Laurane-, cyclolaurane-, and cuparane-type sesquiterpenes from the marine red alga Laurencia okamurai.

Chemical investigation of the secondary metabolites extracted from the marine red alga Laurencia okamurai has resulted in the isolation of one new (lauramurin, 1) and six known (2-7) sesquiterpenes. On the basis of the data obtained by our detailed spectroscopic analysis as well as by comparison with those reported, the structures of these compounds were elucidated as four laurane sesquiterpenes including lauramurin (1), laur-11-en-10-ol (2), aplysinol (3), and debromoaplysinol (4), two cyclolaurane sesquiterpenes laurequinone (5) and laurentristich-4-ol (6), and one cuparane ether sesquiterpene (7). The antibacterial activity against Staphylococcus aureus and brine shrimp (Artemia salina) lethality for the isolated compounds were evaluated. Compounds 2 and 5-7 displayed moderate lethality against brine shrimp.

Dapholdhamines A-D, alkaloids from Daphniphyllum oldhami.

Four new Daphniphyllum alkaloids, dapholdhamines A-D (1-4), were isolated from the leaves of Daphniphyllum oldhami. The structures and relative configurations of 1-4 were elucidated on the basis of spectroscopic data.

Daphenylline, a new alkaloid with an unusual skeleton, from Daphniphyllum longeracemosum.

A new alkaloid, daphenylline (1), with an unprecedented rearranged 22-nor-calyciphylline skeleton, was isolated from the fruits of Daphniphyllum longeracemosum. Its structure and stereochemistry were elucidated on the basis of spectroscopic and computational approaches. A plausible biosynthetic pathway of 1 was also proposed.

Carboline alkaloids from Trigonostemon lii.

Three types with six new carboline alkaloids, trigonostemonines A-F (1- 6), were isolated from the roots and stems of Trigonostemon lii. Their structures were elucidated by spectroscopic analyses. It is the first time that beta-carboline alkaloids have been reported in Trigonostemon species. Trigonostemonine F (6) exhibited moderate cytotoxic activity against HL-60 with an IC (50) value of 16 microM.

Tetranortriterpenoids from the Leaves of Cipadessa cinerascens.

Seven known and six new tetranortriterpenoids, cineracipadesins A-F (1-6), were isolated from the leaves of Cipadessa cinerascens. Compound 1 has a mexicanolide-type structural skeleton with a rare 9alpha,11alpha-epoxide ring; compound 2 has a methyl angolensate-type structure with 9,11-dihydroxy groups, representing the first example of a precursor of a trijugin-type limonoid; and 3 is the first reported methyl angolensate-type limonoid with a ketone group at ring C. Their structures were determined with extensive spectroscopic analysis. X-ray crystallography confirmed the structure of 1. The ability of compounds 1-7 to inhibit the growth of the P-388 murine leukemia cell line was evaluated.

Daphniphyllum and diterpenoid alkaloids from Daphniphyllum longeracemosum.

Four new Daphniphyllum alkaloids, daphlongamines A-D (1-4), were isolated from the fruits of Daphniphyllum longeracemosum. Their structures were characterized by spectroscopic methods, especially 2D NMR techniques. A single-crystal X-ray diffraction analysis was used to confirm the stereochemistry of 3. Remarkably, this is the first report of aconitine- and veatchine-type diterpenoid alkaloids from the genus Daphniphyllum.

Alkaloids from Daphniphyllum oldhami.

Four new Daphniphyllum alkaloids, daphnioldhanines H-K ( 1- 4), along with 34 known alkaloids, were isolated from Daphniphyllum oldhami. The known alkaloid dehydrodaphnigraciline ( 5) is now reported as a natural product. Their structures were elucidated by spectroscopic methods, especially 2D NMR techniques. The effects against platelet aggregation of compounds 1, 3, and 5 were evaluated, and 3 showed stronger activity against platelet aggregation induced by PAF. This is the first report of quinolizidine alkaloids from the genus Daphniphyllum.

Daphnipaxianines A-D, alkaloids from Daphniphyllum paxianum.

Four new Daphniphyllum alkaloids, daphnipaxianines A-D ( 1- 4), along with six known ones, have been isolated from the leaves and fruits of Daphniphyllum paxianum. Daphnipaxianines A and B ( 1, 2), a pair of epimers differing at C-10, are the first caliciphylline A type Daphniphyllum alkaloids with a Delta (9(15))-unsaturated cyclic ketone unit, and daphnipaxianine D ( 4) is the first yuzurine-type Daphniphyllum alkaloid containing a hexacyclic ring system. The structures of these alkaloids were characterized by spectroscopic methods, especially 2D NMR techniques. A single-crystal X-ray diffraction analysis was used to confirm the structure of 1.

Yuzurimine-type alkaloids from Daphniphyllum yunnanense.

Five new yuzurimine-type alkaloids, yunnandaphnines A-E (2-6), together with two known analogues, macrodaphniphyllamine (1) and calycinine A (7), have been isolated from the leaves and twigs of Daphniphyllum yunnanense. The structures of the new alkaloids were elucidated by spectroscopic methods. Yunnandaphnine E (6) is a novel heptacyclic yuzurimine-type alkaloid with an oxazine ring.