Two novel diterpenoids, jatrocurcadiones A (1) and B (2), possessing an unusual 10,11-seco-premyrsinane skeleton were isolated from the twigs of Jatropha curcas. Their structures were determined by combined spectroscopic and chemical methods, and the absolute configurations were elucidated by quantum chemical calculations and Rh 2 (OCOCF 3 ) 4 -induced CD analysis. Jatrocurcadione A exhibited more potent inhibitory activity (IC 50 = 10.0 µ µ µ µM) than the positive control (curcumin, IC 50 = 25.0 µ µ µ µM) against thioredoxin reductase (TrxR), a potential target for cancer chemotherapy with redox balance and antioxidant functions. Premyrsinanes are a group of highly oxygenated diterpenoids with a 5/7/6/3-tetracyclic carbon framework. So far about 30 premyrsinanes have been reported and all of them were isolated from the species of the family Euphorbiaceae. 1 Biosynthetically they are derived from the 6,12-cyclization of lathyrane diterpenes and serve as the precursors of myrsinane and cyclomyrsinane diterpenes. 2 The structural diversity of this compound class comes from the various oxidation patterns and substituents on the scaffold. In particular, the different oxidation patterns of Me-17 further divided them into three sub-classes. 2 Recently, their fascinating structures and important biological activities have attracted broad interests from both natural products and pharmaceutical chemists. 1,3 Jatropha curcas LINN. (Euphorbiaceae) is a drought-resistant shrub widely distributed in many parts of Africa and Southeast Asia. It has become a famous natural resource plant for the production of biodiesel, animal feed, biopesticide, and of 1b and 1a, respectively. The above calculation showed positive specific optical rotations for 1a (+197.6) and 1b (+412.6). Comparing to the experimental OR data (+268.8), 1c and 1d were excluded for their negative OR values. Structures of 1a and 1b both showed a S configuration at C-6, which was consistent with those of premyrsinanes and myrsinanes from the biosynthetic point of view. However, the ECD calculations of 1a and 1b generated similar results (Fig. S3 †), which could not be used to ambiguously select one of the isomers. Thus, the absolute configuration of C-1 was further determined by Rh 2 (OCOCF 3 ) 4 -induced CD analysis. On the basis of the bulkiness rule for secondary alcohols, a positive Cotton effect around 350 nm (the band E) in the Rh 2 (OCOCF 3 ) 4 -induced CD spectrum indicated a S-configuration, while negative Cotton effect implied a R-configuration. 17 Thus, a positive Cotton effect at around 350 nm in the Rh 2 (OCOCF 3 ) 4 -induced CD spectrum of 1 assigned the 1S configuration (Figure 4). Consequently, the 2S configuration was defined by the trans-relationship of CH 3 -16 and OH-1. Thus, the absolute configuration of 1 was assigned as 1S, 2S, 6S, and compound 1 was named jatrocurcadione A. Compound 2, a light yellow oil, had the molecular formula C 22 H 28 O 4 , as determined by HRESIMS. The NMR spectra of 2 showed high similarity to those of 1 except for ...
Two novel Rhodococcus strains, LHW50502T and LHW51113T, were isolated from marine sponges obtained on Xisha Island, Hainan Province, PR China. Rods and cocci, typical characteristics of the genus Rhodococcus , were observed. The strains contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall hydrolysates and galactose, arabinose, ribose and glucose as the whole-cell sugars. The major fatty acid identified was C16 : 0. MK-8(H4) was the predominat menaquinone of both strains. Stains LHW50502T and LHW51113T had almost identical (99.6 %) 16S rRNA gene sequences but shared relatively low similarities with previously characterized Rhodococcus species (well below 98.7 %). The results of phylogenetic analysis supported their closest relationship; however, the average nucleotide identity and digital DNA–DNA hybridization values between these two strains indicated that they belonged to distinct species. Taken together, the results of this study indicate that strains LHW50502T and LHW51113T represent two novel species of the genus Rhodococcus , for which the names Rhodococcus spongiicola sp. nov. (type strain LHW50502T=DSM 106291T=CCTCC AA 2018033T) and Rhodococcus xishaensis sp. nov. (type strain LHW51113T=DSM 106204T=CCTCC AA 2018034T) are proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.