Zacharias Tanee Fomum

Triterpenoids with antimicrobial activity from Drypetes inaequalis

The air-dried stems and ripe fruit of Drypetes inaequalis Hutch. (Euphorbiaceae) were studied. Four triterpene derivatives, characterized as lup-20(29)-en-3beta,6alpha-diol, 3beta-acetoxylup-20(29)-en-6alpha-ol, 3beta-caffeoyloxylup-20(29)-en-6alpha-ol and 28-betad-glucopyranosyl-30-methyl 3beta-hydroxyolean-12-en-28,30-dioate along with 10 known compounds were isolated from the whole stems. One triterpene, characterized as 3alpha-hydroxyfriedelan-25-al along with six known compounds were isolated from the ripe fruit. Their structures were established on the basis of spectroscopic analysis and chemical evidence. The triterpenes were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria, and two of them appeared to be modestly active.

Pentacyclic triterpenoid and saponins from Gambeya boukokoensis.

Chemical studies of the EtOAc extract of Gambeya boukokoensis Aubr. et Pellegr. stem bark led to the isolation of eight compounds. Three of them were elucidated as new compounds and designated as: gamboukokoensein A, 1alpha,2alpha,3beta,19alpha,23-pentahydroxyurs-12-en-28-oic acid; gamboukokoenside A, 2beta,3beta,6beta,28-tetrahydroxyolean-12-en-23-oic acid 23-O-alpha-L-arabinopyranosyl ester and gamboukokoenside B, 6beta,28-dihydroxy-3-oxoolean-12-en-23-oic acid 23-O-alpha-L-arabinopyranosyl ester. The other five compounds were known and identified as myrianthic acid, protobassic acid, oleanolic acid, erythrodiol and chondrillasterol. Their structures were elucidated on the basis of one and two dimensional NMR spectroscopic techniques, FABMS, ESMS and chemical evidence.

Phenolic metabolites from Erythrina species

From the stem and root bark of Erythrina sigmoidea and E. eriotricha, one new prenylated flavanone, named sigmoidin L, and two new esters of ferulic and isoferulic acid, erythrinassinates C and D, were isolated together with eight known compounds, including one ester of isoferulic acid [3β-O-(E)-isoferuloyl oleanolic acid], one flavanone (sigmoidin A), four isoflavones (scandenone, 6,8-diprenylgenistein), flemiphilippinin B and 8-prenyldaidzein and two pterocarpans (gangetinin and calopocarpin). Their structures were elucidated by analysis of spectral data and chemical evidence. The in vitro anitmicrobial spectrum and potencies of the isolated compounds are also reported.

Scaphopetalone and scaphopetalumate, a lignan and a triterpene ester from Scaphopetalum thonneri.

From the methanol extract of the stem bark of Scaphopetalum thonneri, two new compounds, including one lignan, named scaphopetalone, one new ester of ferulic acid, named scaphopetalumate were isolated together with three known compounds including: two coumarins (scopoletin and scopolin), and one pentacyclic triterpene (oleanolic acid). The structure of the new compounds were elucidated by means of spectroscopic analyses.

Furanoflavones from root bark of Millettia sanagana

Abstract A new furanoflavone, named sanaganone, was isolated from the root bark of Millettia sanagana in addition to four known compounds, pongamol, lanceolatin B, kanjone and 5-methoxy furano [7,8:4″,5″] flavone. The structure of the new compound was elucidated by spectroscopic analysis, including 2D NMR techniques (DQF COSY, HETCOR, long-range HETCOR and NOESY), as 2‴,2‴-dimethylpyrano [5,6:5‴,6‴] furano [7,8:4″,5″] flavone.

Triterpenoids from Drypetes chevalieri Beille (euphorbiaceae)

The CH2Cl2/CH3OH (1/1) extract of the dried stem of Drypetes chevalieri Beille afforded two new triterpenoïds named drypechevalin A (11-oxo-β-amyrin-3β-ylcaffeate) and drypechevalin B (3,7-dioxo-D:A-friedooleanan-24-al) along with five known compounds: lupeol, lupeone, erythrodiol, putranjivadione, friedelin. Their structures were established on the basis of spectroscopic analysis and chemical evidence. ‡‡Part 5 in the series Drypetes studies.

2-Oxo-2H-Pyrimido[2,1-b]Benzothiazoles Inhibit Brain Benzodiazepine Receptor Binding in vitro

2-Oxo-2H-pyrimido[2,1-b]benzothiazole derivatives were found to inhibit the in vitro binding of 3H-Ro 15-1788 (3H-flumazenil) to rat cortical benzodiazepine receptors with IC50 values in the range of 0.7–13 μmol/l. The most potent compound, 2-oxo-4-phenyl-2H-pyrimido[2,1-b]- benzothiazole showed a similar potency to inhibit 3H-Ro 15-1788 binding to membrane preparations of rat brain cortex, cerebellum and hippocampus as well as to various subunit combinations of recombinant human γ-aminobutyric acidA/benzodiazepine receptors. Scatchard plot analysis showed that 2-oxo-4-phenyl-2H-pyrimido[2,1-b]benzothiazole is a competitive inhibitor of 3H-Ro 15-1788 binding to rat brain cortical membrane preparations.