The major bioactive components of seaweeds and their mosquitocidal potential

Seaweeds are one of the most widely studied natural resources for their biological activities. Novel seaweed compounds with unique chemical structures have been reported for their pharmacological properties. The urge to search for novel insecticidal compound with a new mode of action for development of botanical insecticides supports the relevant scientific research on discovering the bioactive compounds in seaweeds. The mosquitocidal potential of seaweed extracts and their isolated compounds are documented in this review paper, along with the discussion on bioactivities of the major components of seaweeds such as polysaccharides, phenolics, proteins, terpenes, lipids, and halogenated compounds. The effects of seaweed extracts and compounds toward different life stages of mosquito (egg, larva, pupa, and adult), its growth, development, and reproduction are elaborated. The structure-activity relationships of mosquitocidal compounds are discussed to extrapolate the possible chemical characteristics of seaweed compounds responsible for insecticidal properties. Furthermore, the possible target sites and mode of actions of the mosquitocidal seaweed compounds are included in this paper. The potential synergistic effects between seaweeds and commercial insecticides as well as the toxic effects of seaweed extracts and compounds toward other insects and non-target organisms in the same habitat are also described. On top of that, various factors that influence the mosquitocidal potential of seaweeds, such as abiotic and biotic variables, sample preparation, test procedures, and considerations for a precise experimental design are discussed. The potential of active seaweed extracts and compounds in the development of effective bioinsecticide are also discussed.     

Insecticidal Activities of the Leaf Oils of Eight Cinnamomum. species Against Aedes aegypti. and Aedes albopictus.

Abstract

The leaf oils of eight Cinnamomum. species (C. rhyncophyllum. Miq., C. microphyllum. Ridl., C. pubescens. Kochummen, C. mollissimum. Hook. f., C. impressicostatum. Kosterm, C. scortechinii. Gamb., C. sintoc. Bl., and C. cordatum. Kosterm) were investigated for their larvicidal and adulticidal activities against Aedes aegypti. (Aedes aegypti Lynn) and Aedes albopictus. (Aedes albopictus Skuse). Acute mortalities of the fourth instar larvae and the adult mosquitoes were determined according to the standard WHO methods. Among the essential oils studied, the leaf oils of C. rhyncophyllum., C. microphyllum., C. pubescens., C. mollissimum., and C. impressicostatum. showed significant effects against the larvae of Ae. aegypti. and Ae. albopictus. with concentrations that caused 50% mortality (LC₅₀) values of less than 12.8 and 11.8 µg ml^?1, respectively. The essential oils that showed strong larvicidal effects also demonstrated relatively strong adulticidal effects on the mosquitoes after 3 h exposure with LC₅₀ values ranging from 133.0 to 243.0 µg ml^?1 against Ae. aegypti. and from 118.0 to 194.0 µg ml^?1 against Ae. albopictus.. The efficacy of the oils toward the larvae and adult mosquitoes of both species was nonselective as the LC₅₀ values showed little variation. The chemical composition of the oils was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). This study suggested that the essential oils containing high levels of benzyl benzoate and benzyl salicylate exhibited strong insecticidal activities against the larvae and adult mosquitoes.     

Multi-level basis selection of wavelet packet decomposition tree for heart sound classification

Wavelet packet transform decomposes a signal into a set of orthonormal bases (nodes) and provides opportunities to select an appropriate set of these bases for feature extraction. In this paper, multi-level basis selection (MLBS) is proposed to preserve the most informative bases of a wavelet packet decomposition tree through removing less informative bases by applying three exclusion criteria: frequency range, noise frequency, and energy threshold. MLBS achieved an accuracy of 97.56% for classifying normal heart sound, aortic stenosis, mitral regurgitation, and aortic regurgitation. MLBS is a promising basis selection to be suggested for signals with a small range of frequencies.     

