A Sesquiterpene, Clerodane Diterpenes and a Furanone from the Roots of Casearia Multinervosa (Flacourtiaceae/Salicaceae)

The roots of Casearia multinervosa (Flacourtiaceae/Salicaceae) have yielded the new compounds 10ε-acetoxyhumula-3,7-diene (1), (rel)-(2S,5S,6S,8R,9R,10S)-6-hydroxy-2-(2-methylbutanoyloxy)-clero-3,13(16),14-trien-4,5-dial (2), (rel)-(2R,5R,6R,8S,9S,10R)-6-methoxy-2-(2-methylbutanoyloxy)-clero-3,13(16),14-trien-4,5-dial (3), (rel) (2S,5S,6S,8R,9R,10S, 18R,19S)-18-acetoxy-18,19-epoxy-6-hydroxy-2-(2-methylbutanoyloxy)-19-methoxyclero-3,13(16),14-triene (4), and 3ε-(hexadec-11-enyl)-4ε-hydroxy-5-methylene-2,3-dihydrofuran-2-one (5).

New Clerodane and Halimane Diterpenes from the Leaves and Woody Stems of Casearia grayi (Flacourtiaceae/Salicaceae)

The leaves and woody stems of Casearia grayi (Flacourtiaceae/Salicaceae) have yielded several known flavone glycosides and a number of clerodane and halimane diterpenes, which were characterized mainly by analysis of NMR spectra. New compounds were identified as (rel)-2(R)-hydroxy-18(S),19(R)-diacetoxy-18,19-epoxy-4(S),5(S),8(S),9(S),10(R)-clerodan-13(16),14-dien-6-one (1), (rel)-2(R),18(S),19(R)-triacetoxy-18,19-epoxy-4(S),5(S),8(S),9(S),10(R)-clerodan-13(16),14-dien-6-one (4), (rel)-2(R)-hydroxy-18(S),19(R)-diacetoxy-18,19-epoxy-4(S),5(S),8(S),9(S),10(R)-clerodan-12(E),14-dien-6-one (7), (rel)-18(S),19(R)-diacetoxy-18,19-epoxy-2(R)-hydroxy-4(S),5(R),8(S),9(S),10(R)-clerodan-12(E),14-diene (8), and 16-hydroxy-halima-5(10),13(E)-dien-15-oic acid (9).

Novel C-Geranyl 7-Hydroxycoumarins from the Aerial Parts of Eriostemon tomentellus

From the aerial parts of Eriostemon tomentellus five coumarins have been isolated. These have been characterized as ostruthin (6-geranyl-7-hydroxycoumarin (1)) and the novel compounds, 8-geranyl-7-hydroxycoumarin (2), (E)-6-(7-hydroxy-3,7-dimethylocta-2,5-dienyl)- 7-hydroxycoumarin (3), (E)-6-(7-hydroperoxy-3,7-dimethylocta-2,5-dienyl)-7-hydroxycoumarin (4), and 6-(6-hydroxy-3,7-dimethylocta-2,7-dienyl)-7-hydroxycoumarin (5). In addition tembamide (2-{4-methoxyphenyl}-2-hydroxy-N-benzoylethylamine (6 ) was isolated and the l3C NMR spectrum reported for the first time.

Dammarane and Ceanothane Triterpenes from Zizyphus glabrata

From the leaves of Zizyphus glabrata, a new dammarane-type triterpene, pseudojujubogenin -3-O- β -D-glucopyranoside, along with the known ceanothane triterpenes, granulosic acid, ceanothic acid and daucosterol were isolated. The structures of the compounds were fully characterized by detailed NMR investigations including 1H and 13C NMR, HSQC, COSY, HMBC and NOESY experiments. In addition, the dammarane glycoside was tested for its potential to inhibit various bacteria and was found to possess significant bactericidal activity. The 1H, 13C and full 2D-NMR data on granulosic acid has also been presented. This is the first report on the chemical constituents of the leaves of Z. glabrata.

