Bioactive extracts fromSenecio samnitumHuet

The antimicrobial and cytotoxic activities of extracts from Senecio samnitum Huet are reported. Extracts from S. samnitum were able to inhibit the in vitro proliferation of four human tumor cell lines. The dichloromethane extract demonstrated effective cytotoxic activity with IC50 of 22.89 microg mL(-1) on the Caco-2 cell line and the EtOAc extract had IC50 value of 11.91 microg mL(-1) against the COR-L23 cell line. The n-hexane extract displayed the best antibacterial activity against Gram positive bacteria, particularly Staphylococcus aureus. The antifungal activity of all extracts was also seen, particularly against the dermatophytes Trichophyton tonsurans and Microsporum gypseum for the methanol and n-hexane extracts.

In vitrocytotoxicity activity on several cancer cell lines of acridone alkaloids andN-phenylethyl-benzamide derivatives fromSwinglea glutinosa(Bl.) Merr

The methanol extract from the stems and fruits of Swinglea glutinosa (Rutaceae) afforded 11 known acridone alkaloids and three N-phenylethyl-benzamide derivatives, glycocitrine-IV, 1,3,5-trihydroxy-4-methoxy-10-methyl-2,8-bis(3-methylbut-2-enyl)acridin-9(10H)-one, 1,3,5- trihydroxy-2,8-bis(3-methylbut-2-enyl)-10-methyl-9-acridone, citbrasine, citrusinine-II, citrusinine-I, 5-dihydroxyacronycine, pyranofoline, 3,4-dihydro-3,5,8-trihydroxy-6-methoxy-2,2,7-trimethyl-2H-pyrano[2,3-a]acridin-12(7H)-one, 2,3-dihydro-4,9-dihydroxy-2-(2-hydroxy-propan-2-yl)-11-methoxy-10-methylfuro[3,2-b]acridin-5(10H)-one, bis-5-hydroxyacronycine, N-(2-{4-[(3,7-dimethylocta-2,6-dien-1-yl)oxy]phenyl}ethyl)benzamide, N-(2-{4-[(3,7-dimethyl-4-acethyl-octa-2,6-dien-1-yl)oxy]phenyl}ethyl)benzamide, and severine acetate. All compounds isolated were examined for their activity against three cancer cell lines: human lung carcinoma (COR-L23), human breast adenocarcinoma (MCF7), human melanoma (C32), and normal human fetal lung cell line, MRC-5. The acridones tested exhibited weak cytotoxicity but the amides showed moderate nonselective cytotoxic activity.

mTOR and cancer therapy

Proteins regulating the mammalian target of rapamycin (mTOR), as well as some of the targets of the mTOR kinase, are overexpressed or mutated in cancer. Rapamycin, the naturally occurring inhibitor of mTOR, along with a number of recently developed rapamycin analogs (rapalogs) consisting of synthetically derived compounds containing minor chemical modifications to the parent structure, inhibit the growth of cell lines derived from multiple tumor types in vitro, and tumor models in vivo. Results from clinical trials indicate that the rapalogs may be useful for the treatment of subsets of certain types of cancer. The sporadic responses from the initial clinical trials, based on the hypothesis of general translation inhibition of cancer cells are now beginning to be understood owing to a more complete understanding of the dynamics of mTOR regulation and the function of mTOR in the tumor microenvironment. This review will summarize the preclinical and clinical data and recent discoveries of the function of mTOR in cancer and growth regulation.

alpha-Amylase inhibitory activity of some Malaysian plants used to treat diabetes; with particular reference to Phyllanthus amarus

Extracts of six selected Malaysian plants with a reputation of usefulness in treating diabetes were examined for alpha-amylase inhibition using an in vitro model. Inhibitory activity studied by two different protocols (with and without pre-incubation) showed that Phyllanthus amarus hexane extract had alpha-amylase inhibitory properties. Hexane and dichloromethane extracts of Anacardium occidentale, Lagerstroemia speciosa, Averrhoa bilimbiPithecellobium jiringa and Parkia speciosa were not active when tested without pre-incubation. Extraction and fractionation of Phyllanthus amarus hexane extract led to the isolation of dotriacontanyl docosanoate, triacontanol and a mixture of oleanolic acid and ursolic acid. Dotriacontanyl docosanoate and the mixture of oleanolic acid and ursolic acid are reported from this plant species for the first time. All compounds were tested in the alpha-amylase inhibition assay and the results revealed that the oleanolic acid and ursolic acid (2:1) mixture was a potent alpha-amylase inhibitor with IC(50)=2.01 microg/ml (4.41 microM) and that it contributes significantly to the alpha-amylase inhibition activity of the extract. Three pure pentacyclic triterpenoids, oleanolic acid, ursolic acid and lupeol were shown to inhibit alpha-amylase.

