Li-Ning Wang

Scaparvin A, A Novel Caged cis-Clerodane with an Unprecedented C-6/C-11 Bond, and Related Diterpenoids from the Liverwort Scapania parva

A novel caged cis-clerodane diterpenoid, scaparvin A, possessing an unprecedented C-6/C-11 bond and a ketal ring, as well as four new cis-clerodane derivatives, scaparvins B-E, were isolated from the Chinese liverwort Scapania parva. Their absolute structures were elucidated by analysis of NMR and CD data coupled with electronic circular dichroism (ECD) calculations. It was proposed that an enzymatic intramolecular aldol reaction was the key step in the biogenetic pathway of scaparvin A.

Phaeosphaerins A-F, cytotoxic perylenequinones from an endolichenic fungus, Phaeosphaeria sp.

Six novel phototoxins, phaeosphaerins A-F, together with six known perylenequinones were isolated from an endolichenic fungus Phaeosphaeria sp. Their structures were determined unequivocally on the basis of comprehensive analysis of MS and NMR data as well as electronic circular dichroism calculations. These toxins kill cancer cells in vitro with accumulation in lysosomes, and the killing effects were potently intensified in the presence of light.

Pallambins A and B, Unprecedented Hexacyclic 19-nor-Secolabdane Diterpenoids from the Chinese Liverwort Pallavicinia ambigua

Pallambins A (1) and B (2), two novel 19-nor-7,8-secolabdane diterpenoids with unprecedented tetracyclo[4.4.0(3,5).0(2,8)]decane skeletons, along with a pair of structurally related isomers, pallambins C (3) and D (4), were isolated from the Chinese liverwort Pallavicinia ambigua. Their structures with absolute configurations were determined by means of NMR, X-ray diffraction, and CD analyses. Their preliminary cytotoxicity to human cancer cells was also tested.

Phenolic compounds with NF-κB inhibitory effects from the fungus Phellinus baumii

Chemical investigation of the fungus Phellinus baumii has resulted in characterization of five previously undescribed hispidin derivatives, phellibaumins A-E (1-5), as well as two pairs of new non-equivalent epimeric benzyl dihydroflavones, methylphelligrin A (9), epi-methylphelligrin A (10), methylphelligrin B (11), and epi-methylphelligrin B (12), together with five known compounds, interfungin B (6), phelligridin H (7), phelligridimer A (8), phelligrin A (13), and epi-phelligrin A (14). Phellibaumin A (1) was a novel hispidin derivative with a unique 3,4-dihydroxybenzofuran unit. These compounds exhibited NF-κB inhibitory activity with IC(50) values of 52.96 μM (1), 41.40 μM (2), 52.92 μM (5), 36.44 μM (9 and 10), and 22.46 μM (11 and 12), respectively.

A novel derivative of riccardin D induces cell death through lysosomal rupture in vitro and inhibits tumor growth in vivo

In the present study, the effect of a novel derivative of riccardin D (RD-N) against cancer cell lines was investigated in vitro and in vivo. We found that RD-N accumulated in the lysosomes associated with lysosomal swelling. As a result, the destabilized lysosomes induced cathepsins to release from the lysosomes into the cytosol and induced cell death which displayed features characteristic to both apoptosis and necrosis. In vivo tumor xenograft model indicated treatment of RD-N significantly reduced size and weight of the tumor compared with vehicles. These findings suggest RD-N could be a promising candidate for treatment of cancer.

Interconversion of the Pallambins through Photoinduced Rearrangement

A new photoinduced interconversion of four naturally occurring 19-nor-7,8-secolabdane diterpenoids was discovered and analyzed. The photochemical mechanism, intramolecular diradical rearrangement reaction, was investigated by time-lapse monitoring of the end product formations with HPLC and UV, as well as detailed theoretical calculations.