Antimicrobial activities of 26 Yunnan plants extracts against clinical multi-drug resistant pathogens in vitro

研究26种云南滇东南产植物80％乙醇提取物的体外抗耐药菌作用.制备植物的醇提物,用琼脂打孔法对其进行抗菌活性的筛选.通过微量稀释法测定提取物的最低抑菌浓度[minimum inhibitory concentration(MIC)]、最低杀细菌浓度[minimum bactericidal concentration(MBC)]及最低杀真菌浓度[minimum fungicidal concentration(MFC)].结果表明:26种提取物中有9种对金黄色葡萄球菌(简称金葡菌)、大肠埃希菌、铜绿假单胞菌、白色念珠菌有不同程度的抑制活性;其中以红花荷、马蹄参、百花贝母兰、二色大包兰和光序肉实树提取物对耐甲氧西林金葡菌的抑菌作用最强,其MIC/MBC(mg/L)范围分别为512/2048～＞2048,512/2048～＞2048,256-512/2048～＞2048,512～1024/1024～＞2048和512～1024/＞2048.另外,肋果茶提取物对铜绿假单胞菌及白色念珠菌有较好的抑制作用,其对铜绿假单胞菌及其耐药菌株的MIC/MBC为512～2048/＞2048mg/L;对白色念珠菌及其耐药菌株的MIC/MFC均为2048/＞2048 mg/L.26种植物提取物对大肠埃希菌的抑制作用均较弱.     

23种中草药的体外抗菌活性筛选研究

为考察中草药抗菌物质基础筛选出活性提取物,该研究通过80%乙醇冷浸和95%乙醇回流提取制备23种中草药的提取物,采用琼脂扩散法测量抑菌圈直径,用微量液体培养基倍比稀释法测定最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal/fungicidal concentration,MBC/MFC),并测定了提取物对临床4种常见病原菌体外抗菌活性。结果表明:紫珠草、千斤拔、黄龙尾等9种中草药对金黄色葡萄球菌有较强的抑菌活性,其MIC/MBC值除个别菌是12.5 mg·mL~(-1)外,其他都在0.09～3.12 mg·mL~(-1)之间;千斤拔、大红袍、过江龙等5种中草药对铜绿假单胞菌有较强抑菌活性,其MIC/MBC值在3.12～12.5 mg·mL~(-1)之间;紫珠草、千里光、石楠等13种中草药对大肠埃希菌有较强的抑菌活性,其MIC/MBC值在0.09～6.25 mg·mL~(-1)之间;八角对白色念珠菌有较强抑菌活性,其MIC/MFC值在0.78～12.5 mg·mL~(-1)之间。23种中草药的抗细菌活性较好,尤其是千斤拔、大红袍、过江龙、八角、黄药子对金黄色葡萄球菌、大肠埃希菌、铜绿假单胞菌都具有较好的抑菌活性,具有广谱抗菌活性;但对真菌抑菌效果不明显,仅有八角对白色念珠菌有抑菌活性。此外,提取溶剂浓度、提取温度和提取时间对中草药的提取率和活性均有影响,冷提稍优于热提。     

23种中草药体外抗菌活性筛选

为研究23种中草药的80%乙醇提取物对4种临床常见致病菌的体外抗菌活性,该研究用琼脂扩散法测定抑菌圈直径,微量肉汤培养基倍比稀释法测定最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal/fungicidal concentration,MBC/MFC)。结果表明:滇龙胆草、金丝梅、溪黄草等16种提取物对金黄色葡萄球菌的MIC/MBC值在0.19～3.12 mg·mL^-1之间,有很强的抑菌活性。头花蓼、淡竹叶、半枝莲等14种提取物对铜绿假单胞菌的MIC/MBC值在1.56～6.25 mg·mL^-1之间,有较强的抑菌活性。除槐角外,其余提取物对大肠埃希菌的MIC/MBC值均在3.12～12.5 mg·mL^-1之间,有较强的抑菌活性。黄藤、藿香提取物对白色念珠菌的MIC/MFC值在0.78～6.25 mg·mL^-1之间,有较强的抑菌活性; 滇龙胆草、金丝梅、水杨梅、苦参、胡椒、赶黄草、荜菝、淡竹叶提取物对白色念珠菌的MIC/MFC值在6.25～12.5 mg·mL^-1之间,也具有一定抑菌活性。因此,所选中草药的抑菌效果均较好,大部分均具有广谱抗菌活性。其中,藿香、黄藤的提取物对白色念珠菌抑菌活性较强,金丝梅、水杨梅、仙鹤草、苦参、赶黄草、溪黄草的提取物对金黄色葡萄球菌抑菌活性很强,这几种中草药可为进一步追踪其活性单体化合物和作用机制提供一定的参考。     

