Leishmanicidal activity of Himatanthus sucuuba latex against Leishmania amazonensis

Himatanthus sucuuba (HsL) latex exhibited a potent leishmanicidal activity against intracellular amastigotes of Leishmania amazonensis, a causative agent of cutaneous leishmaniasis. HsL inhibited intracellular amastigote growth in a dose-dependent manner (IC₅₀ = 15.7 µg/mL). Moreover, HsL increased nitric oxide (NO) and Tumor Nuclear Factor-α (TNF-α) and decreased Transforming Growth Factor-β (TGF-β) production in macrophages. As assessed by plasma membrane integrity and mitochondrial activity, HsL showed low toxicity for host macrophages. HsL in vivo was active by the oral route, reducing the parasite load in established footpad lesions after only five doses. In summary, these findings support HsL as an interesting candidate for further evaluations regarding its potential application as a therapeutical agent against Leishmania.     

Efficacy of biogenic selenium nanoparticles against Leishmania major: In vitro and in vivo studies

Project: This study investigated the in vitro and in vivo effectiveness of biogenic selenium nanoparticles (Se NPs), biosynthesized by Bacillus sp. MSh-1, against Leishmania major (MRHO/IR/75/ER). Procedure: The 3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity effects of the biogenic Se NPs against both promastigote and amastigote forms of L. major. In a separate in vivo experiment, we also determined the preventive and therapeutic effects of biogenic Se NPs in BALB/c mice following subcutaneous infected with L. major. Results: The MTT assays showed that the highest toxicity occurred after 72 h against both promastigote and amastigote forms of L. major. The cytotoxicity of Se NPs was higher at all incubation times (24, 48, and 72 h) against the promastigote than the amastigote form (p < 0.05). The 50% inhibitory concentrations (IC₅₀) of the Se NPs were 1.62 ± 0.6 and 4.4 ± 0.6 μg ml^?1 against the promastigote and amastigote forms, respectively, after a 72-h incubation period. Apoptosis assays showed DNA fragmentation in promastigotes treated with Se NPs. In an animal challenge, prophylactic doses of biogenic Se NPs delayed the development of localized cutaneous lesions. Moreover, daily administration of Se NPs (5 or 10 mg kg^?1 day^?1) in similarly infected BALB/c mice that had not received prophylactic doses of Se NPs also abolished the localized lesions after 14 days. Conclusion: Based on these in vitro and in vivo studies, biogenic Se NPs can be considered as a novel therapeutic agent for treatment of the localized lesions typical of cutaneous leishmaniasis.     

In vitro effects of triterpenic acids from olive leaf extracts on the mitochondrial membrane potential of promastigote stage of Leishmania spp

Protozoan diseases, such as leishmaniasis, are a cause of considerable morbidity throughout the world, affecting millions every year. In this study, two triterpenic acids (maslinic and oleanolic acids) were isolated from Tunisian olive leaf extracts and their in vitro activity against the promastigotes stage of Leishmania (L.) infantum and Leishmania (L.) amazonensis was investigated. Maslinic acid showed the highest activity with an IC₅₀ of 9.32 ± 1.654 and 12.460 ± 1.25 μg/ml against L. infantum and L. amazonensis, respectively. The mechanism of action of these drugs was investigated by detecting changes in the phosphatidylserine (PS) exposure, the plasma membrane permeability, the mitochondrial membrane potential and the ATP level production in the treated parasites. By using the fluorescent probe SYTOX® Green, both triterpenic acids showed that they produce a time-dependent plasma membrane permeabilization in the treated Leishmania species. In addition, spectrofluorimeteric data revealed the surface exposure of PS in promastigotes. Both molecules reduced the mitochondrial membrane potential and decreased the ATP levels to 15% in parasites treated with IC₉₀ for 24 h. We conclude that the triterpenic acids tested in this study, show potential as future therapeutic alternative against leishmaniasis. Further studies are needed to confirm this.     

