Patchouli alcohol: in vitro direct anti-influenza virus sesquiterpene in <Emphasis Type="Italic">Pogostemon cablin</Emphasis> Benth.

During the screening of anti-influenza virus substances from traditional herbal medicines, the methanol extract from the leaves of Pogostemon cablin Benth. showed potent in vitro antiviral activity (99.8% inhibition at a concentration of 10 μg/mL) against influenza virus A/PR/8/34 (H1N1). The anti-influenza virus principle was isolated from the hexane-soluble fraction, through solvent fractionation, repeated silica gel column chromatography, and reversed-phase HPLC. The major active principle was a volatile substance that was identified as a sesquiterpene, patchouli alcohol (1), on the basis of its spectral analyses. When anti-influenza virus activity against A/PR/8/34 was evaluated by the plaque forming assay, patchouli alcohol reduced the number of plaques by 75% at 2 μg/mL and 89% at 10 μg/mL. Patchouli alcohol showed dose-dependent anti-influenza virus activity, and its IC₅₀ value was estimated to be 2.635 μM. Although 11 different sesquiterpenes were tested for antiviral activity against influenza virus A/PR/8/34, no or negligible activity was observed except for patchouli alcohol. Patchouli alcohol did not show anti-influenza virus activity against A/Guizhou/54/89 (H3N2), but showed weak activity against B/Ibaraki/2/85 (IC₅₀ = 40.82 μM). Patchouli alcohol did not show inhibitory activity against influenza virus neuraminidase.     

Design and synthesis of 4′‐((5‐benzylidene‐2,4‐dioxothiazolidin‐3‐yl)methyl)biphenyl‐2‐carbonitrile analogs as bacterial peptide deformylase inhibitors

Herein, we report the synthesis and screening of 4′‐((5‐benzylidene‐2,4‐dioxothiazolidin‐3‐yl)methyl)biphenyl‐2‐carbonitrile analogs 11(a–j) as bacterial peptide deformylase (PDF) enzyme inhibitors. The compounds 11b (IC₅₀ value = 139.28 μm ), 11g (IC₅₀ value = 136.18 μm ), and 11h (IC₅₀ value = 131.65 μm ) had shown good PDF inhibition activity. The compounds 11b (MIC range = 103.36–167.26 μg/mL), 11g (MIC range = 93.75–145.67 μg/mL), and 11h (MIC range = 63.61–126.63 μg/mL) had also shown potent antibacterial activity when compared with standard ampicillin (MIC range = 100.00–250.00 μg/mL). Thus, the active derivatives were not only PDF inhibitors but also efficient antibacterial agents. To gain more insight on the binding mode of the compounds with PDF enzyme, the synthesized compounds 11(a–j) were docked against PDF enzyme of Escherichia coli and compounds exhibited good binding properties. The results suggest that this class of compounds has potential for development and use in future as antibacterial drugs.     

Synthesis and antiviral activities of a novel class of thioflavone and flavonoid analogues

A novel class of thioflavone and flavonoid derivatives has been prepared and their antiviral activities against enterovirus 71 (EV71) and the coxsackievirus B3 (CVB3) and B6 (CVB6) were evaluated. Compounds 7d and 9b showed potent antiviral activities against EV71 with IC₅₀ values of 8.27 and 5.48 μM, respectively. Compound 7f, which has been synthesized for the first time in this work, showed the highest level of inhibitory activity against both CVB3 and CVB6 with an IC₅₀ value of 0.62 and 0.87 μM. Compounds 4b, 7a, 9c and 9e also showed strong inhibitory activities against both the CVB3 and CVB6 at low concentrations (IC₅₀=1.42?7.15 μM), whereas compounds 4d, 7c, 7e and 7g showed strong activity against CVB6 (IC₅₀=2.91–3.77 μM) together with low levels of activity against CVB3. Compound 7d exhibited stronger inhibitory activity against CVB3 (IC₅₀=6.44 μM) than CVB6 (IC₅₀>8.29 μM). The thioflavone derivatives 7a, 7c, 7d, 7e, 7f and 7g, represent a new class of lead compounds for the development of novel antiviral agents.     

