Cytotoxicity Bioassay Research Articles

Abstract 2144: Next generation inhibitors to reverse ABCB1 transport mediated multidrug resistance in cancer

Abstract The therapeutic efficacy of anticancer drugs is often limited by chemoresistance. Cancer can present intrinsic or acquired resistance to chemotherapy drugs through different mechanisms of multidrug resistance (MDR). The accelerated drug efflux facilitated by overexpression of ATP-binding cassette (ABC) transporters is one of the key mechanisms of MDR. Specifically, overexpression of ABCB1 (MDR1, P-gp) is known to be a major cause of resistance to structurally dissimilar anticancer drugs such as paclitaxel and doxorubicin. To circumvent ABC transport mediated MDR, many small molecules and kinase inhibitors have been researched and employed to retain the efficacy of the anticancer drugs. Though many small molecule inhibitors demonstrate to be useful reversal agents, understanding the mechanisms at a molecular level is important in order to design candidate drug inhibitors which are safe, selective and effective. To investigate the functional groups and molecular structures which can efficiently reverse ABCB1-mediated MDR, multiple series of thiazole-valine peptide compounds were designed, synthesized and tested in vitro. The results indicated BTT-10A was most effective in sensitizing ABCB1-mediated resistance to anticancer drugs. Both transfected and drug-selected cell lines overexpressing the ABCB1 transporter were utilized in this study. We identified BTT-10A, at nontoxic concentrations (10 μM), to have optimal MDR reversal activity through cell viability MTT cytotoxicity and reversal bioassays. BTT-10A sensitized resistant cells to the anticancer drugs in a concentration dependent manner, without downregulating the transporter expression. BTT-10A significantly increased the accumulation of ABCB1 anticancer substrate drugs by blocking the efflux function of ABCB1 transporter, as demonstrated by significant increased [3H]-paclitaxel accumulation, and increased intracellular doxorubicin accumulation through immunofluorescent detection in ABCB1 overexpressing cells. Alongside these findings, docking studies showed site-1 to be the preferable binding site for BTT-10A within the drug-binding pocket of human ABCB1 homology model. Therefore, we report that BTT-10A antagonizes MDR by inhibiting the efflux activity of the overexpressed ABCB1 transporter. These findings reveal more evidence of specific molecular structure and function of ABCB1-mediated MDR reversal agents. The therapeutic application of BTT-10A co-administered with ABCB1 substrate anticancer drugs holds promise for cancer patients resistant to specific chemotherapies, overexpressing the ABCB1 transporter. Further in vivo studies will be conducted using drug resistant xenograft models. This research will help inspire further investigations of ABC transport-mediated MDR in cancer, to find the next generation of targeted and safe reversal agents to combat chemoresistance. Citation Format: Anna Maria Barbuti, Bhargav A. Patel, Tanaji T. Talele, Zhe-Sheng Chen. Next generation inhibitors to reverse ABCB1 transport mediated multidrug resistance in cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2144.

Chemical synthesis, pharmacological evaluation and in silico analysis of new 2,3,3a,4,5,6-hexahydrocyclopenta[c]pyrazole derivatives as potential anti-mitotic agents

We have synthesized new, biologically active mono- and di-substituted 2,3,3a,4,5,6-hexahydrocyclopenta[c]pyrazole derivatives bearing electron withdrawing groups and electron donating groups. These derivative structures were characterized by their spectral and analytical data. The newly synthesized hexahydropyrazole analogues were evaluated for their in vitro anticancer activity against breast and lung cancer cell lines using a cytotoxicity bioassay. To understand their mechanism of action, tubulin binding assays were performed which pointed to their binding to microtubules in a mode similar to but not identical to colchicine, as evidenced by their KD value evaluation. Computational docking studies also suggested binding near the colchicine binding site on tubulin. These results were further confirmed by colchicine-binding assays on the most active compounds, which indicated that they bound to tubulin near but not at the colchicine site. The moderate cytotoxic effects of these compounds may be due to the presence of electron donating groups on the para-position of the phenyl ring, along with the hexahydropyrazole core nucleus. The observed anti-cancer activity based on inhibition of microtubule formation may be helpful in designing more potent compounds with a hexahydropyrazole moiety.

