Abstract：Five Eucalyptus spp. leaf extracts were prepared by methanol soaking extraction at room temperature. The antibacterial activities of the leaf extracts were determined by TLC-MTT-bioautography method. The antifungal activities of the leaf extracts on Colletotrichum gloeosporioides were determined by mycelium growth rate method. The antioxidant activities of the leaf extracts were determined using the multi-orifice plate-DPPH coloration method. And HPLC was employed to analyze the different Eucalyptus leaf extracts. Five Eucalyptus spp. leaf extracts showed certain inhibitory activities against the tested bacteria, but the differences were obvious. W5 leaf extract performed strongest antibacterial activities against Ralstonia solanacearum, Bacillus subtilis, Escherichia coli and Pseudomonas lachrymans, and diameters of the inhibition spot were more than 10 mm. Rf values felling into the range between 0.00 and 1.00 displayed antibacterial activities. W5 and Leilin 1 leaf extracts showed certain inhibitory activities against C. gloeosporioides, whose EC50 values were (16.82±0.20)mg/mL and (22.21±0.57)mg/mL, respectively. The result about antioxidant activity indicated different Eucalyptus spp. leaf extracts performed certain antioxidant activities. Apart from Guanglin 9, the antioxidant activities of the remaining four Eucalyptus spp. leaf extracts were stronger than the positive control BHT. The HPLC analysis showed that the difference about type and amount of the major compounds from the different Eucalyptus leaf extracts was not obvious, but the relative contents of the same compound are significant different. W5 leaf extract exhibits the strong antibacterial, antifungal and antioxidant activities, which can be used as candidate plant resources for further isolation, purification and identification of active component.
2020, Vol. 33 
