Chan Tui

The dominant constituent of the cast-off exoskeleton, a large N-acetyl-glucosamine polysaccharide. As a high-molecular-weight polymer it is poorly absorbed; it contributes to the shell's structure and is unlikely to pass into breast milk in significant amounts.

Characteristic dimeric N-acetyldopamine derivatives isolated from Periostracum Cicadae. They show anti-inflammatory and immunomodulatory activity, including regulation of Th1/Th17 differentiation, and are used as chemical markers for quality control.

The shell is rich in structural protein and 17+ free amino acids embedded in the chitinous matrix, contributing to its nutritive and tonic properties in decoction.

A range of mineral trace elements deposited in the exoskeleton; used together with organic markers in origin-authentication studies of Cicadae Periostracum.

Cross-linked catecholamine-derived pigment responsible for the brown coloration of the molt; contributes to antioxidant activity reported for the extract.

Typically 3-6 g of cleaned, dried molt is decocted in water. The legs and internal debris are usually removed and the shell rinsed of soil before use. Being light and dispersing, it is added toward the end and not cooked for long periods.

Dried molt is ground to a fine powder; small doses (often 1-3 g) are taken directly or added to formulas, particularly in pediatric practice for rashes, hoarseness and night crying.

Cicadae Periostracum water extract prolonged the latency to convulsion and death in pentylenetetrazol-induced mice and reduced hippocampal neuronal damage. In H2O2-stimulated PC12 cells it improved cell viability and suppressed apoptosis by activating PI3K/Akt/Nrf2 signaling, providing a mechanistic basis for the traditional use in calming Liver-wind and stopping spasms.