Inhibitory effect of selected medicinal plants on the release of pro-inflammatory cytokines in lipopolysaccharide-stimulated human peripheral blood mononuclear cells

The inhibitory activities of the methanol extracts from 20 selected medicinal plants on the release of pro-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs) were evaluated. The major compound from the most active plant extract was also investigated. The inhibitory effect of the methanol extracts on the release of pro-inflammatory cytokines was tested by incubating PBMCs with the sample and then stimulating by lipopolysaccharide at 0.1 μg/ml. The level of cytokines was determined using enzyme-linked immunosorbent assay. Among the extracts tested, Andrographis paniculata extract demonstrated the strongest inhibition of interleukin (IL)-1β, IL-1α, and IL-6 release, with IC₅₀ values of 1.54, 1.06, and 0.74 μg/ml, respectively. The IC₅₀ value of A. paniculata extract was significantly higher than that of andrographolide on IL-1α, IL-1β, and IL-6 (p < 0.001) release. The IC₅₀ values of andrographolide for IL-1α, IL-1β, and IL-6 were significantly higher (p < 0.001) than that of dexamethasone. Cymbopogon citratus and Zingiber officinale strongly inhibited the release of IL-1β, with IC₅₀ values of 3.22 and 3.17 μg/ml, respectively. To our knowledge, this is the first report that A. paniculata extract and its major compound andrographolide strongly inhibited the release of IL-1α, whereas previous studies only showed their inhibitory effect on the release of another IL-1 family member, IL-1β. The results show that these extracts and this compound have potential effects as anti-inflammatory agents by inhibiting the release of pro-inflammatory cytokines.     

Induction of cell death and modulation of Annexin A1 by phytoestrogens in human leukemic cell lines

BackgroundPhytoestrogens are polyphenolic plant compounds which are structurally similar to the endogenous mammalian estrogen, 17β-estradiol. Annexin A1 (ANXA1) is an endogenous protein which inhibits cyclo-oxygenase 2 (COX-2) and phospholipase A2, signal transduction, DNA replication, cell transformation, and mediation of apoptosis.ObjectiveThis study aimed to determine the effects of selected phytoestrogens on annexin A1 (ANXA1) expression, mode of cell death and cell cycle arrest in different human leukemic cell lines.MethodsCells viability were examined by MTT assay and ANXA1 quantification via Enzyme-linked Immunosorbent Assay. Cell cycle and apoptosis were examined by flow cytometer and phagocytosis effect was evaluated using haematoxylin-eosin staining.ResultsCoumestrol significantly (p < 0.05) reduced the total level of ANXA1 in both K562 and U937 cells and genistein significantly (p < 0.05) reduced it in K562, Jurkat and U937 cells, meanwhile estradiol and daidzein induced similar reduction in U937 and Jurkat cells. Coumestrol and daidzein induced apoptosis in K562 and Jurkat cells, while genistein and estradiol induced apoptosis in all tested cells. Coumestrol and estradiol induced cell cycle arrest at G2/M phase in K562 and Jurkat cells with an addition of U937 cells for estradiol. Genistein induced cell cycle arrest at S phase for both K562 and Jurkat cells. However, daidzein induced cell cycle arrest at G0/G1 phase in K562, and G2/M phase of Jurkat cells. Coumestrol, genistein and estradiol induced phagocytosis in all tested cells but daidzein induced significant (p < 0.05) phagocytosis in K562 and Jurkat cells only.ConclusionThe selected phytoestrogens induced cell cycle arrest, apoptosis and phagocytosis and at the same time they reduced ANXA1 level in the tested cells. The IC50 value of phytoestrogens was undetectable at the concentrations tested, their ability to induce leukemic cells death may be related with their ability to reduce the levels of ANXA1. These findings can be used as a new approach in cancer treatment particularly in leukemia.     

