Bioflavonoid-Induced Apoptosis and DNA Damage in Amastigotes and Promastigotes of Leishmania donovani: Deciphering the Mode of Action

Natural products from plants contain many interesting biomolecules. Among them, quercetin (Q), gallic acid (GA), and rutin (R) all have well-reported antileishmanial activity; however, their exact mechanisms of action are still not known. The current study is a step forward towards unveil the possible modes of action of these compounds against Leishmania donovani (the causative agent of visceral leishmaniasis). The selected compounds were checked for their mechanisms of action against L. donovani using different biological assays including apoptosis and necrosis evaluation, effects on genetic material (DNA), quantitative testing of nitric oxide production, ultrastructural modification via transmission electron microscopy, and real-time PCR analysis. The results confirmed that these compounds are active against L. donovani, with IC₅₀ values of 84.65 µg/mL, 86 µg/mL, and 98 µg/mL for Q, GA, and R, respectively. These compounds increased nitric oxide production and caused apoptosis and DNA damage, which led to changes in the treated cells’ ultrastructural behavior and finally to the death of L. donovani. These compounds also suppressed essential enzymes like trypanothione reductase and trypanothione synthetase, which are critical for leishmanial survival. The selected compounds have high antileishmanial potentials, and thus in-vivo testing and further screening are highly recommended.     

In Vitro Antileishmanial and Antischistosomal Activities of Anemonin Isolated from the Fresh Leaves of Ranunculus multifidus Forsk

Leishmaniasis and schistosomiasis are neglected tropical diseases (NTDs) infecting the world’s poorest populations. Effectiveness of the current antileishmanial and antischistosomal therapies are significantly declining, which calls for an urgent need of new effective and safe drugs. In Ethiopia fresh leaves of Ranunculus multifidus Forsk. are traditionally used for the treatment of various ailments including leishmaniasis and eradication of intestinal worms. In the current study, anemonin isolated from the fresh leaves of R. multifidus was assessed for its in vitro antileishmanial and antischistosomal activities. Anemonin was isolated from the hydro-distilled extract of the leaves of R. multifidus. Antileishmanial activity was assessed on clinical isolates of the promastigote and amastigote forms of Leishmania aethiopica and L. donovani clinical isolates. Resazurin reduction assay was used to determine antipromastigote activity, while macrophages were employed for antiamastigote and cytotoxicity assays. Antischistosomal assays were performed against adult Schistosoma mansoni and newly transformed schistosomules (NTS). Anemonin displayed significant antileishmanial activity with IC₅₀ values of 1.33 nM and 1.58 nM against promastigotes and 1.24 nM and 1.91 nM against amastigotes of L. aethiopica and L. donovani, respectively. It also showed moderate activity against adult S. mansoni and NTS (49% activity against adult S. mansoni at 10 µM and 41% activity against NTS at 1 µM). The results obtained in this investigation indicate that anemonin has the potential to be used as a template for designing novel antileishmanial and antischistosomal pharmacophores.     

Anticancer,Anticoagulant, Antioxidant and Antimicrobial Activities of Thevetia peruviana Latex with Molecular Docking of Antimicrobial and Anticancer Activities

