Isolation of the Binding Protein of Periplocoside E from BBMVs in Midgut of the Oriental Amyworm Mythimna separata Walker (Lepidoptera: Noctuidae) through Affinity Chromatography

Identification and mechanism of insecticidal periplocosides from the root bark of Periploca sepium Bunge

BACKGROUND

The Periploca sepium bark root (PSBR) has been regarded as a potential botanical insecticide because of its significant insecticidal activity of secondary metabolites. Several periplocosides were isolated from it as promising pesticides to control crop pests in agriculture.

RESULTS

In our research, two new periplocosides, along with four known periplocosides were isolated from PSBR. The names of new periplocosides were periplocoside T (PST) and periplocoside U (PSU) while another four periplocosides were known as follows: periplocoside A (PSA), periplocoside F (PSF), periplocoside E (PSE) and periplocoside D (PSD). All periplocosides were evalulated for insecticidal activity against 3rd Mythimna separata (Walker) and Plutella xylostella. The biometric data showed that periplocoside T, PSD and PSF had remarkable insecticidal activity against tested insects. Its values of LD₅₀ were 1.31, 3.94 and 3.42 μg·lavare^-1 against 3rd M. separata respectively, while the activity of those compounds against 3rd P. xylostella were 5.45, 12.17 and 13.95 μg·lavare^-1 , respectively. It was apparent after further study of the mechanism of action against M. separata was conducted that PST possessed the most significant insecticidal activity. The results of enzymatic activity displayed that powerful activation of tryptase, especially weak alkaline tryptase might be a dominant factor causing death of M. separata in vivo.

CONCLUSION

We herein report isolation and the mechanisms of action of insecticidal periplocosides, which established the fundamental development of natural agents to prevent pest damage to crops. © 2020 Society of Chemical Industry.

Genus Periploca (Apocynaceae): A Review of Its Classification, Phytochemistry, Biological Activities and Toxicology

The genus Periploca belongs to the family Apocynaceae, which is composed of approximately ten species of plants according to incomplete statistics. Most of these plants serve as folk medicines with a long history, especially Periploca sepium and Periploca forrestii. The botanical classifications, chemical constituents, biological activities and toxicities of the genus Periploca were summarized in the literature from 1897 to early 2019. Though the botanical classification of this genus is controversial, these species are well-known to be rich sources of diverse and complex natural products-above all, cardiac steroids and C₂₁ pregnane steroids with special structures and obvious pharmacological activities. The various crude extracts and 314 isolated metabolites from this genus have attracted much attention in intensive biological studies, indicating that they are equipped with cardiotonic, anti-inflammatory, immunosuppressive, antitumor, antimicrobial, antioxidant, insecticidal and other properties. It is noteworthy that some cardiac glycosides showed hepatotoxicity and cardiotoxicity at certain doses. Therefore, in view of the medical and agricultural value of the genus Periploca, in-depth investigations of the pharmacology in vivo, the mechanisms of biological actions, and the pharmacokinetics of the active ingredients should be carried out in the future. Moreover, in order to ensure the safety of clinical medication, the potential toxicities of cardiac glycosides or other compounds should also be paid attention. This systematic review provides an important reference base for applied research on pharmaceuticals and pesticides from this genus.

Comparative Proteomic Analysis of the Effect of Periplocoside P from Periploca sepium on Brush Border Membrane Vesicles in Midgut Epithelium of Mythimna separata Larvae

Periplocoside P (PSP), a novel compound isolated from Periploca sepium Bunge, possesses insecticidal activity against some lepidopterans, such as Mythimna separata. In M. separata, the brush border membrane vesicles of the midgut epithelium are the initial site of action of periplocosides. We conducted two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry analysis to analyze differentially expressed proteins (DEPs) from periplocoside P (PSP)-treated M. separata. We successfully isolated seven up-regulated and three down-regulated DEPs that have been previously identified, as well as a novel DEP. The DEPs are implicated in protein degradation, transporter, folding, and synthesis, and in juvenile hormone biosynthesis. DEPs involved in the oxidative phosphorylation energy metabolism pathway are enriched. Through real-time polymerase chain reaction assay, we confirmed that vma1 expression is significantly up-regulated expression levels in PSP-treated M. separata larvae. Enzymology validation further indicated that PSP can significantly inhibit V-type ATPase activity in a concentration-dependent manner. Given these results, we speculate that in M. separata, the V-type ATPase A subunit in the midgut epithelium is the putative target binding site of periplocosides. This finding provides preliminary evidence for the mode of action of periplocosides.

Centipede venoms as a source of drug leads

INTRODUCTION

Centipedes are one of the oldest and most successful lineages of venomous terrestrial predators. Despite their use for centuries in traditional medicine, centipede venoms remain poorly studied. However, recent work indicates that centipede venoms are highly complex chemical arsenals that are rich in disulfide-constrained peptides that have novel pharmacology and three-dimensional structure. Areas covered: This review summarizes what is currently known about centipede venom proteins, with a focus on disulfide-rich peptides that have novel or unexpected pharmacology that might be useful from a therapeutic perspective. The authors also highlight the remarkable diversity of constrained three-dimensional peptide scaffolds present in these venoms that might be useful for bioengineering of drug leads. Expert opinion: Like most arthropod predators, centipede venoms are rich in peptides that target neuronal ion channels and receptors, but it is also becoming increasingly apparent that many of these peptides have novel or unexpected pharmacological properties with potential applications in drug discovery and development.