Naphthoquinones exhibit important biological activities and are present in walnut husk residues in significant amounts. However, their potential as alternatives to synthetic nematicides has not been fully explored. This work aimed to assess the effects of pure naphthoquinones (juglone; 1,4-naphthoquinone; plumbagin) on the mortality of the root-knot nematode Meloidogyne hispanica second-stage juveniles (J2). Extracts from Juglans spp. walnut husks were characterized, and the effects of J. nigra extracts on attraction and life cycle of M. hispanica were evaluated. 1,4-Naphthoquinone was the most effective compound causing 42% J2 mortality at 50 ppm. The extract from in natura J. nigra walnut husks presented similar effects on J2 mortality to those observed for pure 1,4-naphthoquinone. The extract from dried husks was repellent and reduced nematode root penetration but did not affect reproduction. Therefore, walnut residues can be valorized as renewable sources of naphthoquinone-based products and potentially employed as bionematicides against Meloidogyne spp.

Dexamethasone (DXMT) is a glucocorticoid that belongs to an important class of synthetic steroid hormones with potential to treat chronic immune and inflammatory diseases. In this work, the solid solubility of dexamethasone in supercritical carbon dioxide (scCO2) was measured using a static method. Experimental data were measured at (308.2, 318.2, and 328.2) K in the pressure range from (15.1 to 35.7) MPa. The solubility in scCO2 was found to be low and between (1.25·10–6 or 9.1·10–3) kg·m–3 (at 308.2 K and 15.1 MPa) and (2.81·10–6 or 22.0·10–3) kg·m–3 (at 328.2 K and 34.8 MPa) in terms of mole fraction or mass of drug per volume of solvent, respectively. Experimental data were correlated using semiempirical density based models (Méndez-Santiago–Teja, Bartle, and Chrastil). Obtained average absolute relative deviation [AARD (%)] values were lower than 13 %.

BACKGROUND Pine bark, which represents approximately 10 to 20% in weight of the tree trunk, is an abundant and low cost agro‐industrial waste. In order to obtain condensed tannin‐rich pine bark extracts (for future application in leather tanning/retanning processes), conventional aqueous extractions were performed, varying the type and amount of the solvent additive: sodium hydroxide (0.5, 1.0 and 1.5%, w/v), formic acid (0.5, 1.0 and 1.5%, v/v) and ethanol (5, 10 and 15%, v/v). Extractions were performed with and without the addition of sodium sulfite (1.0%, w/v). RESULTS The most favorable solvent additive in terms of total phenolics and condensed tannins was ethanol: extracts achieved 34.8% of gallic acid equivalents and 62.8% of catechin monohydrate equivalents. Moreover, the favorable pH values (∼3.5) of the resultant aqueous solutions and their relatively low viscosities are suitable for subsequent tanning applications. CONCLUSIONS The results of this study suggest that the high added‐value aqueous extracts of Pinus pinaster bark, which were achieved with small amounts of ethanol, have appropriate characteristics for leather tanning, and therefore they may be used as eco‐friendly tanning agents to partially replace chromium salts, thus reducing some of the environmental impacts typically associated with the leather industry. © 2017 Society of Chemical Industry

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