Phytochemical composition and biological activities of Asteriscus graveolens (Forssk) extracts

In the present study the phytochemical composition and biological activities of the aerial part extracts of Asteriscus graveolens against pathogenic bacteria and leishmania parasite were evaluated. Phytochemical analysis revealed the presence of polyphenols, flavonoids and tannins. The ethyl acetate fraction exhibited high antioxidant potential of 359.72 ± 32.03 μg and 326.76 ± 15.86 μg of ascorbic acid equivalents and 13.32 ± 0.19 μg/mL by PM, FRAP and DPPH assays respectively. This fraction also displayed a moderate antibacterial activity against Listeria monocytogenes ATCC 19115 (MIC = 0.312 mg/mL) and strong antileishmanial activity against both promastigote and amastigote forms with IC50 ranging from 22.93 ± 0.39 μg/mL to 35.23 ± 0.62 μg/mL. Furthermore the ethyl acetate fraction exhibited low cytotoxicity and good selectivity index towards the macrophage cell line Raw 264.7. HPLC analysis of the active fraction revealed the presence of hydroxycinnamic acid as major compound (30.56%). Asteriscus graveolens is a promising source of bioactive compounds that could be potentially used in cosmetic and pharmaceutical industry.     

Thymol and eugenol derivatives as potential antileishmanial agents

In Northeastern Brazil visceral leishmaniasis is endemic with lethal cases among humans and dogs. Treatment is toxic and 5–10% of humans die despite treatment. The aim of this work was to survey natural active compounds to find new molecules with high activity and low toxicity against Leishmania infantum chagasi. The compounds thymol and eugenol were chosen to be starting compounds to synthesize acetyl and benzoyl derivatives and to test their antileishmanial activity in vitro and in vivo against L. i. chagasi. A screening assay using luciferase-expressing promastigotes was used to measure the growth inhibition of promastigotes, and an ELISA in situ was performed to evaluate the growth inhibition of amastigote. For the in vivo assay, thymol and eugenol derivatives were given IP to BALB/c mice at 100 mg/kg/day for 30 days. The thymol derivatives demonstrated the greater activity than the eugenol derivatives, and benzoyl-thymol was the best inhibitor (8.67 ± 0.28 μg/mL). All compounds demonstrated similar activity against amastigotes, and acetyl-thymol was more active than thymol and the positive control drug amphotericin B. Immunohistochemistry demonstrated the presence of Leishmania amastigote only in the spleen but not the liver of mice treated with acetyl-thymol. Thus, these synthesized derivatives demonstrated anti-leishmanial activity both in vitro and in vivo. These may constitute useful compounds to generate new agents for treatment of leishmaniasis.     

Phytosynthesis of silver nanoparticles from Jatropha integerrima Jacq. flower extract and their possible applications as antibacterial and antioxidant agent

Jatropha integerrima Jacq. flower extract was used for the synthesis of silver nanoparticles in the current study. Various spectroscopic analyses were used to characterize the synthesized nanoparticles (JIF-AgNPs). The antibacterial efficacy of JIF-AgNPs was studied by well diffusion and microdilution techniques. In addition, the impact of JIF-AgNPs on free radicals was evaluated. On the ultraviolet–visible spectrum, the nanoparticles exhibit the highest absorbance at 422 nm. Based on the Fourier transform infrared spectrum, phenols and amino acids were involved in capping the JIF-AgNPs. Crystalline sphere-shaped nanoparticles with an average size of 50.07 nm and zeta potential of ?19.0 mV were confirmed by X-ray diffraction, transmission electron microscopy, and dynamic light scattering analysis respectively. The JIF-AgNPs exhibit the highest and lowest growth inhibitory activity towards E. coli and B. subtilis. The minimal inhibitory concentration of JIF-AgNPs against E. coli, K. pneumoniae, S. aureus, and B. subtilis were 2.5, 5.0, 5.0, and 7.5 μg/mL, respectively. The JIF-AgNPs exhibited significant radical scavenging activities against DPPH (IC₅₀-32.5 ± 0.06 µg/mL), hydroxyl (IC₅₀-25 ± 0.09 µg/mL), Superoxide (IC₅₀-42.5 ± 0.13 µg/mL), and ABTs (IC₅₀-33.5 ± 0.15 µg/mL). Thus, synthesized nanoparticles were a good alternative to develop an antibacterial and antioxidant agent.     