Betulinic Acid: Recent Advances in Chemical Modifications,Effective Delivery,and Molecular Mechanisms of a Promising Anticancer Therapy

An important method of drug discovery is examination of diverse life forms, including medicinal plants and natural products or bioactive compounds isolated from these sources. In cancer research, lead structures of compounds from natural sources can be used to design novel chemotherapies with enhanced biological properties. Betulinic acid (3β‐hydroxy‐lup‐20(29)‐en‐28‐oic acid or BetA) is a naturally occurring pentacyclic triterpene with a wide variety of biological activities, including potent antitumor properties. Non‐malignant cells and normal tissues are not affected by BetA. Because BetA exerts its effects directly on the mitochondrion and triggers death of cancerous cells, it is an important alternative when certain chemotherapy drugs fail. Mitochondrion‐targeted agents such as BetA hold great promise to circumvent drug resistance in human cancers. BetA is being developed by a large network of clinical trial groups with the support of the U.S. National Cancer Institute. This article discusses recent advances in research into anticancer activity of BetA, relevant modes of delivery, and the agent's therapeutic efficacy, mechanism of action, and future perspective as a pipeline anticancer drug. BetA is a potentially important agent in cancer therapeutics.     

Evaluation of multifunctional synthetic tetralone derivatives for treatment of Alzheimer's disease

Neurodegeneration, a complex disease state, comprises several pathways that contribute to cell death. Conventional approach of targeting only one of these pathways has not been proven to be entirely successful and has demanded a hypothetical change as to how researchers design and develop new drugs. In this study, effects of a series of α, β‐unsaturated carbonyl‐based tetralone derivatives against Alzheimer's disease (AD) were investigated. Moreover, their activity toward amyloid β‐induced cytotoxicity was also studied. Six compounds including 3f , 3o , 3u , 3ae , 3af , and 3ag were discovered to be most protective against Aβ‐induced neuronal cell death in PC12 cells. The findings of in vitro experiment revealed that most of these compounds exhibited potent inhibitory activity against MAO‐B, AChE, and self‐induced Aβ_1–42 aggregation. The compound 3f exhibited best AChE (IC₅₀ = 0.045 ± 0.02 μm ) inhibitory potential in addition to potent inhibition of MAO‐B (IC₅₀ = 0.88 ± 0.12 μm ). Furthermore, compound 3f disassembled the Aβ fibrils produced by self‐induced Aβ aggregation by 78.2 ± 4.8%. Collectively, these findings suggest that some compounds from this series have potential to be promising multifunctional agents for AD treatment.     

Two new methyl chanofruticosinates from Kopsia flavida blume

Two new indole alkaloids with the methyl chanofruticosinate skeletal system viz., methyl 3-oxo-12-methoxy- N 1 -decarbomethoxy-14,15-didehydrochanofruticosinate ( 1 ) and methyl 3-oxo-11,12-methylenedioxy- N 1 -decarbomethoxy-14,15-didehydrochanofruticosinate ( 2 ), together with four known compounds, methyl 12-methoxy- N 1 -decarbomethoxychanofruticosinate, methyl 12-methoxychanofruticosinate, methyl 11,12-dimethoxychanofruticosinate and methyl 11,12-methylenedioxy- N 1 -decarbomethoxychanofruticosinate, were isolated in continuing studies on the leaves of Kopsia flavida Blume. The structures of the new indole alkaloids were assigned by NMR spectral data using various 2D-techniques.     

Bioassay-Guided Isolation of a Potent Platelet-Activating Factor Antagonist Alkenylresorcinol from Ardisia elliptica

In the course of our search for novel platelet-activating factor (PAF) antagonists from medicinal plants, the methanol extract of the leaves of Ardisia elliptica Thunb. was investigated for its inhibitory effects on PAF receptor binding to rabbit platelets using ³H-PAF as a ligand. The methanol extract showed inhibitory activity of 53.9% and its ethyl acetate, n-butanol, and methanol fractions exhibited 48.6%, 39.0%, and 22.0% inhibition, respectively. Bioassay-guided fractionation of the ethyl acetate fraction led to the isolation of a new alkenylresorcinol, 5-(Z-heptadec-4′-enyl)resorcinol, together with 5-pentadecylresorcinol. The alkenylresorcinol showed a strong inhibition with an IC₅₀ value of 7.1 µM. The structures of the compounds were elucidated by spectroscopic techniques.