Study on teleocidin compounds produced by Streptomyces ardus WS-65090 and their biological activities
Microorganisms provide a large amount of lead compound resources for the development of drugs and pesticides. Streptomyces is a major group of actinomycetes, with diverse secondary metabolite structures and significant biological activity. It is considered a source of many antibiotics and potential sources of drugs. In recent years, some metabolites with good biological activity have been discovered from Streptomyces, such as aldgamycin P, a new macrocyclic lipid compound isolated from Streptomyces sp. KIB-K1, which has a significant inhibitory effect on Staphylococcus aureus with a MIC value of 7.81 μ g/mL. Compounds endostemonines A-J are newly reported natural pyrrole-2-carboxylate derivatives isolated and identified from a strain of Streptomyces BS-1 for the first time. They exhibit strong lethal activity against cotton aphids, with a 72 hour LC50 value ranging from 3.55-32.00mg/L.
In the process of searching for active metabolites from actinomycetes, we found that a fermented extract of Streptomyces ardus WS65090 had good insecticidal activity. In order to clarify its active metabolites, it was isolated and purified, and some teleocidin compounds were obtained. Teleocidin was first isolated as a toxic substance from the methanol extract of the mycelium of Mediterranean Streptomyces in 1960. It has a unique indole lactam skeleton with A1, A2, B-1, B-2, B-3, and B-46 stereoisomers, and has attracted much attention due to its unique structure and diverse biological activities. At present, various teleocidin structure related compounds have been isolated from microorganisms, such as lyngbyatoxin A~C, olivoretin A~C, 14-O – (N-acetylglucosaminyl) teleocidin A, and 2-oxo teleocidin A1. These compounds exhibit important biological activities, such as skin irritants, tumor promoters, PKC activators, and cytotoxic activity. The new teleocidin B-class analogues and their insecticidal and cytotoxic activities reported in this study enrich the structural types and activities of such compounds, as well as the types of active metabolites of Streptomyces, providing basic data for their research in agriculture.

Five teleocidin compounds were isolated from the fermented extract of Streptomyces ardus WS-65090, all of which exhibit insecticidal and cytotoxic activities. Among them, 14-O-acetyltoleocidin B-2 (1) is a new compound, and 14-O-acetyltoleocidin B-3 (2) is a new natural product, and its nuclear magnetic resonance spectrum data has been elaborated for the first time. This is also the first time in recent years that teleocidin B-type compounds with insecticidal activity against fall armyworms, cotton bollworms, diamondback moths, and aphids have been isolated from soil derived Streptomyces strains. In addition, these two new teleocidin analogues contain acetyl groups at C-14, and their insecticidal activity is stronger than the three known compounds. Based on the experimental results of cytotoxic activity, it is demonstrated that the acetyl group at position C-14 of teleocidin analogs has a significant impact on their biological activity. The biological activities of teleocidin compounds are mainly focused on medical activities. The compounds reported in this study enrich the types of teleocidin compounds, expand their biological activities, and provide exploration for their research in agriculture.