No abstract

Methanol extracts of Alpinia galanga, Alpinia zerumbet, Alpinia zerumbet variegata and Alpinia purpurata were evaluated for total phenolic content (TPC) and antioxidant activities (AOA). The AOA were investigated using 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), reducing power (RP), ferrous ion chelating as well asβ‐carotene bleaching assays. High antioxidant activities shown in leaves of A. zerumbet, A. zerumbet variegata and A. purpurata by using DPPH and RP assays were associated with high TPC values. In spite of lower TPC values, A. galanga leaves and flowers showed highest chelating andβ‐carotene bleaching abilities. The antimicrobial activities were screened by using disc diffusion method. Extracts from A. galanga and A. purpurata flowers showed the largest zone of inhibition of Micrococcus luteus. Only the extract from A. galanga rhizome showed antifungal activity toward Aspergillus niger. This work shows that leaves of A. zerumbet, A. zerumbet variegata and A. purpurata may serve as potential dietary sources of natural antioxidants. PRACTICAL APPLICATIONS Alpinia species are widely used in traditional cures and as food ingredients. Alpinia galanga rhizome is used as spice and food flavoring agent, and its leaves and inflorescence are consumed as vegetable. Its rhizome is also used to treat diseases such as fungal skin infections, intestinal infections, Type II diabetes, bronchitis and rheumatism. Alpinia zerumbet is used as ingredients in traditional health supplement, as diuretic agent and hypertension control. Alpinia zerumbet variegate and Alpinia purpurata are ornamental plants.