ChemInform Abstract: Sarglaperoxides A and B, Sesquiterpene—Normonoterpene Conjugates with a Peroxide Bridge from the Seeds of Sarcandra glabra.

AbstractSarglaperoxide A (I) demonstrates moderate antibacterial and antiinflammatory activities in vitro.

Identification and comparison of the volatile constituents of fresh and dried leaves of Spondias mombin found in North-central Nigeria: in vitro evaluation of their cytotoxic and antioxidant activities

Context: Various studies have shown that the leaf extracts of Spondias mombin Linn (Anacardiaceae) possess pharmacological properties such as antioxidant and antiviral effects. However, no biological activity from its essential oil has been reported in literature.Objective: To analyse the chemical constituents, cytotoxic activity and antioxidant capability of the essential oils from fresh and dried leaves of S. mombin.Materials and methods: Hydrodistillation using Clevenger-type apparatus was employed to obtain the essential oil. Oil analysis was performed using an HP 6890 Gas Chromatograph coupled with an HP 5973 Mass Selective Detector. The cytotoxicity bioassay was carried out using the brine shrimp lethality test (10,000–0.01 μg/mL). Additionally, the reactive oxygen species scavenging potential of the two S. mombin oils (1000–200 μg/mL) were investigated using a hydroxyl radical scavenging and ferric iron reducing system.Results: Chemical analysis of essential oils from S. mombin revealed the presence of 41 compounds, with predominance of monoterpenoids, sesquiterpenoids and non-terpenoids derivatives. In both fractions, the principal component was β-caryophellene (27.9–30.9%), followed by γ-cadinene (9.7–12.3%). There was an increase in the oxygenated monoterpenoid contents and a concomitant decrease in the amounts of sesquiterpenoids hydrocarbons observed on drying the leaves. The oil obtained from the fresh leaves was more active than that obtained from dried leaves, with LC50 values (from the brine shrimp lethality assay) of 0.01 and 4.78 μg/mL, respectively. The two oils (from fresh and dried leaves) at 1.0 mg/mL scavenged hydroxyl radical by 83% and 99.8%, respectively. Moreover, they reduced ferric ion significantly and compared favourably with vitamin C.Conclusions: Essential oil derived from the leaves of S. mombin could hold promise for future application in the treatment of cancer-related diseases.

GC-MS analysis and cytotoxic activity of essential oils from the leaves of Abrus precatorius L. Gaertn

ObjectiveTo determine the chemical constituents, cytotoxic activity and possible applications of the essential oils from the leaves of Abrus precatorius L. Gaertn. MethodsHydro-distillation using Clevenger-type apparatus was employed to obtain the essential oils. Oil analysis was performed using an HP 6890 gas chromatograph coupled with an HP 5973 mass selective detector. The cytotoxicity bioassay was carried out using the brine shrimp lethality test. ResultsForty-five compounds were identified representing 100% of the oil. The principal components were γ-cadinene (19.1%), α-selinene (15.3%), α-cubenene (12.8%), β-caryophyllene (8.2%), germacrene B (7.9%), α-copaene (7.7%) and linalool (6.3%). Others are caryophyllene oxide (5.5%), β-elemene (5.4%) and α-caryophyllene (4.0%). The oil was potent with the LC50 value of 0.45 μg/mL. ConclusionsThe essential oil from the leaves of Abrus precatorius L. Gaertn. could hold promise for future applications in the treatment of cancer-related diseases, in addition to flavor and fragrance industry.

Discovery of Dual ETA/ETB Receptor Antagonists from Traditional Chinese Herbs through in Silico and in Vitro Screening.

