Animal models to test drugs with potential antidiabetic activity

Although medicinal plants have been historically used for diabetes treatment throughout the world, few of them have been validated by scientific criteria. Recently, a large diversity of animal models has been developed to better understand the pathogenesis of diabetes mellitus and new drugs have been introduced in the market to treat this disease. The aim of this work was to review the available animal models of diabetes and some in vitro models which have been used as tools to investigate the mechanism of action of drugs with potential antidiabetic properties. In addition, a MEDLINE/PUBMED search for articles on natural products, pancreatectomy and diabetes mellitus treatment published between 1996 and 2006 was done. In the majority of the studies, natural products mainly derived from plants have been tested in diabetes models induced by chemical agents. This review contributes to the researcher in the ethnopharmacology field to designs new strategies for the development of novel drugs to treat this serious condition that constitutes a global public health.     

不同产地天麻乙酸乙酯提取物对大鼠胸主动脉环张力的影响

目的:比较云南、湖北、陕西天麻乙酸乙酯提取物对大鼠胸主动脉环张力的影响。方法:主动脉环张力测定法记录天麻乙酸乙酯提取物对大鼠胸主动脉环张力的影响。结果:三产地天麻乙酸乙酯提取物能抑制KC l引起的大鼠胸主动脉环收缩,使CaC l2量效曲线右移,最大收缩张力降低。结论:三产地天麻乙酸乙酯提取物对大鼠胸主动脉环均有舒张作用,以云南天麻作用最强。     

Isolation of narciprimine from Cyrtanthus contractus (Amaryllidaceae) and evaluation of its acetylcholinesterase inhibitory activity

Ethnopharmacological relevance

Plants of the family Amaryllidaceae are used widely in traditional medicine in South Africa. Several of these, including representatives of the genus Cyrtanthus find use in the treatment of mental illness and age-related dementia.

Aim of the study

Based on the distribution of central nervous system-activating alkaloidal constituents within the genus Cyrtanthus, Cyrtanthus contractus was here explored for such compounds which could interact with acetylcholinesterase (AChE), of significance in the progression of neurodegeneration associated with Alzheimer's disease.

Materials and methods

The known phenanthridone alkaloid narciprimine was isolated via column chromatography of the ethanolic extract of bulbs of Cyrtanthus contractus. The structure of the compound was determined by high field 2D NMR and mass spectroscopic techniques. The classical method of Ellman et al. was used in the determination of AChE inhibitory activity.

Results

The isolation of narciprimine from Cyrtanthus contractus is a landmark find since it has previously only been identified in Zephyranthes, Narcissus and Lycoris, genera endemic to the Americas, Europe and Asia, respectively. Narciprimine exhibited micromolar inhibitory activity (IC₅₀ 78.9) against the enzyme acetylcholinesterase.

Conclusion

This work represents the first isolation of narciprimine from an African Amaryllidaceae species, which may be of chemotaxonomic significance. The AChE inhibitory activity of narciprimine, taken together with activities of other structurally similar inhibitors within the series affords further insight to the structural details of the lycorine alkaloid acetylcholinesterase inhibitory pharmacophore.     

Eupatorium perfoliatum L.: phytochemistry, traditional use and current applications

Ethnopharmacological relevance

Eupatorium perfoliatum L. originates from North America, where it has been widely used since centuries by native Indians. Additionally extracts are used also in Europe as immunostimulating agent for treatment of fever and cold. The following review summarizes published data on phytochemistry, ethnopharmacological use, as well as clinical and preclinical data.

Materials and methods

Literature survey was performed via SciFinder^® on papers and patents and by systematic research in ethnopharmacological literature at various university libraries.

