滇白珠抗炎镇痛活性部位的化学成分研究

目的对滇白珠Gaultheria leucocarpa var.yunnanensis抗炎镇痛活性部位(ARF)的化学成分进行研究。方法利用MCI-Gel CHP、AB-8大孔吸附树脂、薄层色谱等方法进行分离和纯化,根据理化性质和波谱数据进行结构鉴定。结果从滇白珠30%乙醇提取物即ARF中分离得到16个化合物,其中水杨酸甲酯糖苷类化合物4个:水杨酸甲酯-2-O-β-D-吡喃葡萄糖苷(1)、冬绿苷(2)、水杨酸甲酯-2-O-β-D-吡喃木糖基(1→2)[O-β-D-吡喃木糖基(1→6)]-O-β-D-吡喃葡萄糖苷(3)、水杨酸甲酯-2-O-β-D-吡喃葡萄糖基(1→2)[O-β-D-吡喃木糖基(1→6)]-O-β-D-吡喃葡萄糖苷(4);醇苷类化合物3个:乙基-O-β-D-吡喃木糖苷(5)、乙基-O-β-D-吡喃木糖基(1→6)-O-β-D-吡喃葡萄糖苷(6)、甲基-O-β-D-吡喃木糖基(1→6)-O-β-D-吡喃葡萄糖苷(7);单萜苷类化合物2个:长寿花糖苷(8)、芍药苷(9);苯甲酸类化合物5个:香草酸(10)、2,5-二羟基苯甲酸(11)、3,4-二甲氧基肉桂酸(12)、阿魏酸(13)、绿原酸(14);其他成分2个:4-羟基-2,6-二甲氧基苯基-O-β-D-葡萄糖苷(15)和3-甲氧基-1H-吡咯(16)。结论化合物5~9、12、15、16是首次从该植物中分离得到,其中化合物7为首次从白珠树属植物中分离得到,化合物8、9、12、15是首次从杜鹃花科植物中分离得到。     

栀子花的化学成分研究

目的对栀子Gardenia jasminoides花进行化学成分研究。方法采用大孔吸附树脂、硅胶柱色谱和高效液相色谱等方法进行分离纯化,并通过理化常数和各种波谱学技术鉴定所分离化合物的化学结构。结果共分离并鉴定了10个化合物,分别为山柰酚3-O-β-D-吡喃葡萄糖苷(1)、山柰酚3-O-β-D-吡喃半乳糖苷(2)、山柰酚3-O-洋槐糖苷(3)、山柰酚3-O-芸香糖苷(4)、(6S,9S)-长寿花糖苷(5)、反式对羟基肉桂酸甲酯(6)、香草醛(7)、咖啡酸(8)、原儿茶酸(9)和β-谷甾醇(10);其中,化合物1~4为4个黄酮苷类化合物,化合物5为单萜苷类化合物,化合物6~9为3个酚酸类化合物。结论化合物2、3、5~7为首次从栀子属植物中分离得到,化合物1、4、8和9为首次从栀子的干燥花中分离得到。     

月季花的化学成分研究

目的对山西产月季花Rosa chinensis的化学成分进行系统的分离和鉴定。方法采用色谱分离技术进行分离纯化,通过理化性质、波谱分析鉴定其结构。结果从月季花的甲醇提取物中分离并鉴定了13个化合物,分别为槲皮素-3-O-α-L-鼠李糖苷(1)、胡桃苷(2)、槲皮素-3-O-β-D-半乳糖苷(3)、萹蓄苷(4)、山柰酚-3-O-6″-反式-香豆酰基-β-D-葡萄糖苷(5)、槲皮素(6)、没食子酸(7)、山柰酚-3-O-α-L-鼠李糖苷(8)、槲皮素-3-O-6″-反式-香豆酰基-β-D-葡萄糖苷(9)、山柰酚-3-O-2″-没食子酰基-β-D-葡萄糖苷(10)、槲皮素-3-O-2″-没食子酰基-β-D-葡萄糖苷(11)、山柰酚(12)和β-谷甾醇(13)。结论月季花中主要含黄酮苷类化合物;在分离鉴定的成分中,化合物1~5、9~11和13为首次从该植物中分离得到。     

