Insomnia is the second most prevalent mental illness worldwide. Periostracum cicadae (PC), as an animal traditional Chinese medicine with rich pharmacological effects, has been documented as a treatment for children’s night cries, and later extended to treat insomnia. This study aimed to investigate the effects of PC extract and N-acetyldopamine compounds in ameliorating insomnia. The UPLC-ESI-QTOF-MS analysis determined that PC extract mainly contained N-acetyldopamine components. Previously, we also isolated some acetyldopamine polymers from PC extract, among which acetyldopamine dimer A (NADA) was present in high content. Molecular docking and molecular dynamic simulations demonstrated that NADA could form stable complexes with 5-HT1A, BDNF, and D2R proteins, respectively. The effects of PC extract and NADA on insomnia were evaluated in the PCPA-induced insomnia model. The results indicated that PC extract and NADA could effectively ameliorate hypothalamic pathology of insomnia rats, increase the levels of 5-HT, GABA, and BDNF, and decrease the levels of DA, DOPAC, and HVA. Meanwhile, the PC extract and NADA also could significantly affect the expression of 5-HT1A, BDNF, and DARPP-32 proteins. This study proved that PC extract and acetyldopamine dimer A could effectively improve PCPA-induced insomnia in rats. It is speculated that the main pharmacological substances of PC were acetyldopamine components.

Four pairs of novel dopamine enantiomer trimers, (±)-cryptamides A–D (1–4), and 10 pairs of previously described dopamine enantiomer dimers (5–14) were isolated from the Periostracum cicadae, the cast-off shell of the insect Cryptotympana pustulata. Aside from being pairs of enantiomers, the eight trimers were also elucidated to be regioisomers, most likely resulting from their mechanism of formation, [4 + 2] cycloaddition. The discovery of dopamine trimers is rarely reported when it comes to natural products derived from insects.

Insomnia seriously affects people’s health and daily life. There is a growing interest in sleep-promoting agents from natural sources. Nelumbinis Plumula (NP), a traditional Chinese medicine with dual food-medicine homology, has the effects of clearing the heart and calming the mind, showing promising efficacy in treating insomnia. In this study, the effects of NP extract, total alkaloid extract of NP, and crude polysaccharide of NP were measured in para-chlorophenylalanine-induced insomnia rats combined with the pentobarbital sodium experiment. The results indicated both total alkaloid extract and NP total extract could improve insomnia in rats, with the total alkaloid extract demonstrating a stronger effect than NP total extract. Total alkaloid extract significantly prolonged sleep duration and shortened sleep latency. Therefore, total alkaloids in NP appeared to be the main pharmacological substances that exerted sedative effect. Simultaneously, total alkaloid extract could increase the GABA level and reduce the DA level as well as affect the activities of GABRA1, DRD2, 5-HT1A, and AChE proteins. This study can lay an experimental foundation for the further development and application of NP as a remedy for treating insomnia.