Predicted mechanisms of resistance to mTOR inhibitors

The serine/threonine kinase, mTOR (mammalian Target of Rapamycin) has become a focus for cancer drug development. Rapamycins are highly specific inhibitors of mTOR and potently suppress tumour cell growth by retarding cells in G1 phase or potentially inducing apoptosis. Currently, both rapamycin and several analogues are being evaluated as anticancer agents in clinical trials. Results indicate that many human cancers have intrinsic resistance and tumours initially sensitive to rapamycins become refractory, demonstrating acquired resistance. Here, we consider mechanisms of resistance to inhibitors of mTOR.

Hydroperoxysterols from the Brazilian Brown Seaweeds Dictyopteris justii and Spatoglossum schroederi (Dictyotales): A Defensive Strategy against Herbivory

Extracts of the Brazilian brown seaweeds Dictyopteris justii and Spatoglossum schroederi showed the presence of a cytotoxic mixture of 24R- and 24S-epimers of 24-hydroperoxy-24-vinylcholesterol (1). The derivation of 1 from fucosterol is proposed. Laboratory experiments assessed the anti-herbivory properties against the crab, Pachygrapsus transversus, of the crude extract and the epimers of 1 found in D. justii. The crude extract did not inhibit feeding, but the mixture of 1 epimers had a significant inhibitory effect. We propose that these unusual sterol compounds cannot be easily converted to assimilable compounds by this crustacean, thus acting as a defensive strategy for the seaweed against herbivory.

Fibroblast growth stimulation by extracts and compounds of Onosma argentatum roots

The roots of Onosma argentatum are used traditionally in Turkey for wound healing and burns. The n-hexane-dichloromethane extract of the roots, and four shikonin derivatives (deoxyshikonin, acetyl shikonin, 3-hydroxy-isovaleryl shikonin and 5,8-O-dimethyl acetyl shikonin) isolated from the n-hexane-dichloromethane extract were investigated for their ability to stimulate the growth of human amnion fibroblasts. A range of concentrations was studied and the extract found to stimulate the growth of human amnion fibroblasts in vitro at 0.1 microg/mL whilst 5,8-O-dimethyl acetyl shikonin had the same effect at 0.05-5 microg/mL, although cytotoxicity was observed at 50 microg/mL for all samples. The extract and all the other isolated compounds showed cytotoxicity at 10 microg/mL with the extract and 3-hydroxy-isovaleryl shikonin showing cytotoxicity at 5 microg/mL. It is suggested that any wound healing effect of the roots of Onosma argentatum might be partly due to an additive effect of the shikonin derivatives present.

Anti-inflammatory activities of the methanol extracts and an isolated furanoditerpene constituent of Sphenocentrum jollyanum Pierre (Menispermaceae)

Sphenocentrum jollyanum crude extracts and an isolated constituent were evaluated for anti-inflammatory activity using the carrageenan-induced hind paw oedema of healthy adult albino rats and utilizing the oral route of administration. The fruit methanol extract (79.58% inhibition at 200 mg kg(-1)) gave a higher anti-inflammatory activity than the root extract (53.75% inhibition at 200 mg ml(-1)). Further purification of the most active fruit methanol extract (MFE) led to the isolation of three furanoditerpenes identified as columbin, isocolumbin, fibleucin (uv, ir, nmr and ms) as well as a flavonoid-rich fraction (FDE). Both columbin (67.08% inhibition at 20 mg kg(-1), p<0.05) and FDE (76.25% inhibition at 200 mg kg(-1); p<0.05) gave significant anti-inflammatory activities in comparable range with reference acetylsalicylic acid (72.5% inhibition at 100 mg kg(-1)). The results provide some justification for the folkloric uses of Sphenocentrum jollyanum in the treatment of inflammatory-based diseases across the West African sub-region.

