In Vitro Anti-Bacterial and Anti-Fungal Activities of Extracts from Different Parts of 7 Zingiberaceae Plants

This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family. The inhibitory rate, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of leaf and stem, and root and rhizome extracts from Alpinia katsumadai Hayata, Alpinia oxyphylla Miq x Alpinia henryi K. Schumann, Alpinia oblongifolia Hayata, Alpinia nigra (Gaertn.) Burtt, Amomum villosum Lour, Alpinia zerumbet (Pers.) Burtt. et Smith and Alpinia oxyphylla Miq were determined using the fungus cake method and double dilution method. The seven Zingiberaceae plants exhibited characteristic antibacterial activities against pathogenic bacteria and fungi. At a 1.5 mg mL(-1), A. zerumbet root and rhizome extracts exhibited strong inhibitory activity against S. aureus and E. coli, with 83.23% and 79.62%, respectively. In addition, A. zerumbet leaf and stem extracts had an inhibitory rate of 90.85% against P. aeruginosa. At the same concentration, the leaf and stem, root and rhizome extracts of A. katsumadai had the best antibacterial effect against F. oxysporum, with inhibition rates of 84.46% and 84.73%, respectively. Moreover, A. katsumadai and A. zerumbet leaf and stem extracts had the most significant antibacterial effect against S. aureus, with a MIC of 0.063 mg mL(-1). Thus, both A. katsumadai and A. zerumbet extracts had significant antibacterial activity. In addition, by comparing the inhibitory effect of extracts from different parts, it was found that the inhibitory rate and average inhibitory rate of extracts from leaf and stem were higher than those from root and rhizome. The chemical constituents of A. katsumadai and A. zerumbet, determined by the high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), revealed that citric acid (CA), alpinetin, and pinocembrin (PNCB) were the functional constituents yielding the antibacterial activity. Overall, A. katsumadai and A. zerumbet have the potential to be developed as new plant fungicides and bactericides.