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Two new bicyclic polyketide lactones, polyrhacitides A (1) and B (2), were isolated from Chinese medicinal ants, Polyrhacis lamellidens, which have been used as an effective therapeutic agent to treat rheumatoid arthritis and hepatitis in China. Their absolute structures were elucidated on the basis of spectroscopic analyses and chemical evidence. The occurrence of polyketides with similar structures in plants of the Lamiaceae, Lauraceae, and Staphyleaceae indicates their significance in the study of chemical ecology.

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Four new steroidal saponins, named disporosides A ± D (1 ± 4), corresponding to (3b,25R)-3- [(b-dglucopyranosyl- Introduction. ± Our previous studies on the chemical constituents of the family Liliaceae has shown that plants belonging to the tribe polygonateae, such as Polygonatum kingianum [1] or P. pratii [2], are rich in steroidal saponins. The genus Disporopsis, which is taxonomically close to the genus Polygonatum, is endemic to Southeast Asia. It comprises four known species, all of which are distributed in the Yunnan province of China. Until now, no chemical investigation has been performed on this genus.Disporopsis pernyi (Hua) Diels, a Chinese folk medicine, is a remedy to rheumatism, coughing, tonsillitis, and conjunctivitis, and is often being used as a tonic [3]. As a part of our continuing work to discover novel secondary metabolites from liliaceous plants [4 ± 11], we investigated the rhizomes of D. pernyi and isolated seven steroidal saponins, among which disporosides A ± D (1 ± 4) are unknown natural products. In the present paper, we report the structural characterization of these compounds.

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A divergent synthesis of solanidine and 22-epi-solanidine, two 25S natural steroidal alkaloids, from 25R-configured diosgenin acetate, is described. Initially, solanidine was synthesized through a series of transformations including a cascade ring-switching process of furostan-26-acid, an epimerization of C25 controlled by the conformation of six-membered lactone ring, an intramolecular Schmidt reaction, and an imine reduction/intramolecular aminolysis process. To address the epimerization issue during Schmidt reaction, an improved synthesis was developed, which also led to a synthesis of 22-epi-solanidine. In this synthesis, selective transformation of azido lactone to azido diol and amino diol was realized through a reduction relay tactic. The azido diol was transformed to solanidine via an intramolecular Schmidt reaction/N-alkylation/reduction process and to 22-epi-solanidine via an intramolecular double N-alkylation process.

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Four new steroidal saponins, polypunctosides A-D (1-4, resp.), were isolated from the rhizomes of Polygonatum punctatum, together with five known steroidal saponins. On the basis of chemical and spectral evidence, the structures of the new saponins were established as (3beta,23S,25R)-23-(alpha-L-arabinopyranosyloxy)spirost-5-en-3-yl 4-O-(6-deoxy-alpha-L-mannopyranosyl)-D-glucopyranoside (1), (3beta,23S,25R)-23-[(2-O-acetyl-alpha-L-arabinopyranosyl)oxy]spirost-5-en-3-yl 4-O-(6-deoxy-alpha-L-mannopyranosyl)-D-glucopyranoside (2), (3beta,23S,25R)-23-[(3-O-acetyl-alpha-L-arabinopyranosyl)oxy]spirost-5-en-3-yl 4-O-(6-deoxy-alpha-L-mannopyranosyl)-D-glucopyranoside (3), and (3beta,23S,25R)-23-[(4-O-acetyl-alpha-L-arabinopyranosyl)oxy]spirost-5-en-3-yl 4-O-(6-deoxy-alpha-L-mannopyranosyl)-D-glucopyranoside (4). The cytotoxic activity of the isolated saponins was evaluated towards HeLa cells.