Specimens of Dictyota pfaffii from Atol das Rocas, Northeast Brazil, afforded the rare dolabellane diterpene 10,18-diacetoxy-8-hydroxy-2, 6-dolabelladiene (1) and the new 10-acetoxy-8,18-di-hydroxy-2,6-dolabelladiene (2). Reduction of 1 yielded 8,10,18-trihydroxy-2,6-dolabelladiene (3), also present in the crude ex-tract of D. pfaffii. All three structures were assigned by 1D and 2D NMR spectral data. These substances showed strong anti-HSV-1 activity in vitro but only 3 inhibited the reverse transcriptase enzyme of HIV-1.

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This paper describes the effect of two weak bases (ammonium chloride and chloroquine) on the morphogenesis of Mayaro virus. When Mayaro virus-infected TC7 (monkey kidney) cells were treated with these agents it was observed that weak bases caused a signi®cant reduction in virus yield. Also, cellular protein synthesis, which is inhibited by Mayaro virus infection, recovered to nearly normal levels. However, the synthesis of Mayaro virus proteins was affected. These phenomena were dose-dependent. The process of Mayaro virus infection in vertebrate cells is very rapid. Virus precursors are not observed in cell cytoplasm and budding through the plasma membrane seems to be the only way of virus release. Electron microscopy of cells infected with Mayaro virus and treated with weak bases revealed an accumulation of virus structures in cell cytoplasm. The study also noted an inhibition of budding through the plasma membrane and the appearance of virus particles inside intracytoplasmic vacuoles. These observations indicate an impairment at the ®nal stages of the virus replication cycle.

The synthesis of new 4-(phenylamino)-1-phenyl-1H-pyrazolo [3,4-b]pyridine-4-carboxylic acid (3a-l) derivatives and the new 4-[(methylpyridin-2-yl)amino]-1-phenyl-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid (5a-c) derivatives was achieved with an efficient synthetic route. Ethyl 4-chloro-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate (1) on fusion with appropriate substituted anilines or aminopicolines gave the required new ethyl 4-(phenylamino)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylates (2a-l) (52-82%) or new ethyl 4-[(methylpyridin-2-yl)amino]-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylates (4a-c) (50-60%), respectively. Subsequent hydrolysis of the esters afforded the corresponding carboxylic acids (3a-l) (86-93%) and (5a-c) in high yield (80-93%). Inhibitory effects of 4-(phenylamino)/4-[(methylpyridin-2-yl)amino]-1-phenyl-1H-pyrazolo [3,4-b]pyridine-4-carboxylic acids. Derivatives on Herpes simplex virus type 1 (HSV-1), Mayaro virus (MAY) and vesicular stomatitis virus (VSV) were investigated. Compounds 2d, 3f, 3a, and 3c exhibited antiviral activity against

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