Results

The phytochemical composition of Eupatorium perfoliatum is described in detail for volatile oil, caffeic acid derivatives, flavonoids, sesquiterpene lactones, tannins, polysaccharides. Methods for analytical quality control, as well as specification for relevant lead structures can be deduced from published batch analysis. Preclinical studies indicate anti-inflammatory effects of ethanolic extracts, which can be correlated on a molecular level to eupafolin and sesquiterpen lactones. Antiplasmodial, antioxidative and immunomodulating activities are additionally discussed. Clinical data on the use of Eupatorium perfoliatum do not meet modern GCP requirements, but do indicate positive tendencies for use of ethanolic extracts for treatment of common colds.

Conclusion

While the postulated immunostimulating properties of Eupatorium perfoliatum have not been confirmed by in vitro data, animal-studies and in vitro experiments with plant extracts both indicate antiinflammatory effects beside antiplasmodial effect against Plasmodium falciparum. Such an antiinflammation caused by the ethanolic extracts can be correlated well with clinical symptoms related to diseases as common cold, rheumatism, athritis etc. These data also support the plausibility of the plant's traditional use by the North American indigenous population and early European settlers. In principle quality aspects of the herbal material have to be affirmed by establishing modern pharmacopoeial control methods to guarantee constant and reliable quality.     

Anti-inflammatory activity of Eupatorium perfoliatum L. extracts, eupafolin, and dimeric guaianolide via iNOS inhibitory activity and modulation of inflammation-related cytokines and chemokines

Ethnopharmacological relevance

Eupatorium perfoliatum L. has been used traditionally for the treatment of fever, malaria and inflammation-associated diseases. Nowadays it is mostly used as immune activating remedy. The following study was performed to evaluate extracts with different polarity and defined lead-compounds from the herbal material on potential in vitro activities concerning immune cell activation, phagocytosis, and inflammation-related processes.

Materials and methods

MeOH-, EtOH-, and DCM extracts, beside several subfractions and isolated polysaccharides, sesquiterpene lactones and flavonoids were prepared and characterized analytically from the aerial parts of E. perfoliatum. Immunological activity was tested within lymphocyte transformation test on PBMC, test on enhancement of phagocytosis and of NO-production by murine RAW 264.7 macrophages. Anti-inflammatory effects were assessed from LPS-stimulated RAW 264.7 cells by NO/iNOS quantification, gene array, real-time PCR and ELISA.

Results

No stimulatory activity was found within lymphocyte transformation test, for phagocytic activity and NO formation in macrophages. MeOH-, EtOH- and DCM extracts showed anti-inflammatory activity against LPS-stimulated macrophages by inhibition of NO release (IC₅₀ > 100, 89, 19 μg/mL resp.) with eupafolin and a dimeric guaianolide having prominent NO inhibiting activity (IC₅₀ 6 resp. 16 μM). Anti-inflammatory activity was found on gene and protein level by significant down-regulation of cytokines CSF-3, IL-1α, IL-1β, and chemokines CCL2, CCL22 and CXCL10. Also TNF was down-regulated moderately (−17%).

Conclusions

Although the postulated immunostimulating properties of E. perfoliatum have not been confirmed, the anti-inflammatory effects can be seen as a verification of the traditional use against inflammatory diseases.     

Anti-mycobacterial diynes from the Canadian medicinal plant Aralia nudicaulis

Ethnopharmacological relevance

Aralia nudicaulis, or wild sarsaparilla, is used as a traditional medicinal plant for the treatment of various illnesses by many of the Canadian First Nations. Iroquois and Algonquin First Nations of Eastern Canada use a tea prepared from dried Aralia nudicaulis rhizome as a cough medicine and for the treatment of tuberculosis. Previous investigations of aqueous extracts of Aralia nudicaulis rhizomes have shown it to possess antimycobacterial activity.

Aim of the study

To isolate and identify antimycobacterial constituents from Aralia nudicaulis rhizomes.

Materials and methods

Methanolic extracts of Aralia nudicaulis rhizomes were subjected to bioassay guided fractionation using the microplate resazurin assay (MRA) to assess inhibitory activity against Mycobacterium tuberculosis strain H37Ra. The antimycobacterial constituents were identified by NMR, MS and polarimetry.