A Facile One‐Pot Synthesis of 2‐Arylamino‐5‐Aryloxylalkyl‐1,3,4‐Oxadiazoles and Their Urease Inhibition Studies

A one‐pot method for the synthesis of structural type urease inhibitors, 2‐amino‐1,3,4‐oxadiazoles, was developed. The structures of the compounds were established using spectroanalytical techniques and unambiguously confirmed by single‐crystal X‐ray analysis of compound 3o . The synthesized compounds were tested against jack beans urease, and most of the compounds ( 3c , 3g , 3j , 3k , 3n , 3r – 3v ) were found more active than the standard. The most potent compound ( 3u ) had an IC₅₀ value of 6.03 ± 0.02 μm as compared to the IC₅₀ value of the standard (thiourea; 22.0 ± 1.2 μm ). The prominent urease inhibition activity of these compounds may serve as an important finding in the development of less toxic and more potent antiulcer drugs. The compounds were also investigated against four bacterial strains, and some of the compounds ( 3g and 3r ) were found more potent than the standard drug (ciprofloxacin) against all the tested strains. The MIC value for compound 3g was 0.156 μmol/mL against the tested bacterial strains.     

Isolation and identification of compounds from Kalanchoe pinnata having human alphaherpesvirus and vaccinia virus antiviral activity

Context: Kalanchoe pinnata (Lam.) Pers. (Crassulaceae) is a succulent plant that is known for its traditional antivirus and antibacterial usage.

Objective: This work examines two compounds identified from the K. pinnata plant for their antivirus activity against human alphaherpesvirus (HHV) 1 and 2 and vaccinia virus (VACV).

Materials and methods: Compounds KPB-100 and KPB-200 were isolated using HPLC and were identified using NMR and MS. Both compounds were tested in plaque reduction assay of HHV-2 wild type (WT) and VACV. Both compounds were then tested in virus spread inhibition and virus yield reduction (VYR) assays of VACV. KPB-100 was further tested in viral cytopathic effect (CPE) inhibition assay of HHV-2 TK-mutant and VYR assay of HHV-1?WT.

Results: KPB-100 and KPB-200 inhibited HHV-2 at IC₅₀ values of 2.5 and 2.9?μg/mL, respectively, and VACV at IC₅₀ values of 3.1 and 7.4?μg/mL, respectively, in plaque reduction assays. In virus spread inhibition assay of VACV KPB-100 and KPB-200 yielded IC₅₀ values of 1.63 and 13.2?μg/mL, respectively, and KPB-100 showed a nearly 2-log reduction in virus in VYR assay of VACV at 20?μg/mL. Finally, KPB-100 inhibited HHV-2 TK- at an IC₅₀ value of 4.5?μg/mL in CPE inhibition assay and HHV-1 at an IC₉₀ of 3.0?μg/mL in VYR assay.

Discussion and conclusion: Both compounds are promising targets for synthetic optimization and in vivo study. KPB-100 in particular showed strong inhibition of all viruses tested.     

Anticancer,antioxidant and antibiotic activities of mushroom Ramaria flava

Ramaria flava is a species of edible mushroom with some bioactivity. The anticancer, antioxidant and antibiotic activities and chemical composition of R. flava ethanol extract (EE) were evaluated. The present study exhibited that the EE displayed the strongest inhibitory activity against tumor cell MDA-MB-231 with an IC₅₀ value of 66.54 μg/mL in three tested tumor cell lines, and the inhibition percent was 71.66% at the concentration of 200 μg/mL (MTT assay). The total phenolic compounds varied among four fractions of the EE from 6.66 to 61.01 mg gallic acid equivalent (GAE) per g dry weight. Water fraction exhibited high DPPH and OH radical-scavenging activities with low IC₅₀ values of 5.86 and 18.08 μg/mL, respectively. Meanwhile, three phenolic compounds from water fraction were also identified by HPLC. The antibiotic activities of the EE were evaluated against three microorganisms and three fungi strains by means of the agar well diffusion method and the poisoned medium technique, respectively. The EE also showed moderate antibiotic activities. These results suggest that R. flava could hold a good potential source for human health.     

Leishmanicidal and cytotoxic activities of Nigella sativa and its active principle,thymoquinone

Abstract

Context: Leishmaniasis is a complex disease with a broad spectrum of clinical presentations.

Objective: We evaluated the anti-leishmanial effects of Nigella sativa L. (Ranunculaceae) against Leishmania tropica and Leishmania infantum with an in vitro model.

Materials and methods: Antileishmanial effects of essential oil and methanolic extract of N. sativa (0–200?µg/mL) and thymoquinone (0–25?µg/mL) on promastigotes of both species and their cytotoxicity activities against murine macrophages were evaluated using the MTT assay at 24, 48, and 72?h. Moreover, their leishmanicidal effects against amastigotes were investigated in a macrophage model, for 48 and 72?h.