Natural origin molecules represent reliable and excellent sources to overcome some medicinal problems. The study of anticancer, anticoagulant, and antimicrobial activities of Thevetia peruviana latex were the aim of the current research. An investigation using high-performance liquid chromatography (HPLC) revealed that the major content of the flavonoids are rutin (11.45 µg/mL), quersestin (7.15 µg/mL), naringin (5.25 µg/mL), and hisperdin (6.07 µg/mL), while phenolic had chlorogenic (12.39 µg/mL), syringenic (7.45 µg/mL), and ferulic (5.07 µg/mL) acids in latex of T. peruviana. Via 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging, the experiment demonstrated that latex had a potent antioxidant activity with the IC₅₀ 43.9 µg/mL for scavenging DPPH. Hemolysis inhibition was 58.5% at 1000 µg/mL of latex compared with 91.0% at 200 µg/mL of indomethacin as positive control. Negligible anticoagulant properties of latex were reported where the recorded time was 11.9 s of prothrombin time (PT) and 29.2 s of the activated partial thromboplastin time (APTT) at 25 µg/mL, compared with the same concentration of heparin (PT 94.6 s and APPT 117.7 s). The anticancer potential of latex was recorded against PC-3 (97.11% toxicity) and MCF-7 (96.23% toxicity) at 1000 μg/mL with IC₅₀ 48.26 μg/mL and 40.31 µg/mL, respectively. Disc diffusion assessment for antimicrobial activity recorded that the most sensitive tested microorganisms to latex were Bacillus subtilis followed by Escherichia coli, with an inhibition zone (IZ) of 31 mm with minimum inhibitory concentration (MIC) (10.2 μg/mL) and 30 mm (MIC, 12.51 μg/mL), respectively. Moreover, Candida albicans was sensitive (IZ, 28 mm) to latex, unlike black fungus (Mucor circinelloides). TEM examination exhibited ultrastructure changes in cell walls and cell membranes of Staphylococcus aureus and Pseudomonas aeruginosa treated with latex. Energy scores of the molecular docking of chlorogenic acid with E. coli DNA (7C7N), and Rutin with human prostate-specific antigen (3QUM) and breast cancer-associated protein (1JNX), result in excellent harmony with the experimental results. The outcome of research recommended that the latex is rich in constituents and considered a promising source that contributes to fighting cancer and pathogenic microorganisms.     

Six New Phenylpropanoid Derivatives from Chemically Converted Extract of Alpinia galanga (L.) and Their Antiparasitic Activities

Chemical conversion of the extract of natural resources is a very attractive way to expand the chemical space to discover bioactive compounds. In order to search for new medicines to treat parasitic diseases that cause high morbidity and mortality in affected countries in the world, the ethyl acetate extract from the rhizome of Alpinia galanga (L.) has been chemically converted by epoxidation using dioxirane generated in situ. The biological activity of chemically converted extract (CCE) of A. galanga (L.) significantly increased the activity against Leishmania major up to 82.6 ± 6.2 % at 25 μg/mL (whereas 2.7 ± 0.8% for the original extract). By bioassay-guided fractionation, new phenylpropanoids (1–6) and four known compounds, hydroquinone (7), 4-hydroxy(4-hydroxyphenyl)methoxy)benzaldehyde (8), isocoumarin cis 4-hydroxymelein (9), and (2S,3S,6R,7R,9S,10S)-humulene triepoxide (10) were isolated from CCE. The structures of isolated compounds were determined by spectroscopic analyses of 1D and 2D NMR, IR, and MS spectra. The most active compound was hydroquinone (7) with IC₅₀ = 0.37 ± 1.37 μg/mL as a substantial active principle of CCE. In addition, the new phenylpropanoid 2 (IC₅₀ = 27.8 ± 0.34 μg/mL) also showed significant activity against L. major compared to the positive control miltefosine (IC₅₀ = 7.47 ± 0.3 μg/mL). The activities of the isolated compounds were also evaluated against Plasmodium falciparum, Trypanosoma brucei gambisense and Trypanosoma brucei rhodeisense. Interestingly, compound 2 was selectively active against trypanosomes with potent activity. To the best of our knowledge, this is the first report on the bioactive “unnatural” natural products from the crude extract of A. galanga (L.) by chemical conversion and on its activities against causal pathogens of leishmaniasis, trypanosomiasis, and malaria.     

Activity of Compounds from Temperate Propolis against Trypanosoma brucei and Leishmania mexicana

