Free radical scavenging effects of the Philippine endemic medicinal plant Alpinia elegans (Zingiberaceae)

Alpinia elegans (C.Presl) K.Schum. is an endemic Philippine medicinal plant used in the treatment of various conditions such as muscoloskeletal diseases, hemoptysis, headache, migraine, stomach ache, and as an anti-relapse for women. The major phytochemical constituents of the ethanolic extract from the leaves of Alpinia elegans were screened and their antioxidant activity was evaluated using an in vitro 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging (antioxidant) activity assay. Flavonoids, steroids, saponins, tannins, alkaloids, and cyanogenic glycosides were found to be present in the ethanolic leaf extract of Alpinia elegans, while anthraquinone was not detected. High DPPH radical scavenging (antioxidant) activity was observed in the ethanolic leaf extract of Alpinia elegans with a percentage DPPH inhibition of 95.11±1.00 at 500 μg/ml. The present study suggests that the leaf extract is a source of medicinal or pharmaceutical antioxidants. Information derived herein provides a preliminary scientific basis for the existing ethnobotanical knowledge of local communities.