19种常见中药材醇提物的体外抗菌活性筛选

为考察19种中药材乙醇提取物的体外抗临床常见致病菌的活性,该文将中药粗粉用80%乙醇浸泡提取, 提取液减压浓缩制备成浸膏,采用琼脂打孔法测定提取物抑菌圈, 通过微量倍比稀释法测定最低抑菌浓度(MIC)和最低杀菌浓度(MBC/MFC)。结果表明:所筛选的19种中药材乙醇提取物对不同的菌株具有不同程度的抑制作用, 14种中药材乙醇提取物抗SA、EC、PA和CA的抑菌圈范围在8～27 mm之间, 其中地锦草、四块瓦、三颗针、马尾黄连和土大黄的提取物抗SA、EC的抑菌圈范围在10.3～26.6 mm之间。马尾黄连、孜然、地锦草、广西莪术、穿心莲、益母草、吴茱萸、土大黄、叶上花、土连翘、凤尾草和三颗针的醇提物对MRSA和铜绿假单胞菌耐药菌均具有显著的抗微生物活性, 其MIC/MBC值在391～6 250 μg·mL^-1之间; 地锦草、三颗针抗MRSA的最低MIC值分别为391、781 μg·mL^-1, 抗PA耐药菌的最低MIC值均为1 562.5 μg·mL^-1; 马尾黄连、孜然和三颗针的醇提物对白色念珠菌耐药菌有中等抑制作用, 杀菌效果不明显。该研究结果为后续相关植物作为潜在抗菌化合物及其抗菌药物佐剂的研究提供了参考。     

响应面法优化苦丁茶熊果酸提取工艺及其抑菌活性研究

为优化苦丁茶熊果酸的提取工艺,并探讨其抑菌活性。在单因素试验基础上,通过响应面分析法,研究了液料比、提取温度、乙醇浓度对苦丁茶熊果酸得率的影响。以金黄色葡萄球菌、枯草芽孢杆菌、生孢梭菌、铜绿假单胞菌、大肠杆菌、白色念珠菌、黑曲霉为供试菌,探究了苦丁茶熊果酸的抑菌活性及最小抑菌浓度(Minimum inhibitory concentration,MIC)。结果表明,最优提取工艺为:液料比为17∶1(mL/g)、乙醇浓度为83%、提取温度83℃;抑菌实验表明,苦丁茶熊果酸对7种菌均有一定的抑制效果,对大肠杆菌、铜绿假单胞菌的MIC为6. 25 mg/mL,对生孢梭菌、金黄色葡萄球菌、枯草芽孢杆菌的MIC为12. 5 mg/mL,对白色念珠菌、黑曲霉的MIC为25 mg/mL。     

10种中草药提取物体外抗铜绿假单胞菌作用研究

通过对粗糠柴等10种中草药采用80%乙醇室温下浸渍制备的提取物进行体外抗铜绿假单胞菌及其耐药菌活性研究,并采取药敏纸片法测定临床分离菌株的耐药性。结果表明:这10种中草药80%乙醇提取物中,粗糠柴的乙酸乙酯层对铜绿假单胞菌标准菌及其耐药菌的抑菌效果最好,其抑菌圈直径范围在10~17 mm之间,MIC范围在0.125~0.5 mg·mL~(-1)之间,MBC范围在0.5~1 mg·mL~(-1)之间;正丁醇层、水层的抑菌活性较乙酸乙酯层弱,石油醚层对铜绿假单胞菌没有效果。而小叶藤黄、滇南红厚壳、续随子的乙酸乙酯层,巴豆、罗汉松、肉桂醇提物对铜绿假单胞菌及其耐药菌株有较弱抗菌活性;滇南红厚壳的正丁醇层、续随子乙酸乙酯层以及大八角和郁金的醇提物对铜绿假单胞菌及其耐药菌株均无活性。从这些数据中可以得出,粗糠柴的乙酸乙酯层、正丁醇层和水层对铜绿假单胞菌及其耐药菌有较好的抑菌活性,尤以乙酸乙酯层活性最好,而粗糠柴的石油醚层没有活性。     

