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Screening tests for hypotensive substances were conducted on 57 items from 50 plants. Intravenous administration of fractions from Solidago altissima L. (leaves), asparagus, okra, cornhusk, corncob, tassel and bamboo leaves showed falls in blood pressure in SHR and SHRSP, especially the first marked and continuous falls. Furthermore, extracts from Solidago altissima L. and cornhusk were fractionated on columns of silica gel and Sephadex G-50. The crystalline compounds in the cornhusk fraction were identified as adenosine and guanosine. In addition, the hypotensive substance of fraction A1 from Solidago altissima L. may be a glycoprotein with a molecular weight of over 10, 000.

We attempted isolation of the hypotensive substance contained in hot water extracts of chlorella raw cells. When chlorella extracts were fractionated by gel filtration, fraction E showed a depressive effect. Blood pressure of SHR and SHRSP showed falls of about 60mmHg at 1 hour after intravenous administration and of 30 to 40mmHg at 2 hours after intragastric administration. Fraction E was subsequently purified by passage through a column of Sephadex G-10, and then crystallized from ethanol. Both the crystalline compound and the mother liquor showed hypotensive effects, but the effect of the latter was more potent. The crystalline compound was identified as adenosine by means of chemical and physical methods, and the mother liquor was considered to be a mixture of adenosine and an unknown compound containing glycine. As a result, the hypotensive effect of fraction E on SHR and SHRSP may be ascribable to adenosine or to an oligopeptide with a molecular weight of approximately 200.