Stereoselective synthesis of hyptolide and 6-epi-hyptolide

Ternifolipyrons A-J: new cytotoxic α-pyrones from Isodon ternifolius (D. Don) Kudô

Isodon ternifolius (D.Don) Kudô is an important Asian herb used in traditional medicine against several diseases. Nineteen compounds were isolated from the dichloromethane-methanol (1 : 1) extract of I. ternifolius roots, including ten new α-pyrone derivatives, named ternifolipyrons A-J. The chemical structures of the isolates were determined by a combination of 1D and 2D NMR, along with LR- and HRMS spectroscopy. The absolute configurations of the α-pyrone derivatives were constructed based upon the X-ray signal crystal of the bromobenzoyl derivative of 1 as well as the electronic circular dichroism (ECD). All isolates (1-19) were investigated for their growth-inhibitory potential towards CCRF-CEM-leukemia cells at a fixed concentration of 30 μM. The compounds which exerted more than 50% inhibition at this concentration, compounds (7, 10, 12, 15-17), were tested at a different concentration range to determine their IC₅₀ values in CCRF-CEM leukemia, MDA-MB-231 triple-negative breast cancer, and MCF7 breast cancer cell lines. Ursolic acid (16) showed the most potent activity against the three cancer cell lines with IC₅₀ values of 8.37, 18.04, and 18.93 μM, respectively.

Total Hyptolide of Indonesian Hyptis pectinata extracts in a various solvent using HPLC and UV-Vis spectroscopy and their toxicities

The bioactive compound of hyptolide has been isolated from an Indonesian plant Hyptis pectinata using various solvents. The pure compound was then used as a standard in quantitative analysis using HPLC and UV-Vis spectroscopy in ethanol (EEth), ethyl acetate (EEa), acetone (Eac) and hexane (Ehex) extract each earned 3.14%, 0.01%, 1.33% and 0.04% (dry weight per sample). The standard curve of hyptolide using UV spectroscopy has been obtained with the coefficient of relationship (r) of 0.997. However, the use of spectroscopy was not recommended for the standardization of hyptolide in the extract due to interference from other compounds that absorb the same wavelength. Furthermore, the toxicity test using the Brine Shrimp lethality test shows LC50 value of 92-181 ppm, which was in EEa compared to EEth, Eac, and Ehex.

A short stereoselective synthesis of (+)-(6R,2'S)-cryptocaryalactone via ring-closing metathesis

A short stereoselective synthesis of (+)-(6R,2'S)-cryptocaryalactone was successfully completed. Key steps included the application of Carreira's asymmetric alkynylation reaction to form a propargylic alcohol and subsequently lactone formation using the powerful ring-closing metathesis reaction.

Structural reassignment, absolute configuration, and conformation of hypurticin, a highly flexible polyacyloxy-6-heptenyl-5,6-dihydro-2H-pyran-2-one

The structural reassignment, absolute configuration, and conformational behavior of the highly flexible natural product hypurticin (pectinolide E), 6S-[3'S,5'R,6'S-triacetoxy-1Z-heptenyl]-5S-acetoxy-5,6-dihydro-2H-pyran-2-one (1), were ascertained by a molecular modeling protocol, which includes extensive conformational searching, geometry optimization by DFT B3LYP/DGDZVP calculations, and comparison between the theoretical (DFT) and experimental (1)H-(1)H NMR coupling constants. Hyptolide (2), a related cytotoxic 5,6-dihydro-2H-pyran-2-one that increased the S phase of the HeLa cell cycle, was employed as a reference substance to validate the theoretical protocol designed to characterize the 3D properties of compound 1. The related synthetic derivative, tri-O-acetyl-3,6-dideoxy-d-glucose diphenyldithioacetal (14), was prepared by a six-step reaction sequence starting from d-glucose and served as an enantiopure building block to reinforce the structural and configurational assignment of 1. This protocol proved to be an important tool for the structural characterization of highly flexible bioactive polyoxygenated natural products.