Antiviral screening on Alpinia eremochlamys, Etlingera flexuosa, and Etlingera acanthoides extracts against HIV-infected MT-4 cells

Alpinia eremochlamys K. Schum, Etlingera flexuosa A.D. Poulsen, and Etlingera acanthoides A.D. Poulsen are endemic Zingiberaceae plants from Central Sulawesi, Indonesia. This study is the first report on screening the potential antiviral activity of ethanol extracts of the leaves, pseudostems, and rhizomes parts on HIV-infected MT-4 cells and identifying chemical constituents by GC-MS. The plants were extracted by the maceration method using 96% ethanol as a solvent. The antiviral activity was measured using Viral-ToxGlo colorimetric method and using the extracts at concentrations ranging from 7.8 to 1000 μg/mL. GC-MS was used to identify the secondary metabolites of potential extracts. The results showed that ethanol extract of E. acanthoides rhizome was the most potent antiviral activity (IC(50) of 1.74 ± 2.46 μg/mL) and less toxic on lymphocyte (MT-4) cells (CC(50) of 204.90 ± 106.35 μg/mL), affording the highest value of selectivity index (SI) of 117.76. A. eremochlamys rhizomes also showed promising antiviral activity with IC(50) of 64.18 ± 2.58 μg/mL and no toxicity on MT-4 cells affording a high SI value 19.05. Preliminary GC-MS identification showed the presence of terpenoids and fatty acids as major compounds. Zerumbone, ar-turmerone, caryophyllene, and caryophyllene oxide were also detected. Chemical constituents identified by GC-MS might be responsible for the antiviral activity of extracts, suggesting further isolation and antiviral testing of the purified compounds.