Activity guided fractionations led to the isolation of two antitumor compounds 5a,8a-epidioxy-24(R )-methylcholesta-6,22-dien-3b-D-glucopyranoside and 5,6-epoxy-24(R )-methylcholesta-7,22-dien-3b-ol from the methanol extract of Cordyceps sinensis. Two previously known compounds, ergosteryl-3-O-b-D-glucopyranoside and 22-dihydroergosteryl-3-O-b-D-glucopyranoside were also isolated. The structures of hitherto unknown sterols were established by 1D and 2D NMR spectroscopic techniques with the former synthesized in order to con®rm the identity of the sugar moiety by chemical correlation. The glycosylated form of ergosterol peroxide was found to be a greater inhibitor to the proliferation of K562, Jurkat, WM-1341, HL-60 and RPMI-8226 tumor cell lines by 10 to 40% at 10 mg/ml than its previously identi®ed aglycone, 5a,8a-epidioxy-24(R )-methylcholesta-6,22-dien3b-ol. #

Two new (3 and 5), as well as three known (1, 2, and 4), polyynes were isolated from Devil's Club (Oplopanax horridus; Araliaceae), a medicinal plant of North America. The structures were established by 1H and 13C NMR. The absolute configurations of 2 and 5 were determined by application of Mosher's method. All the polyynes exhibited significant anti-Candida, antibacterial, and antimycobacterial activity, with an ability to kill Mycobacterium tuberculosis and isoniazid-resistant Mycobacterium avium at 10 micrograms/disk in a disk diffusion assay.

Light provides an effective means of willfully inducing reactivity to study kinetically complex biological processes and to localize drug action for photodynamic therapy. In most cases, photoactivation is a consequence of irreversible photodeprotection to cleanly unleash the biologically active molecule of interest. Examples include substrates such as ATP, 1a GABA, 1b estradiol, 1c N-ras-peptides, 1d and an mRNA target for ribozymes, 1e,f allosteric ligands such as cAMP 1g and inositol triphosphate, 1h toxins such as ricin, 1i antibodies to protein-A, 1j and enzymes such as thrombin 1k,l and RNaseA. 1m

Site-specific RNA cleavage has received considerable attention over the years. Directed synthesis to append imidazoles or amines or both to oligonucleotides to target specific RNA cleavage represents an exciting avenue of research. However, to date catalysis by such synthetic constructs, particularly in terms of turnover, has been difficult to observe. This is the first report of a truly catalytic M2+-independent DNAzyme synthetically modified with imidazoles and cationic amines that would seem to mimic RNaseA. This work now demonstrates how synthetic organic chemistry, when merged with combinatorial selection, can result in a new class of DNAzymes that meets the ongoing synthetic challenges for developing relatively small biomimetic catalysts.

A DNAzyme, synthetically modified with both primary amines and imidazoles, is found to act as a M2+ -independent AP lyase-endonuclease. In the course of the cleavage reaction, this DNAzyme forms a covalent Schiff base intermediate with an abasic site on a complementary oligodeoxyribonucleotide. This intermediate, which is inferred from NaCNBH3 trapping as well as cyanide inhibition, does not evidently accumulate because the second step, dehydrophosphorylative elimination, is fast compared to Schiff base formation. The 5'-product that remains linked to the catalyst hydrolyzes slowly to regenerate free catalyst. The use of duly modified DNAzymes to perform Schiff base catalysis demonstrates the value of modified nucleotides for enhancing the catalytic repertoire of nucleic acids. This work suggests that DNAzymes will be capable of catalyzing aldol condensation reactions.