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The diphenyl(phenylethynyl)phosphine complexes cir-PtX(Y)(Ph2PC=CPh)2 [X = Y = Cl, I, CF3, CsFs, Me; X (Y) = 0-C6H4O2, Me(Cl)] have been synthesized, and for all of the complexes except the dimethyl complex, intramolecular coupling of the phosphinoacetylene ligands occurs on heating to form c/r-PtX(Y){o-Ci6Hio(PPh2)2}• A mixture of the two possible structural isomers is formed for ci'i-PtMe(Cl){o-C16Hi0(PPh2)2}• The complex cis-PtMe2{o-Ci6Hio(PPh2)2} has been obtained by reaction of the dichloro analogue with methyllithium. The unsymmetrical diphosphine 1-phenyl-2,3-bis(diphenylphosphino)naphthalene [o-C16Hio(PPh2)2], produced as a coordinated ligand via these intramolecular coupling reactions, has been isolated in moderate yield from the dichloro complex and its structure determined by X-ray diffraction. Crystals of o-CieHiofPPlhh are triclinic, space group , with a = 11.437(13) A, b = 9.628(12) A, c = 16.712(21) A, a = 82.31(9)°, ß = 119.08(3)°, y = 110.03(5)°, and Z = 2. The structure was solved and refined to R = 0.058, Rv = 0.070. Structure determinations of cis-PtCl2(Ph2POsCPh)2-2MeCN, cir-PtMe(Cl)(Ph2PG=CPh)2-0.5CH2Cl2, and ti5-PtMe2(Ph2PC=CPh)2 have been carried out to evaluate interligand interactions in the complexes. Crystallographic data: rir-PtCl2(Ph2-PC=CPh)2'2MeCN, monoclinic, space group P2\/c, a = 11.604

Three new erythrina alkaloids, (+)-10,11-dioxoerythratine (1), (+)-10,11-dioxoepierythratidine (2), and (+)-10,11-dioxoerythratidinone (3), and a new pterocarpan, 1-methoxyerythrabyssin II (4), were isolated from the bark of Erythrina subumbrans, together with seven known pterocarpans, erythrabyssin II, erybraedin A, erystagallin A, erycristagallin, erythrabissin-1, eryvarin A, and hydroxycristacarpone, three flavanones, 5-hydroxysophoranone, abyssinone V, and lespedezaflavanone B, three triterpenes, sophoradiol, soyasapogenol B, and lupeol, and one isoflavanone, vogelin C. Their structures were elucidated on the basis of spectroscopic data. Some isolates were tested for antiplasmodial, antimycobacterial, and cytotoxic activities.

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Phytochemical investigation of the hexane and CH2Cl2 extracts of Erythrina stricta roots and E. subumbrans stems led to the isolation of six pterocarpans, one flavanone, one isoflavone, two alkaloids, five triterpenes, six steroids and alkyl trans-ferulates. The structures of all known compounds were determined on the basis of spectroscopic evidence. Sophoradiol (15), a mixture of stigmast-4-en-3-one (19) and stigmasta-4,22-dien-3-one (20), lupeol (21), cycloeucalenol (22), a mixture of 3beta-hydroxystigmast-5-en-7-one (23) and 3beta-hydroxystigmast-5,22-dien-7-one (24) and melilotigenin C (25) were first isolated from the genus Erythrina. The isolated compounds were evaluated for antiplasmodial activity, antimycobacterial activity and cytotoxicity. Among the tested compounds, 5-hydroxysophoranone (8) exhibited the highest antiplasmodial activity against Plasmodium falciparum (IC50 2.5 microg/mL). Compound 8, erystagallin A (5), erycristagallin (7) and erysubin F (10) showed the same level of antimycobacterial activity against Mycobacterium tuberculosis (MIC 12.5 microg/mL). For cytotoxicity, erybraedin A (2) showed the highest activity against the NCI-H187 and BC cells (IC50 2.1 and 2.9 microg/mL, respectively), whereas 10 exhibited the highest activity against the KB cells (IC50 4.5 microg/mL).

A novel piperine dimer, named chabamide, was isolated from stems of Piper chaba Hunter and its structure was elucidated on the basis of spectroscopic evidence. Chabamide showed antimalarial activity with an IC(50) value of 2.7 microg/ml and antituberculosis activity with the minimum inhibitory concentration (MIC) of 12.5 microg/ml.

A and B (11a, b), one chalcone, isobavachalcone (12), and one isoflavone, wighteone (13), were isolated from the bark of Erythrina fusca LOUR. Their structures were elucidated on the basis of spectroscopic data. Some isolates were tested for antiplasmodial and cytotoxic activities and it was found that 5 and 9 exhibited moderate antiplasmodial activity against Plasmodium falciparum. For cytotoxicity, compounds 1, 4, 5, 9 and 12 showed moderate to weak activity against KB, BC and NCI-H187 cells, whereas 2 exhibited only weak activity against KB cells.

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