Stumps of Eucalyptus globulus as a Source of Antioxidant and Antimicrobial Polyphenols

Abstract

These past years have seen an enormous development of the area of natural antioxidants and antimicrobials. Eucalyptus globulus is widely cultivated in subtropical and Mediterranean regions in intensive short rotation coppice plantations. In the Portuguese context, E. globulus is the third species in terms of forest area. The stump is the basal part of the tree, including the near-the-ground stem portion and the woody roots that remain after stem felling. The purpose of this work was to study the phytochemical profile and to evaluate the antioxidant and antimicrobial properties of several crude stump wood and stump bark extracts of E. globulus, comparing it with similar extracts of E. globulus wood (industrial chips). The results showed the presence of high concentrations of total phenolic compounds (>200 mg GAE/g extract) and flavonoids (>10 mg QE/g extract) in E. globulus stump extracts. Generally the stump wood extracts stands out from the other ones, presenting the highest percentages of inhibition of linoleic acid oxidation. It was also possible to conclude that the extracts were more active against Gram-positive bacteria, presenting low MIC values. This study thus provides information supporting the economic valorization of E. globulus stump wood.

Bark Characterisation of the Brazilian Hardwood Goupia glabra in Terms of Its Valorisation

“…Sultana et al (2007) found 93, 165, 120, and 120 mg GAE/g extracts in the ethanol-water of Eugenia jambolana, Acacia nilotica, Azadirachta indica, and Terminalia arjuna, respectively. Luis et al (2014) reported 383 mg GAE/g extract in 70% ethanol for E. globulus stemp bark. Puttaswamy et al (2014) reported for E. tereticornis bark 198 mg GAE/g aqueous methanolic extract.…”

“…A large range of values has been reported for other hardwood barks, such as C. langsdorffii (442 mg CE/g extract, Carmo et al 2016), Delonix elata (75 mg quercetin equivalent/g extract in ethanol, Krishnappa et al 2014), Eugenia jambolana, A. nilotica, A. indica, andT. arjuna (respectively, 21, 49, 31, and35 mg CE/g extract in ethanol-water, Sultana et al 2007), E. globulus stump (12 mg quercetin equivalents/g extract in ethanol-water, Luis et al 2014), or Eucalyptus tereticornis (160 mg rutin equivalents/g of bark, Puttaswamy et al 2014).…”

“…The acetone-water extract of bark of the E. globulus stump contained 29 mg GAE/g extract (Luis et al 2014) and E. tereticornis bark 103 mg tannic acid equivalents/g of bark (Puttaswamy et al 2014). …”

Medicinal Plants of Israel: A Model Approach to Enable an Efficient, Extensive, and Comprehensive Field Survey

“…Some families of compounds synthesized by plants may have a variety of biological activities, and in many cases high antioxidant activity is linked with anti-infectious activity [34][35][36][37]. In other cases, specifi c molecules are synthesized by the plant for unique activities.…”

Characterization of Eucalyptus maidenii Timber for Structural Application: Physical and Mechanical Properties at Two Moisture Conditions

“…Eucalyptus maidenii is a tall to very tall forest tree usually 30 to 45 meters in height with a diameter of up to 2.5 meters, whose bark is smooth, whitish or cream, decorticating in strips to ground level, or sometimes with a short stocking of undecorticated rough bark [15]. Maiden's Gum trees could provide acid oils from their leaves [16] and their fruits [17] or medicines from their leaves [11], as well as extracts from their barks [18,19]. Wood from Maiden's Gum has sapwood susceptible to Lyctus borer attack, and its light brown heartwood with pinkish to orange tints is hard, moderately strong and durable, coarse, uniform in texture, and with grain that is sometimes interlocked [1,15].…”