Design, synthesis, neuroprotective, antibacterial activities and docking studies of novel thieno[2,3-d]pyrimidine-alkyne Mannich base and oxadiazole hybrids.

A series of thieno[2,3-d]pyrimidine alkyne Mannich base derivatives (7a-e, 8a-e) and thieno[2,3-d]pyrimidine 1,3,4-oxadiazole derivatives (9a-e, 10a-e) have been synthesized and evaluated for their neuroprotective and neurotoxicity activities where 9a, 10d displayed good neuroprotection 10.6 and 11.88 µg/mL respectively against the H2O2 induced cell death at the EC50 values and 9b, 9d showed respective toxic effects on PC12 cells at CC50 86.12 and 94.16 µg/mL. Compounds 9a, 9e, 10a and 10b showed strong antibacterial activity against two gram positive (S. aureus, B. subtilis) and two gram-negative strains (E. coli, P. aeruginosa) and showed good binding affinities with C(30) carotenoid dehydrosqualene synthase, Gyrase A and LpxC. This is the first report for the demonstration of thieno[2,3-d] pyrimidine derivatives as promising neuroprotective agents against H2O2 induced neurotoxicity on PC12 cells.

Stereoselective synthesis of C18-guggultetrol and C18-phytosphingosine analogues from D-fructose.

A series of C(18)-guggultetrol stereo isomers and C(18)-phytosphingosine regio/stereo isomers were synthesised in a stereoselective fashion involving metal mediated fragmentation, stereoselective reduction, 1,4 O → O silyl migration, and Grubbs' cross metathesis as key steps. d-Fructose was used as a raw material for the preparation of all the analogues. The isophytosphingosine derivatives were evaluated against their 5-LOX (5-lipoxigenase) inhibitory activity.

Synthesis, structural revision, and antioxidant activities of antimutagenic homoisoflavonoids from Hoffmanosseggia intricata.

Intricatinol and intricatin, the two homoisoflavonoids isolated from Hoffmanosseggia intricata, and two analogs have been synthesized from pyrogallol in three steps. The spectral data of synthetic intricatinol are in good agreement with those of natural metabolite, but the spectral data of intricatin are not corroborative with those of the natural product. The structure of intricatin has been thus revised to 8-methoxybonducellin, a compound isolated from Caesalpinia pulcherrima. The antioxidant activity of all the four homoisoflavonoids was determined by superoxide (NBT) and DPPH free radical scavenging methods. The synthetic analog 7,8-dihydroxy-3-[(3,4-dihydroxyphenyl)methylene]chroman-4-one displayed excellent activity in both methods.

Two new homoisoflavonoids from Caesalpinia pulcherrima.

Two new homoisoflavonoids, (E)-7-methoxy-3-(4'-methoxybenzylidene)chroman-4-one (1) and (E)-7-hydroxy-3-(3',4',5'-trimethoxybenzylidene)chroman-4-one (5), along with three known homoisoflavonoids (Z)-7-hydroxy-3-(4'-methoxybenzylidene)chroman-4-one (isobon ducellin) (2), (E)-7-hydroxy-3-(4'-methoxybenzylidene)chroman-4-one (bonducellin) (3) and (E)-7-hydroxy-3-(2',4'-dimethoxybenzylidene)chroman-4-one (4) were isolated from the whole plant of Caesalpinia pulcherrima. The structures of these new compounds were elucidated by electron impact mass spectrometry (EI-MS) and 1D and 2D-NMR spectral studies. Antimicrobial activity of the new compounds was evaluated.

Two new 5-deoxyflavonoids from Calliandra inermis.

Two new 5-deoxyflavonoids, 7,2',3',4'-tetramethoxyflavone (1) and 7,2',3',4'-tetramethoxyflavanone (2) together with a known flavone 7,4'-dimethoxy-3'-hydroxyflavone (3) were isolated from the whole plant of Calliandra inermis. The structures of these new compounds were elucidated by high resolution electron impact mass spectrometry (HR-EI-MS) and 1D and 2D-NMR spectral studies including 1H-1H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser enhancement spectroscopy (NOESY).

Two new 5-deoxyflavones from Albizia odoratissima.

Two new 5-deoxyflavones, 7,8-dimethoxy-3',4'-methylenedioxyflavone (1) and 7,2',4'-trimethoxyflavone (2) together with a known flavone, 7,4'-dimethoxy-3'-hydroxyflavone (3) were isolated from the rootbark of Albizia odoratissima. The structures of these new compounds were elucidated by electrospray ionization mass spectrometry (ESI-MS) and 1D and 2D-NMR spectral studies including (1)H-(1)H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser enhancement spectroscopy (NOESY).