Endothelin-1 receptors (ETAR and ETBR) act as a pivotal regulator in the biological effects of ET-1 and represent a potential drug target for the treatment of multiple cardiovascular diseases. The purpose of the study is to discover dual ETA/ETB receptor antagonists from traditional Chinese herbs. Ligand- and structure-based virtual screening was performed to screen an in-house database of traditional Chinese herbs, followed by a series of in vitro bioassay evaluation. Aristolochic acid A (AAA) was first confirmed to be a dual ETA/ETB receptor antagonist based intracellular calcium influx assay and impedance-based assay. Dose-response curves showed that AAA can block both ETAR and ETBR with IC50 of 7.91 and 7.40 μM, respectively. Target specificity and cytotoxicity bioassay proved that AAA is a selective dual ETA/ETB receptor antagonist and has no significant cytotoxicity on HEK293/ETAR and HEK293/ETBR cells within 24 h. It is a feasible and effective approach to discover bioactive compounds from traditional Chinese herbs using in silico screening combined with in vitro bioassay evaluation. The structural characteristic of AAA for its activity was especially interpreted, which could provide valuable reference for the further structural modification of AAA.

Sarglaperoxides A and B, Sesquiterpene-Normonoterpene Conjugates with a Peroxide Bridge from the Seeds of Sarcandra glabra.

Sarglaperoxides A (1) and B (2), a pair of unusual sesquiterpene-normonoterpene conjugates with a peroxide bridge, were isolated from the seeds of Sarcandra glabra. The structures and absolute configurations of 1 and 2 were determined on the basis of spectroscopic data analysis, including MS, NMR, CD, and XRD. The two compounds were screened in antimicrobial, anti-inflammatory, and cytotoxic bioassays and showed moderate bioactivities.

Studies on the Red Sea Sponge Haliclona sp. for its Chemical and Cytotoxic Properties.

Background:A great number of novel compounds with rich chemical diversity and significant bioactivity have been reported from Red Sea sponges.Objective:To isolate, identify, and evaluate the cytotoxic activity of the chemical constituents of a sponge belonging to genus Haliclona collected from the Eastern coast of the Red Sea.Materials and Methods:The total ethanolic extract of the titled sponge was subjected to intensive chromatographic fractionation and purification guided by cytotoxic bioassay toward various cancer cell lines. The structures of the isolated compounds were elucidated using spectroscopic techniques including one-dimension and two-dimension nuclear magnetic resonance, mass spectrometry, ultraviolet, and infrared data, as well as comparison with the reported spectral data for the known compounds. X-ray single-crystal structure determination was performed to determine the absolute configuration of compound 4. The screening of antiproliferative activity of the compounds was carried on three tumor cell lines, namely the human cervical cancer (HeLa), human hepatocellular carcinoma (HepG2), and human medulloblastoma (Daoy) cells using MTT assay.Results:This investigation resulted in the isolation of a new indole alkaloid, 1-(1H-indol-3-yloxy) propan-2-ol (1), with the previously synthesized pyrrolidine alkaloid, (2R, 3S, 4R, 5R) pyrrolidine-(1-hydroxyethyl)-3,4-diol hydrochloride (4), isolated here from a natural source for the first time. In addition, six known compounds tetillapyrone (2), nortetillapyrone (3), 2-methyl maleimide-5-oxime (5), maleimide-5-oxime (6), 5-(hydroxymethyl) dihydrofuran-2 (3H)-one (7), and ergosta-5,24 (28)-dien-3-ol (8) were also identified. Most of the isolated compounds exhibited weak cytotoxic activity against HepG-2, Daoy, and HeLa cancer cell lines.Conclusion:This is the first report of the occurrence of the indole and pyrrolidine alkaloids, 1-(1H-indol-2-yloxy) propan-2-ol (1), and the - (1-hydroxyethyl)-3,4-diol hydrochloride (4), in the Red Sea Haliclona sp.SUMMARY From the Red Sea Haliclona sp. two alkaloids with indole and pyrrolidine nuclei, 1-(1H-indol-2-yloxy) propan-2-ol-(1) and pyrrolidine-(1-hydroxyethyl)-3,4-diol hydrochloride (4) were isolated and fully characterized; in addition to six known compounds (2, 3, 5-8)The absolute configuration and the three-dimension stereo-molecular structure of compound 4 were determined by X-ray crystallographyThe different extracts and isolated compounds showed weak cytotoxic activity against HepG-2, Daoy, and HeLa cancer cell lines.