Flavonoids from Three Ethiopian Species of Premna

Two novel hepta-oxygenated flavonols have been isolated from the aerial parts of Premna

oligotricha and identified, primarily on the basis of N M R spectroscopy, as 3,5,5'-trihydroxy- 6,7,3',4'-tetram ethoxyflavone (2) and 3,5,7,5'-tetrahydroxy-6,3',4'-trim ethoxyflavone (3). Known flavonoids, with lower levels of oxygenation were obtained from two other Premna

species, P. schimperi and P. recinosa.

Factors affecting levels of some phenolic compounds, digestibility, and nitrogen content of the mature leaves ofBarteria fistulosa (Passifloraceae)

Levels of total phenolics, condensed tannins, acid detergent fiber, pepsin/cellulase digestibility, and nitrogen in mature leaves of 26 individuals of the ant-plant,Barteria fistulosa, have been determined. Analysis of the results in terms of the presence or absence of ants and the position of the branch from which the leaves were collected showed no relationship with concentrations of phenolics or fiber and only a weak relationship with digestibility and nitrogen. By contrast, light intensity strongly influenced levels of phenolics, notably condensed tannins, so that mature leaves of individuals growing in direct sunlight were less digestible and appeared to be of lower quality as food for herbivores than did mature leaves of individuals in shaded positions. Possible reasons for the variation in condensed tannin levels are discussed.

Light-induced variation in phenolic levels in foliage of rain-forest plants : II. Potential significance to herbivores

The allelochemic activity of the polyphenolics isolated from the leaves of four west African rain-forest plants,Acacia pennata, Cynometra leonensis, Diospyros thomasii, andTrema guineensis, was examined by means of protein precipitation experiments to estimate their specific activity as precipitants. Results indicated that light-induced phenol synthesis in the more heavily insolated foliage of a species led to greater protein-precipitating capacity in these leaves. It is considered doubtful that this produced a quantitative difference in protein availability to an herbivore as, on average, even in the most shaded leaves there was sufficient tannin present to precipitate all the foliar protein. However, taking into account the considerable variability inherent in the results obtained and the adaptations herbivores possess to circumvent the antinutritional properties of tannins, it was concluded that shaded foliage was generally likely to present a nutritionally more acceptable food package on a statistical basis but that acceptable leaves could be found from throughout the light continuum encountered in any of the species studied.

Chemical composition and cytotoxicity of oils and eremophilanes derived from various parts of Eremophila mitchellii Benth. (Myoporaceae)

A detailed investigation of the wood, leaf, branch and root oil of Eremophila mitchellii (Benth.) was carried out by a combination of GC-FID, GC-MS and NMR. The wood oil was composed predominantly of eremophilanes, a rare class of biologically active, bicyclic sesquiterpenoids. The root oil was also found to contain the eremophilanes together with the zizaene sesquiterpene, sesquithuriferone. 9-Hydroxy-1,7(11),9-eremophilatrien-8-one and the known 1(10),11-eremophiladien-9-one (eremophilone), 9-hydroxy-7(11),9-eremophiladien-8-one (2-hydroxyeremophilone), 8-hydroxy-11-eremophilen-9-one (santalcamphor), 8-hydroxy-10,11-eremophiladien-9-one, sesquithuriferone and 8-hydroxy-1,11-eremophiladien-9-one were purified and elucidated by NMR. Three approaches to the purification of the major eremophilanes from the wood oil are described. (+) Spathulenol, α-pinene, globulol, viridiflorene were the major constituents of the leaf oil. All of the essential oils and the eremophilanes exhibited cytotoxicity against P388D(1) mouse lymphoblast cells in-vitro.

Identification of Sakurasosaponin as a Cytotoxic Principle from Jacquinia flammea

The crude ethanolic extract of leaves, stem-bark and roots of J. flammea were tested for their cytotoxic effect against two mammalian cell lines (HeLa and RAW 264.7) and four bacterial species (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa). When tested at the concentration of 100 μg/mL, the root extract showed the highest cytotoxic activity against mammalian cells followed by the stem-bark extract while the leaves extract did not show significant activity. No antibacterial activity was detected for all extracts when tested up to 500 μg/disc in the disc diffusion assay. The cytotoxic root extract was subjected to fractionation using solvents of ascending polarity: petroleum ether, chloroform, ethylacetate, butanol and water. The water fraction which showed cytotoxic activity was further subjected to routine bioassay-guided fraction to lead to the isolation of sakurasosaponin as the active principle. The recorded IC50 value for sakurasosaponin was 11.3 ± 1.52 and 3.8 ± 0.25 μM (n=3) against HeLa and RAW 264.7 respectively. The identification of sakurasosaponin was based on analysis of spectroscopic data.