Ethanolic extracts of samples of temperate zone propolis, four from the UK and one from Poland, were tested against three Trypanosoma brucei strains and displayed EC₅₀ values < 20 µg/mL. The extracts were fractionated, from which 12 compounds and one two-component mixture were isolated, and characterized by NMR and high-resolution mass spectrometry, as 3-acetoxypinobanksin, tectochrysin, kaempferol, pinocembrin, 4′-methoxykaempferol, galangin, chrysin, apigenin, pinostrobin, cinnamic acid, coumaric acid, cinnamyl ester/coumaric acid benzyl ester (mixture), 4′,7-dimethoxykaempferol, and naringenin 4′,7-dimethyl ether. The isolated compounds were tested against drug-sensitive and drug-resistant strains of T. brucei and Leishmania mexicana, with the highest activities ≤ 15 µM. The most active compounds against T. brucei were naringenin 4′,7 dimethyl ether and 4′methoxy kaempferol with activity of 15–20 µM against the three T. brucei strains. The most active compounds against L. mexicana were 4′,7-dimethoxykaempferol and the coumaric acid ester mixture, with EC₅₀ values of 12.9 ± 3.7 µM and 13.1 ± 1.0 µM. No loss of activity was found with the diamidine- and arsenical-resistant or phenanthridine-resistant T. brucei strains, or the miltefosine-resistant L. mexicana strain; no clear structure activity relationship was observed for the isolated compounds. Temperate propolis yields multiple compounds with anti-kinetoplastid activity.     

Cinnamides Target Leishmania amazonensis Arginase Selectively

Caffeic acid and related natural compounds were previously described as Leishmania amazonensis arginase (L-ARG) inhibitors, and against the whole parasite in vitro. In this study, we tested cinnamides that were previously synthesized to target human arginase. The compound caffeic acid phenethyl amide (CAPA), a weak inhibitor of human arginase (IC₅₀ = 60.3 ± 7.8 μM) was found to have 9-fold more potency against L-ARG (IC₅₀ = 6.9 ± 0.7 μM). The other compounds that did not inhibit human arginase were characterized as L-ARG, showing an IC₅₀ between 1.3–17.8 μM, and where the most active was compound 15 (IC₅₀ = 1.3 ± 0.1 μM). All compounds were also tested against L. amazonensis promastigotes, and only the compound CAPA showed an inhibitory activity (IC₅₀ = 80 μM). In addition, in an attempt to gain an insight into the mechanism of competitive L-ARG inhibitors, and their selectivity over mammalian enzymes, we performed an extensive computational investigation, to provide the basis for the selective inhibition of L-ARG for this series of compounds. In conclusion, our results indicated that the compounds based on cinnamoyl or 3,4-hydroxy cinnamoyl moiety could be a promising starting point for the design of potential antileishmanial drugs based on selective L-ARG inhibitors.     

Proposed Mechanism for the Antitrypanosomal Activity of Quercetin and Myricetin Isolated from Hypericum afrum Lam.: Phytochemistry,In Vitro Testing and Modeling Studies

The in vitro activity of L. donovani (promastigotes, axenic amastigotes and intracellular amastigotes in THP1 cells) and T. brucei, from the fractions obtained from the hydroalcoholic extract of the aerial part of Hypericum afrum and the isolated compounds, has been evaluated. The chloroform, ethyl acetate and n-butanol extracts showed significant antitrypanosomal activity towards T. brucei, with IC₅₀ values of 12.35, 13.53 and 12.93 µg/mL and with IC₉₀ values of 14.94, 19.31 and 18.67 µg/mL, respectively. The phytochemical investigation of the fractions led to the isolation and identification of quercetin (1), myricitrin (2), biapigenin (3), myricetin (4), hyperoside (5), myricetin-3-O-β-d-galactopyranoside (6) and myricetin-3’-O-β-d-glucopyranoside (7). Myricetin-3’-O-β-d-glucopyranoside (7) has been isolated for the first time from this genus. The chemical structures were elucidated by using comprehensive one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopic data, as well as high-resolution electrospray ionization mass spectrometry (HR-ESI–MS). These compounds have also been evaluated for their antiprotozoal activity. Quercetin (1) and myricetin (4) showed noteworthy activity against T. brucei, with IC₅₀ and IC₉₀ values of 7.52 and 5.71 µM, and 9.76 and 7.97 µM, respectively. The T. brucei hexokinase (TbHK1) enzyme was further explored as a potential target of quercetin and myricetin, using molecular modeling studies. This proposed mechanism assists in the exploration of new candidates for novel antitrypanosomal drugs.     