Phytochemical and Biological Investigations of Conradina Canescens

Conradina canescens (Lamiaceae) is an endemic evergreen shrub native to Florida, Mississippi and Alabama, with no phytochemical or biological studies registered in the literature. Thus, a phytochemical study and a toxicity analysis of the chloroform extract obtained from the leaves of C. canescens were performed for the first time. In our preliminary screening, the crude extract and its fractions were subjected to cytotoxicity, antimicrobial and antileishmanial bioassays. The crude extract showed substantial cytotoxic, antimicrobial and antileishmanial activities. A total of six compounds, namely ursolic acid (62.4%), betulin (8.4%), β-amyrin (4.6%), myrtenic acid (2.9%), n-tetracosane (1.4%), and oleanolic acid (1.1%), were isolated. The structures of the isolated compounds were established by spectroscopic studies using NMR and IR spectroscopy.

First report of goniodomin A production by the dinoflagellate Alexandrium pseudogonyaulax developing in southern Mediterranean (Bizerte Lagoon, Tunisia)

The dinoflagellate Alexandrium pseudogonyaulax is widely distributed around the world including the Mediterranean waters. The objectives of this study were to determine the morphology and phylogenic affiliation of A. pseudogonyaulax strain isolated from Bizerte Lagoon (Mediterranean waters, Tunisia) and investigate its toxicity. Molecular analyses confirmed the morphological identification of the isolated strain (APBZ12) as A. pseudogonyaulax. Moreover, it showed that it is 100% identical with strains of this species found in New Zealand, Japan, China and North Sea (Norway and Denmark) suggesting that this species is cosmopolitan. Until now, no toxin studies have been conducted on fully characterized (morphologically and molecularly) A. pseudogonyaulax. Cellular toxin production was determined using high pressure liquid chromatography coupled to mass spectrometry (HPLC/MS). Results showed for the first time that A. pseudogonyaulax contains goniodomin A (GDA), a highly toxic macrolide polyether previously shown to be produced by two other dinoflagellate species Alexandrium monilatum (Hsia et al., 2006) and Alexandrium hiranoi (erroneously identified as A. pseudogonyaulax in Murakami et al., 1988) in American and Japanese waters, respectively. This biologically active toxin has been associated over decades with fish mortality. Our study showed that the cell extracts of APBZ12 showed an important bioactivity using GH4C1 rat pituitary cytotoxicity bioassay.

Cytotoxic and inflammatory potential of size-fractionated particulate matter collected repeatedly within a small urban area.

