Sheng Yin

Antimicrobial Diterpenes from Trigonostemon chinensis

Five new diterpenes, trigonochinenes A-E (1-5), and two known ones, 3,4- seco-sonderianol (6) and 3,4- seco-sonderianic acid (7), were isolated from the aerial part of Trigonostemon chinensis. Compounds 1-4 possess a rare 3,4-seco-cleistanthanic skeleton, and compound 5 is a highly aromatized tetranorditerpene. Structures of these compounds were elucidated by spectroscopic analysis. The antimicrobial activities of compounds 1-7 were evaluated against a panel of bacteria and fungi.

Sesquiterpenes and Dimeric Sesquiterpenoids from Sarcandra glabra

Two new sesquiterpenes, sarcandralactones A (1) and B (2), and five new dimeric sesquiterpenoids, sarcandrolides A-E (3-7), along with 10 known compounds were isolated from the whole plants of Sarcandra glabra. Their structures were elucidated on the basis of spectroscopic analysis. Some of the new isolates exhibit significant cytotoxicities when tested against a small panel of tumor cell lines.

Structural elucidation of limonoids and steroids from Trichilia connaroides

Six limonoids, trijugins D-H (1-5) and methyl 8alpha-hydroxy-8,30-dihydroangolensate (6), two degraded limonoids, trichiconnarins A and B (7-8), and a pregnane steroid, 3beta,4alpha-dihydroxypregnan-21-one (9), along with the known trijugin C (10) and 3beta,4alpha-dihydroxypregnan-16-one (11) were isolated from twigs and leaves of Trichilia connaroides. Their structures were established on the basis of extensive spectroscopic analysis.

Walsucochins A and B with an Unprecedented Skeleton Isolated from Walsura cochinchinensis

Walsucochins A (1) and B (2) with an unprecedented skeleton were isolated from Walsura cochinchinensis. Their structures including absolute configuration were elucidated by spectral methods. A biosynthetic pathway of 1 and 2 was postulated. Both 1 and 2 exhibited significant cell protecting activities against H2O2-induced PC12 cell damage.

Limonoids from Khaya ivorensis

Four limonoids, 1-O-deacetyl-6-deoxykhayanolide E (1), 1-O-deacetyl-2 alpha-hydroxykhayanolide E (2), 3-acetyl-khayalactone (3), 11 alpha-acetoxy-2 alpha-hydroxy-6-deoxy-destigloylswietenine acetate (4), along with 12 known limonoids, were isolated from the stems of Khaya ivorensis. Their structures were elucidated on the basis of spectroscopic analysis.

Sesquiterpenoids and Phenylpropanoids from Chloranthus serratus

Seven new sesquiterpenoids, chlorantenes A-G (1-7), two new phenylpropanoids (8 and 9), and six known sesquiterpenoids were isolated from the whole plants of Chloranthus serratus. Their structures were elucidated on the basis of spectroscopic analyses. Chlorantene A (1) was a sesquiterpene with a unique C-4 and C-10 linkage, and chlorantene B (2) possessed a nitro group at C-1. The structure of a eudesmane-type sesquiterpene previously isolated from Chloranthus henryi was revised as its 4-epimer (3a).

Sesquiterpenoids from Hedyosmum orientale

Five new guaiane-type sesquiterpenoids, hedyosumins A-E (1-5), together with five known ones (6-10), were isolated from the aerial parts of Hedyosmum orientale. Two known sesquiterpenoids, 10alpha-hydroxy-1,5alpha H-guaia-3,7(11)-dien-8alpha,12-olide and 9alpha-hydroxyasterolide, were obtained as natural products for the first time. Their structures were elucidated on the basis of spectroscopic methods. 9alpha-Hydroxyasterolide (7) showed moderate activities against A-549 and HL-60 tumor cell lines with the IC 50 values of 3.1 and 8.8 microM, respectively.

Two Novel Triterpenoids from Dysoxylum hainanense

Two novel rearranged oleanane-type triterpenes, dysoxyhainanin A ( 1) possessing a unique 1,3- cyclo-2,3- seco A ring with a formamido-containing appendage and dysoxyhainanin B ( 2) featuring an unprecedented 1,2-dinor-3,10:9,10- bisseco skeleton, were isolated from Dysoxylum hainanense. Dysoxyhainanin A ( 1) exhibited significant antibacterial activity against Gram-positive bacteria.

Ring A-seco triterpenoids with antibacterial activity from Dysoxylum hainanense

Five new ring A-seco triterpenoids, dysoxyhainic acids F-J (1-5), along with a known ring A-seco triterpenoid koetjapic acid (6) were isolated from the twigs and leaves of Dysoxylum hainanense. Their structures were established on the basis of extensive spectroscopic analysis. Antimicrobial activity of all the compounds against fungi and bacteria were tested. Compounds 2-4 and 6 exhibited significant antimicrobial activity against Gram-positive bacteria, and the antibacterial SAR (structure-activity relationship) was also briefly discussed.

Monoterpenoid Indole Alkaloids Bearing an N4‐Iridoid from Gelsemium elegans

Five new alkaloids, gelseganines A-D (1-4) and humantenine N(4)-oxide (5), were isolated from the stems and leaves of Gelsemium elegans. Compounds 1-4 represent a rare class of monoterpenoid indole alkaloids that bear an N(4)-iridoid unit. The structures of 1-5 were determined by spectroscopic analysis, single-crystal X-ray diffraction, and chemical correlation, and their absolute configurations were elucidated by CD analysis. A plausible biogenetic pathway for alkaloids 1-5 was also postulated.