野生蓝莓提取物对四种致病菌的抑制作用

本研究选用中国野生蓝莓,研究了其提取物对铜绿假单胞菌、单增李斯特菌、金黄色葡萄球菌与副溶血性弧菌等四种致病菌的抑制作用,分别采用试管二倍稀释法和平板涂布法测定了野生蓝莓提取物的最小抑菌浓度(MIC)和最小杀菌浓度(MBC)。结果表明,野生蓝莓提取物对四种致病菌均有一定的抑制作用,对铜绿假单胞菌、单增李斯特菌、金黄色葡萄球菌与副溶血性弧菌的MIC分别为62.5、250、500 mg/m L与31.25 mg/m L,MBC分别为250、250、500与125 mg/m L。本研究首次报道了中国野生蓝莓对这四种致病菌的抑制作用,为中国野生蓝莓的开发和利用提供了依据。     

鱼腥草素钠与红霉素抗铜绿假单胞菌生物被膜的协同作用

目的研究鱼腥草素钠与红霉素抗铜绿假单胞菌(Pseudomonas aeruginosa,PA)生物被膜(Biofilm,BF)的协同作用。方法采用微量倍比稀释法测定鱼腥草素钠、红霉素对铜绿假单胞菌最低抑菌浓度(MIC),MTT法测定鱼腥草素钠、红霉素及两药联合抗铜绿假单胞菌的最小抑膜浓度SMIC(SMIC50和SMIC80),光学显微镜及扫描电镜下观测鱼腥草素钠抗铜绿假单胞菌生物被膜的动态过程。结果鱼腥草素钠和红霉素抗铜绿假单胞菌的MIC分别为512 mg/L和256 mg/L。红霉素对铜绿假单胞菌生物被膜SMIC50黏附期为64 mg/L,早期生物被膜阶段为64 mg/L,成熟期生物被膜阶段为128 mg/L,两药联合后铜绿假单胞菌生物被膜SMIC50黏附期为16 mg/L,早期为16 mg/L,成熟期为32 mg/L。红霉素对铜绿假单胞菌生物被膜SMIC80黏附期为128 mg/L,早期生物被膜阶段为128 mg/L,成熟期生物被膜阶段为256mg/L,两药联合后铜绿假单胞菌生物被膜SMIC80黏附期为64 mg/L,早期为64 mg/L,成熟期为128 mg/L。结论鱼腥草素钠联合红霉素抗铜绿假单胞菌生物被膜具有协同作用。     

铜绿假单胞菌菌苗预防白色念珠菌感染的实验研究

目的利用铜绿假单胞菌菌苗探索阻断白色念珠菌感染的影响。方法家兔耳皮内注射白色念珠菌,进行活菌攻击,建立动物感染模型。观察用铜绿假单胞菌菌苗免疫的家兔状况;用试管凝集法测定家免的抗体效价;采用小白鼠体内吞噬法测定免疫组和空白对照组巨噬细胞的吞噬百分率和吞噬指数,以得出铜绿假单胞菌菌苗的免疫性。结果观察发现：与对照组比较,铜绿假单胞菌菌苗免疫组抗体效价,巨噬细胞的吞噬能力明显提高;注射区局部感染及全身症状明显减轻;肾脏感染灶减少,病理切片显示病情较轻。结论铜绿假单胞菌菌苗能够减轻注射区局部感染及全身症状,对肾脏的播散性白色念珠菌感染具有一定的阻断作用。     

乳酸杆菌代谢产物对一些常见菌黏附阴道上皮细胞的抑制作用的初步探讨

目的 探讨乳酸杆菌代谢产物对大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌和白色念珠菌黏附阴道上皮细胞的抑制作用.方法 刮取健康妇女阴道上皮细胞进行体外培养,观察在乳酸杆菌代谢产物的干预下大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌和白色念珠菌黏附阴道上皮细胞的情况.结果 和结论 乳酸杆菌代谢产物能够明显抑制大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌和白色念珠菌对阴道上皮细胞的黏附.     

