Abietane diterpenoid dimers from the roots of Salvia prionitis

Three abietane diterpenoid dimers, bisprioterones A-C (1-3), were isolated from roots of the Chinese folk medicinal plant Salvia prionitis Hance (Labiatae). Compounds 1-3 possessed two different abietane diterpenoid skeleta, which were linked via either a C-C single bond (1 and 2) or an ether bridge (3). Their structures were elucidated by analysis of 1D and 2D NMR spectroscopic data. The structure of 1 was further confirmed by a single-crystal X-ray diffraction determination.     

Cytotoxic clerodane diterpenoids from the leaves of Premna tomentosa

Three clerodane diterpenoids, premnones A-C (1-3), were isolated from a chloroform-soluble fraction of Premna tomentosa along with four known flavonoids and three known triterpenoids. Among these isolates, premnones A-C exhibited cytotoxic activity when evaluated against a small panel of tumor cell lines. However, premnone A was found to be inactive when evaluated in a follow-up in vivo hollow fiber assay at the highest dose tested (50mg/kg), using LNCaP, Lu1, and MCF-7 cells.     

Interaction of twoLAC repressor protein segments with polynucleotides

The interaction of the oligopeptides Ala-Gln-GIn-Leu-Ala-Gly-OH and Gln-Leu-Ala-Gly-OMe corresponding, respectively, to the sequence 53–58 and 55–58 oflac repressor protein with four polynucleotides was studied. The two peptides did not interact with poly dA. poly dT, poly d(A-T)·poly d(A-T) or poly d(A-G)·poly d(C-T). But they interacted in a characteristic way with poly d(A-C). poly d (G-T), the sequences of which are in abundance in thelac operator region. Both the peptides stabilised the melting of poly d (A-C). poly d (G-T) at a peptide to nucleotide ratio (P/N) of 4; at lower ratios, they destabilised the DNA slightly. The circular dichroism of the alternating polynucleotide with CAC/GTG sequences was perturbed by both the oligopeptides. The hexapeptide at a P/N of 4 caused the transformation of the B-form circular dichroism spectrum to a new state, characterised by strong 220 and 240 nm bands, and a rather weak long wavelength spectrum.     

Dihydrophenanthrenes and other antifungal stilbenoids from Stemona cf. pierrei

Three new dihydrophenanthrenes, stemanthrenes A-C, along with the new dihydrostilbene stilbostemin G were isolated and identified from the underground parts of Stemona cf. pierrei together with the known pinosylvin, 4'-methylpinosylvin, dihydropinosylvin, stilbostemins B, D, and E as well as the pyrrolo[1,2-a]azepine alkaloids protostemonine and stemonine. The structures of all new stilbenoids, elucidated by NMR analyses, showed a common substitution pattern for aromatic ring A and characteristic C-methylations for ring B. The trivial name racemosol, previously reported for S. collinsae, was renamed to stemanthrene D due to its priority for another compound. Bioautographic tests on TLC plates with Cladosporium herbarum displayed high antifungal activity for compounds with an unsubstituted aromatic ring A, e.g. pinosylvin, but only weak effects for the higher substituted stilbostemin G and stemanthrenes A-C. Similar results were obtained by germ tube inhibition of five microfungi using 2-fold serial broth dilutions determined by a microplate reader. Because of weak inhibition and chemical instability of stemanthrenes, no EC(50) and EC(90) values could be calculated.     

Antimicrobial and radical scavenging flavonoids from the stem wood of Erythrina latissima

From the stem wood of Erythrina latissima, two isoflavones and a flavanone were isolated and characterized as 7,3'-dihydroxy-4'-methoxy-5'-(gamma,gamma-dimethylallyl)isoflavone (erylatissin A), 7,3'-dihydroxy-6',6'-dimethyl-4',5'-dehydropyrano [2',3': 4',5']isoflavone (erylatissin B), (-)-7,3'-dihydroxy-4'-methoxy-5'-(gamma,gamma-dimethylallyl)flavanone (erylatissin C), respectively, in addition to 10 known flavonoids. Structures of these compounds were determined on the basis of their spectroscopic data. These compounds showed antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Candida mycoderma. The isolated compounds also exhibited weak radical scavenging properties towards DPPH radical.     