Antimicrobial, resistance-modifying effects, antioxidant and free radical scavenging activities ofMezoneuron benthamianum Baill.,Securinega virosa Roxb. &Wlld. andMicroglossa pyrifolia Lam

Mezoneuron benthamianum, Securinega virosa and Microglossa pyrifolia are used in folk medicine in Ghana for the treatment of dermal infections and wounds. Petroleum spirit, chloroform and ethanol extracts of the plants were tested for antimicrobial activity against a battery of organisms using the agar well diffusion technique and a serial dilution microassay. The resistance modifying activities of these extracts on standard antibiotics against Staphylococcus aureus possessing efflux mechanisms of resistance have also been assessed. A 4-fold potentiation of the activity of norfloxacin was observed for ethanol and chloroform extracts of M. benthamianum and S. virosa, respectively, whilst the petroleum spirit extract resulted in a 2-fold potentiation with minimum inhibitory concentration (MIC) values in the range 8-16 microg/mL. Ethanol extracts of all three species, the petroleum spirit extract of M. benthamianum and the chloroform extracts of M. benthamianum and S. virosa, showed interesting antimicrobial activities. Antioxidant and free radical scavenging activities using DPPH spectrophotometric and TBA lipid peroxidation assays were also conducted. Of the five extracts that showed antioxidant activities, the petroleum spirit and chloroform extracts of M. benthamianum rated most highly by displaying strong free radical scavenging activity with IC50 values of 15.33 and 19.72 microg/mL, respectively. Lipid peroxidation inhibition provided by the same two extracts also produced the lowest IC50 values for all the extracts tested, of 23.15 and 30.36 microg/mL. These findings therefore give some support to the ethnopharmacological use of the plants in the treatment of various skin diseases and wounds, as well as demonstrating the potential of some of the plants as sources of compounds possessing the ability to modulate bacterial multidrug resistance.

In-vitro antiproliferative effects on human tumour cell lines of extracts and jacaranone from Senecio leucanthemifolius Poiret

We have studied the cytotoxic activity of extracts and jacaranone from Senecio leucanthemifolius Poiret. Extracts from S. leucanthemifolius were able to inhibit the in-vitro proliferation of a series of human tumour cell lines. The dichloromethane extract demonstrated effective cytotoxic activity with an IC50 of 20.1 microg mL(-1) on the large cell carcinoma cell line COR-L23. The ethyl acetate extract showed an IC50 value of 5.0 microg mL(-1) and the butanol extract an IC50 value of 6.4 microg mL(-1) on the same cell line. A major active constituent of the dichloromethane extract was shown to be jacaranone, which was demonstrated to have a very strong activity against all of the tumour cell lines with IC50 values between 2.86 and 3.85 microg mL(-1), although it did not account for all the activity observed. Constituents of S. leucanthemifolius extracts were identified by GC/MS analysis and NMR.

In vitro tests and ethnopharmacological investigations: wound healing as an example

In vitro tests are now widely employed in ethnopharmacological research because of ethical reasons and their usefulness in bioactive-guided fractionation and determination of active compounds. For many disease conditions, a variety of in vitro tests can now be employed as the biochemical mechanisms underlying disease and healing processes are understood. Approaches to the in vitro investigations of wound healing processes are exemplified by studies on extracts of Buddleja species and three Ghanaian species Spathodea campanulata, Commelina diffusa and Secamone afzelii. Most studies have been carried out on Buddleja officinalis or Buddleja globosa. The extracts have been shown to have anti-inflammatory and antioxidant properties due to flavonoids, triterpenoids, diterpenoids and caffeic acid derivatives. There appears to a slight effect on proliferation of fibroblasts at lower concentrations, but this was not significant, and higher concentrations appeared to be cytotoxic. Novel findings are the ability of Buddleja globosa leaf extracts to induce differentiation in keratinocytes and to alter the profile of proteins produced by cultured fibroblasts. Extracts also had some effect on lattice contraction. The three Ghanaian species examined show a mixture of antimicrobial and antioxidant activities. The evolution over recent years of tests for wound healing, from in vivo tests to cell-based systems and chemical reactions and on to investigations into effects on secondary messengers and protein expression, is described.

