The cell-free extracts of a landomycin E-producing strain, Streptomyces globisporus 1912-2, were shown to contain a low-molecular-weight compound that, like A-factor, restored the landomycin E and streptomycin biosynthesis and sporulation of the defective mutants S. globisporus 1912-B2 and S. griseus 1439, respectively. The compound was purified by thin layer chromatography and HPLC. It had an absorption maximum at λmax=245 nm and a molecular mass of m/z 244. On the basis of NMR spectroscopy ((1)H, (13)C, HSQC, HMBC, COSY and NOE) the chemical structure of the compound was elucidated as 6-benzyl-3-eth-(Z)-ylidene-1-methyl-piperazine-2,6-dione ((L)-N-methylphenylalanyl-dehydrobutyrine diketopiperazine (MDD)). The sequences of arpA genes in S. globisporus 1912-2 and S. griseus NBRC 13350 are highly conserved. An explanation for the observed biological activity of MDD was proposed.

Literature data up to 2003 were presented and information on methods for preparing and modifying natural 4-arylcoumarins and their synthetic analogs were systematized.The first part of this review [1] presented data on the physicochemical and pharmacological properties of natural 4-arylcoumarins. Natural neoflavones and their synthetic analogs can be used as medical preparations because of their wide spectrum of biological activity and low toxicity. However, this necessitates the development of preparative synthetic methods. Therefore, the second part reviews completely all presently known synthetic approaches to the construction and modification of neoflavones.

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Coumarins in both the free state and as O-glycosides are known to be widely distributed in nature [1]. The carbohydrate unit occurs at various positions of the benzopyran ring. The sugar component of coumarin O-glycosides can be monosaccharides (D-glucopyranose, L-rhamnopyranose, D-galactopyranose, D-and L-arabinopyranose, D-xylopyranose, etc.) and also certain disaccharides. Compared with the coumarins themselves, their glycosides are very soluble in water. Considering the high biological activity of natural and synthetic coumarins and the broad spectrum of their pharmacological activity, the synthesis and investigation of biologically active glycosides of compounds based on the benzopyran-2-one skeleton is very interesting. Therefore, the present study examined the synthesis of 5-hydroxy-and 7-hydroxy-3,4-cycloannelated coumarin D-glycopyranosides and their anticoagulant activity.Hydroxycoumarins 1-3 that were required for further transformations were prepared by Pechmann condensation of polyphenols (resorcinol and orcinol) with ethyl-2-oxocyclopentanecarboxylate or ethyl-2-oxocyclohexanecarboxylate in the presence of conc. H 2 SO 4 at 0°C [2, 3]; 3-hydroxybenzo[c]chromen-6-one (4), by Hartley condensation in NaOH solution of 2-bromobenzoic acid and resorcinol with a catalyst of copper sulfate solution (10%) [4].3,4-Cyclocondensed coumarin O-glycosides were synthesized using the most convenient method based on condensation of a glycosyl donor and potassium salts of hydroxycoumarins in aqueous acetone with cooling (0°C) (Modified Michael method) and were used successfully to synthesize a similar type of compounds [5][6][7]. Solutions of these salts were prepared using equivalent amounts of the respective hydroxycoumarin and KOH solution (10%) and double (relative to the volume of base) the amount of acetone. The glycosyl donors in this synthesis were acetobromosugars (D-isomers): α-acetobromoglucose (Ac 4 GlupBr), β-acetobromogalactose (Ac 4 GalpBr), α-acetobromoxylose (Ac 3 XylpBr), and β-acetobromoarabinose (Ac 3 ArapBr), which were prepared by known methods [8,9]. The synthesis gave 42-51% yields of the O-peracetates of glucopyranosides 5 and 6, galactopyranoside 7, xylopyranoside 8, and arabinopyranosides 9 and 10, which contain a carbohydrate in the 5-or 7-position of the coumarin ring.The structures of the resulting glycosides and the configurations of their anomeric centers were unambiguously confirmed using PMR spectroscopy. The PMR spectra of 5-10 contain signals for four (for glucosides and galactosides) or three (for arabinosides and xylosides) acetyls at 2.00-2.20 ppm and signals for the carbohydrate and aglycon moieties.