Synthesis and in-vitro anti-leishmanial activity of (4-arylpiperazin-1-yl)(1-(thiophen-2-yl)-9H-pyrido[3,4-b]indol-3-yl)methanone derivatives

In the present study, we have reported synthesis and biological evaluation of a series of fifteen 1-(thiophen-2-yl)-9H-pyrido[3,4-b]indole derivatives against both promastigotes and amastigotes of Leishmania parasites responsible for visceral (L. donovani) and cutaneous (L. amazonensis) leishmaniasis. Among these reported analogues, compounds 7b, 7c, 7f, 7g, 7i, 7j, 7m, 7o displayed potent activity (15.55, 7.70, 7.00, 3.80, 14.10, 9.25, 3.10, 4.85 μM, respectively) against L. donovani promastigotes than standard drugs miltefosine (15.70 μM) and pentamidine (32.70 μM) with good selectivity index. In further, in-vitro evaluation against amastigote forms, two compounds 7g (8.80 μM) and 7i (7.50 μM) showed significant inhibition of L. donovani amastigotes. Standard drug amphotericin B is also used as control to compare inhibition potency of compounds against both promastigote (0.24 μM) and amastigote (0.05 μM) forms.     

Target and non-target effects of Foeniculum vulgare and Matricaria chamomilla combined extract on Culex pipiens mosquitoes

The present study focused on extracting green larvicides from extracts of the combination of Foeniculum vulgare and Matricaria chamomilla using different solvents of increasing polarity in a Soxhlet extractor and evaluating their ovicidal, larvicidal, and cytotoxic activities. The most promising among all tested extracts was hexane extract. The ovicidal activity of the hexane PH2 extract resulted in a significant (p < 0.05) decrease in egg hatchability from 95.00 ± 6.16% to 15 ± 9.04% at doses ranging from 62.5 to 500 µg/mL. The larval mortality with the hexane extract ranged from 13.33 ± 3.3% to 93.33 ± 3.3% at doses ranging from 31.25 to 250 µg/mL, respectively. The LC₅₀ and LC₉₀ values of the larvicidal activity of the hexane extract were estimated to be 148.3 and 242.17 µg/mL, respectively, after 24 h of exposure. Similarly, the LC₅₀ values after 48 and 72 h of exposure were 124.93 and 100.3 µg/mL, respectively, against the third instar of Cx. pipiens. PH2 treatment of larvae resulted in histopathological changes such as degenerated epithelial cells and destruction of microvilli on the epithelial cells. The PH2 extract achieved a dose-dependent decrease in the rate of cell survival. The IC₅₀ value of PH2-treated HUVECs was 192.07 µg/mL after 24 h of incubation. The cells showed changes in cellular and nuclear morphology. In conclusion, the hexane extract of PH2 could be used in mosquito management programs.     

Triazino indole–quinoline hybrid: A novel approach to antileishmanial agents

A novel series of 1,2,4-triazino-[5,6b]indole-3-thione covalently linked to 7-chloro-4-aminoquinoline have been synthesized and evaluated for their in vitro activity against extracellular promastigote and intracellular amastigote form of Leishmania donovani. Among all tested compounds, compounds 7a and 7b were found to be the most active with IC₅₀ values 1.11, 0.36 μM and selectivity index (SI) values 67, >1111, respectively, against amastigote form of L. donovani which is several folds more potent than the standard drugs, miltefosine (IC₅₀ = 8.10 μM, SI = 7) and sodium stibo-gluconate (IC₅₀ = 54.60 μM, SI ⩾ 7).     