蔓性千斤拔根的化学成分研究

目的研究蔓性千斤拔Flemingia philippinensis根的化学成分。方法采用多种色谱方法进行分离纯化,运用各种波谱学方法鉴定化合物的结构。结果从蔓性千斤拔乙醇提取物的正丁醇萃取物中分离得到6个化合物,分别鉴定为3,5,7,4′-四羟基-3′-甲氧基黄酮-6-C-β-D-吡喃葡萄糖苷(1)、山柰酚-6-C-β-D-吡喃葡萄糖苷(2)、染料木苷(3)、芒柄花苷(4)、印度黄檀苷(5)和3′-O-甲基-香豌豆酚-7-O-β-D-吡喃葡萄糖苷(6)。结论化合物1为新的黄酮醇碳苷类化合物,命名为千斤拔苷A,化合物2和4为首次从该属植物中分离得到。     

野生大血藤水溶性部位中的糖苷类化合物(英文)

目的:对野生大血藤水溶性部位成分进行分离和鉴定。方法:运用硅胶柱和凝胶柱层析等方法分离纯化化合物,通过质谱和核磁等波谱手段进行结构鉴定。结果:从大血藤水溶性部位中分得8个糖苷类化合物:(-)-南烛木树脂酚-9-O-β-D-葡萄糖苷(1),(+)-南烛木树脂酚-9-O-β-D-葡萄糖苷(2),(-)-南烛木树脂酚-9′-O-β-D-葡萄糖苷(3),(+)-丁香树脂酚-4-O-β-D-葡萄糖苷(4),草夹竹桃苷(5),(+)-丁香苷(6),sargentol(7),胡萝卜苷(8)。结论:化合物1,3和6为首次从该植物中分得。并且也是首次对野生大血藤水溶性部位的化学成分进行系统研究。     

云贵腺药珍珠菜化学成分研究

目的对云贵腺药珍珠菜Lysimachia stenosepala var.flavescens的化学成分进行研究。方法运用硅胶柱、凝胶柱、中压柱、聚酰胺柱等色谱技术进行分离纯化,根据波谱数据进行结构鉴定。结果从云贵腺药珍珠菜乙醇提取物中分离得到12个化合物,分别鉴定为山柰酚(1)、槲皮素(2)、鼠李柠檬素(3)、山柰酚-3-O-β-D-葡萄糖苷(4)、槲皮素-3-O-β-D-葡萄糖苷(5)、山柰酚-3-O-α-L-鼠李糖苷-(1→2)-β-D-葡萄糖苷(6)、山柰酚-3-O-α-L-鼠李糖苷-(1→6)-β-D-葡萄糖苷(7)、槲皮素-3-O-β-D-木糖苷-(1→2)-O-β-D-葡萄糖苷(8)、山柰酚-3-O-(2-O-α-L-鼠李糖苷-6-O-β-D-木糖苷)-β-D-葡萄糖苷(9)、β-谷甾醇(10)、原报春花素A(11)、β-胡萝卜苷(12)。结论化合物1～12为首次从该植物中分离得到,其中化合物8、9为首次从珍珠菜属中分离得到。     

金铁锁根中2个新的麦芽酚苷类化合物

目的研究金铁锁Psammosilene tunicoides根的化学成分。方法经硅胶、Sephadex LH-20凝胶、ODS反相硅胶等柱色谱方法进行分离,并运用NMR、HR-ESI-MS等波谱学方法进行化合物的结构鉴定。结果从金铁锁根80%乙醇水提取物中分离得到2个麦芽酚苷类化合物,分别鉴定为麦芽酚-3-O-[6-O-(4-O-α-L-吡喃鼠李糖基)-Z-p-香豆酰基]-β-D-吡喃葡萄糖苷(1)和麦芽酚-3-O-[6-O-(4-O-α-L-吡喃鼠李糖基)-E-p-香豆酰基]-β-D-吡喃葡萄糖苷(2)。结论化合物1和2为新的麦芽酚苷类化合物,分别命名为金铁锁酚苷A和B。     