Identification of sakurasosaponin as a cytotoxic principle from Jacquinia flammea

The crude ethanolic extract of leaves, stem-bark and roots of J. flammea were tested for their cytotoxic effect against two mammalian cell lines (HeLa and RAW 264.7) and four bacterial species (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa). When tested at the concentration of 100 microg/mL, the root extract showed the highest cytotoxic activity against mammalian cells followed by the stem-bark extract while the leaves extract did not show significant activity. No antibacterial activity was detected for all extracts when tested up to 500 microg/disc in the disc diffusion assay. The cytotoxic root extract was subjected to fractionation using solvents of ascending polarity: petroleum ether, chloroform, ethylacetate, butanol and water. The water fraction which showed cytotoxic activity was further subjected to routine bioassay-guided fraction to lead to the isolation of sakurasosaponin as the active principle. The recorded IC50 value for sakurasosaponin was 11.3 +/- 1.52 and 3.8 +/- 0.25 microM (n=3) against HeLa and RAW 264.7 respectively. The identification of sakurasosaponin was based on analysis of spectroscopic data.

Prenylated alkylbisphenols from Grevillea whiteana

Eleven new bisresorcinols including four mixtures each of two isomers and one resorcinol/phloroglucinol derivative, together with five known resorcinols have been isolated from the ethyl acetate extract of stems of Grevillea whiteana. The new compounds were identified as 4-(3-hydroxy-3-methylbutyl)grebustol-B (10a), 4'-(3-hydroxy-3-methylbutyl)grebustol-B (10b), 4-(4-hydroxy-3-methylbutyl)grebustol-B (2a) and 4'-(4-hydroxy-3-methylbutyl) rebustol-B (2b), 2,2-dimethyldihydropyrano grebustol-B (11a) and iso-2,2-dimethyldihydropyranogrebustol-B (11b), 2,2-dimethyl-3xi-hydroxydihydropyranogrebustol-B (7a) and iso-2,2-dimethyl-3xi-hydroxydihydropyranogrebustol-B (7b), 15-(2-(4-hydroxy-3-methylbutyl)-resorcinol-5-yl)-1-(phloroglucinolyl)-9(Z)pentadecen-one (whiteanone) (4), 5,5'-(hexadecan-diyl)bisresorcinol (12) and 2-methyl-5,5'-(8(Z)-hexadecen-1,16-diyl)bisresorcinol (9). This is the first record of pyranobisresorcinols in the genus and the first report of a phloroglucinol terminal phenolic unit in any Grevillea species.

Prenylated Alkylbisphenols from Grevillea whiteana

Eleven new bisresorcinols including four mixtures each of two isomers and one resorcinol/phloroglucinol derivative, together with five known resorcinols have been isolated from the ethyl acetate extract of stems of Grevillea whiteana. The new compounds were identified as 4-(3-hydroxy-3-methylbutyl)grebustol-B (10a), 4′-(3-hydroxy-3-methylbutyl)grebustol-B (10b), 4-(4-hydroxy-3-methylbutyl)grebustol-B (2a) and 4′-(4-hydroxy-3-methylbutyl) rebustol-B (2b), 2,2-dimethyldihydropyrano grebustol-B (11a) and iso-2,2-dimethyldihydropyranogrebustol-B (11b), 2,2-dimethyl-3ξ-hydroxydihydropyranogrebustol-B (7a) and iso-2,2-dimethyl-3ξ-hydroxydihydropyranogrebustol-B (7b), 15-(2-(4-hydroxy-3-methylbutyl)-resorcinol-5-yl)-1-(phloroglucinolyl)-9( Z)pentadecen-one (whiteanone) (4), 5,5′-(hexadecan-diyl)bisresorcinol (12) and 2-methyl-5,5′-(8( Z)-hexadecen-1,16-diyl)bisresorcinol (9). This is the first record of pyranobisresorcinols in the genus and the first report of a phloroglucinol terminal phenolic unit in any Grevillea species.