Boswellic Acids Show In Vitro Activity against Leishmania donovani

In continuation of our search for leads from medicinal plants against protozoal pathogens, we detected antileishmanial activity in polar fractions of a dichloromethane extract from Boswellia serrata resin. 11-keto-β-boswellic acid (KBA) could be isolated from these fractions and was tested in vitro against Leishmania donovani axenic amastigotes along with five further boswellic acid derivatives. 3-O-acetyl-11-keto-β-boswellic acid (AKBA) showed the strongest activity with an IC₅₀ value of 0.88 µM against axenic amastigotes but was inactive against intracellular amastigotes in murine macrophages     

Essential Oil from Melaleuca leucadendra: Antimicrobial,Antikinetoplastid, Antiproliferative and Cytotoxic Assessment

Essential oils (EOs) are known for their use in cosmetics, food industries, and traditional medicine. This study presents the chemical composition and therapeutic properties against kinetoplastid and eukaryotic cells of the EO from Melaleuca leucadendra (L.) L. (Myrtaceae). Forty-five compounds were identified in the oil by GC-MS, containing a major component the 1,8-cineole (61%). The EO inhibits the growth of Leishmania amazonensis and Trypanosoma brucei at IC₅₀ values <10 μg/mL. However, 1,8 cineole was not the main compound responsible for the activity. Against malignant (22Rv1, MCF-7, EFO-21, including resistant sublines MCF-7/Rap and MCF-7/4OHTAMO) and non-malignant (MCF-10A, J774A.1 and peritoneal macrophage) cells, IC₅₀ values from 55 to 98 μg/mL and from 94 to 144 μg/mL were obtained, respectively. However, no activity was observed on Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, Candida parapsilosis, Microsporum canis, or Trypanosoma cruzi. The EO was able to control the lesion size and parasite burden in the model of cutaneous leishmaniasis in BALB/c mice caused by L. amazonensis compared to untreated animals (p < 0.05) and similar with those treated with Glucantime^® (p > 0.05). This work constitutes the first evidence of antiproliferative potentialities of EO from M. leucadendra growing in Cuba and could promote further preclinical investigations to confirm the medical value of this plant, in particular for leishmaniasis treatment.     

Chemical Composition and Insecticidal Activities of Essential Oils against the Pulse Beetle

Pulse beetles, Callosobruchus chinensis and Callosobruchus maculatus, are essential pests of cowpea, gram, soybean and pulses. Application of synthetic insecticides against the pulse beetle has led to insect resistance; insecticide residues on grains affect human health and the environment. Essential oils (EOs) are the best alternatives to synthetics due to their safety to the environment and health. The main objective of the investigation was to study the chemical composition and insecticidal activities of EOs, their combinations and compounds against the pulse beetle under laboratory. Neo-isomenthol, carvone and β-ocimene are the significant components of tested oils using GC-MS. Mentha spicata showed promising fumigant toxicity against C. chinensis (LC₅₀ = 0.94 µL/mL) and was followed by M. piperita (LC₅₀ = 0.98 µL/mL), whereas M. piperita (LC₅₀ = 0.92 µL/mL) against C. maculatus. A combination of Tagetes minuta + M. piperita showed more toxicity against C. chinensis after 48 h (LC₅₀ = 0.87 µL/mL) than T. minuta + M. spicata (LC₅₀ = 1.07 µL/mL). L-Carvone showed fumigant toxicity against C. chinensis after 48 h (LC₅₀ = 1.19 µL/mL). Binary mixtures of T. minuta +M. piperita and M. spicata showed promising toxicity and synergistic activity. EOs also exhibited repellence and ovipositional inhibition. The application of M. piperita can be recommended for the control of the pulse beetle.     

Identification of Phenolic Compounds by LC-MS/MS and Evaluation of Bioactive Properties of Two Edible Halophytes: Limonium effusum and L. sinuatum

