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Triterpenes are among the most diverse plant natural products, and their diversity is closely related to various triterpene skeletons catalyzed by different 2,3-oxidosqualene cyclases (OSCs). Celastrol, a friedelane-type triterpene with significant bioactivities, is specifically distributed in higher plants, such as Celastraceae species. Friedelin is an important precursor for the biosynthesis of celastrol, and it is synthesized through the cyclization of 2,3-oxidosqualene, with the highest number of rearrangements being catalyzed by friedelane-type triterpene cyclases. However, the molecular mechanisms underlying the catalysis of friedelin production by friedelane-type triterpene cyclases have not yet been fully elucidated. In this study, transcriptome data of four celastrol-producing plants from Celastraceae were used to identify a total of 21 putative OSCs. Through functional characterization, the friedelane-type triterpene cyclases were separately verified in the four plants. Analysis of the selection pressure showed that purifying selection acted on these OSCs, and the friedelane-type triterpene cyclases may undergo weaker selective restriction during evolution. Molecular docking and site-directed mutagenesis revealed that changes in some amino acids that are unique to friedelane-type triterpene cyclases may lead to variations in catalytic specificity or efficiency, thereby affecting the synthesis of friedelin. Our research explored the functional diversity of triterpene synthases from a multispecies perspective. It also provides some references for further research on the relative mechanisms of friedelin biosynthesis.

Lithium-sulfur batteries with high energy density are considered as one of the most promising future energy storage devices. However, the parasitic lithium polysulfides shuttle phenomenon severely hinders the commercialization of such batteries. Ionic liquids have been found to suppress the lithium polysulfides solubility, diminishing the shuttle effect effectively. Herein, we performed classical molecular dynamics simulations to explore the microscopic mechanism and transport behaviors of typical Li2 S8 species in ionic liquids and ionic liquid-based electrolyte systems. We found that the trifluoromethanesulfonate anions ([OTf]- ) exhibit higher coordination strength with lithium ions compared with bis(trifluoromethanesulfonyl)imide anions ([TFSI]- ) in static microstructures. However, the dynamical characteristics indicate that the presence of the [OTf]- anions in ionic liquid electrolytes bring faster Li+ exchange rate and easier dissociation of Li+ solvation structures. Our simulation models offer a significant guidance to future studies on designing ionic liquid electrolytes for lithium-sulfur batteries.

Summary Tripterygium wilfordii, which has long been used as a medicinal plant, exhibits impressive and effective anti-inflammatory, immunosuppressive and anti-tumor activities. The main active ingredients are diterpenoids and triterpenoids, such as triptolide and celastrol, respectively. A major challenge to harnessing these natural products is that they are found in very low amounts in planta. Access has been further limited by the lack of knowledge regarding their underlying biosynthetic pathways, particularly for the abeo-abietane tri-epoxide lactone triptolide. Here suspension cell cultures of T. wilfordii were found to produce triptolide in an inducible fashion, with feeding studies indicating that miltiradiene is the relevant abietane olefin precursor. Subsequently, transcriptome data were used to identify eight putative (di)terpene synthases that were then characterized for their potential involvement in triptolide biosynthesis. This included not only biochemical studies which revealed the expected presence of class II diterpene cyclases that produce the intermediate copalyl diphosphate (CPP), along with the more surprising finding of an atypical class I (di)terpene synthase that acts on CPP to produce the abietane olefin miltiradiene, but also their subcellular localization and, critically, genetic analysis. In particular, RNA interference targeting either both of the CPP synthases, TwTPS7v2 and TwTPS9v2, or the subsequently acting miltiradiene synthase, TwTPS27v2, led to decreased production of triptolide. Importantly, these results then both confirm that miltiradiene is the relevant precursor and the relevance of the identified diterpene synthases, enabling future studies of the biosynthesis of this important bioactive natural product.

Tripterygium wilfordii (Celastraceae) is a traditional Chinese medicine; and the dried root and rhizome constitute the main officinal parts. Tripterygium wilfordii has been identified as a potential candidate for the treatment of systemic lupus erythematosus, rheumatoid arthritis, nephritis, asthma, leprosy, and cancer. The phylogenetic relationships within the Tripterygium genus are ambiguous; thus, our aim is to clarify the relationships within this genus using phylogeographic and phylogenetic analyses. Here, we first sequenced three plastid DNA regions (i.e., psbA-trnH, rpl32-trnL, and trnL-trnF) and found that Tripterygium hypoglaucum and T. wilfordii were clustered together based on the strength of the topology in the phylogenetic analysis: T. hypoglaucum is polyphyletic, and T. wilfordii is paraphyletic. A spatial analysis of molecular variance showed that the best group value is 4, and the groups were almost consistent with the topology of in the phylogenetic analysis. The Mantel analyses of Tripterygium using IBD web showed statistically significant relationships between genetic and geographical distance distributions (r = .3479, p