Studies on Essential Oil of Sea Weeds-II

On the Essential Oil Contents of Various Kinds of Sea Weeds

Abstract

Some kinds of sea weeds give, just after collected at the sea, a terpene odor besides the ordinary beach ordor due to dimethyl sulphide. The terpene odor is due to the essential oil contained in the algal body. In the previous paper (Part 1.), the late Prof. M. Takaoka and the present author reported that the essential oil of Dictyopteris divaricata war proved to contain mainly Cadinene, the common component of the land perfume plants.
In the present work, the author carried, out to estimate the essential oil contents of twenty species of sea weeds mostly collected at Oshoro, and Muroran, Hokkaido. The results are shown in Table 1. In this, Dictyopteris divaricata shows the highest percentage of the oil content. The seasonal variation of the oil content in that species is shown in Table 2 and Fig. 1. It has no relation with the variation of the water temperature. The percentage of the oil content was most high in the early July when the ripe tetrasporangias were found abundantly on the frond surface. Abrupt decrease of the oil content toward the end of July and during August may correlate with the fact that the spores are dischayed one after another and the upper parts of the frond are decayed gradually with the progress of the season.
Biological significance of the essential oil contained as a photosynthetic product in the cells of sea weeds is not clear at present. In the author's opinion, it probably plays a role for protecting the plant body from the injuries of herbivorous animals in virtue of its bitter or smart taste.