Microwave-Assisted Extraction of Condensed Tannins from Branches of Prunus spinosa L.: Response Surface Modeling and Optimization (original) (raw)
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Optimal conditions for microwave-assisted extraction (MAE) of total phenols (TP), epicatechin gallate and antioxidant activity from prune (Prunus domestica), rejected in transformation process of plum to prune, were determined by response surface methodology. The central composite design was used to study the effects of three independent variables: microwave power, irradiation time and solvent polarity on the TP, epicatechin gallate and antioxidant activity. Epicatechin gallate was identified as a major phenolic compound in prune extract by RP-HPLC. Microwave power and irradiation time significantly affected all responses (P < 0.01). The highest TP (598.89 mg GAE/100 g prune) was obtained using water as an extraction solvent at 500 W, during 115 s. However, the optimal conditions for epicatechin gallate extraction were ethanol 80%, 435 W and 120 s. MAE is more efficient than conventional extraction method to obtain TP from prune. The experimental values were reasonably close to the predicted values confirming the validity of the predicted models.
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Herein, we evaluated the content of condensed tannins present in the bark of four tree species that are Quercus laurina Humb. & Bonpl., Quercus crassifolia Humb. & Bonpl., Arbutus xalapensis Kunth, and Prunus serotina Ehrn. An analytical method using high-performance liquid chromatography (HPLC) for condensed tannin extracts was developed and validated. Also, the aqueous extracts were analyzed by Fourier transform infrared spectroscopy (FTIR). Based on the Stiasny number, A. xalapensis, and Q. laurina represent an important source of condensed tannins, which may be subject to exploitation. Using infrared spectroscopy, it was observed that tannins do not show an important signal of carbonyl groups (aromatic esters) with respect to high purity catechin. Furthermore, the band of the hydroxyl group is less pronounced in tannins, because various hydroxyl are interacting with each other. However, it can be seen that the method of extraction of wood tannins developed in this work, presents...
Anais da Academia Brasileira de Ciências, 2021
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Tannins are polyphenolic compounds naturally found in vegetables. Their presence in nature has prompted their historical use in many different ways. The revision of their traditional utilization has allowed their further modification aiming for an industrial application. Sometimes these modifications have implied the addition of harmful substances such as formaldehyde, classified as a carcinogen of category B1. In other cases, these natural tannins have been replaced by synthetic compounds that threaten human and animal health and damage the environment. Therefore, currently, both academy and industry are searching for the substitution of these unsafe complexes by the increasing inclusion of tannins, natural molecules that can be obtained from several and diverse renewable resources, modified using harmless additives. To achieve promising results, cost-efficient and eco-friendly extraction methods have been designed. Once these green alternatives have been isolated, they have been s...
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Proanthocyanidins, also known as condensed tannins are widespread in woody plants, but are also found in certain forages. Castanea sativa Mill. are exploited for various purposes, but a little is known about potential of this species and possible application in diet and therapy. The parts of chestnut such as: seed, peeled seed, brown seed shell, red internal seed shell, leaves, catkin, spiny bur, as well as the new and old chestnut bark were extracted with 50% ethanol as an extragents. Contents of total phenolics and total flavonoids were measured by application of the standard colorimetric assay. The total condensed tannins content estimated was highest in red internal seed shell 15.29%CE (vanillin assay) and 3.12%CT (acid butanol assay). Also high content of total phenolic compounds and condensed tannins had extracts of catkin, brown seed shell of chestnut and new chestnut bark. Extracts of C. sativa Mill. can be a potential resource of natural tannins with possible application in...