Runhua Lu

Enantiodifferentiating photoisomerization of cyclooctene included and sensitized by aroyl-beta-cyclodextrins: A critical enantioselectivity control by substituents

A series of 6-O-benzoyl-beta-cyclodextrins (CDs) with methyl, methoxy, methoxycarbonyl, and bromo substituent(s) at the ortho-, meta-, and/or para-position(s) were synthesized as chiral sensitizing hosts for the use in supramolecular enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to its chiral (E)-isomer (1E). The complex stability constants (K(S)) of the modified beta-CDs with 1Z in aqueous methanol solutions were highly sensitive to the substituent(s) introduced to the benzoate moiety, and the log K(S) values decreased linearly with slightly different slopes with increasing methanol content. The enantiomeric excess (ee) of 1E obtained upon photosensitization with these hosts was a critical function of the size and position of the substituent, varying from almost zero to 46% ee. This indicates that even an apparently small structural difference between methyl and methoxy can critically affect the enantiodifferentiating photoisomerization of a guest included in the chiral cavity, probably through manipulation of both the orientation of ground-state 1Z and the subsequent rotational relaxation of excited 1Z inside the chiral cavity.

Lathyrane diterpenes from Euphorbia lathyris as modulators of multidrug resistance and their crystal structures

Two lathyrane diterpenes (1-2) together with previous ones (3-6) were isolated from Euphorbia lathyris. The structures of 1 and 2 were established on the basis of extensive spectroscopic methods, including two-dimensional NMR techniques. Stereo configuration and conformation of 1 and 2 were analyzed by X-ray diffraction for the first time. The configuration of the unique isolathyrol diterpene 2 from the seeds of E. Lathyris, was rectified from S * to R * at C-5. All compounds were examined as modulators of multidrug resistance on MCF-7/ADM cell lines in vitro. Their structure-activity relationship was discussed from aspect of different skeletons. A class of potential P-gp inhibitors with five different types (jokinol, isolathyrol, epoxylathyrol, 7-hydroxylathyrol, lathyrol) was discovered.

Lathyrol Diterpenes as Modulators of P-Glycoprotein Dependent Multidrug Resistance: Structure–Activity Relationship Studies on Euphorbia Factor L3 Derivatives

Five series of 37 new acylate and epoxide derivatives (3-39) of Euphorbia factor L3, a lathyrol diterpene isolated from Euphorbia lathyris, were designed by modifying the hydroxyl moiety of C-3, C-5, or C-15. Chemoreversal effects of the acylates on multidrug resistance (MDR) were evaluated in breast cancer multidrug-resistant MCF-7/ADR cells that overexpress P-glycoprotein (P-gp). Eight derivatives exhibited greater chemoreversal ability than verapamil (VRP) against adriamycin (ADR) resistance. Compounds 19 and 25 exhibited 4.8 and 4.0 times, respectively, more effective reversal ability than VRP against ADR resistance. To determine the key characteristics of Euphorbia factor L3 derivatives that contribute to MDR reversal, we conducted a structure-activity relationship study of these compounds. The simulation studies indicated different possible mechanisms and revealed the important influence of hydrophobic interactions and hydrogen bonds in the flexible cavity of P-gp.

1-Hydro­xy-2,3,4,7-tetra­methoxy­xanthone from Swertia Chirayita

The title compound, 1-hydroxy-2,3,4,7-tetraxadmethoxy-9H-xanthen-9-one, C17H16O7, was isolated from Swertia Chirayita and is found to be planar with only two of the methoxy substituents lying out of the plane of the molxadecule.

Euphorbia factor L8: a diterpenoid from the seeds of Euphorbia lathyris

The title compound [systematic name: (2S*,3S*,4R*,5R*,9S*,11S*,15R*)-5,15-diacetoxy-3-nicotinoyloxy-14-oxolathyra-6(17),12(E)-diene], C30H37NO7, was isolated from the seeds of Euphorbia lathyris. The tricyclic diterpenoid molecule contains an 11-membered ring, a five-membered ring exhibiting an envelope conformation and a three-membered ring. The 11-membered ring is cis-fused with the three-membered ring and trans-fused with the five-membered ring.

Euphorbia Factor L2: an ester of 7-hydroxylathyrol

In the crystal structure of the title macrocyclic diterpenoid [systematic name: (2S*,3S*,4R*,5R*,7R*,9S*,11S*,15R*)-5,15-diacetxadoxy-14-oxolathyra-6(17),12(E)-diene-3,7-diyl dixadbenxadzxadoate], C38H42O9, the molxadecule exhibits the tricyclic terpenoid skeleton of lathyrane, consisting of fused five-, 11- and three-membered rings. The five-membered ring adopts an envelope conformation. Intra- and interxadmolecular weak C—H⋯O hydrogen bonding helps to stabilize the crystal structure.

6β,10β-Cadinene-6,10-diol: a sesquiterpenoid from the rhizome of Acorus calamus L.

The title compound [systematic name: (1S,6R,7S,10S)-7-isopropyl-10-methyl-4-methylxadenedecaxadhydroxadnaphthalene-6,10-diol], C15H26O2, was isolated from the rhizome of Acorus calamus L. The molxadecule contains two fused six-membered rings, each in a chair conformation. The molxadecules are linked together by interxadmolecular O—H⋯O hydrogen bonding.