ABSTRACT
This chapter discusses the work which lead to the structure elucidation of moroidin and lophyrotomin, two toxic peptides obtained from natural sources in Queensland. Serious losses of livestock in Queensland due to poisoning by naturally occurring toxic substances have been reported since early settlement. Most of the cases are caused by poisonous plants or microbial toxins in plants. The sting from the plants occurs when the skin is pierced by long needle-like hairs found on the leaves and green stems of the plants. The hairs are poison reservoirs with siliculated tips at the upper end. Biological testing with pure moroidin gave less immediate response than some impure extracts, but moroidin appeared to be responsible for the reported long duration of the sting. A stinging sensation in the area injected with moroidin could be felt even after several months, and this could be precipitated by a change of temperature.
