Natural rubber base matrix containing Calendula officinalis plant as a source of molluscicdal saponin

Natural rubber (NR) has been used as a binding matrix for Calendula officinalis, where it is used as a vulcanizate. Various doses of the plant covering the range from 100 up to 200 parts per 100 of rubber (phr) were found suitable for processing conditions using conventional rubber mixing equipment. The release rate of saponin was extended to over 4 months. Incorporation of fillers, such as HAF and Hisil, in the compounded rubber decreased the release of saponin; especially in the first period of immersion. The amount of saponin released was affected by the environmental temperature and the type of fillers present in the formulations. The scanning electron micrographs illustrate the presence of a tortuous pass and pore structure that formed after soaking in water and leaching process occurred.