BackgroundExposure to coarse, fine, and ultrafine particles is associated with adverse population health impacts. We investigated whether size-fractionated particles collected repeatedly in the vicinity of industrial (steel mills and associated coking operations, wastewater treatment), high traffic, and residential areas display systematic differences in biological potency.MethodsParticulate matter (PM<0.1, PM0.1–0.5, PM0.5–2.5, PM2.5–10, PM>10) samples collected at sites within Windsor, Ontario, were screened for biological potency in human A549 lung epithelial and murine J774A.1 macrophage-like cells using cytotoxicity bioassays (cellular ATP, resazurin reduction, lactate dehydrogenase (LDH) release), cytokine production, and transcript profiles. Potency was determined from the slope of each dose-effect relationship.ResultsCytotoxic potency varied across size fractions and within a fraction across sites and sampling periods, suggesting that particle composition, in addition to size and mass, affected particle toxicity. While ATP and LDH profiles showed some similarity, resazurin reduction (a measure of metabolic activity) exhibited a unique pattern of response, indicating that the cytotoxicity assays were sensitive to distinct particle characteristics. Chemical speciation varied in relation to prevailing winds, consistent with enrichment of source emissions (e.g. higher metal and polycyclic aromatic hydrocarbon content downwind of the industrial site). Notwithstanding this variability, site-dependent differences in particle toxicity were evident, including greater potency of coarse fractions at the industrial site and of ultrafine particles at the traffic site (Site × Size interactions, p < 0.05). Regression of potency against particle constituents revealed correlations between resazurin reduction, induction of metal-responsive genes, and metal content, which were particularly strong for the coarse fraction, and between cytokine release and endotoxin, suggesting that these factors were important drivers of biological effects that explain, at least in part, the contrasting potencies of particles compared on an equivalent mass basis.ConclusionsThe data show that 1) particle potency and composition can exhibit significant temporal variation in relation to source contributions; 2) sources may differentially impact the potency of specific size fractions; and 3) particle constituents, notably metals and endotoxin, may elicit distinct biological responses. Together, the data are consistent with the notion that sources and composition, in addition to size and mass concentration, are relevant to particle toxicity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-015-0099-z) contains supplementary material, which is available to authorized users.

Deep-Ultraviolet Resonance Raman (DUVRR) Spectroscopy of Therapeutic Monoclonal Antibodies Subjected to Thermal Stress

The structural assessment of Rituximab, an IgG1 mAb, was investigated with deep-ultraviolet resonance Raman (DUVRR) spectroscopy. DUVRR spectroscopy was used to monitor the changes to the secondary structure of Rituximab under thermal stress. DUVRR spectra showed obvious changes from 22 to 72 °C. Specifically, changes in the amide I vibrational mode were assigned to an increase in unordered structure (random coil). Structural changes in samples heated to 72 °C were related to loss in drug potency via a complement dependent cytotoxicity (CDC) bioassay. The DUVRR spectroscopic method shows promise as a tool for the quality assessment of mAb drug products and would represent an improvement over current methodology in terms of analysis time and sample preparation. To determine the scope of the method, protein pharmaceuticals of different molecular weights (ranging from 4 to 143 kDa) and secondary structure (β-sheet, α-helix and unordered structure) were analyzed. The model illustrated the method's sensitivity for the analysis of protein drug products of different secondary structure. Results show promise for DUVRR spectroscopy as a rapid screening tool of a variety of formulated protein pharmaceuticals.

Bioassay Guided Isolation and Identification of a Cytotoxic Compound from Azadirachta indica Leaves

AbstractThis study aimed to investigate the structural features of the isolated flavonol glycoside, which might behave as a cytotoxic compound. The hexane, chloroform, ethyl acetate, and aqueous fractions of an 80% methanol solution of Neem (Azadirachta indica) (Family: Meliaceae) leaves were subjected to a cytotoxicity bioassay against brine shrimp, Artemia salina. The ethyl acetate fraction exhibited the highest cytotoxic effect, supported by the lowest lethal concentration, a LC50 value of 1.35±0.40 ppm. A compound, Quercetin 3‐O‐β‐D‐glucopyranoside, was isolated from the most toxic fraction of the ethyl acetate via preparative liquid chromatography and then identified via ultraviolet‐visible (UV‐Vis), infrared (IR), mass spectrum (MS) and nuclear magnetic resonance (NMR) analyses. The compound was further confirmed by physical state, color, solubility, and melting point determination. The cytotoxic results suggest that the leaf ethyl acetate fraction consists of toxic compounds, which point towards the isolation of Quercetin 3‐O‐β‐D‐glucopyranoside.