Colchicinoid glucosides from seedless pods of Thai origin Gloriosa superba

Three new colchicinoid glucosides, dongduengosides A-C were isolated from seedless pods of Thai origin Gloriosa superba together with colchicoside, colchicine, 2-demethylcolchicine and luteolin 7-O-β-d-glucopyranoside. In addition, colchicine, 2-demethylcolchicine, 3-methylcolchicine, colchicoside, epi-catechin and quercetin 3-O-β-d-glucopyranoside were identified from seeds. The structure determinations were based on physical data and spectroscopic evidence including 1D- and 2D-experiments. This study showed that the different part of seedless pods and seeds provided the major difference in compounds.     

Glucosides from Vitex agnus-castus

The methanolic extract of the flowering stems of Vitex agnus-castus yielded three new iridoids: 6'-O-foliamenthoylmussaenosidic acid (agnucastoside A), 6'-O-(6,7-dihydrofoliamenthoyl)mussaenosidic acid (agnucastoside B) and 7-O-trans-p-coumaroyl-6'-O-trans-caffeoyl-8-epiloganic acid (agnucastoside C) in addition to four known iridoids (aucubin, agnuside, mussaenosidic acid and 6'-O-p-hydroxybenzoylmussaenosidic acid) and one known phenylbutanone glucoside (myzodendrone). The structure elucidations were mainly done by spectroscopic methods (1D and 2D NMR spectra) and MS data interpretation. The purified compounds were tested for biological activities against various microorganisms and cancer cell lines.     

Dinklagins A,B and C: three prenylated flavonoids and other constituents from the twigs of Dorstenia dinklagei

The dichloromethane extract of the aerial parts of Artabotrys hexapetalus afforded three beta-methoxy-gamma-methylene-alpha,beta-unsaturated-gamma-butyrolactones, which are proposed to be derived from a C(18) unsaturated fatty acid by a biosynthetic route similar to that proposed for the Annonaceous acetogenins. The structure of the unique beta-methoxy-gamma-methylene-substituted, alpha,beta-unsaturated-gamma-butyrolactone ring of artapetalins A-C (1-3) was determined by 2D-NMR spectroscopic analyses. Two unusual simple butyrolactones, (+)-tulipalin B and (2R,3R)- 3-hydroxy-2-methylbutyrolactone were also isolated from this species.     

neo-Clerodane diterpenoids from Scutellaria barbata with cytotoxic activities

Three neo-clerodane diterpenoids, named barbatins A-C (1-3), and the neo-clerodane diterpenoid nicotinyl ester, named scutebarbatine B (4), were isolated from the whole plant of Scutellaria barbata D. Don. Their structures were elucidated by spectroscopic analyses (UV, IR, HRFAB-MS, 1D NMR and 2D NMR). In vitro, compounds 1-4 showed significant cytotoxic activities against three human cancer lines, namely, HONE-1 nasopharyngeal, KB oral epidermoid carcinoma, and HT29 colorectal carcinoma cells, with IC50 values in the range 3.5-8.1 microM.     

Flavonoids and other constituents of Hymenostegia afzelii (Caesalpiniaceae)

Phytochemical investigation of the stem bark and leaves of Hymenostegia afzelii resulted in the isolation of three new flavonoids, named afzelin A-C (1–3), together with five known compounds: 7,6-(2″,2″-dimethylpyrano)-3,5,4′-trihydroxyflavone, apigenin, 3-O-α-l-rhamnopyranosylcincholic acid, 3-O-β-d-glucopyranosylcincholic acid, and dodecanoic acid 1,1′-[(1S)-1-(hydroxymethyl)-1,2-ethanediyl] ester. The structures of 1–3 were determined by means of spectroscopic methods. Compounds 1–3 were tested in vitro for their preliminary cytotoxicity using the Artemia salina assay.