Bisresorcinols and Arbutin Derivatives from Grevillea banksii R. Br

This work is part of a series of chemical investigations of the genus Grevillea. Two new arbutin derivatives, seven new bisresorcinols, including a mixture of two isomers, three known flavonol glycosides, and four known resorcinols, including a mixture of two homologous compounds, were isolated from the ethyl acetate extract of the leaves and methanol extract of the stems of Grevillea banksii. The new compounds were identified, on the basis of spectroscopic data, as 6′- O-(3-(2-(hydroxymethyl)acryloyloxy)-2-methylpropanoyl)arbutin (1), 6′- O-(2-methylacryloyl) arbutin (2), 5,5′-(4( Z)-dodecen-1,12-diyl)bisresorcinol (6), 2′-methyl-5,5′-(4( Z)-tetradecen-1,14-diyl)bisresorcinol (8), 2,2′-di(4-hydroxyprenyl)-5,5′-(6( Z)-tetradecen-1,14-diyl)bisresorcinol (9), 2-(4-acetoxyprenyl)-2′-(4-hydroxyprenyl) 5,5′-(6( Z)-tetradecen-1,14-diyl)bisresorcinol (10), 2-(4-acetoxyprenyl)-2′-(4-hydroxyprenyl)5,5′-(8( Z)-tetradecen-1,14-diyl)bisresorcinol (11), 5,5′-(10( Z)-tetradecen-1-on-diyl)bisresorcinol (12) and 5,5′-(4( Z)-tetradecen-1-on-diyl)bisresorcinol (13).

The current status of chemical systematics

Chemical systematics sets out to interpret the phylogenetic implications of the occurrence and distribution of secondary metabolites. In this review, a number of the major contributions from the 1960's and 1970's are identified and re-assessed in the light of recent evidence gained from DNA studies. It is shown that for the most part conclusions drawn on the basis of secondary metabolite distribution have been confirmed by the new techniques and it is concluded that chemical systematics can continue to provide useful insights into plant phylogeny.

Roles for secondary metabolites in plants

More than about 20,000 secondary metabolites have now been identified and their isolation and characterization continues at an undiminishing rate. Although the production of most secondary metabolites is under genetic control, in relatively few cases have convincing arguments been put forward to rationalize their occurrence in terms of primary metabolic functions. Whatever the initial reason for their evolution, secondary metabolites are now an essential part of the armamentaria used by plants in the battle to survive and propagate, to the extent where the expenditure of energy, photosynthate and nutrients for their production can be demonstrated to be 'cost effective' for that. Their role may centre on defence of the producer against predators (herbivores), pathogens or competitors, on aid to pollination or seed dispersal, or on protection against or adaptation to extrinsic abiotic factors, or on combinations of these functions. Various examples are given in support of this argument.

Cytotoxic and antiprotozoal activity of flavonoids from Lonchocarpus spp

A number of flavonoids isolated from Lonchocarpus spp. were evaluated for their antiprotozoal and cytotoxic activity. Flavone 6 and chalcone 7 were found to be the most active against Leishmania parasites and against cell cultures of Leukemia P388DI and adenocarcinoma prostate PC-3.

New pseudan (2-alkyl-4(1H)-quinolinone) alkaloids from Boronia ternata var. elongata and Boronia alulata (Rutaceae)

The aerial parts of Boronia ternata var. elongata from western Australia has yielded three new 2-acyl-4(1H)-quinolinone alkaloids, characterised as 2-n-pentyl-4(1H)-quinolinone, 1-methyl-2-n-pentyl-4(1H)-quinolinone and 1-methyl-2-(1 xi-methyl)-propyl-4(1H)-quinolinone, as well as known alkaloids of this class and a furoquinoline alkaloid. Boronia alulata, from northeast Queensland, also yielded 2-n-pentyl-4(1H)-quinolinone together with the known 2-n-propyl-4(1H)-quinolinone. Both species are assigned to Boronia section Valvatae which, alone among the sections of Boronia, appears to be characterised by the presence of alkaloids.

