The effect of extracts from ginger rhizome on inflammatory mediator production.

Compounds from rhizomes of Zingiber officinale, commonly called ginger, have been purported to have anti-inflammatory actions. We have used an in vitro test system to test the anti-inflammatory activity of compounds isolated from ginger rhizome. U937 cells were differentiated and exposed to lipopolysaccharide (LPS) from Escherichia coli (1 microg/ml) in the presence or absence of organic extracts or standard compounds found in ginger (6-, 8-, 10-gingerol or 6-shogaol) for 24 h. Supernatants were collected and analyzed for the production of prostaglandin E(2) (PGE(2)) and tumor necrosis factor alpha (TNF-alpha) by standard ELISA assays. Predominant compounds in the organic extracts were identified as 6-, 8- 10-gingerols and 6-, 8-, 10-shogaols. Organic extracts or standards containing gingerols were not cytotoxic, while extracts or standards containing predominantly shogaols were cytotoxic at concentrations above 20 microg/ml. Crude organic extracts of ginger were capable of inhibiting LPS induced PGE(2) (IC(50)<0.1 microg/ml) production. However, extracts were not nearly as effective at inhibiting TNF-alpha (IC(50)>30 microg/ml). Thirty three fractions and subfractions, prepared by column chromatography, were analyzed for bioactivity. Extracts containing either predominantly gingerols or shogaols (identified by HPLC) were both highly active at inhibiting LPS-induced PGE(2) production (IC(50)<0.1 microg/ml), while extracts that contained unknown compounds were less effective (IC(50)<3.2 microg/ml). Extracts or standards containing predominantly gingerols were capable of inhibiting LPS-induced COX-2 expression while shogaol containing extracts had no effect on COX-2 expression. These data demonstrate that compounds found in ginger are capable of inhibiting PGE(2) production and that the compounds may act at several sites.

The effect of turmeric extracts on inflammatory mediator production.

Major compounds of several commonly used botanicals, including turmeric, have been purported to have anti-inflammatory actions. In order to test the anti-inflammatory activity of compounds isolated from rhizomes of Curcuma longa L. (Zingiberaceae), we have established an in vitro test system. HL-60 cells were differentiated and exposed to lipopolysaccharide (LPS) from Escherichia coli (1 microg/ml) in the presence or absence of botanical compounds for 24 h. Supernatants were collected and analyzed for the production of tumor necrosis factor alpha (TNF-alpha) and prostaglandin E2 (PGE2) using standard ELISA assays. Water-soluble extracts were not cytotoxic and did not exhibit biological activity. Organic extracts of turmeric were cytotoxic only at concentrations above 50 microg/ml. Crude organic extracts of turmeric were capable of inhibiting LPS-induced TNF-alpha (IC50 value = 15.2 microg/ml) and PGE2 (IC50 value = 0.92 microg/ml) production. Purified curcumin was more active than either demethoxy- or bisdemethoxycurcumin. Fractions and subfractions of turmeric extracts collected via preparative HPLC had differing biological activity, ranging from no activity to IC50 values of < 1 microg/ml. For some fractions, subfractionation resulted in a loss of activity, indicating interaction of the compounds within the fraction to produce an anti-inflammatory effect. A combination of several of the fractions that contain the turmeric oils was more effective than the curcuminoids at inhibiting PGE2. While curcumin inhibited COX-2 expression, turmeric oils had no effect on levels of COX-2 mRNA.

Novel antihyperglycemic terpenoid-quinones from Pycnanthus angolensis.

Two new compounds, pycnanthuquinone A (1) and pycnanthuquinone B (2), were isolated from leaves and stems of the African plant, Pycnanthus angolensis (Welw.) Warb (Myristicaceae), by bioassay-guided fractionation of an ethanolic extract using a diabetic mouse model. Pycnanthuquinones A and B are the first representatives of a novel terpenoid-type quinone skeleton, and both compounds possess significant antihyperglycemic activity.

Antihyperglycemic acetylenic glucosides from Bidens pilosa.

In vivo bioassay-guided fractionation of the aqueous alcohol extract of the aerial parts of Bidens pilosa Sch. Bip. var. radiata (Asteraceae) using C57 BL/Ks-db/db mice as a model for type 2 diabetes, yielded two known polyacetylenic glucosides, identified as 2-beta-D-glucopyranosyloxy-1-hydroxy-5(E)-tridecene-7,9,11-+ ++triyne (1) and 3-beta-D-glucopyranosyloxy-1-hydroxy-6(E)-tetradecene-8,10,1 2-triyne (2). A 3:2 mixture of compounds 1 and 2 effected a significant drop in blood glucose.

Antihyperglycemic activity of Teramnus labialis (Fabaceae).