Results: The findings showed that essential oil (L. tropica IC₅₀ 9.3?μg/mL and L. infantum IC₅₀ 11.7?μg/mL) and methanolic extract (L. tropica IC₅₀ 14.8?μg/mL and L. infantum IC₅₀ 15.7?μg/mL) of N. sativa, particularly thymoquinone (L. tropica IC₅₀ 1.16?μg/mL and L. infantum IC₅₀ 1.47?μg/mL), had potent antileishmanial activity on promastigotes of both species after 72?h. In addition, essential oil (L. tropica IC₅₀ 21.4?μg/mL and L. infantum IC₅₀ 26.3?μg/mL), methanolic extract (L. tropica IC₅₀ 30.8?μg/mL and L. infantum IC₅₀ 34.6?μg/mL), and thymoquinone (L. tropica IC₅₀ 2.1?μg/mL and L. infantum IC₅₀ 2.6?μg/mL) mediated a significant decrease in the growth rate of amastigote forms of both species. Thymoquinone (CC₅₀ 38.8?μg/mL) exhibited higher cytotoxic effects against murine macrophages than the other extracts.

Conclusion: N. sativa, especially its active principle, thymoquinone, showed a potent leishmanicidal activity against L. tropica and L.infantum with an in vitro model.     

In vitro Antiviral Effects and 3D QSAR Study of Resveratrol Derivatives as Potent Inhibitors of Influenza H1N1 Neuraminidase

The anti-influenza virus activities of 50 resveratrol (RV: 3, 5, 4′-trihydroxy-trans-stilbene) derivatives were evaluated using a neuraminidase (NA) activity assay. The results showed that 35 compounds exerted an inhibitory effect on the NA activity of the influenza virus strain A/PR/8/34 (H1N1) with 50% inhibitory concentration (IC₅₀) values ranging from 3.56 to 186.1 μm . Next, the 35 RV derivatives were used to develop 3D quantitative structure–activity relationship (3D QSAR) models for understanding the chemical–biological interactions governing their activities against NA. The comparative molecular field analysis (CoMFA r² = 0.973, q² = 0.620, q_test² = 0.661) and the comparative molecular similarity indices analysis (CoMSIA r² = 0.956, q² = 0.610, q_test² = 0.531) were applied. Afterward, molecular docking was performed to study the molecular interactions between the RV derivatives and NA. Finally, a cytopathic effect (CPE) reduction assay was used to evaluate the antiviral effects of the RV derivatives in vitro. Time-of-addition studies demonstrated that the RV derivatives might have a direct effect on viral particle infectivity. Our results indicate that the RV derivatives are potentially useful antiviral compounds for new drug design and development for influenza treatment.     

Synthesis and Evaluation of Salicylanilide Derivatives as Potential Epidermal Growth Factor Receptor Inhibitors

Two series of novel salicylanilide were synthesized as potential epidermal growth factor receptor (EGFR) inhibitors. The enzyme inhibitory activity against EGFR of all compounds was carried out, and their antiproliferative activities against the A549 and A431 cell lines were also evaluated. Of the compounds studied, majority of them exhibited high antiproliferative activities compared with gefitinib; especially, 12a and 12b exhibited stronger inhibitory activity against EGFR with IC₅₀ values of 10.4 ± 2.25 and 15.4 ± 2.33 nm , respectively, which were comparable to the positive control of gefitinib (IC₅₀ = 12.1 ± 2.21 nm ). Compound 12b also showed outstanding inhibitory activity against A431 and A549 cell lines with the IC₅₀ values of 0.42 ± 0.43 μm and 0.57 ± 0.43 μm , which was better than the positive controls. In the molecular modeling study, compound 12b was bound into the active pocket of EGFR with two hydrogen bond and with minimum binding free energy ▵G_b = −25.1125 kcal/mol. The result also suggested that compound 12b could bind the EGFR kinase well.     