This work aimed to evaluate the phenolic content and in vitro antioxidant, antimicrobial and enzyme inhibitory activities of the methanol extracts and their fractions of two edible halophytic Limonium species, L. effusum (LE) and L. sinuatum (LS). The total phenolic content resulted about two-fold higher in the ethyl acetate fraction of LE (522.82 ± 5.67 mg GAE/g extract) than in that of LS (274.87 ± 1.87 mg GAE/g extract). LC-MS/MS analysis indicated that tannic acid was the most abundant phenolic acid in both species (71,439.56 ± 3643.3 µg/g extract in LE and 105,453.5 ± 5328.1 µg/g extract in LS), whereas hyperoside was the most abundant flavonoid (14,006.90 ± 686.1 µg/g extract in LE and 1708.51 ± 83.6 µg/g extract in LS). The antioxidant capacity was evaluated by DPPH and TAC assays, and the stronger antioxidant activity in ethyl acetate fractions was highlighted. Both species were more active against Gram-positive bacteria than Gram negatives and showed considerable growth inhibitions against tested fungi. Interestingly, selective acetylcholinesterase (AChE) activity was observed with LE and LS. Particularly, the water fraction of LS strongly inhibited AChE (IC₅₀ = 0.199 ± 0.009 µg/mL). The ethyl acetate fractions of LE and LS, as well as the n-hexane fraction of LE, exhibited significant antityrosinase activity (IC₅₀ = 245.56 ± 3.6, 295.18 ± 10.57 and 148.27 ± 3.33 µg/mL, respectively). The ethyl acetate fraction and methanol extract of LS also significantly inhibited pancreatic lipase (IC₅₀ = 83.76 ± 4.19 and 162.2 ± 7.29 µg/mL, respectively). Taken together, these findings warrant further investigations to assess the potential of LE and LS as a bioactive source that can be exploited in pharmaceutical, cosmetics and food industries.     

Synthesis,Structure and Biological Evaluations of Zn(II) Pincer Complexes Based on S-Triazine Type Chelator

2,4-bis (3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (BPMT) pincer ligand was used to synthesize the new [Zn(BPMT)(NCS)₂] (1) and [Zn(BPMT)(Br)₂] (2) complexes by a reaction with Zn(NO₃)₂·6H₂O in the presence of either KSCN or KBr, respectively. The structure of complex 1 has been exclusively confirmed using single crystal X-ray diffraction. In this neutral heteroleptic complex, the BPMT is a pincer chelate coordinating the Zn(II) ion via three interactions with the two pyrazole moieties and the s-triazine core. Hence, BPMT is a tridentate NNN-chelate. The coordination environment of Zn(II) is completed by two strong interactions with two terminal SCN⁻ ions via the N-atom. Hence, the Zn(II) is penta-coordinated with a distorted square pyramidal coordination geometry. Hirshfeld analysis indicated the predominance of H…H, H…C and N…H intermolecular interactions. Additionally, the S…H, S…C and S…N contacts are the most significant. The free ligand has no or weak antimicrobial, antioxidant and anticancer activities while the studied Zn(II) complexes showed interesting biological activity. Complex 1 has excellent antibacterial activity against B. subtilis (2.4 μg/mL) and P. vulgaris (4.8 μg/mL) compared to Gentamycin (4.8 μg/mL). Additionally, complex 1 (78.09 ± 4.23 µg/mL) has better antioxidant activity than 2 (365.60 ± 20.89 µg/mL). In addition, complex 1 (43.86 ± 3.12 µg/mL) and 2 (30.23 ± 1.26 µg/mL) have 8 and 12 times the anticancer activity of the free BPMT ligand (372.79 ± 13.64 µg/mL).     

The Antiproliferative and Apoptosis-Inducing Effects of the Red Macroalgae Gelidium latifolium Extract against Melanoma Cells

The red macroalga Gelidium latifolium is widely distributed in the coastal areas of Indonesia. However, current knowledge on its potential biological activities is still limited. In this study, we investigated the potential bioactive compounds in Gelidium latifolium ethanol extract (GLE), and its cytotoxic effects against the murine B16-F10 melanoma cell line. GLE shows high total phenolic content (107.06 ± 17.42 mg GAE/g) and total flavonoid content (151.77 ± 3.45 mg QE/g), which potentially contribute to its potential antioxidant activity (DPPH = 650.42 ± 2.01 µg/mL; ABTS = 557.01 ± 1.94 µg/mL). ESI-HR-TOF-MS analysis revealed large absorption in the [M-H]^- of 327.2339 m/z, corresponding to the monoisotopic molecular mass of brassicolene. The presence of this compound potentially contributes to GLE’s cytotoxic activity (IC₅₀ = 84.29 ± 1.93 µg/mL). Furthermore, GLE significantly increased the number of apoptotic cells (66.83 ± 3.06%) compared to controls (18.83 ± 3.76%). Apoptosis was also confirmed by changes in the expression levels of apoptosis-related genes (i.e., p53, Bax, Bak, and Bcl2). Downregulated expression of Bcl2 indicates an intrinsic apoptotic pathway. Current results suggest that components of Gelidium latifolium should be further investigated as possible sources of novel antitumor drugs.     