M4 agonists/5HT7 antagonists with potential as antischizophrenic drugs: Serominic compounds

Chronic low-dose treatment of rats with the psychomimetic drug, phencyclidine, induces regionally specific metabolic and neurochemical changes in the CNS that mirror those observed in the brains of schizophrenic patients. Recent evidence suggests that drugs targeting serotoninergic and muscarinic receptors, and in particular 5-HT(7) antagonists and M(4) agonists, exert beneficial effects in this model of schizophrenia. Compounds that display this combined pattern of activity we refer to as serominic compounds. Based upon leads from natural product screening, we have designed and synthesised such serominic compounds, which are principally arylamidine derivatives of tetrahydroisoquinolines, and shown that they have the required serominic profile in ligand binding assays and show potential antipsychotic activity in functional assays.

Volatile chemical constituents of Piper aduncum L and Piper gibbilimbum C. DC (Piperaceae) from Papua New Guinea

Exhaustive hydro-distillation of the leaves of Piper aduncum and fruits of Piper gibbilimbum (Piperaceae) afforded colorless and pale orange colored oils in 0.35 and 0.30 % yields, respectively. Detailed chemical analysis by GC/MS indicated the volatile constituents of Piper aduncum to be composed of dill apiole (43.3%), beta-caryophyllene (8.2%), piperitione (6.7%) and alpha-humulene (5.1%), whilst the oil of P. gibbilimbum is dominated by the gibbilimbols A-D (74.2%), with the remaining major constituents being the terpenes camphene (13.6%) and alpha-pinene (6.5%).

Alkaloids from the stem bark of an Australian population of Zanthoxylum ovalifolium

The aerial parts of Zanthoxylum ovalifolium (Rutaceae) have yielded the two novel benzo[c]phenanthridine alkaloids terihanine (8-demethylnitidine) and isoterihanine (9-demethylnitidine) together with nitidine, the unusual furoquinoline 5-methoxydictamnine, canthin-6-one and several common furocoumarins. The finding of benzo[c]phenanthridine and furoquinoline alkaloids in Australian material of this species confirms its chemical homogeneity throughout its range from India to Australia.

Triumphalone, a diketone from the volatile oil of the leaves of Melaleuca triumphalis, and its spontaneous conversion into isotriumphalone

The major component (35-65%) of the volatile oil obtained by steam distillation of the leaves of Melaleuca triumphalis has been identified as (rel)-1beta-pentyl-1alpha,6alpha-dihydroxy-3,3,5,5-tetramethylcyclohexa-2,4-dione (trivial name triumphalone). Relative stereochemistry was established by nuclear Overhauser experiments and X-ray studies on the 2-(3,5-dinitrobenzoic acid) derivative. The remainder of the oil was composed of mono- and sesquiterpene hydrocarbons and alcohols. On prolonged standing the presence of a rearrangement product of triumphalone was observed which was characterized as (rel)-1beta-pentyl-1alpha,3alpha-dihydroxy-4,4,6,6-tetramethylcyclohexa-2,5-dione (trivial name isotriumphalone), presumably arising from an acid catalyzed shift of the pentyl group from C-1 to C-2.