Synthesis,Antibacterial Activities,and 3D‐QSAR of Sulfone Derivatives Containing 1, 3, 4‐Oxadiazole Moiety

A series of sulfone derivatives containing 1, 3, 4‐oxadiazole moiety were prepared and evaluated for their antibacterial activities by the turbidimeter test. Most compounds inhibited growth of Ralstonia solanacearum (R. solanacearum) from tomato and tobacco bacterial wilt with high potency, among which compounds 5a and 5b exhibited the most potent inhibition against R. solanacearum from tomato and tobacco bacterial wilts with EC₅₀ values of 19.77 and 8.29 μg/mL, respectively. Our results also demonstrated that 5a, 5b , and a number of other compounds were more potent than commercial bactericides Kocide 3000 and Thiodiazole Copper, which inhibited R. solanacearum from tomato bacterial wilt with EC₅₀ values of 93.59 and 99.80 μg/mL and tobacco bacterial wilt with EC₅₀ values of 45.91 and 216.70 μg/mL, respectively. The structure–activity relationship (SAR) of compounds was studied using three‐dimensional quantitative structure–activity relationship (3D‐QSAR) models created by comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) based on compound bioactivities against tomato and tobacco bacterial wilts. The 3D‐QSAR models effectively predicted the correlation between inhibitory activity and steric–electrostatic properties of compounds.     

Design,Synthesis and Molecular Docking Studies of Novel Indole–Pyrimidine Hybrids as Tubulin Polymerization Inhibitors

A series of novel hybrids of indole–pyrimidine‐containing piperazine moiety were designed, synthesized and evaluated for their antiproliferative and tubulin polymerization inhibitory activities. The results indicated that most of these compounds possessed significant cytotoxic potency against four cancer cell lines, HT‐29, A549, MDA‐MB‐231 and MCF‐7. Particularly, the most promising compound 34 showed more potent and broad‐spectrum cytotoxic activities with the IC₅₀ values ranged from 5.01 to 14.36 μm against A549, MDA‐MB‐231 and MCF‐7 cell lines. Meanwhile, 34 also displayed the most potent tubulin polymerization inhibitory activity with IC₅₀ value of 11.2 μm . Furthermore, molecular docking analysis demonstrated 34 interacts and binds efficiently with the tubulin protein at the colchicine‐binding site. It was worth noting that the compound did not affect the normal human embryonic kidney cells, HEK‐293. These results suggest that this novel class of indole–pyrimidine hybrids may have potential to be developed as new a class of tubulin polymerization inhibitors.     

Rational drug design of indazole‐based diarylurea derivatives as anticancer agents

A series of novel indazole‐based diarylurea derivatives targeting c‐kit were designed by structure‐based drug design. The derivatives were prepared, and their antiproliferative activities were evaluated against human colon cancer HCT‐116 cell line and hepatocellular carcinoma PLC/PRF/5 cell line. The antiproliferative activities demonstrated that six of nine compounds exhibited comparable activities with sorafenib against HCT‐116. The structure–activity relationship (SAR) analysis indicated that the indazole ring part tolerated different kinds of substituents, and the N position of the central pyridine ring played key roles in antiproliferative activity. The SAR and interaction mechanisms were further explored using molecular docking method. Compound 1i with N‐(2‐(pyrrolidin‐1‐yl)ethyl)‐carboxamide possessed improved solubility, 596.1 ng/ml and best activities, IC₅₀ at 1.0 μm against HCT‐116, and 3.48 μm against PLC/PRF/5. It is a promising anticancer agent for further development.     

Antimalarial and free radical scavenging activities of rhizomes of Polygonatum verticillatum supported by isolated metabolites

Antimalarial activity of the crude extract of Polygonatum verticillatum rhizomes and its sequentially partitioned fractions were investigated against Plasmodium falciparum. The crude extract possessed notable activity (IC₅₀: 21.67?μg/mL) that enhanced reasonably upon fractionation. The antiparasitic potency of the n-hexane fraction was maximum (IC₅₀: 2.33?μg/mL) followed by chloroform (IC₅₀: 4.62?μg/mL). However, the remaining fractions showed insignificant activity in the assay. The extracts of the plant showed marked scavenging activity on stable free radical, DDPH. The most potent antioxidant was the chloroform fraction (IC₅₀: 90?μg/mL) followed by ethyl acetate (IC₅₀: 93?μg/mL) and n-butanol (IC₅₀: 95?μg/mL) fractions. In the brine shrimps lethality test, the extracts were found nontoxic with the exception of ethyl acetate fraction (LD₅₀: 492.846?μg/mL). The bioactivity-guided isolation resulted into 5-hydroxymethyl-2-furaldehyde (HMF) and diosgenin which strongly supports the present experimental findings.     

