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An investigation was carried out without the use of thermal treatment to determine whether waste oils have color-altering effects on wood material surfaces. Waste vegetable oils (walnut, sunflower, corn, and olive) were applied to the surfaces of wood materials from ayous (Triplochiton scleroxylon K. Schum), fukadi (Terminalia amazonia), guatambú (Balfourodendron riedelianum (Engl.) Engl.), mahogany (Swietenia mahagoni (L.) Jacq.), and rengas (Gluta renghas L.) tree species. Subsequently, a control group was established, and experimental samples were compared. Changes in color parameters (L*, Δa*, C*, ΔL*, a*, Δb*, ho, ΔH*, b*, ΔC*, and ΔE*) were investigated. The results of multivariate analysis of variance for color parameters (C*, ho, L*, a*, and b*) were found to be statistically significant. A decrease in ho and L* was observed for all wood types and waste oils. On the other hand, a* and b* values increased and C* values decreased in guatambú and ayous wood on application of all waste vegetable oils. However, in the case of mahogany and rengas wood, a* and b* values decreased while C* values increased. [ABSTRACT FROM AUTHOR]

Irritant contact dermatitis (ICD) is an inflammation of skin caused by direct cytotoxic effects of chemical, physical or biological agents on epidermal cells without a presence of specific antibody production. It was reported that a 40-year-old man, complaining of itching and a burned sensation on his skins accompanied by pain after contaminated by sap of Rengas. Diagnosis of ICD was established by history taking and physical examination: there are erythematous, multiple, discrete papules, partly necrotic-erythematous skin base on his forearm and right lower abdomen. The patient was treated with mometasone furoate smeared and antihistamines once a night. A characteristic of the sap is black on its woods. Compounds of the sap contain ursiol, rengol, glutarengol, laccol and thitsiol that are irritants causing the ICD.

Rengas ( Gluta torquata ) wood is as potential source of antioxidants and α-amylase and α-glucosidase inhibitory activities. This is the first report of the inhibitory effects on α-amylase and α-glucosidase tested in vitro . The ability of Rengas wood compounds delay the breakdown of carbohydrates potentially helping to control postprandial hyperglycaemia. The antioxidant properties of the leaf, bark, and wood methanolic extracts were analyzed by the ferric reducing antioxidant power (FRAP), 2′-azinobis(2-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. The wood extract exhibited highest antioxidant activities and enzymes inhibitions. Subsequently, the Ultra Performance Liquid Chromatography (UPLC) analysis revealed the presence of the caffeic acid, quercetin and sulfuretin in the wood extract samples. The analyses of the antioxidant, antihyperglycemic properties and the phenolic compounds found in this study revealed great potential of rengas wood extracts that may be potentially useful in pharmaceutical industries. [ABSTRACT FROM AUTHOR]