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Six 14-membered cyclopeptide alkaloids, i.e., ramosines A–C, mucronine J, and lotusines A and D, were isolated from the roots of Paliurus ramosissimus, and an additional four, hemsines A–D, from the roots of P. hemsleyanus. Among these, ramosines A–C (1, 5, and 6, resp.) and hemsines A and B (7 and 8, resp.) are new bases of the amphibine-B type, and hemsines C and D (9 and 10, resp.) are new integerrine-type alkaloids. Additionally, ramosine C (6) represents the first 14-membered cyclopeptide alkaloid possessing a substitution (OH) at C(13′). Their structural elucidations were based on spectral analysis and molecular-modeling studies. Pronounced solvent effects in the 1H- and 13C-NMR spectra of these two types of alkaloids were observed.

Seven zizyphine A-type cyclopeptide alkaloids were isolated from the roots of Paliurus ramossisimus by the combination of centrifugal partition chromatography and conventional separation methods. The novel structures of paliurines A-F (1-6) were characterized and established on the basis of MS and elaborate NMR spectral analyses. Terminal dipeptide stereochemistry was confirmed by correlation with the synthetic dipeptides via comparison of their (13)C NMR data.

Seven ellagitannins isolated from Phyllanthus myrtifolius and P. urinaria (Euphorbiaceae) have been shown, for the first time, to be active against Epstein-Barr virus DNA polymerase (EBV-DP) at the microM level. All these compounds have the same moiety of a corilagin, and differ from each other by different substitutions at C-2 and C-4 of the glucose core. SAR analysis and molecular modeling reveal that the essential pharmacophore of these tannins resides in the corilagin moiety. The outer complex carboxylic acid moieties appear to act only as auxopharmacore.

Six lignans comprising phyllamyricins D (1), E (2), and F (3) and phyllamyricosides A (4), B (5), and C (6) were isolated in a continuing study of Phyllanthus myrtifolius. Compounds 1 and 2 are 2a-methoxy-4-aryl-2,3-naphthalides. Compounds 3-6 belong to the 4-arylnaphthalene class, with compounds 4-6 being O-beta-glucosides. Their structures were elucidated on the basis of spectral analysis. Compound 4 increased the activity of HIV-1 reverse transcriptase by 65% at a concentration of 1.89 microM.

Two lignans, phyllamycin B and retrojusticidin B isolated from Phyllanthus myrtifolius Moon have been demonstrated to have a strong inhibitory effect on human immunodeficiency virus-1 reverse transcriptase activity (HIV-1 RT), but much less inhibitory effect on human DNA polymerase-alpha (HDNAP-alpha) activity. Fifty percent inhibitory concentrations of phyllamycin B and retrojusticidin B were determined to be 3.5 and 5.5 microM for HIV-1 RT, and 289 and 989 microM for HDNAP-alpha, respectively. The mode of inhibition was found to be non-competitive inhibition with respect to template-primer and triphosphate substrate. Several tannins such as caffeoylquinates (CQs) isolated from Lonicera japonica Thunb, galloylquinates (GQs) and galloylshikimates (GSs) purified from Castanopsis hystrix were shown to have a much less selective inhibitory effect on HIV-1 RT.

Chemical investigation on the aerial and the root parts of Phyllanthus urinaria L. culminated in the isolation of four lignans, namely 5-demethoxyniranthin, urinatetralin, dextrobursehernin, urinaligran, together with nine known lignans. Their structures, including the absolute stereochemistry, were elucidated by spectral analysis (NMR and CD) and chemical correlation.

Chemical investigation of Drypetes littoralis yielded three new tricyclic diterpenes, drypetenones A, B, and C (1--3), and one new xanthone (4). Spectral analyses and chemical correlations established the structures as 10S-12-hydroxy-11-methoxy-13-methylpodocarpa-1,5,8,11,13-pentaene-3,7-dione, (1), 10S-12-hydroxy-11-methoxy-13-methylpodocarpa-5,8,11,13-tetraene-3,7-dione (2), 10S-12-hydroxy-6,11-dimethoxy-13-methylpodocarpa-1,5,8,11,13-pentaene-3,7-dione (3), and 1-hydroxy-7-hydroxymethyl-6-methoxyxanthone (4). Complete (13)C NMR assignment of boehmenan D (5) is also made.