霸王花黄酮类成分研究

目的:研究霸王花的化学成分。方法:采用各种现代色谱技术进行分离纯化,根据化合物的理化性质和波谱数据进行结构鉴定。结果:从霸王花的95%乙醇提取物中分离并鉴定了13种黄酮醇及其苷类化合物,分别为:山柰酚(1)、槲皮素(2)、异鼠李素(3)、山柰酚3-O-α-L-阿拉伯糖苷(4)、山柰酚3-O-β-D-葡萄糖苷(5)、槲皮素3-O-β-D-葡萄糖苷(6)、异鼠李素3-O-β-D-葡萄糖苷(7)、山柰酚3-O-β-D-半乳糖苷(8)、槲皮素3-O-β-D-半乳糖苷(9)、山柰酚3-O-β-D-芸香糖苷(10)、异鼠李素3-O-β-D-芸香糖苷(11)、山柰酚3-O-α-L-鼠李糖-(1→6)-β-D-半乳糖苷(12)和异鼠李素3-O-α-L-鼠李糖-(1→6)-β-D-半乳糖苷(13)。结论:以上化合物均为首次从该植物中分离得到。     

注射用银杏叶提取物中黄酮苷类化学成分研究

目的 研究注射用银杏叶提取物中黄酮苷类化学成分.方法 利用硅胶、大孔树脂、MCI、ODS、Sephadex LH-20凝胶柱色谱及反相制备液相色谱等技术对银杏叶提取物中黄酮苷类成分进行分离纯化,根据化合物的理化性质和波谱数据进行结构鉴定.结果 分离得到16个化合物,分别鉴定为5,7-二羟基-4’-甲氧基黄酮醇-3-O-芸香糖苷(1)、槲皮素-3-O-(2”,6”-α也-二鼠李糖)-β-D-葡萄糖苷(2)、槲皮素-3-O-α-L-鼠李糖-2”-(6"-对香豆酰基)-β-D-葡萄糖-7-O-β-D-葡萄糖苷(3)、异鼠李素-3-O-(2”,6”-α-L-二鼠李糖)-β-D-葡萄糖苷(4)、芦丁(5)、木犀草素-7-O-β-D-葡萄糖苷(6)、槲皮素-3-O-β-D-葡萄糖苷(7)、槲皮素-3-O-(2”-β-D-葡萄糖)-α-L-鼠李糖苷(8)、山柰酚-3-O-芸香糖苷(9)、槲皮素-3-O-α-L-鼠李糖苷(10)、异鼠李素-3-O-芸香糖苷(11)、芹菜素-7-O-β-D-葡萄糖苷(12)、丁香亭-3-O-芸香糖苷(13)、山柰酚-3-O-(2”-β-D-葡萄糖)-α-L-鼠李糖苷(14)、槲皮素-3-O-α-L-鼠李糖-2”-(6"-对香豆酰基)-β-D-葡萄糖苷(15)、山柰酚-3-O-α-L-鼠李糖-2”-(6”-对香豆酰基)-β-D-葡萄糖苷(16).结论 经UPLC-PDA分析检测,所有化合物均为黄酮苷类成分,且在银杏叶提取物及注射液样品中全部标定定位,其中化合物1为新化合物,命名为黄酮醇苷K.     