Results

Two C17 polyacetylenes with significant antimycobacterial activity were isolated from the Aralia nudicaulis rhizome extract. The polyacetylenes were identified as (3R)-falcarinol and (3R, 9R, 10S)-panaxydol. Falcarinol and panaxydol displayed MICs of 25.6 μM and 36.0 μM and IC₅₀s of 15.3 μM and 23.5 μM against Mycobacterium tuberculosis H37Ra.

Conclusions

Falcarinol and panaxydol were identified as the principal constituents responsible for the antimycobacterial activity of Aralia nudicaulis rhizomes validating an ethnopharmacological use of this plant by the Canadian First Nations.     

三棱乙酸乙酯部位HPLC指纹图谱及4种酚类成分含量测定

目的：建立醋炙三棱乙酸乙酯部位HPLC指纹图谱,并同时测定对羟基苯甲酸、香兰素、对香豆酸和阿魏酸4种酚类物质含量,为三棱药材的质量控制提供借鉴。方法：富集醋炙三棱乙酸乙酯部位,采用高效液相色谱（HPLC）法,应用Inert Sustain C₁₈色谱柱（4.6 mm×250 mm,5 μm）,流动相甲醇-0.1%甲酸溶液进行梯度洗脱,检测波长254 nm,流速0.80 mL·min^-1,测定对羟基苯甲酸、香兰素、对香豆酸和阿魏酸4种酚类物质的含量。结果：建立了三棱乙酸乙酯部位的HPLC指纹图谱,检出共有峰16个,各批次药材的相似度均大于0.9;通过与对照品比对,确定了指纹图谱中5,8,9,10号峰分别为对羟基苯甲酸、香兰素、对香豆酸和阿魏酸,并对其进行定量分析,结果对羟基苯甲酸的线性范围为0.008~0.924 μg,平均回收率为98.5%,香兰素的线性范围为0.039~4.712 μg,平均回收率为101.1%,对香豆酸的线性范围为0.054~6.572 μg,平均回收率为100.3%,阿魏酸的线性范围为0.018~2.236 ng,平均回收率为101.0%。结论：HPLC指纹图谱方法与含量测定方法简便,结果准确,重复性好,可作为三棱的质量控制方法。     

Immunomodulatory activity of Asparagus racemosus on systemic Th1/Th2 immunity: Implications for immunoadjuvant potential

Ethnopharmacological relevance

Roots of Asparagus racemosus Willd (Shatavari in vernacular) are widely used in Ayurveda as Rasayana for immunostimulation, galactogogue as also in treatment of conditions like ulcers and cancer. Various studies have indicated immunomodulatory properties of Shatavari root extracts and formulations.

Aim of the study

To study the effect of standardized Asparagus racemosus root aqueous extract (ARE) on systemic Th1/Th2 immunity of SRBC sensitized animals.

Materials and methods

We used HPTLC to quantify steroidal saponins (Shatavarin IV, Immunoside^®) and flow cytometry to study effects of ARE on Th1/Th2 immunity. SRBC specific antibody titres and DTH responses were also monitored as markers of Th2 and Th1 responses, respectively. We also studied lymphocyte proliferation. Cyclosporin, cyclophosphamide and levamisole were used as controls.

Results

Treatment with ARE (100 mg/(kg b.w. p.o.)) resulted in significant increase of CD3⁺ and CD4/CD8⁺ percentages suggesting its effect on T cell activation. ARE treated animals showed significant up-regulation of Th1 (IL-2, IFN-g) and Th2 (IL-4) cytokines suggesting its mixed Th1/Th2 adjuvant activity. Consistent to this, ARE also showed higher antibody titres and DTH responses. ARE, in combination with LPS, Con A or SRBC, produced a significant proliferation suggesting effect on activated lymphocytes.

Conclusion

The study suggests mixed Th1/Th2 activity of ARE supports its immunoadjuvant potential.     

