Limonoids and sesquiterpenoids from Amoora tsangii

Seven new limonoids, amotsangins A-G (1-7), two known limonoids, and four known sesquiterpenoids were isolated from the twigs and leaves of Amoora tsangii. Their structures were elucidated primarily on the basis of spectroscopic data.

Limonoids from the stem bark of Khaya grandifoliola

Three limonoids, deacetylkhayanolide E (1), 6S-hydroxykhayalactone (2), and grandifolide A (3), along with three known ones, were isolated from stem bark of the Nigerian medicinal plant Khaya grandifoliola. Their structures were characterized on the basis of the application of spectroscopic methods. In vitro antimicrobial and cytotoxic activities of the isolates were also tested, but were all found to be inactive.

Eucalyptals A-C with a new skeleton isolated from Eucalyptus globulus

Eucalyptals A-C (1-3) with a new skeleton of 3,5-diformyl-isopentyl phloroglucinol-coupled cadinane were isolated from the fruits of Eucalyptus globulus. Their structures were elucidated by spectroscopic analysis, and that of 1 was confirmed by single-crystal X-ray diffraction. The biosynthetic pathway of 1-3 was also postulated. Compounds 1-3 exhibited selective cytotoxicity against the HL-60 cell line.

Nortriterpenoids from Chukrasia tabularis var. velutina

Five new limonoids, tabularisins E-I ( 1- 5), and a new dinorcycloartane, (24 R)-28,29-dinor-cycloartane-3beta,24,25-triol ( 6), together with three known compounds, were isolated from the twigs and leaves of Chukrasia tabularis var. velutina. Their structures were elucidated primarily on the basis of spectroscopic methods.

Agladupols A-E, triterpenoids from Aglaia duperreana

Three new apotirucallane-type triterpenoids, agladupols A-C (1- 3), and two new tirucallane-type triterpenoids, agladupols D and E (4 and 5), along with four known compounds, were isolated from the leaves and stems of Aglaia duperreana (Meliaceae). The structures of compounds 1- 5 were elucidated by spectroscopic data. A (13)C NMR-based general rule for assignment of the C-21 configuration in the side chain of apotirucallane- and tirucallane-type triterpenoids was proposed. According to this, the relative stereochemistry of 21- O-methyltoosendanpentol (1a), a known compound with the relative configurations of the stereocenters in the side chain undetermined, was completely assigned.

Limonoids from the leaves and stems of Toona ciliata

Three new norlimonoids, toonaciliatins A (1), F (6), and G (7), four new limonoids, toonaciliatins B-E (2-5), and five known compounds, 5alpha,6beta,8alpha-trihydroxy-28-norisotoonafolin (8), toonaciliatins H (9) and I (10), febrifugin (11), and khayasin T (12), were isolated from the leaves and stems of Toona ciliata. Compounds 1-3 have an unusual 1-en-3-one system with a 1,11-oxygen bridge, limonoids 11 and 12 have a mexicanolide-type structural frame, and others are typical A,B-seco- (4, 5, 9, and 10) or B-seco-29-nor- (3, 6, 7, and 8) limonoids. Toonaciliatins H (9) and I (10) were obtained for the first time as natural products. The structures were established by extensive spectroscopic methods, particularly 1D and 2D NMR techniques.

Tetranortriterpenoids from Cipadessa baccifera

Five new mexicanolide-type tetranortriterpenoids, tigloylseneganolide A (1), 2'R-methylbutanoylproceranolide (2), 2'S-methylbutanoylproceranolide (3), 2'R-cipadesin A (4), and 2'R-cipadesin (6), as well as the known 2'S-epimers of 4 and 6 (5 and 7), together with six other known limonoids, were isolated from the seeds of Cipadessa baccifera. The structures of these compounds were elucidated on the basis of spectroscopic analyses and chemical methods. 1H NMR-based conformational analysis was applied to establish the absolute configuration of the sterically hindered 2-methylbutanoyl in three epimeric pairs (2-7). A general rule for the determination of the absolute configurations of 2R- and 2S-methylbutanoyl groups at C-3 of a limonoid in a mixture is proposed.

Chuktabularins A−D, Four New Limonoids with Unprecedented Carbon Skeletons from the Stem Bark of Chukrasia tabularis

Chuktabularins A-D (1-4), four novel 16-norphragmalin-type limonoids that feature unprecedented skeletons with a biosynthetically extended C2 or C3 unit at C-15 forming a unique 2,7-dioxabicyclo[2.2.1]heptane moiety, were isolated from the stem bark of Chukrasia tabularis. Their structures were elucidated by spectroscopic analysis and computer modeling. The biosynthetic pathway of 1-4 was postulated.