Leishmanicidal activity of lipophilic extracts of some Hypericum species

Leishmaniasis has emerged as the third most prevalent parasite-borne disease worldwide after malaria and filariasis, with about 350 million people at risk of infection. Antileishmanial drugs currently available have various limitations, mainly because of the parasite resistance and side effects. The search of new antileishmanial drugs is ventured throughout the world.PurposeThe purpose of this study was to assess the leishmanicidal activity of lipophilic extracts of eight Hypericum species against promastigote forms of Leishmania (Leishmania) amazonensis.Material and methodsThe dried and powered materials of aerial parts of H. andinum Gleason, H. brevistylum Choisy, H. caprifoliatum Cham. & Schltdl., H. carinatum Griseb., H. linoides A. St.-Hil., H. myrianthum Cham. & Schltdl., H. polyanthemum Klotzsch ex Reichardt and H. silenoides Juss. were extracted by static maceration with n-hexane. Extracts were evaporated to dryness under reduced pressure and stored at −20 °C until biological evaluation and HPLC analysis. The metabolites investigated were dimeric phloroglucinol derivatives, benzophenones and benzopyrans. The yields were expressed as mean of three injections in mg of compound per g of extract (mg/g extract). The effect of Hypericum species on the viability of infective forms of L. (L.) amazonensis was determined using a hemocytometer. Amphotericin B was used as a standard drug. The 50% inhibitory concentration (IC₅₀) values for each extract were determined by linear regression analysis. The cytotoxic effects of extracts were assessed on peritoneal macrophages of BALB/c mice by MTT assay. The concentration that causes 50% of macrophage cytotoxicity (CC₅₀) was determined by linear regression analysis. The selectivity index (SI) of the extracts was determined considering the following equation: CC₅₀ against mammalian cells/IC₅₀ against L. amazonensis.ResultsWe demonstrated that H. carinatum, H. linoides and H. polyanthemum were able to kill the parasites in a dose dependent manner. These extracts presented low cytotoxicity against murine macrophages. At 48 h of incubation H. polyanthemum presented significant leishmanicidal activity with a 50% inhibitory concentration (IC₅₀) of 36.1 µg/ml. The leishmanicidal activity of H. myrianthum was significantly lower than that presented by H. polyanthemum, H. carinatum and H. linoides extracts. H. brevistylum and H. caprifoliatum showed significant leishmanicidal activity only at high concentrations (500 and 1000 µg/ml), while H. andinum and H. silenoides were ineffective.ConclusionThe promising results demonstrate the importance of the species of the genus Hypericum as source of compounds potentially useful for the treatment of leishmaniasis.     

Oleanolic acid (OA) as an antileishmanial agent: Biological evaluation and in silico mechanistic insights

Although a worldwide health problem, leishmaniasis is considered a highly neglected disease, lacking efficient and low toxic treatment. The efforts for new drug development are based on alternatives such as new uses for well-known drugs, in silico and synthetic studies and naturally derived compounds. Oleanolic acid (OA) is a pentacyclic triterpenoid widely distributed throughout the Plantae kingdom that displays several pharmacological activities. OA showed potent leishmancidal effects in different Leishmania species, both against promastigotes (IC_{50 L. braziliensis} 30.47 ± 6.35 μM; IC_{50 L. amazonensis} 40.46 ± 14.21 μM; IC_{50 L. infantum} 65.93 ± 15.12 μM) and amastigotes (IC_{50 L. braziliensis} 68.75 ± 16.55 μM; IC_{50 L. amazonensis} 38.45 ± 12.05 μM; IC_{50 L. infantum} 64.08 ± 23.52 μM), with low cytotoxicity against mouse peritoneal macrophages (CC₅₀ 235.80 ± 36.95 μM). Moreover, in silico studies performed to evaluate OA molecular properties and to elucidate the possible mechanism of action over the Leishmania enzyme sterol 14α-demethylase (CYP51) suggested that OA interacts efficiently with CYP51 and could inhibit the ergosterol synthesis pathway. Collectively, these data indicate that OA is a good candidate as leading compound for the development of a new leishmaniasis treatment.     