Synthesis,biological evaluation,and molecular docking studies of novel 3‐aryl‐5‐(alkyl‐thio)‐1H‐1,2,4‐triazoles derivatives targeting Mycobacterium tuberculosis

A small library of new 3‐aryl‐5‐(alkyl‐thio)‐1H‐1,2,4‐triazoles was synthesized and screened for the antimycobacterial potency against Mycobacterium tuberculosis H₃₇Ra strain and Mycobacterium bovis BCG both in active and dormant stage. Among the synthesized library, 25 compounds exhibited promising anti‐TB activity in the range of IC₅₀0.03–5.88 μg/ml for dormant stage and 20 compounds in the range of 0.03–6.96 μg/ml for active stage. Their lower toxicity (>100 μg/ml) and higher selectivity (SI = >10) against all cancer cell lines screened make them interesting compounds with potential antimycobacterial effects. Furthermore, to rationalize the observed biological activity data and to establish a structural basis for inhibition of M. tuberculosis, the molecular docking study was carried out against a potential target MTB CYP121 which revealed a significant correlation between the binding score and biological activity for these compounds. Cytotoxicity and in vivo pharmacokinetic studies suggested that 1,2,4‐triazole analogues have an acceptable safety index, in vivo stability and bio‐availability.     

Metronidazole containing pyrazole derivatives potently inhibit tyrosyl‐tRNA synthetase: design,synthesis, and biological evaluation

As an important enzyme in bacterial protein biosynthesis, tyrosyl‐tRNA synthetase (TyrRS) has been an absorbing therapeutic target for exploring novel antibacterial agents. A series of metronidazole‐based antibacterial agents has been synthesized and identified as TyrRS inhibitors with low cytotoxicity and significant antibacterial activity, especially against Gram‐negative organisms. Of the compounds obtained, 4f is the most potent agent which inhibited the growth of Pseudomonas aeruginosa ATCC 13525 (MIC = 0.98 μg/mL) and exhibited TryRS inhibitory activity (IC₅₀ = 0.92 μm ). Docking simulation was performed to further understand its potency. Membrane‐mediated apoptosis in P. aeruginosa was verified by flow cytometry.     

New alkenyl derivative from Piper malacophyllum and analogues: Antiparasitic activity against Trypanosoma cruzi and Leishmania infantum

Alkylphenols isolated from Piper malacophyllum (Piperaceae), gibbilimbols A and B, showed interesting activity against the parasites Trypanosoma cruzi and Leishmania infantum. In continuation to our previous work, a new natural product from the essential oil of the leaves of P. malacophyllum was isolated, the 5‐[(3E)‐oct‐3‐en‐1‐il]‐1,3‐benzodioxole, and also a new set of five compounds was prepared. The antiparasitic activity of the natural product was evaluated in vitro against these parasites, indicating potential against the promastigote/trypomastigote/amastigote forms (IC₅₀ 32–83 μm ) of the parasites and low toxicity (CC₅₀ > 200 μm ) to mammalian cells. The results obtained to the synthetic compounds indicated that the new derivatives maintained the promising antiparasitic activity, but the cytotoxicity was considerably lowered. The amine derivative LINS03011 displayed the most potent IC₅₀ values (13.3 and 16.7 μm ) against amastigotes of T. cruzi and L. infantum, respectively, indicating comparable activity to the phenolic prototype LINS03003, with threefold decreased (CC₅₀ 73.5 μm ) cytotoxicity, leading the selectivity index (SI) towards the parasites up to 24.5. In counterpart, LINS03011 has not shown membrane disruptor activity in SYTOX Green model. In summary, this new set showed the hydroxyl is not essential for the antiparasitic activity, and its substitution could decrease the toxicity to mammalian cells.     

In vitro activity of the interaction between taxifolin (dihydroquercetin) and pyrimethamine against Toxoplasma gondii

Toxoplasmosis is one of the most neglected zoonotic foodborne parasitic diseases that cause public health and socioeconomic concern worldwide. The current drugs used for the treatment of toxoplasmosis have been identified to have clinical limitations. Hence, new drugs are urgently needed to eradicate T.gondii infections globally. Here, an in vitro anti‐Toxoplasma gondii activity of taxifolin (dihydroquercetin) and dihydrofolate inhibitor (pyrimethamine) alone and in combination with a fixed concentration of pyrimethamine were investigated against the rapidly proliferating T.gondii RH strain at 48 hr using colorimetric assay. Pyrimethamine showed the highest anti‐T. gondii activity with IC_50P of 0.84 μg/ml (p > .05), respectively. The combination of pyrimethamine with dihydroquercetin gave a significant inhibitory activity against tachyzoites in in vitro with IC_50p of 1.39 μg/ml (p < .05). The IC_50p ranges obtained for the individual and the combination of taxifolin with pyrimethamine inhibition of parasite growth were not cytotoxic to the infected HFF and Hek‐293 cell lines used. These compounds combination should be investigated further using in vivo model of toxoplasmosis.     

