Antioxidative activity of defensive secretions of Pachyiulus hungaricus (Karsch, 1881) and Megaphyllum unilineatum (C. L. Koch, 1838) (Diplopoda, Julida, Julidae)

Abstract

In several cultures millipedes have been used as medical remedies or food items and are recognized as a promising resource for humans. So far, a wide spectrum of biologically active compounds has been identified from millipedes, especially their defensive secretions, and some of them can be considered as potentially strong antioxidants. The aim of the study was to evaluate antioxidative potential of ethanol, methanol, hexane and dichloromethane extracts of two widely distributed millipede species, Pachyiulus hungaricus and Megaphyllum unilineatum. Antioxidative activities of defensive secretion extracts were determined by ABTS, DPPH and total reducing power tests. Tested extracts showed strong antioxidative potentials which varied depending on solvent used for the extraction or applied assay. Generally, extracts of P. hungaricus exhibited stronger antioxidative activity in comparison with M. unilineatum defensive secretion. The highest antioxidative capacities were noticed for MetOH extract of P. hungaricus defensive secretions, in both ABTS assay (0.972 ± 0.036 mg/mL) and in DPPH assay (0.114 ± 0.002 mg/mL). EC50 values of L-ascorbic acid were 0.263 ± 0.011 mg/mL and 0.041 ± 0.002 mg/mL, in ABTS and DPPH test, respectively. At the same time the lowest antioxidative activity was observed for MetOH extracts of M. unilineatum secretions in both assays (5.439 ± 0.441 mg/mL and 3.451 ± 0.184 mg/mL, respectively). The same trend characterized reducing power capacity with the maximum reducing power of MetOH extract of P. hungaricus (1.003 ± 0.036 mg AAE/mg of dried extract) which was comparable with L-ascorbic acid. Strong antioxidative activity is probably the result of the presence of hydroquinone, p-benzoquinone, as well as hydroxyl derivatives of p-benzoquinone which are known as potent antioxidants. Also, higher scavenging ability of P. hungaricus extracts can be correlated with the higher proportion of alkyl esters of long chain carboxylic acids.