Characterization of secretory phospholipase A2 inhibitory activity in
Tragia hispida as potential therapeutic agent for treatment of dengue
Abstract
Background: As secretory phospholipase A2 (sPLA2) was shown to
be elevated in patients who progress to severe dengue, it would be
important to evaluate the usefulness of therapeutics that inhibit sPLA2
enzymes to prevent progression to severe dengue. Methods:
Aqueous and butanol extracts of Tragia hispida, Justicia
adathoda and tubers of Cyperus rotundus were screened for the
presence of potential sPLA2 inhibitors using a commercial assay
measuring sPLA2 activity. Results: Both the aqueous (THA) and
butanol extracts (THB) of Tragia hispida had sPLA2 inhibition
levels comparable to the levels seen with the commercial sPLA2 inhibitor
CAY10590. THB at concentrations of 0.1 µg/µL and 0.2 µg/µL,
significantly reduced the sPLA2 activity (p<0.0001) in the
sera of dengue patients and the inhibitory activity was significantly
higher (p<0.0001) than of CAY10590. Thin layer chromatography
of THB showed that it was likely to contain a mixture of flavonoid and
phenolic compounds. HPLC displayed peaks at 3.207 min (λmax 222 nm, 272
nm) and 7.972 min (λmax 224 nm, 272 nm) which were most likely to
represent phenolics and peaks at 11.883 min (λmax 276 nm, 366 nm) and
16.898 min ( λmax 254 nm, 370 nm) which were most likely to represent
flavonoids. Conclusions: T. hispida aqueous and butanol
soluble fraction had potent sPLA2 inhibitory activities, which should be
further explored for their potential to be used for treatment of dengue.