Unlocking the in vitro anti-inflammatory and antidiabetic potential of Polygonum maritimum

Context: Several Polygonum species (Polygonaceae) are used in traditional medicine in Asia, Europe and Africa to treat inflammation and diabetes.

Objective: Evaluate the in vitro antioxidant, anti-inflammatory and antidiabetic potential of methanol and dichloromethane extracts of leaves and roots of the halophyte Polygonum maritimum L.

Material and methods: Antioxidant activity was determined (up to 1?mg/mL) as radical-scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), copper (CCA) and iron (ICA) chelating activities and iron reducing power (FRAP). NO production was measured in lipopolysaccharide (LPS)-stimulated macrophages for 24?h at concentrations up to 100?μg/mL and antidiabetic potential was assessed by α-amylase and α-glucosidase inhibition (up to 10?mg/mL) assays. The phytochemical composition of the extracts was determined by gas chromatography-mass spectrometry (GC-MS).

Results: The methanol leaf extract had the highest activity against DPPH? (IC₅₀ =?26?μg/mL) and ABTS⁺? (IC₅₀ =?140?μg/mL), FRAP (IC₅₀ =?48?μg/mL) and CCA (IC₅₀ =?770?μg/mL). Only the dichloromethane leaf extract (LDCM) showed anti-inflammatory activity (IC₅₀ =?48?μg/mL). The methanol root (IC₅₀ =?19?μg/mL) and leaf (IC₅₀ =?29?μg/mL) extracts strongly inhibited baker’s yeast α-glucosidase, but LDCM had higher rat’s α-glucosidase inhibition (IC₅₀ =?2527?μg/mL) than acarbose (IC₅₀ =?4638?μg/mL). GC-MS analysis identified β-sitosterol, stigmasterol, 1-octacosanol and linolenic acid as possible molecules responsible for the observed bioactivities.

Conclusions: Our findings suggest P. maritimum as a source of high-value health promoting commodities for alleviating symptoms associated with oxidative and inflammatory diseases, including diabetes.     

Synthesis and antiviral activity of a series of novel N-phenylbenzamide and N-phenylacetophenone compounds as anti-HCV and anti-EV71 agents

A series of novel N-phenylbenzamide and N-phenylacetophenone compounds were synthesized and evaluated for their antiviral activity against HCV and EV71 (strain SZ-98). The biological results showed that three compounds (23, 25 and 41) exhibited considerable anti-HCV activity (IC₅₀=0.57–7.12 μmol/L) and several compounds (23, 28, 29, 30, 31 and 42) displayed potent activity against EV71 with the IC₅₀ values lower than 5.00 μmol/L. The potency of compound 23 (IC₅₀=0.57 μmol/L) was superior to that of reported compounds IMB-1f (IC₅₀=1.90 μmol/L) and IMB-1g (IC₅₀=1.00 μmol/L) as anti-HCV agents, and compound 29 possessed the highest anti-EV71 activity, comparable to the comparator drug pirodavir. The efficacy in vivo and antiviral mechanism of these compounds warrant further investigations.KEY WORDS: Synthesis, N-phenylbenzamide, N-phenylacetophenone, Anti-HCV, Anti-EV71, Agents     

In‐vitro antileishmanial potential of peptide drug hirudin

Hirudin is clinically an important drug used for the treatment of cardiac diseases, but has never been elucidated for antileishmanial potential. This study was designed to determine the therapeutic utility of hirudin against leishmaniasis. Binding affinities of 28 potent proteinase inhibitors were screened computationally against leishmanolysin (GP63), out of which hirudin exhibited higher binding affinity with GP63 and good expected IC₅₀ values. Experimentally, hirudin showed most promising activity against promastigote and axenic amastigote forms of leishmanial parasites with IC₅₀ values of 0.60 ± 0.36 μg/mL and 0.43 ± 0.23 μg/mL, respectively, in a dose‐ and time‐dependent assay. The cytotoxicity assay revealed no adverse effects on human macrophages with LD₅₀ value of 860.11 ± 53.44 μg/mL. Hirudin caused leishmanial cell death mainly by apoptosis and membrane permeability. In spite of the basic knowledge obtained, hirudin mechanism is considerably less prone to the induction of resistance than classical drugs. Collectively, this study fosters further studies for the hirudin as new antileishmania lead with a new mode of action.