Synergistic effects between silibinin and antibiotics on methicillin-resistant Staphylococcus aureus isolated from clinical specimens

Methicillin-resistant Staphylococcus aureus (MRSA) is a dangerous microorganism, and creates serious medical problems. It causes many types of infections in humans and often acquires multi-drug resistance. In this study, silibinin was evaluated against 20 clinical isolates of MRSA, either alone or in combination with ampicillin or oxacillin, using a checkerboard assay. The silibinin exhibited good activity against isolates of MRSA, and MRSA ATCC33952 and MSSA ATCC25923, with minimum inhibitory concentrations/minimum bactericidal concentrations (MICs/MBCs) ranging between 2-8/4-16 μg/mL, for ampicillin 2-1024/2-2048 μg/mL, and for oxacillin 0.25-32/0.5-64 μg/mL. The range of MIC(50) and MIC(90) were 0.5-4 μg/mL and 2-8 μg/mL, respectively. The MICs/MBCs for the combination of silibinin plus oxacillin or ampicillin were reduced by ≥4-fold against the MRSA isolates tested, demonstrating a synergistic effect, as defined by a fractional inhibitory concentration index (FICI) of ≤0.5. Furthermore, a time-kill study evaluating the growth of the tested bacteria showed that growth was completely attenuated after 2-5 h of treatment with the 1/2 MIC of silibinin, regardless of whether it was administered alone or with oxacillin (1/2 MIC) or ampicillin (1/2 MIC). In conclusion, silibinin exerted synergistic effects when administered with oxacillin or ampicillin and the antibacterial activity and resistant regulation of silibinin against clinical isolates of MRSA might be useful in controlling MRSA infections.     

Antimicrobial activity of essential oils and other plant extracts

The antimicrobial activity of plant oils and extracts has been recognized for many years. However, few investigations have compared large numbers of oils and extracts using methods that are directly comparable. In the present study, 52 plant oils and extracts were investigated for activity against Acinetobacter baumanii, Aeromonas veronii biogroup sobria, Candida albicans, Enterococcus faecalis, Escherichia col, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serotype typhimurium, Serratia marcescens and Staphylococcus aureus, using an agar dilution method. Lemongrass, oregano and bay inhibited all organisms at concentrations of < or = 2.0% (v/v). Six oils did not inhibit any organisms at the highest concentration, which was 2.0% (v/v) oil for apricot kernel, evening primrose, macadamia, pumpkin, sage and sweet almond. Variable activity was recorded for the remaining oils. Twenty of the plant oils and extracts were investigated, using a broth microdilution method, for activity against C. albicans, Staph. aureus and E. coli. The lowest minimum inhibitory concentrations were 0.03% (v/v) thyme oil against C. albicans and E. coli and 0.008% (v/v) vetiver oil against Staph. aureus. These results support the notion that plant essential oils and extracts may have a role as pharmaceuticals and preservatives.     

In vitro antibacterial activity of laboratory grown culture of Spirulina platensis

The hexane, ethyl acetate, dichloromethane, methanol extracts and spent media (extracellular substances) were tested in vitro for their antibacterial activity for which one Gram-positive bacterium (Staphylococcus aureus) and four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumoniae) were used as test organisms. The methanol extract showed more potent activity than other organic extracts, spent medium of the culture exhibited little activity against E. coli only. No inhibitory effect was found against Klebsiella pneumoniae.The broth microdilution assay gave minimum inhibitory concentrations (MIC) values ranging from 1 to 512 μg/ml. The MIC of methanol extract against S. aureus and E. coli were 128 μg/ml and 256 μg/ml, respectively.     