Evaluation of the antioxidant and free radical scavenging properties ofSecamone afzelii Rhoem

The antioxidant activity of a methanol extract of Secamone afzelii stems was tested using the DPPH assay and the active compound was identified as alpha-tocopherol. HPLC determination showed that 0.12% w/w alpha-tocopherol was present in the plant. The total extract also showed effective free radical scavenging activity in the assay for non-enzymatic lipid peroxidation in liposomes with an IC50 value of 90 microg/mL, with alpha-tocopherol isolated from the plant having an IC50 of 15 microg/mL in the same system, thus demonstrating the presence of other antioxidants.

Structure-activity relationship for antiinflammatory effect of luteolin and its derived glycosides

Luteolin and its derived glycosides such as a cynaroside, cesioside, isoorientin and stereolensin have been isolated and identified from different kinds of plant species. A (13)C NMR spectroscopic analysis of stereolensin has been done for the first time. These structurally related flavonoids were examined in vitro for their abilities to inhibit enzymes for the synthesis of thromboxane B(2) and leukotriene B(4) as well as hydrogen peroxide scavenging activity. Luteolin exhibited a high inhibitory activity against both thromboxane and leukotriene synthesis. In particular, a remarkable inhibitory effect was observed against leukotriene enzyme activity. The glycosides, cynaroside and cesioside, possessed a moderate inhibition activity against both enzyme synthesis pathways, while isoorientin and stereolensin exhibited selectively good activity against thromboxane synthesis. All the flavonoids showed excellent scavenging activity for the hydrogen peroxide at all the concentrations tested. The results demonstrated that the reactivities of luteolin and its related glycosides against arachidonic acid synthesis and hydrogen peroxide scavenging are dependent on their molecular structures. The presence of ortho-dihydroxy groups at the B ring and OH substitution pattern at C-5 position of the A ring could significantly contribute to the antiinflammatory and antioxidant activities of flavonoids.

Screening of Korean herbal medicines used to improve cognitive function for anti-cholinesterase activity

Methanolic extracts of seven herbs (Acorus calamus, Acorus gramineus, Bupleurm facaltum, Dioscorea batatas, Epimedium koreanum, Poria cocos and Zizyphi jujuba) used in traditional Korean medicine for improvement of memory and cognition in old age were tested for cholinesterase inhibitory properties using the Ellman colorimetric method. Significant inhibition of the enzyme at 200 microg/ml was observed for extracts from A. calamus and E. koreanum. The possible bases for the reputation of these and the other herbs tested are discussed in the light of previous investigations into their chemistry and biological activity.

Antioxidant and cytotoxic activities ofRetama raetam subsp.Gussonei

The aim of this study was to evaluate the in vitro antioxidant and cytotoxic activities of the methanol extracts of Retama raetam subsp. gussonei leaves and seeds. The antioxidant activity of the extracts was assessed by means of two different tests: (1) bleaching of the stable 2,2-diphenyl-1-picrylhydrazil (DPPH) radical; and (2) lipid peroxidation of liposomes which were prepared from bovine brain extract. In both tests used leaves extract showed a significant antioxidant effect. The extract of leaves also demonstrated a good cytotoxic activity against COR-L23 (large cell carcinoma) cell line.

Integrating pharmacology and in vivo cancer models in preclinical and clinical drug development

Historically, cancer drug development has been a roller coaster. Numerous agents have shown exciting activity in preclinical models and yet have had minimal activity clinically. These disappointments have led to reasonable scepticism about the true value of both syngeneic and xenograft rodent tumour models in accurately identifying agents that will have important clinical utility. Whereas the development of newer techniques, including transgenic mouse models of cancer, offers the potential to develop more predictive models, the role of such mice in cancer drug development is not yet validated. To advance in our understanding of predictive model systems it may be wise to analyse both the successes and the failures of conventional models in order to understand some of their limitations and perhaps to avoid making the same mistakes in the future. Here we review the value and limitations of xenograft models, and the role of integrating preclinical pharmacology in developing new treatments for solid tumours of childhood.