Larvicidal activities of the stem bark extract and rotenoids of Millettia usaramensis subspecies usaramensis on Aedes aegypti L. (Diptera: Culicidae)

The dichloromethane/methanol (1:1) extract of the stem bark of Millettia usaramensis subspecies usaramensis was tested for its larvicidal activity against the 4th instar Aedes aegypti larvae and demonstrated activity with LC₅₀ value of 50.8 ± 0.06 μg/mL at 48 h. Compounds isolated from the extract were also tested for their larvicidal activities, and the rotenoid usararotenoid-A (LC₅₀ 4.3 ± 0.8 μg/mL at 48 h) was identified as the most active principle. This compound appears to be the first rotenoid having a trans-B/C ring junction and methylenedioxy group at C-2/C-3 with high larvicidal activity. Related rotenoids with the same configuration at the B/C-ring junction did not show significant activity at 100 μg/mL.     

New nemadectin congeners with acaricidal and nematocidal activity from Streptomyces microflavus neau3 Y-3

Two nemadectin congeners 1 and 2 were isolated from the fermentation broth of a mutant strain (Y-3) of Streptomyces microflavus neau3. Their structures were determined on the basis of extensive spectroscopic analysis and comparison with data from the literature. Compound 2 possessed a 5-membered ring lactone that is unprecedented among known milbemycins and avermectins. Both compounds 1 and 2 exhibited potent acaricidal activity and nematocidal activity. Especially, compound 2 demonstrated impressive acaricidal activity against adult mites with an IC₅₀ of 2.3 ± 0.9 μg/mL and mite eggs with an IC₅₀ of 17.5 ± 2.1 μg/mL and nematocidal activity against Caenorhabditis elegans with an IC₅₀ of 0.7 ± 0.2 μg/mL, which are higher than those of nemadectin and the known commercial acaricide and nematocide milbemycin A3/A4.     

In vitro growth inhibitory effects of 13,28-epoxyoleanane triterpene saponins in cancer cells

Two new 13,28-epoxyoleanane triterpene saponins, magnosides A (1) and B (2), were isolated from the 95% ethanolic extract of Cybianthus magnus (Mez) Pipoly roots. Their structures were deduced by a combination of spectral analyses and chemical evidences as compared to data reported in the literature. The hemolytic activity of both compounds was measured. Compound 1 was shown to exhibit the strongest hemolytic activity with a HD₅₀ of 3.8 μM followed by 2 with a HD₅₀ of 33.5 μM. The bioactivity of compounds 1 and 2 was also evaluated in vitro against different cellular models including Mycobacterium tuberculosis, Leishmania amazonensis axenic amastigotes, mouse peritoneal macrophages and eight cancer cell lines. While neither of the tested compounds displayed any activity against M. tuberculosis, both exhibited anti-leishmanial activity against axenic amastigotes as well as in vitro growth inhibitory activity against all tested cancer cell lines with IC₅₀ growth inhibitory concentrations ranging between 4 μM and 33 μM. The compounds displayed similar growth inhibitory activity in cancer cell lines sensitive to pro-apoptotic stimuli versus those displaying various levels of resistance to such stimuli. Quantitative videomicroscopy analyses revealed that compounds 1 and 2 are cytotoxic.     