苍术体外抑菌活性的初步研究

对苍术的体外抑菌活性进行初步的研究。通过用体积分数为50％乙醇浸泡、有机溶剂萃取、薄层层析对苍术抑菌活性物质进行初步分析,用纸片法检测其抑菌活性,用琼脂稀释法测最低抑菌浓度（MIC）。结果表明：苍术提取液对金黄色葡萄球菌的抑菌作用较明显,对白色念珠菌和大肠杆菌的抑菌作用次之,其最低抑茵质量浓度分别为0．7g／mL,1．0g/mL和1．2g/mL;以正丁醇作为萃取液抑菌效果最佳,薄层层析实验结果表明,Rf值为0．76的展开点具有抑菌活性。     

Bioassay-guided discovery of antibacterial agents: in vitro screening of Peperomia vulcanica, Peperomia fernandopoioana and Scleria striatinux

Background

The global burden of bacterial infections is high and has been further aggravated by increasing resistance to antibiotics. In the search for novel antibacterials, three medicinal plants: Peperomia vulcanica, Peperomia fernandopoioana (Piperaceae) and Scleria striatinux (Cyperaceae), were investigated for antibacterial activity and toxicity.

Methods

Crude extracts of these plants were tested by the disc diffusion method against six bacterial test organisms followed by bio-assay guided fractionation, isolation and testing of pure compounds. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations were measured by the microdilution method. The acute toxicity of the active extracts and cytotoxicity of the active compound were performed in mice and mammalian cells, respectively.

Results

The diameter of the zones of inhibition (DZI) of the extracts ranged from 7?C13?mm on Escherichia coli and Staphylococcus aureus of which the methylene chloride:methanol [1:1] extract of Scleria striatinux recorded the highest activity (DZI?=?13?mm). Twenty-nine pure compounds were screened and one, Okundoperoxide, isolated from S. striatinux, recorded a DZI ranging from 10?C19?mm on S. aureus. The MICs and MBCs indicated that the Peperomias had broad-spectrum bacteriostatic activity. Toxicity tests showed that Okundoperoxide may have a low risk of toxicity with an LC₅₀ of 46.88???g/mL.

Conclusions

The antibacterial activity of these plants supports their use in traditional medicine. The pure compound, Okundoperoxide, may yield new antibacterial lead compounds following medicinal chemistry exploration.     

Tylosema esculentum extractives and their bioactivity

The investigation of Tylosema esculentum (Morama) husks, cotyledons, and tuber yielded griffonilide 2, compound 1, griffonin 3, gallic acid 4, protocatechuic acid 5, β-sitosterol 6, behenic acid 7, oleic acid 8, sucrose 9, 2-O-ethyl-α-D-glucopyranoside 10, kaempferol 11 and kaempferol-3-O-β-D-glucopyranoside 12. The structures of the isolates were determined by NMR, HR-TOF EIMS, IR and UV-vis spectroscopy, and by comparison with literature data. The husk EtOAc and n-butanol extracts demonstrated >90% DPPH radical scavenging activity at concentrations of 25, 50 and 250 μg/mL. Furthermore the husk extracts showed higher total phenolic content (233 mg GAE/g). The extractives exhibited minimum inhibitory quantities of 50-100 μg or no activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Candida albicans. The tuber extracts were inactive against Caco-2 and Hela cell lines, while the husk extracts showed low activity against Caco-2 and Vero cell line with IC(50) values >400 μg/mL. The GC-MS analysis showed the beans and tuber non-polar (n-hexane) extracts major constituents as fatty acids.     

Cassia alata and the preclinical search for therapeutic agents for the treatment of opportunistic infections in AIDS patients.