Discovery of Novel Cyclic Ethers with Synergistic Antiplasmodial Activity in Combination with Valinomycin

With drug resistance threatening our first line antimalarial treatments, novel chemotherapeutics need to be developed. Ionophores have garnered interest as novel antimalarials due to their theorized ability to target unique systems found in the Plasmodium-infected erythrocyte. In this study, during the bioassay-guided fractionation of the crude extract of Streptomyces strain PR3, a group of cyclodepsipeptides, including valinomycin, and a novel class of cyclic ethers were identified and elucidated. Further study revealed that the ethers were cyclic polypropylene glycol (cPPG) oligomers that had leached into the bacterial culture from an extraction resin. Molecular dynamics analysis suggests that these ethers are able to bind cations such as K⁺, NH₄⁺ and Na⁺. Combination studies using the fixed ratio isobologram method revealed that the cPPGs synergistically improved the antiplasmodial activity of valinomycin and reduced its cytotoxicity in vitro. The IC₅₀ of valinomycin against P. falciparum NF54 improved by 4–5-fold when valinomycin was combined with the cPPGs. Precisely, it was improved from 3.75 ± 0.77 ng/mL to 0.90 ± 0.2 ng/mL and 0.75 ± 0.08 ng/mL when dosed in the fixed ratios of 3:2 and 2:3 of valinomycin to cPPGs, respectively. Each fixed ratio combination displayed cytotoxicity (IC₅₀) against the Chinese Hamster Ovary cell line of 57–65 µg/mL, which was lower than that of valinomycin (12.4 µg/mL). These results indicate that combinations with these novel ethers may be useful in repurposing valinomycin into a suitable and effective antimalarial.     

Identification of Kaurane-Type Diterpenes as Inhibitors of Leishmania Pteridine Reductase I

The current treatments against Leishmania parasites present high toxicity and multiple side effects, which makes the control and elimination of leishmaniasis challenging. Natural products constitute an interesting and diverse chemical space for the identification of new antileishmanial drugs. To identify new drug options, an in-house database of 360 kauranes (tetracyclic diterpenes) was generated, and a combined ligand- and structure-based virtual screening (VS) approach was performed to select potential inhibitors of Leishmania major (Lm) pteridine reductase I (PTR1). The best-ranked kauranes were employed to verify the validity of the VS approach through LmPTR1 enzyme inhibition assay. The half-maximal inhibitory concentration (IC₅₀) values of selected bioactive compounds were examined using the random forest (RF) model (i.e., 2β-hydroxy-menth-6-en-5β-yl ent-kaurenoate (135) and 3α-cinnamoyloxy-ent-kaur-16-en-19-oic acid (302)) were below 10 μM. A compound similar to 302, 3α-p-coumaroyloxy-ent-kaur-16-en-19-oic acid (302a), was also synthesized and showed the highest activity against LmPTR1. Finally, molecular docking calculations and molecular dynamics simulations were performed for the VS-selected, most-active kauranes within the active sites of PTR1 hybrid models, generated from three Leishmania species that are known to cause cutaneous leishmaniasis in the new world (i.e., L. braziliensis, L. panamensis, and L. amazonensis) to explore the targeting potential of these kauranes to other species-dependent variants of this enzyme.     