Isolation and characterization of bioactive fungi from shark Carcharodon carcharias’ gill with biopharmaceutical prospects

Until recently, little was known about the fungi found in shark gills and their biomedicinal potential. In this article, we described the isolation, bioactivity, diversity, and secondary metabolites of bioactive fungi from the gill of a shark (Carcharodon carcharias). A total of 115 isolates were obtained and grown in 12 culture media. Fifty-eight of these isolates demonstrated significant activity in four antimicrobial, pesticidal, and cytotoxic bioassay models. Four randomly selected bioactive isolates inhibited human cancer cell proliferation during re-screening. These active isolates were segregated into 6 genera using the internal transcribed spacer-large subunit (ITS-LSU) rDNA-sequence BLAST comparison. Four genera, Penicillium, Aspergillus, Mucor, and Chaetomium were the dominant taxa. A phylogenic tree illustrated their intergenera and intragenera genetic diversity. HPLC-DAD-HRMS analysis and subsequent database searching revealed that nine representative strains produced diverse bioactive compound profiles. These results detail the broad range of bioactive fungi found in a shark’s gills, revealing their biopharmaceutical potential. To the best of our knowledge, this is the first study characterizing shark gill fungi and their bioactivity.

Cytotoxic, Acute Toxicity and Phytotoxic Activity of Callicarpa macrophylla in Various Models

The present study describes the cytotoxic, acute toxicity and phytotoxic activities of Callicarpa macrophylla belonging to family Verbanaceae. Brine shrimps cytotoxic bioassay of crude extract of bark of C. macrophylla (CBE) showed 975.22 LD50 value and crude extract of leaves of C. macrophylla (CLE) showed no significant results. However, all the test animals were found absolutely safe in acute toxicity test. In phytotoxic assay against Lemna minor, CLE showed FI50 value of 464.55 and CBE showed no significant results. In conclusion, the CLE showed significant phytotoxic activity and therefore, could be a useful natural herbicidal.

Atrazine induces apoptosis of SH-SY5Y human neuroblastoma cells via the regulation of Bax/Bcl-2 ratio and caspase-3-dependent pathway

Atrazine (ATZ) is a well known herbicide that is frequently detected in ground and surface water at significant levels. Our objective was to study the toxic effect of ATZ on the human neuroblastoma (SH-SY5Y) cells, and the degree of cytotoxicity and morphological changes were followed during the cell death. Application of cytotoxicity bioassays indicates that ATZ (5–50 µg/mL) decreases cell viability in a dose- and time-dependent manner. The evidence of apoptosis was confirmed by an increase in caspase-3 activity, and cell death was blocked when caspase-3 activity was inhibited. Typical apoptotic phenotype that includes nuclear fragmentation, micro nuclei formation, DNA fragmentation and increase in the expressions apoptosis-associated markers Bax, p53 and p21 and decreased expression of Bcl-2 were observed in treated cells. We also observed dose-dependent increase in reactive oxygen species (ROS) levels in ATZ-treated cells. These results suggest that ATZ-induces apoptosis and ROS levels in SH-SY5Y cells, and could be implicated in human neurodegenerative disorder.

Chemical constituents of Abies delavayi

Systematic phytochemical investigations on Abies delavayi afforded 110 compounds, including 49 terpenoids, 13 lignans, 20 flavonoids, three coumarins, and 25 other chemical constituents. By detailed analysis of one- and two-dimensional NMR spectroscopic and high-resolution mass spectrometric data, 10 previously unreported compounds were identified: they comprised three sesquiterpenoids, two diterpenoids, one triterpenoid, one monoterpenoid, one flavonoid, and two phenols. These 10 compounds and some previously known ones were subjected to two cytotoxic bioassays against three human tumor cell lines and NO production inhibition on RAW264.7 macrophages, respectively. (25R)-24,25-Dihydroabieslactone had the strongest cytotoxic activity against Colo-205 cells with an IC50 value of 19.0±3.7μg/mL. (+)-T-cadinol, 8,11,13-abietatrien-15-ol-18-yl acetate, 18-acetoxy-13-epi-manool, imperatorin, bergapten, and 5,7-O-dimethyl poriol exhibited weak inhibitory activity against LPS-induced NO production in RAW264.7 macrophages with IC50 values of approximately 50μg/mL.