In vivo bioassay-guided fractionation of the aqueous alcohol extract of the aerial parts of Teramnus labialis (Roxb.) Benth. (Fabaceae), using C57BL/Ks-db/db mice as a model for type 2 diabetes, yielded an active fraction containing a mixture of coumarins. The major coumarin present in the active fraction was identified as fraxidin.

Antihyperglycemic sesquiterpenes from Psacalium decompositum.

Psacalium decompositum was investigated for antihyperglycemic compounds using diabetic ob/ob mice as a model for type 2 diabetes. In vivo bioassay-guided fractionation of an aqueous extract from the roots of P. decompositum led to the isolation of two new eremophilanolides, 3-hydroxycacalolide (1a) and epi-3-hydroxycacalolide (1b). A 1:1 mixture of 1a/1b exhibited antihyperglycemic activity when tested at 1.09 mmol/kg in ob/ob mice. The known furanoeremophilanes, cacalone (2a) and epicacalone (2b), were also isolated from the aqueous extract and were inactive. The known furanoeremophilane, cacalol (3), was isolated from a CH2Cl2 extract of P. decompositum roots and possessed antihyperglycemic activity. The relative stereochemistry in 1a and 1b was assigned 3R,5S and 3S,5S, respectively, based on ROESY data, 3J H-H values, and molecular mechanics calculations. Complete 13C and 1H NMR chemical shifts were assigned for 1a, 1b, 2a, 2b, and 3, and several revisions in 13C NMR assignments for 2a and 3 were made. Results from the conformational analysis of 1a, 1b, 2a, and 2b indicate that each compound exists in one major conformation in solution with H3-12 in a pseudoaxial position.

Novel terpenoid-type quinones isolated from Pycnanthus angolensis of potential utility in the treatment of type 2 diabetes.

Using an ethnomedical-based drug discovery program, two previously unknown compounds (SP-18904 and SP-18905) from Pycnanthus angolensis were isolated that lower glucose concentrations in mouse models of type 2 diabetes. SP-18904 and SP-18905 are terpenoid-type quinones that significantly lowered plasma glucose concentration (p <.05) when given orally to either ob/ob or db/db mice, both of which are hyperglycemic and hyperinsulinemic. The antihyperglycemic actions of SP-18904 and SP-18905 were associated with significant decreases in plasma insulin concentrations (p <.05), suggesting that both compounds lowered glucose by enhancing insulin-mediated glucose uptake. This was supported by the insulin suppression test in ob/ob mice. Studies in hyperglycemic, insulin-deficient mice and in vitro experiments on 3T3-L1 adipocytes further supported this conclusion. As such, these two terpenoid-type quinones represent a new class of compounds of potential use in the treatment of type 2 diabetes.

Cryptolepis sanguinolenta: an ethnobotanical approach to drug discovery and the isolation of a potentially useful new antihyperglycaemic agent.

Evidence has been published that a wide array of plant-derived active principles, representing numerous classes of chemical compounds, demonstrate activity consistent with their possible use in the treatment of patients with Type 2 diabetes mellitus (DM). Despite these interesting observations, to date, metformin is the only ethical drug approved for treatment of Type 2 DM derived from a medicinal plant. Why is this so, given the fact that higher plants are such a potential source of new drugs? The answer to this rhetorical question may lie in the reliance of most pharmaceutical companies on random, in vitro, mechanism-based, high throughput screening in the initial phases of plant drug research. In this article we describe an alternative pathway to discovery of drugs for the treatment of Type 2 DM: on based on an ethnomedical approach, involving ethnobotany and traditional medicine. In particular, we present evidence that cryptolepine, an indoloquinolone alkaloid isolated from Cryptolepis sanguinolenta, significantly lowers glucose when given orally to a mouse model of diabetes. The antihyperglycaemic effect of cryptolepine leads to a significant decline in plasma insulin concentration, associated with evidence of an enhancement in insulin-mediated glucose disposal. Finally, cryptolepine increases glucose uptake by 3T3-L1 cells. These data permit us to conclude that an ethnobotanical approach to drug discovery can identify a potentially useful drug for the treatment of Type 2 DM.

Ethnobotanical-directed discovery of the antihyperglycemic properties of cryptolepine: its isolation from Cryptolepis sanguinolenta, synthesis, and in vitro and in vivo activities.

Using an ethnobotanical approach in combination with in vivo-guided fractionation as a means for lead discovery, cryptolepine was isolated as an antihyperglycemic component of Cryptolepis sanguinolenta. Two syntheses of cryptolepine, including an unambiguous synthesis, are reported. The hydroiodide, hydrochloride, and hydrotrifluoromethanesulfonate (hydrotriflate) salts of cryptolepine were synthesized, and a comparison of their spectral properties and their in vitro activities in a 3T3-L1 glucose transport assay is made. Cryptolepine and its salt forms lower blood glucose in rodent models of type II diabetes. While a number of bioactivities have been reported for cryptolepine, this is the first report that cryptolepine possesses antihyperglycemic properties.