Synthesis of a Novel Unexpected Cu(II)–Thiazolidine Complex—X-ray Structure,Hirshfeld Surface Analysis,and Biological Studies

An unexpected trinuclear Cu(II)–thiazolidine complex has been synthesized by mixing CuCl₂·2H₂O with the Schiff base ligand, 1-(((4,5-dihydrothiazol-2-yl)ethylidene)hydrazono)methyl)phenol L, in ethanol. Unexpectedly, the reaction proceeded via the hydrolysis of the Schiff base L, followed by cyclization to afford 3-methyl-5,6-dihydrothiazolo[3,2-c][1,2,3]triazole (L^a), then complexation with the Cu(II) salt, forming the trinuclear [Cu₃(L^a)₄(Cl)₆] complex. The complex was characterized by means of FTIR spectra, elemental analysis, and X-ray crystallography. In the trinuclear [Cu₃(L^a)₄(Cl)₆] complex, there are two crystallographically independent hexa- and penta-coordinated Cu(II) sites, where the thiazolidine ligand L^a units act as a monodentate ligand and a linker between the Cu(II) centers. The crystal packing of the [Cu₃(L^a)₄(Cl)₆] complex is primarily affected by the weak non-covalent C-H∙∙∙Cl interactions. In accordance with Hirshfeld surface analysis, the Cl∙∙∙H, H∙∙∙H, S∙∙∙H, and N∙∙∙H percentages are 31.9%, 27.2%, 13.5%, and 9.9%, respectively. X-ray photoelectron spectroscopy confirmed the oxidation state of copper as Cu(II), as well as the presence of two different coordination environments around copper centers. The complex showed interesting antibacterial activity against the Gram-positive bacteria S. subtilis, with MIC = 9.7 µg/mL compared to MIC = 4.8 µg/mL for the control, gentamycin. Moreover, the Cu(II) complex showed an equal MIC (312.5 µg/mL) against C. albicans compared to ketoconazole. It also exhibits a very promising inhibitory activity against colon carcinoma (IC₅₀ = 3.75 ± 0.43 µg/mL).     

Molecular Interaction Studies and Phytochemical Characterization of Mentha pulegium L. Constituents with Multiple Biological Utilities as Antioxidant,Antimicrobial, Anticancer and Anti-Hemolytic Agents

Multiple biological functions of Mentha pulegium extract were evaluated in the current work. Phytochemical components of the M. pulegium extract were detected by Gas Chromatography-Mass Spectrometry (GC-MS) and High-performance liquid chromatography (HPLC). Moreover, M. pulegium extract was estimated for antioxidant potential by 2,2-Diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical scavenging, antimicrobial activity by well diffusion, and anticoagulant activity via prothrombin time (PT) and activated partial thromboplastin time (APTT). GC-MS analysis detected compounds including cholesterol margarate, stigmast-5-en-3-ol, 19-nor-4-androstenediol, androstan-17-one, pulegone-1,2-epoxide, isochiapin B, dotriacontane, hexadecanoic acid and neophytadiene. Chrysoeriol (15.36 µg/mL) was followed by kaempferol (11.14 µg/mL) and 7-OH flavone (10.14 µg/mL), catechin (4.11 µg/mL), hisperdin (3.05 µg/mL), and luteolin (2.36 µg/mL) were detected by HPLC as flavonoids, in addition to ferulic (13.19 µg/mL), cinnamic (12.69 µg/mL), caffeic (11.45 µg/mL), pyrogallol (9.36 µg/mL), p-coumaric (5.06 µg/mL) and salicylic (4.17 µg/mL) as phenolics. Antioxidant activity was detected with IC₅₀ 18 µg/mL, hemolysis inhibition was recorded as 79.8% at 1000 μg/mL, and PT and APTT were at 21.5 s and 49.5 s, respectively, at 50 μg/mL of M. pulegium extract. The acute toxicity of M. pulegium extract was recorded against PC3 (IC₅₀ 97.99 µg/mL) and MCF7 (IC₅₀ 80.21 µg/mL). Antimicrobial activity of M. pulegium extract was documented against Bacillus subtilis, Escherichia coli, Pseudomonas aureus, Candida albicans, Pseudomonas aeruginosa, but not against black fungus Mucor circinelloides. Molecular docking was applied using MOE (Molecular Operating Environment) to explain the biological activity of neophytadiene, luteolin, chrysoeriol and kaempferol. These compounds could be suitable for the development of novel pharmacological agents for treatment of cancer and bacterial infections.     