滨藜叶分药花化学成分研究

对唇形科分药花属植物滨藜叶分药花Perovskia atriplicifolia Benth.的干燥全草90%乙醇提取物的乙酸乙酯部分进行化学成分研究,从中分离得到15个化合物。经通过波谱数据分析及与文献对照,该15个化合物的结构分别鉴定为:蓟黄素(cirsimaritin,1),鼠尾草素(salvigenin,2),丁香醛(syringaldehyde,3),咖啡酸乙烯酯(vinyl caffeate,4),2α,3α-dihydroxyolean-12-en-28-oic acid(5),2α,3α-dihydroxyurs-12-en-28-oic acid(6),niga-ichigoside F1(2α,3β,19α,23-tetrahydroxyurs-12-en-28-oic acidO-β-D-glucopyranoside,7),绢毛榄仁苷(sericoside,8),4-epi-niga-ichigoside F1(2α,3β,19α,24-tetrahydroxyurs-12-en-28-oic acid O-β-D-glucopyranoside,9),瓜子金皂苷丁(2α,3β,24-trihydroxyolean-12-en-28-oic acid O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside,10),夏枯草苷(pruvuloside A,11),2α,3β,23-trihydroxyolean-12-en-28-oic acid O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside(12),迷迭香酸甲酯(rosmarinic acid methyl ester,13),β-谷甾醇(β-sitosterol,14),胡萝卜苷(daucosterol,15)。化合物1~13为首次从该属植物中分离得到。所有化合物均为首次从该种植物中分离得到。     

Antipsychotic and sedative effects of the leaf extract of Crassocephalum bauchiense (Hutch.) Milne-Redh (Asteraceae) in rodents

ETHNOPHARMACOLOGICAL RELEVANCE: Crassocephalum bauchiense (Hutch.) Milne-Redh (Asteraceae) has been used as a medicine for the treatment of epilepsy, insomnia, dementia and psychotic disorders in Cameroonian traditional medicine. AIM OF THE STUDY: This study was designed to examine whether the aqueous extract and the alkaloid fraction prepared from the leaves of Crassocephalum bauchiense possess antipsychotic and sedative properties in rodents. MATERIALS AND METHODS: The rectal temperature of mice was recorded with a probe thermometer at a constant depth. Novelty-induced rearing behavior is used to evaluate a central excitatory locomotor behavior in mice. The antipsychotic effects of the extracts were assessed using the apomorphine animal model of psychosis. The catalepsy test was tested based on the ability of the leaves extracts of Crassocephalum bauchiense to alter the duration of akinesia by placing the naive mice with both forelegs over a horizontal bar. The extracts of Crassocephalum bauchiense effects were evaluated on sodium pentobarbital-induced sleeping time. In addition, gamma-aminobutyric acid concentrations in the brain treated mice were also estimated. RESULTS: The aqueous extract and the alkaloid fraction from Crassocephalum bauchiense caused dose-dependent inhibition of novelty-induced rearing behavior, decreased the apomorphine-induced stereotypy and fighting, and had significant fall of the body temperature. The aqueous extract prolonged the sodium pentobarbital sleeping time. This prolongation was not reversed by bicuculline, a light-sensitive competitive antagonist of GABA(A) receptors complex. However, the effect of the aqueous extract on sodium pentobarbital-induced sleeping time was blocked by N-methyl-β-carboline-3-carboxamide, a partial inverse agonist of the benzodiazepine site in the GABA(A) receptor complex and flumazenil, a specific antagonist of the benzodiazepine site in the GABAA receptor complex. In biochemical experiments, the concentration of the inhibitory amino acid, gamma-aminobutyric acid, was significantly increased in the brain of animals treated with the aqueous extract of Crassocephalum bauchiense and sodium valproate. CONCLUSIONS: The results show that the antipsychotic and sedative properties of Crassocephalum bauchiense are possibly mediated via the blockade of dopamine D-2 receptors and GABAergic activation, respectively. However, pharmacological and chemical studies are continuing in order to characterize the mechanism(s) responsible for these neuropharmacological actions and also to identify the active substances present in the extracts of Crassocephalum bauchiense.