Identification of new potent inhibitor of aldose reductase from Ocimum basilicum

Recent efforts to develop cure for chronic diabetic complications have led to the discovery of potent inhibitors against aldose reductase (AKR1B1, EC 1.1.1.21) whose role in diabetes is well-evident. In the present work, two new natural products were isolated from the ariel part of Ocimum basilicum; 7-(3-hydroxypropyl)-3-methyl-8-β-O-d-glucoside-2H-chromen-2-one (1) and E-4-(6′-hydroxyhex-3′-en-1-yl)phenyl propionate (2) and confirmed their structures with different spectroscopic techniques including NMR spectroscopy etc. The isolated compounds (1, 2) were evaluated for in vitro inhibitory activity against aldose reductase (AKR1B1) and aldehyde reductase (AKR1A1). The natural product (1) showed better inhibitory activity for AKR1B1 with IC₅₀ value of 2.095 ± 0.77 µM compare to standard sorbinil (IC₅₀ = 3.14 ± 0.02 µM). Moreover, the compound (1) also showed multifolds higher activity (IC₅₀ = 0.783 ± 0.07 µM) against AKR1A1 as compared to standard valproic acid (IC₅₀ = 57.4 ± 0.89 µM). However, the natural product (2) showed slightly lower activity for AKR1B1 (IC₅₀ = 4.324 ± 1.25 µM). Moreover, the molecular docking studies of the potent inhibitors were also performed to identify the putative binding modes within the active site of aldose/aldehyde reductases.     

Antioxidant and cytotoxic effect of biologically synthesized selenium nanoparticles in comparison to selenium dioxide

The present study was designed to evaluate antioxidant and cytotoxic effect of selenium nanoparticles (Se NPs) biosynthesized by a newly isolated marine bacterial strain Bacillus sp. MSh-1. An organic–aqueous partitioning system was applied for purification of the biogenic Se NPs and the purified Se NPs were then investigated for antioxidant activity using DPPH scavenging activity and reducing power assay. Cytotoxic effect of the biogenic Se NPs and selenium dioxide (SeO₂) on MCF-7 cell line was assesed by MTT assay. Tranmission electron micrograph (TEM) of the purified Se NPs showed individual and spherical nanostructure in size range of about 80–220 nm. The obtained results showed that, at the same concentration of 200 μg/mL, Se NPs and SeO₂ represented scavenging activity of 23.1 ± 3.4% and 13.2 ± 3.1%, respectively. However, the data obtained from reducing power assay revealed higher electron-donating activity of SeO₂ compared to Se NPs. Higher IC₅₀ of the Se NPs (41.5 ± 0.9 μg/mL) compared to SeO₂ (6.7 ± 0.8 μg/mL) confirmed lower cytotoxicity of the biogenic Se NPs on MCF-7 cell line.     

Antileishmanial activity of a guaianolide from Tanacetum parthenium (L.) Schultz Bip

Leishmaniasis is one of the major infectious diseases affecting the poorest regions of the world. The present study evaluated the antileishmanial activity of a guaianolide purified from the hydroalcoholic extract of aerial parts of Tanacetum parthenium (L.) Schultz Bip. The isolated compound showed activity against the promastigote form of Leishmania amazonensis, with 50% inhibition (IC₅₀) of cell growth at a concentration of 2.6 μg/ml. For the intracellular amastigote form, this guaianolide reduced by 10% the survival index of parasites in macrophages when it was used at 20.0 μg/ml. The selective index (SI) ratio (CC₅₀ for J774G8 cells/IC₅₀ for protozoans) was 385, showing that it is more selective against the parasite than mammalian cells. Morphological alterations of protozoans treated with IC₅₀ included changes in size, shape, and structure (more than one nucleus and flagellum) under both light and scanning electron microscopies.     

The use of herbs against neglected diseases: Evaluation of in vitro leishmanicidal and trypanocidal activity of Stryphnodendron rotundifolium Mart