A Comparative Study of Antimicrobial and Antioxidant Activities of Plant Essential Oils and Extracts as Candidate Ingredients for Edible Coatings to Control Decay in ‘Wonderful’ Pomegranate

This study determined the antimicrobial and antioxidant activity of lemongrass (LO), thyme (TO), and oregano (OO) essential oils and ethanolic extracts of pomegranate peel (PPE) and grape pomace (GPE) as candidate ingredients for edible coatings. Antifungal effects against Botrytis cinerea and Penicillium spp. were tested using paper disc and well diffusion methods. Radical scavenging activity (RSA) was evaluated using 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid assays. Gas chromatography-mass spectrometry analysis identified limonene (16.59%), α-citral (27.45%), β-citral (27.43%), thymol (33.31%), paracymene (43.26%), 1,8-cineole (17.53%), and trans-caryphellene (60.84%) as major compounds of the essential oils. From both paper disc and well diffusion methods, LO recorded the widest zone of inhibition against tested microbes (B. cinerea and Penicillium spp.). The minimum inhibitory concentrations of LO against B. cinerea and Penicillium spp., were 15 µL/mL and 30 µL/mL, respectively. The highest (69.95%) and lowest (1.64%) RSA at 1 mg/mL were recorded for PPE and OO. Application of sodium alginate and chitosan-based coatings formulated with LO (15 or 30 µL/mL) completely inhibited spore germination and reduced the decay severity of ‘Wonderful’ pomegranate. Lemongrass oil proved to be a potential antifungal agent for edible coatings developed to extend shelf life of ‘Wonderful’ pomegranate.     

The Potential of 2-Substituted Quinolines as Antileishmanial Drug Candidates

There is a need for new, cost-effective drugs to treat leishmaniasis. A strategy based on traditional medicine practiced in Bolivia led to the discovery of the 2-substituted quinoline series as a source of molecules with antileishmanial activity and low toxicity. This review documents the development of the series from the first isolated natural compounds through several hundred synthetized molecules to an optimized compound exhibiting an in vitro IC₅₀ value of 0.2 µM against Leishmania donovani, and a selectivity index value of 187, together with in vivo activity on the L. donovani/hamster model. Attempts to establish structure–activity relationships are described, as well as studies that have attempted to determine the mechanism of action. For the latter, it appears that molecules of this series act on multiple targets, possibly including the immune system, which could explain the observed lack of drug resistance after in vitro drug pressure. We also show how nanotechnology strategies could valorize these drugs through adapted formulations and how a mechanistic targeting approach could generate new compounds with increased activity.     

Cinnamomum cassia and Syzygium aromaticum Essential Oils Reduce the Colonization of Salmonella Typhimurium in an In Vivo Infection Model Using Caenorhabditis elegans

The regulation of intestinal colonization in livestock by means of non-bactericidal additives is an important management lever for zoonotic bacteria such as Salmonella spp. Caenorhabditis elegans is proposed here as a model for the evaluation of five essential oils (EOs) as anti-colonization products against Salmonella Typhimurium. An evaluation of the toxicity of EOs for C. elegans showed LD₅₀ values ranging from 74.5 ± 9.6 µg/mL for Cinnamomum cassia (CEO) to 271.6 ± 14.9 µg/mL for Syzygium aromaticum (SyEO). Both EOs significantly inhibited bacterial colonization in the digestive tract of C. elegans with reductions of 0.88 and 0.70 log CFU/nematode at nontoxic concentrations of 50 µg/mL and 150 µg/mL, respectively. With the minimal bactericidal concentrations of CEO and SyEO against S. Typhimurium being 312.5 µg/mL and 625 µg/mL, respectively, an antibacterial effect can be excluded to explain the inhibition of the bacterial load. The anti-colonizing activity of these two EOs could, however, be related to an inhibition of the swimming motility, which was significantly reduced by 23.47% for CEO at 50 µg/mL and 19.56% for SyEO at 150 µg/mL. This study shows the potential of C. elegans as a predictive in vivo model of anti-colonizing activities that is suitable for the evaluation of essential oils.