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A semisynthetic approach was used to prepare lactam analogues of epothilones.

HFR1 has been found to encode an atypical bHLH protein. The protein acts in phytochrome A signal transduction. Phytochromes are photoreceptors plants use to adapt growth and development to light conditions. A new mutant, hfr1 (long hypocotyl in far-red) is described. IT shows reduction in seedling responsiveness to continuous far-red light (FRc). HFR1 may act to modulate phyA signaling via heterodimerization with PIF3. Abundance of HFR1 mRNA is far greater in FRc than in continuous red light. This suggests a potential mechanistic basis for the specificity of HFR1 to phyA signaling.

Selective deacylation followed by attachment of the C-13 side chain were performed to convert the taxoid baccatin IV to various 1-deoxypaclitaxel analogues. The bioactivities of the 1-deoxypaclitaxel derivatives in both tubulin polymerization and cytotoxicity assays were then analyzed. Results revealed several derivatives with activity similar to that of paclitaxel, suggesting that the 1-hydroxyl group is not essential for the activity of paclitaxel.

In early seedling development, far-red-light-induced deetiolation is mediated primarily by phytochrome A (phyA), whereas red-light-induced deetiolation is mediated primarily by phytochrome B (phyB). To map the molecular determinants responsible for this photosensory specificity, we tested the activities of two reciprocal phyA/phyB chimeras in diagnostic light regimes using overexpression in transgenic Arabidopsis. Although previous data have shown that the N[H.sub.2]-terminal halves of phyA and phyB each separately lack normal activity, fusion of the N[H.sub.2]-terminal half of phyA to the COOH-terminal half of phyB (phyAB) and the reciprocal fusion (phyBA) resulted in biologically active phytochromes. The behavior of these two chimeras in red and far-red light indicates: (i) that the N[H.sub.2]-terminal halves of phyA and phyB determine their respective photosensory specificities; (ii) that the COOH-terminal halves of the two photoreceptors are necessary for regulatory activity but are reciprocally interchangeable and thus carry functionally equivalent determinants; and (iii) that the N[H.sub.2]-terminal halves of phyA and phyB carry determinants that direct the differential light lability of the two molecules. The present findings suggest that the contrasting photosensory information gathered by phyA and phyB through their N[H.sub.2]-terminal halves may be transduced to downstream signaling components through a common biochemical mechanism involving the regulatory activity of the COOH-terminal domains of the photoreceptors.

A new series of C-13 amido-containing paclitaxel analogs were accidentally synthesized during structure-activity relationship tests of paclitaxel (Taxol), an antitumor drug from Bristol-Myers Squibb. The analogs included 4-deacetyl-13-amidopaclitaxel, 13-amidopaclitaxel 4-(methyl carborate) derivatives, and 13-amidopaclitaxel. Biological profiling assays, in tubulin polymerization and in vitro cytoxicity assay against a human colon cancer cell line, determined the nonreactivity of the analogs.

The Synechococcus sp PCC 7002 genes cpcE and cpcF are involved in the correct attachment of bilin to the alpha-subunit of phycocyanin. The genes were expressed in Escherichia coli, and the overproduced proteins were analyzed. The results showed that cpcE and cpcF code for a protein-bilin lyase specific for the alpha-subunit attachment site. In addition, phycocyanobilin was shown to be the immediate bilin precursor of the protein-bound bilin.

A new regiospecific method enables the synthesis of novel paclitaxel(Taxol) analogs modified at the C4-position and the preparation of C-4 cyclopropyl ester and the C-4 benzoate of paclitaxel. An in vitro cytotoxicity assay against a human lung carcinoma cell line shows that the C4-cyclo-propyl paclitaxel analog is more potent than paclitaxel, while the C4-benzoate analog exhibits reduced toxicity.

Bromophycolides J-Q is isolated from extracts of the Fijian red alga Callophycus serratus and is identified with one-dimensional (1D) and 2D NMR spectroscopy and mass spectral analyses. The diterpene-benzoate macrolides have represented two novel carbon skeletons and bromophycolides have displayed activities in the low micromolar range against the human malaria parasite Plasmodium falciparum.

The NMR, X-ray and mass spectral analysis of Callophycoic acids A-H and callophycols A and B, isolated from extracts of the Fijian red alga Callophycus serratus is described. The four novel carbon products are first example of diterpene-benzoic acids and diterpene-phenols in macroalgae which exhibit antibacterial, antimalarial and anticancer activity.

The fruits and twigs of Aglaia silvestris are used to isolate two cytotoxic rocaglate derivatives possessing an unusual dioxanyloxy unit, silvestrol and episilvestrol, by bioassay-guided fractionation monitored with a human oral epidermoid carcinoma cell line.