The evaluation of the leishmanicidal and trypanocidal activity of the hydroalcoholic extract of the bark of Stryphnodendron rotundifolium Mart. (EHCSR) was carried out to find an alternative treatment for parasitic diseases. EHCSR was prepared and used at four different concentrations (1000, 500, 250, 125 μg/mL) in in vitro assays for activity against Leishmania promastigotes using the species Leishmania brasiliensis and Leishmania infantum and for trypanocidal activity using the epimastigotes of Trypanosoma cruzi. We also tested EHCSR for cytotoxicity against adhered cultured Murine J774 fibroblasts. The tests were performed in triplicate, and the percent mortality of parasites, IC₅₀ and percent toxicity were determined. With regard to anti-leishmania activity against L. infantum, there was a mean mortality of 45% at all concentrations, and against L. brasiliensis, a substantial effect was seen at 1000 μg/mL with 56.38% mortality, where the IC₅₀ values were 1338.76 and 987.35 μg/mL, respectively. Trypanocidal activity was notably high at 1000 μg/mL extract with 82.31% mortality of epimastigotes. Cytotoxicity at the highest extract concentrations of 500 and 1000 μg/mL was respectively 75.12% and 94.14%, with IC₅₀ = 190.24 μg/mL. Despite that the extract has anti-parasitic activity, its substantial cytotoxicity against fibroblasts cells makes its systemic use nonviable as a therapeutic alternative.     

Synthesis of alpha amylase inhibitors based on privileged indole scaffold

Twenty five derivatives of indole carbohydrazide (1–25) had been synthesized. These compounds were characterized using ¹H NMR and EI-MS, and further evaluated for their α-amylase inhibitory potential. The analogs (1–25) showed varying degree of α-amylase inhibitory potential.ranging between 9.28 and 599.0 µM when compared with standard acarbose having IC₅₀ value 8.78 ± 0.16 µM. Six analogs, 25 (IC₅₀ = 9.28 ± 0.153 µM), 22 (IC₅₀ = 9.79 ± 0.43 µM), 4 (IC₅₀ = 11.08 ± 0.357 µM), 1 (IC₅₀ = 12.65 ± 0.169 µM), 8 (IC₅₀ = 21.37 ± 0.07 µM) and 14 (IC₅₀ = 43.21 ± 0.14 µM) showed potent α-amylase inhibition as compared to the standard acarbose (IC₅₀ = 8.78 ± 0.16 µM). All other analogs displayed good to moderate inhibitory potential. Structure-activity relationship was established through the interaction of the active compounds with enzyme active site with the help of docking studies.     

Effect of modified MRS medium on production and purification of antimicrobial peptide ST4SA produced by Enterococcus mundtii

Highest antimicrobial activity of peptide ST4SA (51,200 AU/mL) was recorded after 14 h of growth in MRS broth with optimal production at pH 6.0 or 6.5. Growth of strain ST4SA in the presence of tryptone, yeast extract, or a combination of the two, yielded 102,400 AU/mL. An increase in production of peptide ST4SA to 102,400 AU/mL was recorded in the presence of 20.0 g/L fructose, but decreased to 25,600 AU/mL in the presence of lactose (20.0 g/L) or mannose (20.0 g/L) as sole carbon source. Lower activity (25,600 AU/mL) was recorded when 2.0 g/L K₂HPO₄ was replaced by 2.0 g/L KH₂PO₄ in MRS broth. An increase of K₂HPO₄ to 10.0 g/L and 20.0 g/L resulted in higher activity (102,400 AU/mL). Addition of glycerol to MRS broth had a negative effect on peptide ST4SA production. Production of peptide ST4SA required the presence of magnesium sulphate, manganese sulphate and 5.0 g/L sodium acetate. Exclusion of tri-ammonium citrate from the medium resulted in reduction of activity to 3,200 AU/mL. Maximum activity (102,400 AU/mL) was recorded in MRS supplemented with 1.0 ppm Vit. C, DL-6,8-thioctic acid or thiamine, respectively. Growth of Listeria ivanovii susbp. ivanovii ATCC 19119 in the presence of peptide ST4SA (12,800 AU/mL) resulted in 99% cell lysis after 18 h. Improved production of peptide ST4SA was recorded in MRS broth (Biolab) pre-treated with Amberlite XAD-1180. Precipitation with ammonium sulphate, followed by gel filtration chromatography, yielded the highest level of peptide ST4SA. This paper describes the partially deproteination of growth medium to facilitate peptide ST4SA purification.