Designing quantitative structure activity relationships to predict specific toxic endpoints for polybrominated diphenyl ethers in mammalian cells

Polybrominated diphenyl ethers (PBDEs) are known as effective flame retardants and have vast industrial application in products like plastics, building materials and textiles. They are found to be structurally similar to thyroid hormones that are responsible for regulating metabolism in the body. Structural similarity with the hormones poses a threat to human health because, once in the system, PBDEs have the potential to affect thyroid hormone transport and metabolism. This study was aimed at designing quantitative structure–activity relationship (QSAR) models for predicting toxic endpoints, namely cell viability and apoptosis, elicited by PBDEs in mammalian cells. Cell viability was evaluated quantitatively using a general cytotoxicity bioassay using Janus Green dye and apoptosis was evaluated using a caspase assay. This study has thus modelled the overall cytotoxic influence of PBDEs at an early and a late endpoint by the Genetic Function Approximation method. This research was a twofold process including running in vitro bioassays to collect data on the toxic endpoints and modeling the evaluated endpoints using QSARs. Cell viability and apoptosis responses for Hep G2 cells exposed to PBDEs were successfully modelled with an r2 of 0.97 and 0.94, respectively.

Burchellin: study of bioactivity against Aedes aegypti

BackgroundThe dengue mosquito Aedes aegypti Linnaeus, 1762 is a widespread insect pest of serious medical importance. Since no effective vaccine is available for treating dengue, the eradication or control of the main mosquito vector is regarded as essential. Since conventional insecticides have limited success, plants may be an alternative source of larvicidal agents, since they contain a rich source of bioactive chemicals. The aim of this study was to evaluate the larvicidal activity of the neolignan burchellin isolated from Ocotea cymbarum (Lauraceae), a plant from the Amazon region, against third instar larvae of A. aegypti.MethodsBurchellin obtained from O. cymbarum was analyzed. The inhibitory activity against A. aegypti eggs and larvae and histological changes in the digestive system of treated L3 larvae were evaluated. In addition, nitric oxide synthase activity and nitric oxide levels were determined, and cytotoxicity bioassays performed.ResultsThe data showed that burchellin interfered with the development cycle of the mosquito, where its strongest toxic effect was 100% mortality in larvae (L3) at concentrations ≥ 30 ppm. This compound did not show target cell toxicity in peritoneal macrophages from BALB/c mice, and proved to have molecular stability when dissolved in water. The L3 and L4 larvae treated with the compound showed cellular destruction and disorganization, cell spacing, and vacuolization of epithelial cells in small regions of the midgut.ConclusionThe neolignan burchellin proved to be a strong candidate for a natural, safe and stable phytolarvicidal to be used in population control of A. aegypti.

Hantzsch and Schiff’s reaction: synthesis, in vitro cytotoxic and antimicrobial activity of [1,3,4]oxadiazoline and [1,3]thiazole derivatives

Two new series of compounds namely, 1-chloro-4-(3,4-dichlorophenyl)-3,4-dihydronaphthalene incorporated [1,3,4]oxadiazoline 4a–j and [1,3]thiazole 6a–j derivatives, were prepared. The precursor 1-chloro-4-(3,4-dichlorophenyl)-3,4-dihydronaphthalene-2-carboxaldehyde 2 has been synthesized by Vilsmeier–Haack reaction, and X-ray crystallographic data were recorded. The Schiff’s bases 3a–j subjected to dehydration followed by cyclization afford [1,3,4]oxadiazoline derivatives 4a–j. The [1,3]thiazole derivatives 6a–j were prepared through Hantzsch thiazole synthesis by the reaction of intermediate 5 with different substituted α-halo ketones. The structures of the synthesized compounds were deduced according to FTIR, 1H NMR, 13C NMR, and mass spectral along with micro-analytical data. The newly synthesized compounds have been tested for their cytotoxicity bioassays, anti-bacterial, and anti-fungal activities. Some of the tested compounds showed significant cytotoxicity activity against HeLa cells. The majority of the synthesized compounds showed moderate to good anti-bacterial and anti-fungal activities.