Biological activity of rainforest plant extracts from far North Queensland, Australia

Abstract

A total of 137 species of trees and three lianas, distributed over 30families, have been collected from tropical rainforests of north Queensland, Australia. The barks of these plants have been extracted and the extracts screened for cytotoxic activity against Hep G2, MDA-MB-231, Hs578T, MCF7, 5637, PC-3, and SK-MEL-28 human tumor cell lines; for antimicrobial activity against the Gram-positive bacteria Bacillus cereus and Staphylococcus aureus, the Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli, and the fungi Candida albicans and Aspergillus niger. Brine shrimp (Artemia salina) lethality tests have also been carried out on the extracts. Of the 140 species tested, 55 showed remarkable cytotoxic activity against at least one of the cell lines while six species [Daphnandra repandula (Monimiaceae), Melicope rubra (Rutaceae), Cryptocarya hypospadia (Lauraceae), Carnarvonia araliifolia (Proteaceae), Pittosporum venulosum (Pittosporaceae), and Calophyllum costatum (Clusiaceae)] showed pronounced activity against all tumor cell lines tested Fifteen species showed antibacterial activity against B. cereus, seven of which [Melicope rubra (Rutaceae), Xanthostemon whitei (Myrtaceae), Grevillea hilliana (Proteaceae), Horsfeldia australiana (Myristicaceae), Syncarpia hillii (Myrtaceaej, Clausena brevistyla (Rutaceae), and Melicopejonesii (Rutaceae)] were also active against S. aureus.