黑骨藤中苷类化合物的研究

目的:研究黑骨藤Periploca forrestii茎正丁醇部位化学成分。方法:采用各种色谱法及重结晶分离纯化,运用理化性质和波谱数据鉴定结构。结果:从黑骨藤中分离得到6个苷类化合物,分别为:大黄素-8-O-β-D-葡萄糖苷(1),大黄素甲醚-8-O-β-D-葡萄糖苷(2),山柰酚-3-O-β-D-半乳糖苷(3),山柰酚-3-O-α-L-吡喃阿拉伯糖苷(4),槲皮素-3-O-β-D-吡喃葡萄糖苷(5),槲皮素-3-O-α-L-吡喃阿拉伯糖苷(6)。结论:6个苷类化合物均为首次从该植物中分离得到。     

山沉香化学成分研究

目的 研究山沉香Syringa pinnatifolia干燥茎的化学成分.方法 采用硅胶、ODS、Sephadex LH-20及RP-HPLC等色谱技术对山沉香干燥茎的化学成分进行分离纯化,根据理化性质及波谱数据鉴定化合物结构.结果 从山沉香干燥茎95％乙醇提取物的醋酸乙酯部位分离得到11个化合物,分别鉴定为开环异落叶松脂醇(1)、(8R,8'R,9R)-3,3',9-三甲氧基-4,4'-二羟基-9,9'-环氧木脂素(2)、(8R,8'R,9S)-3,3',9-三甲氧基-4,4'-二羟基-9,9'-环氧木脂素(3)、左旋松脂醇(4)、(8R,8'R,9'S)-3,3',9 '-三甲氧基-4,4 '-二羟基-9,9'-环氧木脂素(5)、(8R,8'R,9'R)-3,3',9'-三甲氧基-4,4'-二羟基-9,9'-环氧木脂素(6)、(9S)-9-O-methylcubebin (7)、邻苯二甲酸二丁酯(8)、菲律宾胡椒素Ⅵ (9)、蛇菰宁(10)、落叶松萘酮(11).结论 化合物2～11均为首次从该植物中分离得到.     

The constituents of Anisomeles indica and their anti-inflammatory activities

Ethnopharmacological relevance

Anisomeles indica (L.) Kuntze. (Labiatae), popularly known as ‘yu-chen-tsao’, has been traditionally used as anti-inflammatory agent.

Aim of the study

Investigate the chemical constituents from the whole plants of Anisomeles indica, and evaluate their in vitro anti-inflammatory activities.

Results

The combined MeOH extract was successively partitioned with CHCl₃ and n-butanol, then submitted to several column chromatographic, and HPLC purification procedures which led to the isolation of one cembrane-type diterpenoid (3), two benzenoids (4 and 5), five flavonoids (1, 2, 6, 7 and 14), and six phenyl propanoids (8–13). The compounds 1–14 were examined for their inhibitory effects on inflammatory mediator's enhanced production from LPS/IFN-γ-stimulated macrophages. Among these, ovatodiolide (3) exhibited potent inhibition on NO, TNF-α and IL-12 enhanced production at a concentration of 5 μM, followed by pedalitin (1), scutellarein 7-O-β-d-glucuronide methyl ester (6), and acteoside (12) at 40 μM (P < 0.05). Furthermore, 2 μM of 3, and 20 μM of 1 and 6 significantly (P < 0.05) arrested the cell cycle of Con A-stimulated spleen cells at the G0/G1 stage.

Conclusion

This is the first report on the presence of compounds 1 and 4–13 in this plant and of the potent anti-inflammatory activity of 1, 3, 6 and 12in vitro. These compounds may account for the use of Anisomeles indica in folk medicine to treat inflammation.     

Effect of Chinese herbs on CYP3A4 activity and expression in vitro

Ethnopharmacological relevance

Traditional Chinese Medicine (TCM) has become more popular among cancer patients in the Western world, who often use Chinese herbs as adjuvant therapy to reduce the adverse effects of conventional chemotherapy. However, pharmacokinetic (PK) interactions between Chinese herbs and anticancer drugs can occur and have dramatic consequences for these patients. Currently, only a few possible PK interactions between Chinese herbs and conventional Western drugs have been documented.