In our search for therapeutic agents from natural sources with potential for the treatment of opportunistic infections in patients afflicted with acquired immunodeficiency syndrome (AIDS), we investigated antibacterial and antifungal activities of water extracts of Cassia alata (C. alata). The extracts are traditionally used in Ivory Coast, West Africa to treat bacterial infections caused by Escherichia coli (E. coli), and fungal infections caused by Candida albicans (C. albicans) and dermatophytes. Our working hypothesis was that the extract contains active ingredient(s) which can be isolated, identified and developed into useful antibacterial/antifungal agents for the treatment of opportunistic infections in patients with AIDS. We used the broth dilution and agar dilution methods. Specifically, we focused on E. coli and C. albicans and the effectiveness of the extracts was evaluated relative to those of standard antibacterial agent chloramphenicol and antifungal agent amphotericin B. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the water extract of C. alata against E. coli were 1.6 mg/ml and 60 mg/ml, respectively; corresponding data for chloramphenicol were 2 micrograms/ml and 10 micrograms/ml. Similarly, the MIC and minimum fungicidal concentration (MFC) for the extract against C. albicans were 0.39 mg/ml and 60 mg/ml in contrast to 0.58 micrograms/ml and 0.98 micrograms/ml for amphotericin B. From the dose-response curve plots, the extract had an IC50 of 31 mg/ml for E. coli and 28 mg/ml for C. albicans. The data suggest that C. alata extracts contain agent(s) which have therapeutic potential and might be useful if isolated and developed for the treatment of opportunistic infections of AIDS patients.     

Cassia alata and the preclinical search for therapeutic agents for the treatment of opportunistic infections in AIDS patients.

In our search for therapeutic agents from natural sources with potential for the treatment of opportunistic infections in patients afflicted with acquired immunodeficiency syndrome (AIDS), we investigated antibacterial and antifungal activities of water extracts of Cassia alata (C. alata). The extracts are traditionally used in Ivory Coast, West Africa to treat bacterial infections caused by Escherichia coli (E. coli), and fungal infections caused by Candida albicans (C. albicans) and dermatophytes. Our working hypothesis was that the extract contains active ingredient(s) which can be isolated, identified and developed into useful antimicrobial/antifungal agents for the treatment of opportunistic infections in patients with AIDS. We used the broth dilution and agar dilution methods. Specifically, we focused on E. coli and C. albicans and the effectiveness of the extracts was evaluated relative to those of standard antibacterial agent chloramphenicol and antifungal agent amphotericin B. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the water extract of C. alata against E. coli were 1.6 mg/ml and 60 mg/ml respectively; corresponding data for chloramphenicol were 2 ug/ml. Similarly, the MIC and minimum fungicidal concentration (MFC) for the extract against C. albicans were 0.39 mg/ml and 60 mg/ml in contrast to 0.58 ug/ml and 0.98 ug/ml for amphotericin B. From the dose-response curve plots, the extract had an IC50 of 31 mg/ml for E. coli and 28 mg/ml for C. albicans. The data suggest that C. alata extracts contain agent(s) which have therapeutic potential and might be useful if isolated and developed for the treatment of opportunistic infections of AIDS patients.     

Antimicrobial and antiviral screening of novel indole carboxamide and propanamide derivatives

A few series of indole derivatives were screened for antimicrobial, antifungal and anti-HBV activities. The compounds were tested for their in vitro antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and for their antifungal activity against Candida albicans using a disc diffusion method, which measures the diameter of the inhibition zone around a paper disc soaked in a solution of the test compounds. The antimicrobial activity results showed that all compounds are as a active as the standard compound ampicillin against Staphylococcus aureus. It was also found that indole carboxamide derivatives, substituted at 3-position with several benzyl groups, showed better inhibition of Bacillus subtilis than their congeners substituted at 2-position. Activity patterns of the compounds against Escherichia coli and Staphylococcus aureus were found slightly different by the same method. In this case, there was no correlation between structure and activity of the compounds. The antifungal activity of carboxamide derivatives was found higher compared to that of the propanamide derivatives. The minimum inhibitory concentration (MIC) values of some indole derivatives were also determined by the tube dilution technique. The MIC values of the compounds were found nearly 20- to 100-fold smaller compared to the standard compounds ciprofloxacin and ampicillin (1.56-3.13 microg/ml and 1.56-12.5 microg/ml, respectively) against Staphylococcus aureus, Bacillus subtilis and Escherichia coli. The MIC values of the tested compounds showed that these are better inhibitors for Candida albicans. Indole derivatives were screened by the anti-HBV susceptibility test. No compound showed good inhibition against the HBV virus.