The first limonoid peroxide in the Meliaceae family: walsuronoid A from Walsura robusta

Walsuronoid A (1), a limonoid featuring an unprecedented 3,4-peroxide-bridged A-seco skeleton, together with walsuronoids B (2) and C (3) possessing a rare 18(13-->14)-abeo-limonoid skeleton, was isolated from Walsura robusta. The structures were elucidated by spectroscopic analysis and chemical correlation, and that of 1 was confirmed by single-crystal X-ray diffraction. Biosynthetic pathway of 2 and 3 was proposed and was chemically mimicked. Compounds 1 and 2 showed weak antimalarial activity.

Limonoids from the seeds of the marine mangrove Xylocarpus granatum

Five new limonoids, granaxylocarpins A-E (1-5), were isolated from the seeds of the Chinese marine mangrove Xylocarpus granatum. Granaxylocarpins A (1) and B (2) are mexicanolide-type limonoids with a 9,10-seco skeleton, and granaxylocarpin C (3) possesses an 8alpha,30alpha-epoxy ring and a rare 1,29-oxygen bridge. The structures of these limonoids were characterized on the basis of extensive spectroscopic methods and single-crystal X-ray diffraction analysis performed on 4. The structure of xyloccensin U (4a) was revised as 4b by comparison with granaxylocarpin D (4). The cytotoxicity of these isolates was evaluated against the P-388 and A-549 tumor cell lines.

Chlorahololides A and B, Two Potent and Selective Blockers of the Potassium Channel Isolated from Chloranthus holostegius

[structure: see text] Chlorahololides A(1) and B(2), two highly complex sesquiterpenoid dimers, were isolated from Chloranthus holostegius. Their structures and absolute configurations were established by NMR spectroscopy, X-ray crystallography, and CD. Chlorahololides A (1) and B (2) exhibited potent and selective inhibition on the delayed rectifier (IK) K+ current, with an IC50 of 10.9 and 18.6 microM, respectively.

Indole alkaloids from three species of the Ervatamia genus: E. officinalis, E. divaricata, and E. divaricata Gouyahua

Six new indole alkaloids, 14,15-didehydro-10,11-dimethoxy-16-epivincamine (1), 14,15-didehydro-10-hydroxy-11-methoxy-16-epivincamine (2), 14,15-didehydro-10,11-dimethoxyvincamine (3), 14,15-didehydro-10-hydroxy-11-methoxyvincamine (4), 19,20-didehydro-6alpha-hydroxyervatamine (5), and dehydroxyervataminol (6), along with 36 known indole alkaloids, were isolated from three species, E. officinalis, E. divaricata, and E. divaricata Gouyahua, of the Ervatamia genus. The structures of these alkaloids were characterized on the basis of spectroscopic methods and chemical correlation. The in vitro cytotoxic activities of all the alkaloids except 7, 18, 27, 38, 40, and 44 against the tumor cell lines P-388 murine leukemia and A-549 human lung carcinoma were evaluated. Only the dimeric indole alkaloids showed cytotoxic activities.

Xylogranatins A−D: Novel Tetranortriterpenoids with an Unusual 9,10-seco Scaffold from Marine Mangrove Xylocarpus granatum

[reaction: see text] Four novel tetranortriterpenoids, xylogranatins A-D (1-4), with an unusual 9,10-seco skeleton were isolated from the seeds of a Chinese marine mangrove Xylocarpus granatum. Their structures were determined by spectroscopic and chemical means. Xylogranatin A (1) featured by a unique 1,9-oxygen bridge was confirmed by single-crystal X-ray diffraction, and xylogranatin D (4) with an unprecedented skeleton of C-30-C-9 linkage was postulated biogenetically from 3 via an alpha-hydroxyl ketone rearrangement and was chemically mimicked.

Alkaloids from Gelsemium elegans

Three new alkaloids, gelsebanine (1), 14alpha-hydroxyelegansamine (2), and 14alpha-hydroxygelsamydine (3), and a new extraction artifact , gelsebamine (4), together with 12 known alkaloids, were isolated from the stems and leaves of Gelsemium elegans. The structures of 1-4 were determined by spectroscopic methods, especially 2D NMR techniques. Compounds 1-4 were evaluated for cytotoxic activity against four tumor cell lines, and gelsebamine (4) selectively inhibited the A-549 human lung adenocarcinoma cell line.