Aim of the study

Since the drug-metabolizing enzyme cytochrome P450 3A4 (CYP3A4) contributes to most of the PK interactions with (anticancer) drugs, the effect of four Chinese herbs (Oldenlandia diffusa, Codonopsis tangshen, Rehmannia glutinosa and Astragalus propinquus) on the activity and expression of CYP3A4 was investigated in vitro.

Materials and methods

Ethanol and water–ethanol extracts of the four Chinese herbs were prepared from raw material. CYP3A4 inhibition was assessed by the use of Supersomes^™ in a fluorescence assay. Furthermore, CYP3A4 induction was evaluated in a human pregnane X receptor (hPXR)-mediated CYP3A4 reporter gene assay and a quantitative real time PCR assay, both in human colon adenocarcinoma-derived LS180 cells (LS180).

Results

Extracts of Oldenlandia diffusa, Codonopsis tangshen, Rehmannia glutinosa and Astragalus propinquus inhibited CYP3A4 in human CYP3A4 Supersomes^™ (IC₅₀ values: 17–83 µg/mL). Oldenlandia diffusa and Rehmannia glutinosa significantly induced PXR-mediated CYP3A4 (p<0.001). Oldenlandia diffusa also significantly induced CYP3A4 mRNA levels (p<0.001 at 250 µg/mL).

Conclusions

Concomitant use of Oldenlandia diffusa and Rehmannia glutinosa could result in induction of CYP3A4, leading to a reduced efficacy of drugs that are CYP3A4 substrates and have a narrow therapeutic window. Because of the possible enhanced toxicity caused by CYP3A4 inhibition, clinical effects of CYP3A4 inhibition by Astragalus propinquus and Codonopsis tangshen must also be taken into account. In conclusion, herb–drug interactions between Chinese herbs and various CYP3A4 substrates can occur. Further research to investigate the clinical relevance of the interactions caused by Oldenlandia diffusa, Codonopsis tangshen, Rehmannia glutinosa and Astragalus propinquus is required.     

基于近红外光谱技术的散结镇痛胶囊中龙血素A、B的含量测定

目的：利用近红外光谱分析技术（NIRS）快速测定散结镇痛胶囊中龙血素A、B的含量。方法：利用HPLC法测定散结镇痛胶囊龙血素A、B的含量,运用偏最小二乘法（PLS）建立NIRS与HPLC测定值之间的多元校正模型,对未知样品进行预测。结果：龙血素A、B的定量校正模型相关系数r分别为0.987 9、0.981 5,校正集验证均方差（RMSEC）分别为0.021 3、0.020 7,内部交叉验证均方差（RMSEV）分别为0.025 5、0.023 6,对预测集进行预测,预测值与真实值的相关性良好。结论：近红外光谱法对散结镇痛胶囊中龙血素A和龙血素B含量预测结果较好,能满足制药中检测的精度要求,为中药生产过程的在线、无损定量分析提供了依据。     

黑刺菝葜根茎中蒽醌类化学成分的研究

目的 对黑刺菝葜Smilaxscobinicaulis根茎的化学成分进行研究。方法 运用硅胶、Sephadex LH-20凝胶和MCI Gel等柱色谱方法进行分离纯化,根据化合物的理化性质和波谱数据鉴定化合物结构。结果 从黑刺菝葜70%乙醇提取物的石油醚和醋酸乙酯萃取部位分离得到13个化合物,分别鉴定为芦荟大黄素（1）、甲基异茜草素-1-甲醚（2）、1, 3, 6, 8-四羟基蒽醌（3）、大黄素（4）、8-羟基-1-甲氧基-3-甲基蒽醌（5）、大黄酚（6）、多花二醌A（7）、多花二醌C（8）、24-乙基胆甾- 4-烯-3, 6-二酮（9）、5α, 8α-过氧化麦角甾-6, 22-二烯-3β-醇（10）、(22E, 24R)-24-甲基-5α-胆甾-7, 22-二烯-3β, 5, 6β-三醇（11）、missourin（12）、齐墩果酸（13）。结论 化合物1～13均为首次从该植物中分离得到,其中化合物1～3和5～13为首次从菝葜属植物中分离得到。     

MAO-A inhibitory activity of quercetin from Calluna vulgaris (L.) Hull.