Two new lignans with activity against influenza virus from the medicinal plant Rhinacanthus nasutus.

Two new lignans, rhinacanthin E (1) and rhinacanthin F (2), were isolated from the aerial parts of the plant Rhinacanthus nasutus. Their structures were established by detailed spectroscopic analysis. These compounds show significant antiviral activity against influenza virus type A.

Two new naphthoquinones with antiviral activity from Rhinacanthus nasutus.

Two new naphthoquinones, rhinacanthin-C (1) and rhinacanthin-D (2), exhibit inhibitory activity against cytomegalovirus (CMV), with EC50 values of 0.02 and 0.22 microgram/mL, respectively, against human CMV. They were isolated from the medicinal plant Rhinacanthus nasutus (Acanthaceae). The structures of the compounds were determined by analysis of their spectroscopic data, in particular, 2D NMR.

SP-303, an antiviral oligomeric proanthocyanidin from the latex of Croton lechleri (Sangre de Drago).

SP-303, a large proanthocyanidin oligomer isolated from the latex of the plant species Croton lechleri (Eupborbiaceae) has demonstrated broad activity against a variety of DNA and RNA viruses. In cell culture, SP-303 exhibits potent activity against isolates and laboratory strains of respiratory syncytial virus (RSV), influenza A virus (FLU-A) and parainfluenza virus (PIV). Parallel assays of SP-303 and ribavirin showed comparable activity against these viruses. SP-303 also exhibits significant inhibitory activity against herpesvirus (HSV) types 1 and 2, including herpesviruses resistant to acyclovir and foscarnet. Inhibition was also observed against hepatitis A and B viruses. The antiviral mechanism of SP-303 seems to derive from its direct binding to components of the viral envelope, resulting in inhibition of viral attachment and penetration of the plasma membrane. Antiviral effects of SP-303 were measured by three distinct methods: CPE, MTT and precursor uptake/incorporation. Cytotoxicity endpoints were markedly greater than the respective antiviral endpoints. SP-303 exhibited activity in RSV-infected cotton rats and African green monkeys, PIV-3-infected cotton rats, HSV-2 infected mice and guinea pigs and FLU-A-infected mice. The most successful routes of SP-303 administration for producing efficacy were: topical application to HSV-2- genital lesions in mice and guinea pigs, aerosol inhalation to FLU-A-infected mice and PIV-3-infected cotton rats, and oral dosage to RSV-infected cotton rats. A variety of toxicological evaluations demonstrated the safety of SP-303, particularly orally, which was predictable, since condensed tannins are a common dietary component. It is notable that the larger proanthocyanidins as a class have high antiviral activity, whereas most of the monomers are inactive. Clinical trials are ongoing to evaluate SP-303 as a therapeutic antiviral agent.

A new diterpene from Cupressus goveniana var. abramasiana: 5 beta-hydroxy-6-oxasugiol (cupresol).

The petroleum ether-EtOH extract of Cupressus goveniana var. abramasiana (Cupressaceae) yielded sugiol (1) and the new diterpene, cupresol (5 beta-hydroxy-6-oxasugiol), for which structure 2 was established by spectroscopic and chemical means.

Odoratin and paucin: cytotoxic sesquiterpene lactones from Baileya pauciradiata (Compositae).

An ethanol extract of Baileya pauciradiata exhibited cytotoxic activity against the human epidermoid carcinoma of the nasopharynx and the lymphocytic leukemia test systems. Two constituents responsible for this activity were isolated and identified as odoratin and paucin. Their identities were proven by IR, PMR, and mass spectral data; elemental analysis; preparation of their acetates; and melting-point determinations. Odoratin was confirmed by comparison with an authentic sample.

Dehydrodiisoeugenol: a naturally occurring lignan from Aristolochia taliscana (Aristolochiaceae).

The ethanol-water extract of Aristolochia taliscana Hook and Arn (Aristolochiaceae) yielded a compound which was identified as dehydrodiisoeugenol by means of elemental analysis, IR, UV, NMR, and mass spectra, and direct comparison with a synthetic sample.

Cytotoxic agents from Bursera morelensis (Burseraceae): deoxypodophyllotoxin and a new lignan, 5'-desmethoxydeoxypodophyllotoxin.

The isolation and identification of deoxypodophyllotoxin and a new lignan, 5'-desmethoxydeoxypodophyllotoxin, from the dried exudate of Bursera morelensis (Burseraceae) are reported. Deoxypodophyllotoxin showed high activity in the KB and PS test systems; the new lignan, although highly active against the KB test system, demonstrated only marginal activity against the PS test system. A structure is suggested for the new lignan, which was named morelensin.