Antiparasitic, nematicidal and antifouling constituents from Juniperus berries.

A bioassay-guided fractionation of Juniperus procera berries yielded antiparasitic, nematicidal and antifouling constituents, including a wide range of known abietane, pimarane and labdane diterpenes. Among these, abieta-7,13-diene (1) demonstrated in vitro antimalarial activity against Plasmodium falciparum D6 and W2 strains (IC(50) = 1.9 and 2.0 microg/mL, respectively), while totarol (6), ferruginol (7) and 7beta-hydroxyabieta-8,13-diene-11,12-dione (8) inhibited Leishmania donovani promastigotes with IC(50) values of 3.5-4.6 microg/mL. In addition, totarol demonstrated nematicidal and antifouling activities against Caenorhabditis elegans and Artemia salina at a concentration of 80 microg/mL and 1 microg/mL, respectively. The resinous exudate of J. virginiana afforded known antibacterial E-communic acid (4) and 4-epi-abietic acid (5), while the volatile oil from its trunk wood revealed large quantities of cedrol (9). Using GC/MS, the two known abietanes totarol (6) and ferruginol (7) were identified from the berries of J. procera, J. excelsa and J. phoenicea.

neo-Clerodane diterpenoids from Teucrium oliverianum and structure revision of teucrolin E.

The aerial parts of Teucrium oliverianum yielded two neo-clerodane diterpenoids, teucrolin F and G, together with the known teucrolin E. The previously proposed structure for teucrolin E was revised so that it contains a tetrahydrofuran ring instead of an oxetane ring. This was based on analysis of the NMR spectroscopic data of its diacetate, including its NOE spectra. In addition, the structural assignments of the new diterpenoids were based on 1H and 13C NMR spectroscopic studies, mainly 2D NMR experiments, including homonuclear and heteronuclear correlations.

Biotransformation of vulgarin.

Using a standard two-stage fermentation technique, the fungus Beauveria bassiana (ATCC 7159) was found to convert the eudesmanolide vulgarin (1) to 1α,4α-dihydroxy-5αH,6,11ßH-eudesman-6,12-olide (2). The use of the yeastHansenula anomala ATCC 20170 instead, produced the less polar 4α-hydroxy-1-oxo-5αH,6,11ßH-eudesman-6,12-olide(3), in addition to the more polar 3α,4α-dihydroxy-1-oxo-5αH,6,11ßH-eudesman-6,12-olide (4). These metabolites were characterized on the basis of their spectral data and the identity of 4 was further confirmed by chemical synthesis.

Antimycobacterial constituents from Juniperus procera, Ferula communis and Plumbago zeylanica and their in vitro synergistic activity with isonicotinic acid hydrazide.

The synergistic activity of antimycobacterial constituents from Saudi plants was evaluated in combination with isonicotinic acid hydrazide (INH) against four atypical organisms, namely, Mycobacterium intracellulare, M. smegmatis, M. xenopei and M. chelonei. The potency of INH was increased four-fold, using an in vitro checkerboard method, against each mycobacteria when tested with a subtoxic concentration of the totarol, isolated from J. procera. The MIC values of totarol, ferulenol (from Ferula communis) and plumbagin (from Plumbago zeylanica) were thus lowered from 1.25-2.5 to 0.15-0.3 microg/mL due to synergism with INH. When tested against the resistant strain of M. tuberculosis H37Rv, plumbagin and 7beta-hydroxyabieta-8,13-dien-11,12-dione exhibited inhibitory activity at <12.5 microg/mL, while others were inactive at this concentration.

Cytotoxic sesquiterpene lactones from Centaurothamnus maximus and Vicoa pentanema.

The aerial parts of Centaurothamnus maximus yielded three cytotoxic guaianolides, chlorojanerin (1), cynaropicrin (2) and janerin (3). The structure elucidation of 1-3 was based on (1)H and (13)C NMR data, mainly 2D-NMR (1)H-(1)H COSY and (1)H-(13)C HETCOR experiments. Compounds 1-3 showed in vitro cytotoxic activity against human cancer cell lines of malignant melanoma (SK-MEL), epidermoid (KB), ductal (BT-549) and ovarian (SK-OV-3) carcinomas with IC(50) values of 2-6 microgram/mL. In addition, 12 sesquiterpene lactones (4-15), isolated previously from the aerial parts of Vicoa pentanema, were evaluated for cytotoxic and antimicrobial activities. 2alpha- Acetoxy-3beta-hydroxyalantolactone (10) and 8beta-hydroxyparthenolide (14) were found to be the main cytotoxic agents (IC(50) values of 2-6 microgram/mL against SK-MEL, BT-549 and SK-OV-3), while lactones 4, 5, 11 and 15 selectively inhibited the growth of human malignant melanoma (IC(50) value of 3.6-7.3 microgram/mL). Cell aggregation and cell adhesion assays, using HL-60 and HeLa cell lines, evaluated the effect of cytotoxic constituents 1-3, 10 and 14 on immune response and inflammation.