Antiprotozoal and cytotoxic naphthalene derivatives from Diospyros assimilis

Chemical investigation of the roots of Diospyros assimilis had led to the isolation and characterization of six naphthalene derivatives, two 2-naphthaldehyes, namely 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde 1, 4-hydroxy-5-methoxy-2-naphthaldehye 2, its related isomer 5-hydroxy-4-methoxy-2-naphthaldehyde 3 and three commonly occurring naphthoquinones, diospyrin 4, 8'-hydroxyisodiospyrin 5 and the simple monomer, plumbagin 6. Their chemical structures were established by detailed NMR investigations including 1H and 13C NMR, HSQC, HMBC and NOESY experiments. In addition, the naphthalene derivatives 1-5 were evaluated for their in vitro antiprotozoal activity against protozoan parasites belonging to the genera Trypanosoma, Leishmania and Plasmodium. Among the tested compounds, naphthaldehyde 1 showed moderate inhibition of the growth of the parasites, T. brucei, T. cruzi, L. donovani with IC50 values of 19.82, 12.28 and 38.78 microM and displayed cytotoxicity towards rat skeletal myoblasts (L-6 cells) with IC50 of 174.94 microM, while 2 and 3 were found to be comparatively less active to 1. The dimeric quinones 4 and 5 exhibited good activity against T. brucei and L. donovani with IC50 of 1.12 and 8.82 microM and 12.94 and 16.66 microM respectively.

Mono and dimeric naphthalene derivatives from the roots ofDiospyrosassimilis

Three 2-naphthaldehydes, including the novel 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde, the simple naphthoquinone plumbagin and the dimeric naphthoquinones diospyrin and 8'-hydroxyisodiospyrin have been isolated from the roots of Diospyrosassimilis and their structures established by spectroscopic analysis.

A new coumarin and triterpenes from Malaysian Micromelum minutum

A new coumarin, 8,4''-dihydroxy-3'',4''-dihydrocapnolactone-2',3'-diol (1) and two known triterpenes, 5(6)-gluten-3-one (2) and 5(6)-gluten-3alpha-ol (3) were isolated from the leaves of Micromelum minutum (Rutaceae) collected from Sepilok, Sabah, Malaysia and their structures were characterized by spectroscopic methods.

Three ent-trachylobane diterpenes from the leaf exudates of Psiadia punctulata

Three ent-trachylobane diterpenes have been isolated from the leaf exudates of Psiadia punctulata and characterised as 6alpha,17,19-ent-trachylobantriol; 2alpha,18,19-ent-trachylobantriol; and 2beta,6alpha,18,19-ent-trachylobantetraol. The structures were determined on the basis of spectroscopic evidence.

New phenolic glycosides from the stems and leaves ofCasearia multinervosa

Four phenolic glycosides (1-4), including two new ones (3 and 4), have been isolated from the stems of Casearia multinervosa and identified as arbutin (1), 4-O-E-caffeoylarbutin (2), 4-O-E-coumaroylarbutin (3) and 4-O-E-feruloylarbutin (4), respectively. In addition, the two known phenolic glycosides (1 and 2) were also isolated from the leaves. Structures were elucidated on the basis of spectroscopic evidence. Compounds 1-4 were tested for cytotoxicity against the P388 mouse lympholytic cell line by an ATP Lite-M assay method and showed mild to moderate activity.

Novel Metabolites from the Stem Bark of Brombya sp. Nova (Gap Creek) (Rutaceae)

Two piperonyl derivatives, seven coumarins and two furoquinoline alkaloids were isolated from the aerial parts of a new species of Brombya [Brombya sp. nov. (Gap Creek) (Rutaceae)]. Three of the compounds were new natural metabolites; 7-(3,4-methylenedioxyphenyl)octene-2-one (7,8-dehydromoskachen D), the coumarin 6-(1ξ,2ξ,3-trihydroxy-3-methylbutyl)-7-hydroxy-2H-1-benzopyran-2-one, and the furoquinoline alkaloid 4,5,6,7-tetramethoxyfuro[2,3-b]quinoline (5,6,7-trimethoxydictamnine). The secondary metabolites isolated in this study are typical of the Rutaceae, contrasting with earlier studies on the only other species of Brombya, B. platynema, which yielded only brombyins, for which 7,8-dehydromoskachen D is a possible precursor.