Aim of the study

This study investigated MAO-A inhibitory activity of methanol extract of Calluna vulgaris (L.) Hull., which traditionally has been used as a nerve calming remedy.

Materials and methods

A methanolic extract of Calluna vulgaris was partitioned against heptane, ethyl acetate and water. The three fractions were tested in a photometric peroxidase linked MAO-A bioassay. The ethyl acetate phase showed the highest MAO-A inhibitory activity. Quercetin was isolated by VLC through bioassay-guided fractionation and purified by re-crystallisation. The structure was elucidated by LC–MS and ¹H NMR.

Results

The IC₅₀-value for MAO-A inhibition by quercetin was 18 ± 0.2 μM in an assay where the IC₅₀-value for MAO-A inhibition by clorgylin was 0.2 ± 0.02 μM.

Conclusion

The content of quercetin in Calluna vulgaris might explain the reported nerve calming effect of the plant.     

Anti-inflammatory and immunosuppressive effect of flavones isolated from Artemisia vestita

Aim of the study

Artemisia vestita is a common traditional Tibetan medicinal plant which has been used widely in China for treating various inflammatory diseases. Since little is known about its active components, the purpose of this study was to isolate and identify the immunosuppressive compounds from Artemisia vestita.

Materials and methods

A bioassay-guided isolation was performed with picryl chloride-induced contact hypersensitivity in mice. MTT assay and Flow cytometric analysis were used for determining Con A-induced lymphocyte proliferation and CD25 expression in T cells, respectively.

Results

The ethanol extract of the Artemisia vestita was found to possess significant inhibitory activity against the picryl chloride-induced contact hypersensitivity in mice. Then 4 fractions were isolated by macroporous adsorption resin and one of these fractions (AV3), which showed the highest activity in in vivo test, was further subjected to column chromatography. Nine known flavones were isolated and identified as pectolinarigenin (1), jaceosidin (2), cirsilineol (3), cirsimaritin (4), hispidulin (5), quercetin (6), 6-methoxytricin (7), acacetin (8), and apigenin (9). The structures of the 9 flavones were elucidated by spectral techniques. All the compounds were evaluated for their inhibitory activity on the proliferation and activation of T cells in vitro. Among the 9 flavones, cirsilineol (3), 6-methoxytricin (7) and apigenin (9) significantly inhibited T cell proliferation and activation in the bioassays.

Conclusion

The result suggests that cirsilineol, 6-methoxytricin and apigenin are the major active components in Artemisia vestita.     

Effects on the expression of GABAA receptor subunits by jujuboside A treatment in rat hippocampal neurons

Aim of study

To determine the effect of jujuboside A (JuA) in modulating the γ-aminobutyric acid (GABA_A) receptor subunits gene expression of hippocampal neurons at different terms in vitro.

Materials and methods

Hippocampal neurons of rat were cultured in vitro, treated with JuA or diazepam (DZP). Then GABA_A receptor mRNAs were evaluated by semi-quantitative RT-PCR.

Results

JuA at the low dose of 41 μM (about 0.05 g/l) induced significant increase of GABA_A receptor α1, α5, β2 subunit mRNAs in both 24 and 72 h treatments. JuA at the high dose of 82 μM (about 0.1 g/l) significantly increased GABA_A receptor α1, α5 subunit mRNA levels and decreased β2 subunit mRNA level at 24 h treatment, and decreased GABA_A receptor subunit α1, β2 mRNAs expression at 72 h treatment. DZP of 10 μM significantly increased expression of GABA_A receptor subunit α1, α5 and decreased expression of β2 at 24 h treatment, and decreased α1, α5, β2 subunits gene expression at 72 h treatment.