Antioxidant and antimicrobial activities of Onosma argentatum and Rubia peregrina

The n-hexane-dichloromethane (1:1) extract of the roots of Onosma argentatum and the methanol extract (partitioned between water and chloroform, ethyl acetate and n-butanol, respectively), of the underground parts (roots and rhizomes) of Rubia peregrina were tested in vitro for their antioxidant and antimicrobial activities. The highest antioxidant activity (98%) was observed at 0.1% concentration for the roots of O. argentatum. It was 96% at 0.25% concentration on the ethyl acetate fraction of R. peregrina. O. argentatum extract was effective on Staphylococcus aureus, Bacillus subtilis and Escherichia coli. The ethyl acetate and chloroform fractions of R. peregrina were effective on S. aureus and E. coli, respectively. These two species did not have any antifungal activity.

mTOR as a Target for Cancer Therapy

The target of rapamycin, mTOR, acts as a sensor for mitogenic stimuli, such as insulin-like growth factors and cellular nutritional status, regulating cellular growth and division. As many tumors are driven by autocrine or paracrine growth through the type-I insulin-like growth factor receptor, mTOR is potentially an attractive target for molecular-targeted treatment. Further, a rationale for anticipating tumor-selective activity based on transforming events frequently identified in malignant disease is becoming established.

Activities of extract and constituents of Banisteriopsis caapi relevant to parkinsonism

Dopamine deficiency is characteristic of Parkinson's disease (PD) and treatments aim at elevating levels by administration of its precursor L-dihydroxyphenylalanine (L-DOPA), or inhibiting monoamine oxidases (MAOs), thus preventing its breakdown. Reports of improvements in PD patients treated with Banisteriopsis caapi extracts stimulated investigation of B. caapi stem extract and its two ingredients, harmine and harmaline for these activities. Tests for MAO inhibition using liver homogenate showed that extract and harmaline showed a concentration-dependent inhibition of MAO A (IC(50) 1.24 microg/ml and IC(50) 4.54 nM, respectively) but had little effect on MAO B activity. The extract at 2.5 mg/ml caused a highly significant increase in release of [3H]dopamine from rat striatal slices, as did 200 microM harmine and 6 microM harmaline. In both these experiments, the amount of harmine present could not account for the total activity of the extract. The ability of harmine and harmaline to stimulate dopamine release is a novel finding. These results give some basis to the reputed usefulness of B. caapi stem extract in the treatment of PD.

An evaluation of the activity related to inflammation of four plants used in Thailand to treat arthritis

The leaves of Acanthus ebracteatus, stembark of Oroxylum indicum and the stems of Cryptolepis buchanani and Derris scandens are used as traditional remedies in Thailand for arthritis. Aqueous and alcoholic extracts were tested using three different in vitro systems for effects relevant to anti-inflammatory activity. The aqueous extracts of O. indicum and D. scandens significantly reduced myeloperoxide release. Eicosanoid production was reduced only by the aqueous extracts of A. ebracteatus and D. scandens. D. scandens extract showed potent inhibitory activity against generation of leukotriene B(4) and also displayed antioxidant activity. In the rat hind paw edema test, D. scandens extract showed significant activity when given intraperitoneally but did not produce a significant reduction when given orally. The results therefore supported to some extent the traditional use of D. scandens for arthritic conditions and provided slight indication of activity which could explain the use of O. indicum and A. ebracteatus. No relevant activity was demonstrated in any of the tests for C. buchanani extracts.

The activity against leukocyte eicosanoid generation of essential oil and polar fractions of Adesmia boronioides Hook.f

The polar fractions (methanol and aqueous extract) and essential oil of Adesmia boronioides aerial parts were tested in vitro at concentrations of 15 and 50 microg/mL, for their effects on the COX and 5-LOX pathways of eicosanoid generation (TXB2, PGE2 and LTB4) in stimulated rat peritoneal leukocytes. Potent inhibition of LTB4 generation was displayed by the methanol extract and the essential oil, whereas the aqueous extract was essentially inactive. The methanol extract also caused potent inhibition of TXB2 generation but the essential oil and the aqueous extract were much less active. The effects on PGE2 production were much less striking, implying that the main effect is on thromboxane synthetase rather than on COX. Although the essential oil caused LDH release in leukocytes treated concurrently with ionophore, suggesting substantial toxicity to the cells, this extract did not affect cell viability according to the MTT test when incubated with the cells in the absence of ionophore. The two other extracts did not affect cell viability at the concentrations tested. It is concluded that Adesmia boronioides contains substance(s) that preferentially inhibit the 5-lipoxygenase activity of arachidonic acid metabolism and suggest that this may contribute to the antiinflammatory actions of extracts of this plant.