Inhibition of COXs and 5-LOX and activation of PPARs by Australian Clematis species (Ranunculaceae)

The species of Clematis (Ranunculaceae) have been traditionally used for inflammatory conditions by indigenous Australians. We have previously reported that the ethanol extract of Clematis pickeringii inhibited COX-1. In this study, we examined the ethanol extracts and fractions of three Clematis species, Clematis pickeringii, Clematis glycinoides and Clematis microphylla, on cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). We further examined the activating effects on the protein expression of peroxisome proliferator-activated receptor alpha (PPARalpha) and gamma (PPARgamma) in HepG2 cells. The ethanol extracts of three Clematis species inhibited the activities of COX-1, COX-2 and 5-LOX in the different extents. The stem extract of Clematis pickeringii showed the highest inhibitory activities among the three species on COX-1, COX-2 and 5-LOX with the IC(50) values of 73.5, 101.2 and 29.3 microg/mL. One of its fractions also significantly elevated PPARalpha expression by 173, 280 and 435% and PPARgamma expression by 140, 228 and 296% at 4, 8 and 16 microg/mL, respectively.

Phebaclavin I, a novel 3-prenylated coumarin, and trichoclin acetate, a new natural furocoumarin, from the aerial parts of Phebalium aff. tuberculosum (Rutaceae)

Phebaclavin I, a novel 3-prenylated coumarin, was isolated from the aerial parts of Phebalium aff. tuberculosum (Rutaceae) together with five known related compounds, Phebaclavin A, B, D, G, H. The structure of phebaclavin I was established by spectroscopic methods. Several other known coumarins were obtained, including trichoclin acetate, a furocoumarin isolated for the first time from a natural source, but previously described from acetylation of trichoclin.

Novel Polyketide Metabolites from Streptomyces rimosus Mutant Strain R1059

Three novel polyketide metabolites were isolated from laboratory-scale fermentation of the Streptomyces rimosus mutant strain R1059. Structural elucidation of the compounds was based on NMR experiments. The compounds were characterized as naphthalene derivatives: (rel)-4beta,8-dihydroxy-3alpha-hydroxymethyl-4alpha-methyl-1,2,3,4-tetrahydronaphthalene1-one (1), 4xi8-dihydroxy-3-hydroxymethyl-4xi-methyl-1,4-dihydronaphthalene-1-one (2) and (rel)-4beta,8-dihydroxy-3alpha-O-[alpha-glucopyranosyl]hydroxymethyl-4alpha-methyl-1,2,3,4-tetrahydronaphthalene-1-one (3). The compounds isolated appear to be derived via a shorter polyketide backbone than oxytetracycline (4), the normal end-product made by the parent of this strain. Compound 3 was the glucoside of 1 and must be formed as a post-PKS reaction by the activation of a glycosyl transferase, which has not been reported in this species before.

Cytotoxic clerodane diterpenes from Glossocarya calcicola

Three clerodane diterpenes were isolated and identified from leaf extract of Glossocarya calcicola. Compound has been characterised as (rel)-10betaH-trans-12xi-(2-methylbut-2(E)-enoyl)-1beta-(isobutanoyl)-6alpha,13xi-dihydroxyclerodan-4(20),8(18)-dien-7,15-dione-15,16-oxide, to which we have assigned the trivial name calcicolin-A. The other two compounds had the same skeletal structure and C-12 substituent but in compound, the C-1 esterifying group becomes 2-methylbut-2(E)-enoic acid and in it becomes 2-methylbutanoic acid. Although anti-insect activity was not observed for G. calcicola, cytotoxicity against insect and human carcinoma cell lines was detected.

Ablation of the otcC Gene Encoding a Post-polyketide Hydroxylase from the Oxytetracyline Biosynthetic Pathway in Streptomyces rimosus Results in Novel Polyketides with Altered Chain Length

Oxytetracycline (OTC) is a 19-carbon polyketide antibiotic made by Streptomyces rimosus. The otcC gene encodes an anhydrotetracycline oxygenase that catalyzes a hydroxylation of the anthracycline structure at position C-6 after biosynthesis of the polyketide backbone is completed. A recombinant strain of S. rimosus that was disrupted in the genomic copy of otcC synthesized a novel C-17 polyketide. This result indicates that the absence of the otcC gene product significantly influences the ability of the OTC "minimal" polyketide synthase to make a polyketide product of the correct chain length. A mutant copy of otcC was made by site-directed mutagenesis of three essential glycine codons located within the putative NADPH-binding domain. The mutant gene was expressed in Escherichia coli, and biochemical analysis confirmed that the gene product was catalytically inactive. When the mutant gene replaced the ablated gene in the chromosome of S. rimosus, the ability to make a 19-carbon backbone was restored, indicating that OtcC is an essential partner in the quaternary structure of the synthase complex.