Conclusion

Differences in alterations in GABA_A receptor subunit mRNAs expression following JuA and DZP treatments could help to explain the differences in the pharmacological action of the two drugs.     

Dolichos falcata Klein attenuated the inflammation induced by monosodium urate crystals in vivo and in vitro

Ethnopharmacological relevance

Dolichos falcata Klein (DF), a Chinese Dai ethnic medicine popularly known as “Tuoyeteng” in Yunnan province of China, has been widely used as a traditional herbal medicine for the treatment of fracture and beriberoid disease for a long time in China. The present study was carried out to investigate the anti-inflammatory activity and the bioactive chemical constituents of DF, and further to assess its possible mechanism on gouty arthritis in an animal model of the MSU crystals-induced gouty inflammation.

Materials and methods

The ethanol extract (EE) of DF at the doses of 10, 20 and 40 mg/kg was administered to the rats treated with MSU crystals to evaluate the anti-gouty arthritis effect. Subsequently, the components of EE were isolated and identified using classical methods. Phyto-chemical analysis of EE was further carried out by HPLC–DAD. Finally, the anti-inflammatory effect of EE and two isolated components were assessed using the MSU crystals-treated monocyte/macrophage cell line RAW 264.7 in vitro.

Results

EE (10, 20 and 40 mg/kg) significantly attenuated the pain threshold value, the joint swelling degree, the inflammatory cell infiltration of articular tissue and the increased levels of pro-inflammatory cytokines in MSU crystals-treated rats. Moreover, doliroside A (DA) and medicagenic acid-3-O-β-D-glucopyranoside (MG) were isolated and identified from EE. The major components of EE, including DA, MG and other triterpenoids, were well confirmed by HPLC. A further study revealed that EE, DA and MG (10, 20, 40 μg/mL) exhibited stronger inhibitory effects on the production of pro-inflammatory cytokines (including interleukin-1β, interleukin-6 and tumor necrosis factor-α) in MSU crystals-treated RAW 264.7 cells.

Conclusion

These findings indicate that the major triterpenoids present in DF have a remarkable effect on improving symptoms of acute gouty arthritis induced by MSU crystals through inhibiting the production of pro-inflammatory cytokines.     

Identification of Escherichia coli enterotoxin inhibitors from traditional medicinal herbs by in silico, in vitro, and in vivo analyses

Ethnopharmacological relevance

Glycyrrhiza uralensis has been used for the treatment of gastrointestinal disorders, such as diarrhea, in several ancient cultures. Glycyrrhizin is the principal component of liquorice and lots of pharmacological effects have been demonstrated.

Aim of the study

Heat-labile enterotoxin (LT), the virulence factor of enterotoxigenic Escherichia coli, induces diarrhea by initially binding to the G_M1 on the surfaces of intestinal epithelial cells and consequently leading to the massive loss of fluid and ions from cells. Therefore, we evaluated the inhibitory effects of traditional medicinal herbs (TMH) on the B subunit of LT (LTB) and G_M1 interaction.

Materials and methods

The inhibitory effects of TMH on LTB-G_M1 interaction were evaluated by G_M1-enzyme-linked immunosorbent assay (ELISA). The likely active phytochemicals of these TMH were then predicted by in silico model (docking) and analyzed by in vitro (G_M1-ELISA) and in vivo (patent mouse gut assay) models.

Results

We found that various TMH, which have been ethnomedically used for the treatment of diarrhea, inhibited the LTB-G_M1 interaction. Docking data showed that triterpenoids were the most active phytochemicals and the oleanane-type triterpenoids presented better LTB-binding abilities than other types of triterpenoids. Moreover, by in vitro and in vivo models, we demonstrated that glycyrrhizin was the most effective oleanane-type triterpenoid that significantly suppressed both the LTB-binding ability (IC₅₀ = 3.26 ± 0.17 mM) and the LT-induced fluid accumulation in mice.

Conclusions

We found an LT inhibitor, glycyrrhizin, from TMH by in silico, in vitro, and in vivo analyses.