect of the VCAM-1, class II HLA and HLA-E induced surface-expressions on human endothelial cells (52%, 97% and 66%, respectively), lepidotol A exhibited an inhibition of AGEs formation five to thirty times higher than aminoguanidine (positive control). These results are consistent with the marked pharmacological activities of prenylated aromatic metabolites [4], and highlight a new approach to discover protective compounds against graft rejection

Selection of Clusiaceae and Calophyllaceae extracts based on dereplication and anti-inflammatory properties

Inflammation is associated with many pathogenic disorders including endothelial dysfunction. Calophyllaceae and Clusiaceae which are rich in polyphenolic compounds such as coumarins, xanthones, benzophenones and biflavonoids1 are well-known for their anti-inflammatory properties2. Bark, leaves and occasionally fruits of thirteen plants belonging to the genus Calophyllum, Mesua (Calophyllaceae), Garcinia (Clusiaceae) and native from Malaysia, were extracted using DCM and MeOH as the solvents. Extracts of interest were selected according to two distinct criteria. Firstly, a dereplication analysis was conducted though HPLC-PDA-MSn. Secondly the VCAM-1 surface-expression of (TNF-α)-stimulated endothelial cells from human umbilical veins (HUVECs) was evaluated. It appeared that several extracts particularly rich in xanthones and phenylcoumarins significantly decreased inflammatory marker expression. In this context, a new phenylcoumarin was identified as the major component of the bioactive fruits DCM extract from a Mesua. References: [1] V. Cechinel Filho et al. Chem. Biodivers. 2009, 6, 313-327 [2] J. Gonzalez-Gallego et al. Br. J. Nutr. 2010, 104, S15-S2

Anti-inflammatory and immunomodulatory properties of polyphenolic compounds from Clusiaceae/Calophyllaceae: A focus on coumarins

Vascular endothelium plays a central role in the development of inflammatory and immune processes, which are involved in graft rejection [1]. Many Clusiaceae/Calophyllaceae species (pantropical plants) biosynthesize original polyphenolic compounds exhibiting antioxidant and anti-inflammatory properties [2 – 3]. Therefore, different Clusiaceae/Calophyllaceae polyphenols were selected in order to evaluate in vitro their anti-inflammatory and immunomodulatory potential towards Human Umbilical Vein Endothelial Cells (HUVECs). The VCAM-1, ICAM-1, E-selectin, HLA-I, HLA-II, HLA-E and MICA surface-expressions of HUVECs were evaluated by flow cytometry. It appeared that a few coumarins and one benzophenone at 10µM significantly inhibited the expression of several markers previously induced by TNF-α or IFN-γ cytokines, being more active that the immunosuppressive reference compound – zoledronic acid – at the same concentration. Among these active compounds, one phenylcoumarin isolated from the Malaysian Mesua lepidota T. Anderson (Calophyllaceae) was identified as a new one. By comparing biological effects with substitution patterns, preliminary structure-activity relationship was also established

Prenylated polyphenols from Clusiaceae and Calophyllaceae with immunomodulatory activity on endothelial cells

Endothelial cells (ECs) are key players in inflammation and immune responses involved in numerous pathologies. Although attempts were experimentally undertaken to prevent and control EC activation, drug leads and probes still remain necessary. Natural products (NPs) from Clusiaceous and Calophyllaceous plants were previously reported as potential candidates to prevent endothelial dysfunction. The present study aimed to identify more precisely the molecular scaffolds that could limit EC activation. Here, 13 polyphenols belonging to 5 different chemical types of secondary metabolites (i.e., mammea coumarins, a biflavonoid, a pyranochromanone acid, a polyprenylated polycyclic acylphloroglucinol (PPAP) and two xanthones) were tested on resting and cytokine-activated EC cultures. Quantitative and qualitative changes in the expression of both adhesion molecules (VCAM-1, ICAM-1, E-selectin) and major histocompatibility complex (MHC) molecules have been used to measure their pharmaceutical potential. As a result, we identified 3 mammea coumarins that efficiently reduce (up to >90% at 10 μM) both basal and cytokine-regulated levels of MHC class I, class II, MICA and HLA-E on EC surface. They also prevented VCAM-1 induction upon inflammation. From a structural point of view, our results associate the loss of the free prenyl group substituting mammea coumarins with a reduced cellular cytotoxicity but also an abrogation of their anti-inflammatory potential and a reduction of their immunosuppressive effects. A PPAP, guttiferone J, also triggers a strong immunomodulation but restricted to HLA-E and MHC class II molecules. In conclusion, mammea coumarins with a free prenyl group and the PPAP guttiferone J emerge as NPs able to drastically decrease both VCAM-1 and a set of MHC molecules and to potentially reduce the immunogenicity of the endothelium