Cytotoxic and antioxidant activities of alkylated benzoquinones from Maesa lanceolata.

The natural and semi-synthetic analogs of substituted 1,4-benzoquinones were evaluated for in vitro cytotoxic and antioxidant activities. Maesanin, dihydromaesanin, maesanin dimethyl ether and isomeric mixtures of 3-[(Z)-10'-pentadecenyl]-benzoquinone derivatives exhibited cytotoxic activity against HL-60 cell line (IC50 values 4.5, 2.2, 0.43 and 2.8 microg/mL, respectively), while it was found to be inactive against ROS (Reactive Oxygen Species) generation in HL-60. In contrast, the isomeric acylated benzoquinones with shorter alkyl substituents, namely, 2-acetoxy-5-hydoxy-6-methyl-3-tridecyl-1,4-benzoquinone and 2-hydoxy-5-acetoxy-6-methyl-3-tridecyl-1,4-benzoquinone showed most prominent antioxidant and antiproliferative effect on HL-60 (IC50 values 6.2 and 2.2 microg/mL, respectively), as well as cytotoxicities against SK-MEL, KB, BT-549 and SK-OV-3 carcinomas (IC50 values <1.1-4.2 microg/mL). All benzoquinones were found to be inactive against cell aggregation and cell adhesion assays, thus showing no effect on immune responses and inflammation.

HPLC fingerprinting and estimation of the bioactive components of Clutia richardiana L. as a potential hypoglycemic herbal tea.

Clutia richardiana L. is a traditional medicinal herb with demonstrated hypoglycemic effects. An HPLC method (Luna((R)) C(18) column, gradient elution, UV detection at 220 nm) has been utilized to determine the levels of the major diterpenes of C. richardiana in extracts obtained by using three different solvents. Extraction with the organic solvents methanol and acetonitrile was more efficient than aqueous extraction with hot water, but nine markers could be detected equally in all extracts. The aqueous extract was non-toxic against a number of human cell lines, which is a promising indication for its use as a safe and effective antidiabetic herbal preparation.

Antioxidant effect of flavonoids on DCF production in HL-60 cells.

A fluorometric microplate assay was performed for the detection of respiratory burst activity in a human leukaemia cell line HL-60 by assessing oxidation of 2',7'-dichloro fluorescin diacetate (DCFH-DA). This method is based on the detection of DCFH oxidation due to the presence of hydrogen peroxide. In the present study, the antioxidant activity of a number of structurally related flavonoids of plant origin and some of their microbial transformation products (1-18) were evaluated.

Deoxyartemisinin derivatives from photooxygenation of anhydrodeoxydihydroartemisinin and their cytotoxic evaluation.

Photooxygenation of anhydrodeoxydihydroartemisinin (4) followed by chromatographic separation of the reaction mixture yielded the new compounds alpha- (5) and beta-hydroperoxydeoxyartemisitene (8) and the formate ester 7, together with two previously reported compounds, 6 and 9. Reduction of 5 using polymer-bound triphenylphosphine afforded the new compound dihydrodeoxyartemisitene (10). Treatment of 10 with a catalytic amount of BF(3)-OEt(2) yielded the C(2)-symmetrical dimer bis(dihydrodeoxyartemisitene) ether (11) and two new compounds, dihydrodeoxyartemisitene methyl ether (12) and the dimer 13, as minor products. Dehydroacetoxylation of 5 using acetic anhydride in pyridine afforded deoxyartemisitene (14). The identities of the new compounds (5, 7, 8, 10-14) were deduced from their spectral data and by chemical derivatization. The stereochemistry of dimer 11 was defined on the basis of X-ray crystallographic analysis. All compounds were evaluated in vitro in the National Cancer Institute drug-screening program consisting of 60 human cancer cell lines derived from nine different tissues. Of the compounds tested, deoxyartemisitene (14) demonstrated significant cytotoxicity against a number of human cancer cell lines.