Mariana Royer

Polyphenol contents and radical scavenging capacities of red maple (Acer rubrum L.) extracts

The crude ethanol and water extracts of different red maple (Acer rubrum L.) tissues: whole branches (WB), wood of branches (BW), bark of branches (BB), stem bark (SB) and whole twigs (T), were examined in order to determine their phenolic contents as well as their radical scavenging capacities. The total phenols (TP), total extractable tanins (TET) and non-precipitable phenols (NPP), were determined by combination of spectrophotometric and precipitation methods, while total flavonoids, hydroxy cinanmic acids and proanthocyanidins were determined spectrophotometrically. The radical scavenging activities of the extracts were determined against five reactive oxygen species (ROS): superoxide anion (O(2)(·-)), hydroxyl radical (HO(·)), peroxyl radical (ROO(·)), hypochlorite ion (ClO(-)), and hydrogen peroxide (H(2)O(2)) and one reactive nitrogen species (RNS): nitric oxide (NO). The extracts of stem bark were significantly more efficient (exhibiting the highest antioxidant efficiencies, AE) than the other studied extracts against all ROS (at p<0.05, Duncan statistical tests), except against NO. The correlation coefficients determined between total phenolic (TP) content and antiradical efficiencies were R(2)=0.12 for O(2)(·-); R(2)=0.29 for HO(·); R(2)=0.40 for H(2)O(2); R(2)=0.86 for ROO(·); R(2)=0.03 for NO(·) and R(2)=0.73 for ClO(-). Our results indicate potential utilisation of extracts as natural antioxidants.

Antioxidant, toxicological and antiproliferative properties of Canadian polyphenolic extracts on normal and psoriatic keratinocytes.

AIMS OF THE STUDY In a first attempt for establishing the possible utilization of polyphenolic extracts from barks of Canadian wood species in psoriasis treatment, we aimed to study (a) their antioxidant capacity, (b) their toxicological properties on normal human keratinocytes (NHK), and (c) their effect on the growth of normal and psoriatic keratinocytes (PK). MATERIALS AND METHODS Polyphenolic extracts were obtained by 90% ethanolic maceration and hot water extraction (HWE). Scavenging capacity was evaluated towards hydrogen peroxide, hydroxyl, superoxide, nitric oxide and peroxyl radicals. MTT assay and Trypan blue dye exclusion (TBDE) method were used for evaluating the initial toxicity of the most antioxidant extracts on NHK during 24 and 48 h. The effects of extracts on the growth of NHK and PK at non-toxic concentrations were determined after exposure for 48 h. RESULTS Yellow birch extract obtained by maceration (YB(Mac)) and black spruce extract obtained by HWE (BS(HWE)) were determined to have the highest antioxidant capacity, but BS(HWE) was less toxic on NHK. Toxicity of extracts on keratinocyte plasma membrane and mitochondria after 24 h was attributed to their content of hydroxycinnamic acids and proanthocyanidins. BS(HWE) inhibited the growth of NHK and non-lesional PK, but was not selective for lesional PK. CONCLUSION Given that BS(HWE) presented elevated content of total phenols and flavonoids and showed a low toxicity on NHK as well as an adequate chemical reactivity towards different radicals and some antiproliferative properties, it was considered as the most valuable extract obtained from barks of Canadian wood species.

Secondary metabolites of Bagassa guianensis Aubl. wood: A study of the chemotaxonomy of the Moraceae family

In order to explain the durability of the Moraceae plant family, phytochemistry of Bagassa guianensis was performed. Ethyl acetate extract was obtained from the heartwood and 18 secondary metabolites were isolated, including 6 moracins [6-O-methyl-moracin M, 6-O-methyl-moracin N and moracin Z; previously identified: moracin M, moracin N and moracin P], 8 stilbenoids [presently identified: (-)-epialboctalol and arachidin 4; previously identified: alboctalol, trans-resveratrol, arachidin 2, trans-oxyresveratrol and artogomezianol], 3 previously identified flavonoids, steppogenin, katuranin and dihydromorin, beta-sitosterol and resorcinol. Previous studies suggest that stilbenoids are responsible for the natural durability of wood. Our study has determined that B. guianensis is closely related to Morus sp. in phylogeny and should be included in the Moreae sensu stricto tribe of the Moraceae family.

Chemical Changes Induced by High-Speed Rotation Welding of Wood — Application to Two Canadian Hardwood Species

The chemical changes occurring upon rotational welding with dowels of Canadian wood species sugar maple (Acer saccharum) and yellow birch (Betula alleghaniensis) were examined by pyrolysis-GC/MS, DSC and XPS anlayses. The analyses performed separately on wood substrate (reference wood) and welded material by pyrolysis-GC/MS, DSC and XPS indicate that the differences in mechanical performances of the two welded woods are due mainly to the differences in original lignin structures as well as in the welding temperatures determined for the two wood species. The more pronounced guaiacyl character of the maple wood lignin seems to explain the preferential condensation reactions of the guaiacyl moieties in maple lignin with formaldehyde and furanic compounds released from lignin and carbohydrates during the fast pyrolysis associated with the welding process. The higher temperature determined for maple wood welding than for birch could be responsible for enhanced miscibility of wood polymers in the welding zone, explaining, therefore, the more significant presence of xylan polymer together with newly formed lignin carbohydrate complex (LCC) in the welded material. The detailed analysis of the compounds identified by pyrolysis-GC/MS, together with the results of the other two methods applied in this study, has confirmed that the S/G ratio cannot be taken as the sole criterion for the discussion of the chemical changes in lignins during welding of wood.