Oxygen and Nitrogen Reactive Species Are Effectively Scavenged by Eucalyptus globulus Leaf Water Extract

Abstract

Eucalyptus globulus Labill. (Family Myrtaceae) is a plant of Australian origin, with a reported therapeutic use in airway inflammatory diseases. Considering that reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been implicated in the pathogenesis of airway inflammatory diseases such as asthma and chronic obstructive pulmonary disease, an effective scavenging activity against these reactive species may contribute for the therapeutic effect of this plant. In the present study, a water extract of E. globulus leaves was evaluated for its putative in vitro scavenging effects on ROS (HO(*), O(2)(*-), ROO(*), and H(2)O(2)) and RNS ((*)NO and ONOO(-)) and on 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). Qualitative and quantitative analyses of the extract's phenolic composition were also performed. The Eucalyptus leaf water extract presented a remarkable capacity to scavenge all the reactive species tested, with all the 50% inhibitory concentrations being found at the mug/mL level. Phytochemical analysis showed the presence of polyphenols such as flavonoids (rutin and quercitrin) and phenolic acids (chlorogenic acid and ellagic acid), which may be partially responsible for the observed antioxidant activity. These observations provide further support, beyond the well-known antibacterial and antiviral activities of the Eucalyptus plant, for its reported use in traditional medicine such as in the treatment of airway inflammatory diseases, considering the important role of ROS and RNS in the inflammatory process, although further studies are needed to prove the bioavailability of the antioxidants/antibacterial compounds of the extract as well as the ability of the active compounds to reach specific tissues and to act in them.

In vitro scavenging capacity of annatto seed extracts against reactive oxygen and nitrogen species

“…Quercetin showed an IC 50 of 0.5 lg/mL. The IC 50 values of these extracts showed better efficiency as 1 O 2 quenchers than extracts from Juglans regia leaves (Almeida et al, 2008a), Castanea sativa, Quercus robur (Almeida et al, 2008b), Hypericum androsaemum (Almeida, Fernandes, Lima, Costa, & Bahia, 2009) and Eucalyptus globulus leaf water extract (Almeida, Fernandes, Lima, Valentão, et al, 2009). As expected, bixin showed lower IC 50 than all annatto extracts.…”

“…The IC 50 values for all the tested extracts in this study showed better capacity than other extracts found in the literature, such as medicinal tincture from J. regia leaf extract (Almeida et al, 2008a), C. sativa and Q. robur (Almeida et al, 2008b), H. androsaemum (Almeida, Fernandes, Lima, Costa, et al, 2009), E. globulus (Almeida, Fernandes, Lima, Valentão, et al, 2009) and Pedilanthus tithymaloides (Abreu et al, 2006). The H 2 O 2 scavenging capacity of all annatto extracts analysed in this study was also better than that of quercetin (245 lg/mL), tested in the same conditions, ascorbic acid (200 lg/mL) (Abreu et al, 2006;Almeida et al, 2008aAlmeida et al, , 2008bAlmeida, Fernandes, Lima, Costa, et al, 2009;Almeida, Fernandes, Lima, Valentão, et al, 2009).…”

“…NA = no activity was found within the assayed concentration range ( (Almeida et al, 2008a), C. sativa, Q. robur (Almeida et al, 2008b), Hypericum androsaemu (Almeida, Fernandes, Lima, Costa, et al, 2009), E. globulus (Almeida, Fernandes, Lima, Valentão, et al, 2009) and P. tithymaloides (Abreu et al, 2006). The Å NO scavenging capacities for all annatto extracts were lower than quercetin (0.07 lg/mL) and rutin (0.86 lg/mL) (Abreu et al, 2006;Almeida, Fernandes, Lima, Valentão, et al, 2009). In relation to ONOO À scavenging capacity, all the extracts presented very similar IC 50 values, either in the absence or presence of NaHCO 3 , and only bixin standard presented good capacity for ONOO À scavenging as compared to the same extracts cited above for Å NO (Almeida et al, 2008a).…”

The potential of extracts of Caryocar villosum pulp to scavenge reactive oxygen and nitrogen species

“…The efficiency of ethanol/water and water extracts in the scavenging capacity against Å NO was higher than that of Pedilanthus tithymaloides medicinal tincture (Abreu et al, 2006), extracts of seeds, stems, leaves and petals of Catharanthus roseus (Ferreres et al, 2008), extracts of Sesamum indicum seeds (Visavadiya, Soni, & Dalwadi, 2009) and annatto seed extracts (Chisté et al, 2011). Additionally, the IC 50 values of ethanol/water and water extracts, for Å NO-scavenging properties, were similar to the other plant extracts, such as Juglans regia (Almeida et al, 2008a), C. sativa, Q. robur (Almeida et al, 2008b), H. androsaemum (Almeida, Fernandes, Lima, Costa, et al, 2009) and Eucalyptus globulus (Almeida, Fernandes, Lima, Valentão, et al, 2009). On the other hand, the extracts of C. villosum obtained with ethanol, ethanol/ethyl acetate and ethyl acetate, which presented the highest carotenoid contents and the lowest phenolic levels, were the least effective in scavenging Å NO (Fig.…”

“…The H 2 O 2 -scavenging capacity of ellagic acid (IC 50 of 108.3 lg/ml) was higher than that of gallic acid (226 lg/ml) and that of quercetin (290 lg/ml); however, it was lower than that of ascorbic acid (Abreu et al, 2006;Almeida, Fernandes, Lima, Costa, & Bahia, 2008a, 2008b, 2009aAlmeida, Fernandes, Lima, Valentão, et al, 2009). H 2 O 2 alone is practically harmless, whereas it may spread easily through the cell membranes, for example, the membrane of the nucleus, and can react with transition metals (Cu + and Fe 2+ ) inside cells (Fenton reaction) to generate the most reactive ROS, namely hydroxyl radical (HO Å ).…”