Antibacterial and phytochemical constituent of Etlingera rubroloba A.D. Poulsen extract, an endemic ginger from Wallacea Region, Indonesia

Abstract

Abstract. Andila PS, Nugroho LH. 2022. Antibacterial and phytochemical constituent of Etlingera rubroloba A.D. Poulsen extract, an endemic ginger from Wallacea Region, Indonesia. Biodiversitas 23: 3646-3658. Etlingera rubroloba (Blume) AD Poulsen is one of the wild species of the Zingiberaceae which is a native and endemic species in the Wallacea region and has not been studied well for its biology and phytochemical potential. This study aimed to investigate the potential antibacterial activity of hexane extract from the leaves and rhizome of E. rubroloba and study their phytochemical content. The antibacterial activity test was carried out by the agar disc diffusion method against several human pathogenic bacteria and be measured for the Minimum Inhibitory Concentration (MIC) and Zone of inhibition. The phytochemical profile was tested for total phenol content (TPC), total flavonoid content (TFC) and GC-MS analysis. The study results show that TPC of E. rubroloba extracts respectively 15.68±0.80 mg Gallic Acid Equivalent (GAE)/g sample (leaves) and 11.89±0.76 mg GAE/g sample (rhizomes), while TFC value were 33.99±2.24 mg Quercetin Equivalent (QE)/g sample (leaves) and 32.46±0.67 mg QE/g sample (rhizomes). The antibacterial test revealed that E. rubroloba extracts were effective against Bacillus cereus ATCC11778 (with MIC value 0.5 mg/mL using leaves extract and 1 mg/mL in rhizomes), but it was not effective against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis ATCC12228. The hexane extracts of E. rubroloba contained a total of 28 and 58 compounds were identified in the leaf extract and rhizome, respectively. The dominant compounds in the leaf extract (Pentadecanoic acid, 14-methyl-, methyl ester; Methyl stearate) and in the rhizome extract (Hexadecanoic acid, ethyl ester; Isopropyl myristate; 9-Octadecenoic acid (Z)-, methyl ester; 9,12- Octadecadienoic acid, methyl ester, (E,E)-) is well known to have antibacterial activity. Based on the results of the antibacterial and phytochemical studies, it can be suggested that E. rubroloba has the potential as an antibacterial agent.