No abstract

No abstract

The isolation and structural elucidation of a new Phyllanthus glycoside, phyllanthostatin 6 [7], was summarized. Phyllanthostatin 6 [7] was isolated from the roots of Phyllanthus acuminatus (Euphorbiaceae) and was found to inhibit (ED50 = 0.35 micrograms/ml) growth of the murine P-388 lymphocytic leukemia cell line. Two other new constituents were shown to be didesacetylphyllanthostatin 3 [9] and descinnamoylphyllanthocindiol [10]. Structure determinations were achieved employing hrfabms and 2D-nmr spectroscopy. Application of an hplc separation technique to the Phyllanthus glycosides and development of a new isolation procedure for the major antineoplastic constituent, phyllanthoside [1], are also described.

Western (Palau) and Eastern (State of Truk) Caroline Islands and Papua New Guinea sponges of the genera Axinella and Hymeniacidon were found to contain the cytostatic (PS ED50 2.5 and 2.0 (μg/mL) and antineoplastic (PS T/C 143 at 3.6 mg/kg and T/C 138 at 3.6 mg/kg) pyrrologuanidines 1a and 1b. The related hydantoin 2, designated axinohydantoin, was also isolated from an Axinella sp. and its structure was assigned by X-ray crystallographic techniques. Present experience with sponges in the Axinella and Hymeniacidon genera suggests that the previously known hymenialdisine (1b) and analogous imidazole derivatives may be widely distributed among these and related orange colored Porifera. Keywords: axinohydantoin, hymenialdisine, Axinella, Hymeniacidon, cystostatic.

An unusual cytostatic (PS ED50 4 micrograms/ml) lignan ester has been isolated from the Central American tree Phyllanthus acuminatus and designated phyllanthostatin A [1]. Separation of an MeOH extract of the root by size exclusion chromatography, high speed counter-current distribution, and semipreparative hplc afforded glycoside 1 in 0.007% yield. In solution, phyllanthostatin A was slowly transformed into justicidin B [4]. The structure of lignan glycoside 1 was determined by hrfabms and 2D-nmr spectroscopy.

Lyngbya majuscula and Croton cuneatus were used as prototypes for the dereplication of phorbol ester receptor binding activity using a combination of hplc-uv and online phorbol dibutyrate (PDBu) receptor binding and batch fractionation over either Si gel or diolbonded Si gel. Debromoaplysiatoxin was responsible for the bioactivity of Lyngbya, whereas a complex of potent phorbol esters was detected in C. cuneatus.

No abstract

Bryostatin 3 and the corresponding 26-ketone 5, which represents a new bryostatin, were isolated from the marine bryozoan Bugula neritina (Bugulidae). Spectmecopic data from 2D NMR studies indicate that the structure of bryostatin 3 (3) has to be revised to structure 4. Bryostatin 3 showed [sH]phorbol dibutyrate receptor displacement activity similar to that of bryostatin 1, whereas the corresponding 26-ketone 5 was significantly less active.