Use of Carbowaxes (Polyethylene Glycols) as Osmotic Agents

Abstract

Polyethylene glycols (trade name Carbowaxes3) of various assumed average molecular weights are now used extensively in a variety of cosmetic and pharmaceutical applications. It has been established that in the concentrations employed they have a low order of toxicity in animals, including man (Smyth et al., 19). Shortly after these compounds became available, their use as carriers of plant growth regulators was investigated (Zimmerman & Hitchcock, 25). But the paucity of references to their use in the ensuing years, plus the findings of these early studies, suggest that they are not satisfactory for this purpose. The polyethylene glycols are available in what is generally assumed to be a graded series of average molecular weight from approximately 300 to 20,000. The initial objective of the present study was to use them for this purpose in studying the action of auxins and antiauxins in controlling rate of root hair elongation. But, the strongly inhibitory effects of very low concentrations of Carbowaxes upon rate of elongation of root hairs suggested that the Carbowaxes were not acting solely as osmotic agents. That is, the data indicated that the Carbowaxes were exerting some direct effects upon the process of elongation of root hairs quite apart from an osmotic effect. Since the Carbowaxes are being used by various workers (Thimann et al., 21, Janes, 12, Lagerwerff et al, 14) as osmotic agents without, apparently, a proper appreciation of their non-osmotic effects, the following results should be of interest.