Structure-activity relationship of chemical defenses from the freshwater plant Micranthemum umbrosum

Phytochemical investigation of Asarum sieboldii var. seoulense and the phenotypic profiles of its constituents against a Parkinson's Disease olfactory cell line

Asarum sieboldii var. seoulense is a plant species under the family Aristolochiaceae and has been used for centuries as an ingredient in a well-known Traditional Chinese medicine (TCM), "Xixin", to treat symptoms of the neurodegenerative condition Parkinson's Disease (PD). Although there have been studies on the neuroprotective effect of this TCM, the phenotypic profiles of its chemical constituents against PD-implicated cellular organelles have not been reported. This research investigated the chemistry of A. sieboldii var. seoulense extract to identify the active small molecules that exhibited perturbation to the cellular compartments related to PD, potentially supporting its traditional application in treating this condition. 1H NMR-guided chemical investigation of this plant yielded twenty secondary metabolites which belong to isobutylamides, lignans and phenolics. The compounds were evaluated against an olfactory cell line derived from a PD patient using phenotypic assay. Several isolates, 2, 3, 7, 11, 13-16 and 18-20, were found to induce moderate perturbation to the staining of mitochondria, autophagosome and α-tubulin of the cells. Considering that PD pathogenesis is closely related to these cellular compartments, the results provided a rationale for the traditional application of Xixin in the treatment of PD.

Anti-HIV-1 activities of constituents from the rhizomes of Boesenbergia thorelii

A new lignan, thoreliin A (1), and a new bisnorlignan, thoreliin B (2), were isolated from a MeOH extract of the rhizomes of Boesenbergia thorelii. In addition, the known bisnorlignans 3 and 4, neolignan 5, phenylpropanoids 6-15, as well as benzenoids 18-21 were also obtained from the same source. The structures were elucidated based on their spectroscopic data. By single crystal X-ray analysis, the relative stereochemistry of 1 was confirmed. All isolated compounds were evaluated for anti-HIV-1 activities. Among them, thoreliin A (1) exhibited anti-HIV-1 activities on both HIV-1 reverse transcriptase (41.43% inhibition at 200 μg/mL) and syncytium reduction assays (EC₅₀ 20.6 μM, SI 3.7), while compounds 3-6, 9 and 11-21 showed anti-HIV-1 activity only in the anti-syncytium assay (EC₅₀ 6.6-454.1 μM, SI >1.32-7.75).

Cytotoxicity against Cholangiocarcinoma and HepG2 Cell Lines of Lignans from Hernandia nymphaeifolia

Eleven lignans (1-11) were isolated from the seed of Hernandia nymphaeifolia. Most of the lignans exhibited strong to moderate cytotoxicity against cholangiocarcinoma KKU-M156 and HepG2 cell lines. Compounds 4 and 8 showed cytotoxicity against the KKU-M156 cell line with IC50 values of 5.2 μ M (Emax 96%) and 5.4 (Emax 59%) μM, respectively. In the cases of cytotoxicity against the HepG2 cell line, compounds 2, 3, 4, and 8 showed cytotoxicity with IC50 values of 1.7 M (Emax 84%), 4.1 μM (Emax 74%), 4.5 μM (Emax 68%), and 5.2 μM (Emax 78%), respectively.

Total Synthesis of the Claimed Structure of (±)-Hyptinin and Structural Revision of Natural Hyptinin

A total synthesis of (±)-hyptinin was achieved via a convergent route using the key phosphonate, cyclic ketone, and aryl Grignard components. The ¹H and ¹³C NMR spectra of natural hyptinin did not agree with those of the synthesized compound. In particular, there were considerable differences between the signals assigned to the protons and carbons surrounding the lactone carbonyl group for the natural and synthesized compounds. The NMR data strongly suggested that the naturally occurring compound, hyptinin, was a structural isomer of the synthesized compound. The structure of the natural compound was eventually established as (+)-β-apopicropodophyllin, based on the synthesis results.

Methyl eugenol: its occurrence, distribution, and role in nature, especially in relation to insect behavior and pollination

This review discusses the occurrence and distribution (within a plant) of methyl eugenol in different plant species (> 450) from 80 families spanning many plant orders, as well as various roles this chemical plays in nature, especially in the interactions between tephritid fruit flies and plants.

