Pectin purified from pomelo ( Citrus maxima ) peel as a natural hatching agent for fish embryos

Abstract

Pectin is a biodegradable polysaccharide, and it has been recently applied as a gene delivery, drug delivery, wound healing and tissue engineering agent. In this study, pectin was extracted from pomelo (Citrus maxima) peel and characterized. The extraction recovery of pectin form pomelo peel was 14.5%, and it had 72.56% degree of esterification, 1,245.56 equivalent weight, 7.82% methoxyl and 68.27% anhydrouronic acid contents. Use of pomelo pectin as a hatching enhancing agent for fish embryos and its effect on hatching enzyme 1 (ZHE1) was investigated. The pectin-exposed zebrafish embryos (100 µg/ml) showed significantly (p < .05) higher hatching rate (96.6%) compared with untreated (control) embryos (66.6%) at 60 hpf. The mRNA expression of ZHE1 was also significantly (p < .05) elevated up to 55.6-fold in pectin-exposed embryos at 24 hpf. In situ hybridization results revealed remarkably strong expression of ZHE1 in pectin-exposed embryos compared with the control group. In addition, considerably larger size of the hatching gland was observed in pectin-exposed larvae than that of the unexposed larvae group. These results clearly indicate that pectin isolated from pomelo peel has an ability to enhance the hatching process of zebrafish embryos via upregulation of ZHE1.