Acaricidal and cytotoxic activities of extracts from selected genera of Australian Lamiaceae

Crude foliar extracts of 67 species from six subfamilies of Australian Lamiaceae were screened by whole organism contact toxicity on the polyphagous mite Tetranychus urticae Koch (Acari: Tetranychidae) by using a Potter precision spray tower. Cytotoxicity assessments against insect cell lines from Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) also were made. The Spodoptera cell line was more susceptible to extracts than the Drosophila cellline. No direct correlation was observed between the two screening methods, but several interesting relationships were identified. Extracts from subfamilies Ajugoideae, Scutellarioideae, Chloanthoideae, Viticoideae and Nepetoideae showed acaricidal activity, whereas only those from Ajugoideae and Nepetoideae displayed potent cytotoxic effects. A range of activities was observed for the 25 species of Plectranthus, 14 of which showed moderate-to-high contact toxicity against T. urticae. Overall, the lowest toxicity was observed for extracts from the plant subfamily Prostantheroideae, which showed little contact toxicity or cytotoxicity for the 18 extracts studied.

3-Substituted Coumarins from the Twigs of Rhadinothamnus rudis ssp. amblycarpus

The twigs of Rhadinothamnus rudis ssp. amblycarpus (Phebalium rude ssp. amblycarpum) yielded three new 3-substituted coumarins: rudicoumarin A-C (1- 3). Their structures were established on the basis of their NMR and mass spectral data. In addition, ten other known compounds were also isolated, including phebaclavin I, schinicoumarin, seselin, and seven linear furocoumarins.

Screening of some Australian Flacourtiaceae species for in vitro antioxidant, cytotoxic and antimicrobial activity

A total of 27 methanol extracts obtained from different plant parts of 10 species of rain forest trees belonging to four genera of the Flacourtiaceae and originating from Australia were investigated. In vitro cytotoxicity was measured by an ATP Lite-M assay method against the mouse P388 lymphocytic leukemia cell line. The total antioxidant activity has been assessed based on scavenging activity of stable ABTS free radicals. The minimum inhibition concentration (MIC) was determined by the dilution method performed in 96 well plates against four different microbes. The leaf extract of Casearia sp. (RB 3051), mature stem extract of Casearia grayi and stem extract of Scolopia braunii were found to have most antioxidant activity (IC50 = 2.9 microg/ml), cytotoxic activity (LC50 = 0.89 microg/ml) and antimicrobial activity against all four different microbes, respectively. The results obtained suggested that among the four genera studied Casearia is the most promising in respect of finding significant antioxidant, cytotoxic and also antimicrobial activity.

A new anti-inflammatory glucoside from Ficus racemosa L

Bioassay-guided fractionation of the ethanol extract of Ficus racemosa resulted in the identification of a new compound (rel)-4,6-dihydroxy-5-[3-methyl-(E)-propenoic acid-3-yl]-7-beta-glucopyranosyl-[2alpha,3beta-dihydrobenzofuran]-(3,2: b)-[4alpha,5beta-dihydroxy-6alpha-hydroxymethyltetrahydropyran] (racemosic acid). Racemosic acid showed potent inhibitory activity against COX-1 and 5-LOX in vitro with IC50 values of 90 and 18 microM, respectively. Racemosic acid also demonstrated a strong antioxidant activity to scavenge ABTS free radical cations with an IC50 value of 19 microM. In addition, cytotoxic effects of the extracts of F. racemosa were investigated in vitro using the ATP-based luminescence assay and results showed no cytotoxicity on the cell lines skin fibroblasts (1BR3), human Caucasian hepatocyte carcinoma (Hep G2) and human Caucasian promyelocytic leukaemia (HL-60). Bergenin was also isolated from the same active fraction.