Identification of Enzymes Involved in Sesterterpene Biosynthesis in Marine Fungi. Marine Enzymes and Specialized Metabolism - Part A. Elsevier; 2018. pp. 441-98. [DOI: 10.1016/bs.mie.2018.04.023]

The Biosynthesis and Transport of Ophiobolins in Aspergillus ustus 094102

Ophiobolins are a group of sesterterpenoids with a 5-8-5 tricyclic skeleton. They exhibit a significant cytotoxicity and present potential medicinal prospects. However, the biosynthesis and transport mechanisms of these valuable compounds have not been fully resolved. Herein, based on a transcriptome analysis, gene inactivation, heterologous expression and feeding experiments, we fully explain the biosynthesis pathway of ophiobolin K in Aspergillus ustus 094102, especially proved to be an unclustered oxidase OblC_Au that catalyzes dehydrogenation at the site of C16 and C17 of both ophiobolin F and ophiobolin C. We also find that the intermediate ophiobolin C and final product ophiobolin K could be transported into a space between the cell wall and membrane by OblD_Au to avoid the inhibiting of cell growth, which is proved by a fluorescence observation of the subcellular localization and cytotoxicity tests. This study completely resolves the biosynthesis mechanism of ophiobolins in strain A. ustus 094102. At the same time, it is revealed that the burden of strain growth caused by the excessive accumulation and toxicity of secondary metabolites is closely related to compartmentalized biosynthesis.

Sesterterpenoids: chemistry, biology, and biosynthesis

Covering: July 2012 to December 2019Over the last seven years, expanding research efforts focused on sesterterpenoids has led to the isolation, identification, and characterization of numerous structurally novel and biologically active sesterterpenoids. These newly reported sesterterpenoids provide diverse structures that often incorporate unprecedented ring systems and new carbon skeletons, as well as unusual functional group arrays. Biological activities of potential biomedical importance including suppression of cancer cell growth, inhibition of enzymatic activity, and modulation of receptor signaling, as well as ecologically important functions such as antimicrobial effects and deterrence of herbivorous insects have been associated with a variety of sesterterpenoids. There has also been a rapid growth in our knowledge of the genomics, enzymology, and specific pathways associated with sesterterpene biosynthesis. This has opened up new opportunities for future sesterterpene discovery and diversification through the expression of new cryptic metabolites and the engineered manipulation of associated biosynthetic machinery and processes. In this paper we reviewed 498 new sesterterpenoids, including their structures, source organisms, country of origin, relevant bioactivities, and biosynthesis.

Sesterterpenoids

Sesterterpenoids are known as a relatively small group of natural products. However, they represent a variety of simple to more complex structural types. This contribution focuses on the chemical structures of sesterterpenoids and how their structures are constructed in Nature.

Toxicity, Pharmacokinetics, and Gut Microbiome of Oral Administration of Sesterterpene MHO7 Derived from a Marine Fungus

Sesterterpene MHO7 derived from mangrove fungus is a novel estrogen receptor degrader for the treatment of breast cancer. To explore its safety and pharmacokinetics in vivo, Log P/D values, stability in simulated gastric/intestinal (SGF/SIF), toxicity, and pharmacokinetics studies were carried mainly by liquid chromatography technique coupled with tandem mass spectrometry (LC–MS/MS) method in mice, and the effect of MHO7 on mice gut microbiota at different time points was revealed by 16S rRNA sequencing. Log P/D values ranged 0.93–2.48, and the compound in SGF and SIF is stable under the concentration of 5 mM·L⁻¹. The maximum tolerance dose (MTD) of oral administration in mice was 2400 mg·kg⁻¹. The main pharmacokinetics parameters were as following: C_max of 1.38 μg·mL⁻¹, T_max of 8 h, a half-life (t_1/2) of 6.97 h, an apparent volume of mean residual time (MRT) of 8.76 h, and an area under the curve (AUC) of 10.50 h·μg·mL⁻¹. MHO7 displayed a wide tissue distribution in mice, with most of the compound in liver (3.01 ± 1.53 μg·g⁻¹) at 1 h, then in fat (5.20 ± 3.47 μg·g⁻¹) at 4 h, and followed by reproductive organs with the concentrations of 23.90 ± 11.33 μg·g⁻¹,13.69 ± 10.29 μg·g⁻¹, 1.46 ± 1.23 μg·g⁻¹, and 0.36 ± 0.46 μg·g⁻¹ at 8, 12, 20 and 30 h, respectively. The most influenced genera of gut microbiome belonged to phylum Firmicutes (21 of 28), among which 18 genera originated from the order Clostridiales, class Clostridia, and families of Ruminococcaceae (11 of 18) and Lachnospiraceae (4 of 18). These results provide that MHO7 is suitable for oral administration in the treatment of breast cancer with the target organs of reproductive organs and regulation on Ruminococcaceae and Lachnospiraceae.