Triterpenes from Garcia parviflora. Cytotoxic evaluation of natural and semisynthetic friedelanes

Three new friedelane-type triterpenes, 1,2-dehydro-2,3-secofriedelan-3-oic acid (1), 1β-hydroxyfriedelin (2), and 3β-hydroxyfriedelan-23-oic acid (3), and the known compounds friedelin-3,4-lactone (4), acetyl aleuritolic acid (5), 4-hydroxy-5-propionyl-1,3-di-O-methylpyrogallol, elemicin, and (-)-syringaresinol were isolated from the leaves of Garcia parviflora. The structures of 1-3 were elucidated by spectroscopic methods, including 1D and 2D NMR, HREIMS, X-ray, and CD analysis. Some derivatives of 2 (6-14) were prepared via oxidation, reduction, and esterification. The natural triterpenes and the semisynthetic friedelane derivatives were tested for cytotoxic activity against human cancer cell lines U251, PC-3, K562, HCT-15, MCF-7, and SKLU-1. Compound 5 was cytotoxic against U251 cells.

Neural processing, perception, and behavioral responses to natural chemical stimuli by fish and crustaceans

This manuscript reviews the chemical ecology of two of the major aquatic animal models, fish and crustaceans, in the study of chemoreception. By necessity, it is restricted in scope, with most emphasis placed on teleost fish and decapod crustaceans. First, we describe the nature of the chemical world perceived by fish and crustaceans, giving examples of the abilities of these animals to analyze complex natural odors. Fish and crustaceans share the same environments and have evolved some similar chemosensory features: the ability to detect and discern mixtures of small metabolites in highly variable backgrounds and to use this information to identify food, mates, predators, and habitat. Next, we give examples of the molecular nature of some of these natural products, including a description of methodologies used to identify them. Both fish and crustaceans use their olfactory and gustatory systems to detect amino acids, amines, and nucleotides, among many other compounds, while fish olfactory systems also detect mixtures of sex steroids and prostaglandins with high specificity and sensitivity. Third, we discuss the importance of plasticity in chemical sensing by fish and crustaceans. Finally, we conclude with a description of how natural chemical stimuli are processed by chemosensory systems. In both fishes and crustaceans, the olfactory system is especially adept at mixture discrimination, while gustation is well suited to facilitate precise localization and ingestion of food. The behaviors of both fish and crustaceans can be defined by the chemical worlds in which they live and the abilities of their nervous systems to detect and identify specific features in their domains. An understanding of these worlds and the sensory systems that provide the animals with information about them provides insight into the chemical ecology of these species.

Reconstitution of a chemical defense signaling pathway in a heterologous system

Chemical signaling plays an important role in ecological interactions, such as communication and predator-prey dynamics. Since sessile species cannot physically escape predators, many contain compounds that deter predation; however, it is largely unknown how predators physiologically detect deterrent chemicals. Few studies have investigated ecologically relevant aversive taste responses in any predator. Our objective was to determine if a signaling pathway for detecting marine sponge-derived deterrent compounds could be reconstituted in a heterologous expression system to ultimately facilitate investigation of the molecular mechanism of such an aversive behavioral response. Zebrafish (Danio rerio) rejected artificial diets laced with sponge chemical defense compounds that were previously shown to deter a generalist marine predator, Thalassoma bifasciatum, suggesting that zebrafish can recognize deterrent compounds relevant to coral reef systems. Transcripts made from a zebrafish cDNA library were expressed in a heterologous system, Xenopus laevis oocytes, and tested for chemoreceptor activation via electrophysiology, using the cystic fibrosis transmembrane conductance regulator (CFTR) as a reporter. Oocytes expressing gene sequences from the library and CFTR exhibited a CFTR-like electrophysiological response to formoside and ectyoplasides A and B, sponge defense compounds. Therefore, the chemical defense-activated signaling pathway can be reconstituted in Xenopus oocytes. Kinetics of the responses suggested that the responses to formoside and ectyoplasides A and B were receptor-mediated and capable of using the G(alphas) signaling pathway in this system. This bioassay has the potential to lead to the identification of genes that encode receptors capable of interacting with deterrent chemicals, which would enable understanding of predator detection of chemical defenses.