A Novel AHAS-Inhibiting Herbicide Candidate for Controlling Leptochloa chinensis: A Devastating Weedy Grass in Rice Fields

Given the prevalence of the malignant weed Chinese Sprangletop (Leptochloa chinensis (L.) Nees) in rice fields, the development of novel herbicides against this weed has aroused wide interest. Here, we report a novel diphenyl ether-pyrimidine hybrid, DEP-5, serving as a systematic pre/postemergence herbicide candidate for broad-spectrum weed control in rice fields, specifically for L. chinensis. Notably, DEP-5 exhibits over 80% herbicidal activity against the resistant biotypes even at 37.5 g a.i./ha under greenhouse conditions and has complete control of L. chinensis at 150 g a.i./ha in the rice fields. We uncover that DEP-5 acts as a noncompetitive inhibitor of acetohydroxyacid synthase (AHAS) with an inhibition constant (Ki) of 39.4 μM. We propose that DEP-5 binds to AHAS in two hydrophobic-driven binding modes that differ from commercial AHAS inhibitors. Overall, these findings demonstrate that DEP-5 has great potential to be developed into a herbicide for L. chinensis control and inspire fresh concepts for novel AHAS-inhibiting herbicide design.

3D-QSAR model-oriented optimization of Pyrazole β-Ketonitrile derivatives with diphenyl ether moiety as novel potent succinate dehydrogenase inhibitors

BACKGROUND

Succinate dehydrogenase inhibitor (SDHI) fungicides play important roles in the control of plant fungal diseases. However, they are facing serious challenges from issues with resistance and cross-resistance, primarily attributed to their frequent application and structural similarities. There is an urgent need to design and develop SDHI fungicides with novel structures.

RESULTS

Aiming to discover novel potent SDHI fungicides, 31 innovative pyrazole β-ketonitrile derivatives with diphenyl ether moiety were rationally designed and synthesized, which were guided by a 3D-QSAR model from our previous study. The optimal target compound A23 exhibited not only outstanding in vitro inhibitory activities against Rhizoctonia solani with a half-maximal effective concentration (EC50) value of 0.0398 μg mL-1 comparable to that for fluxapyroxad (EC50 = 0.0375 μg mL-1), but also a moderate protective efficacy in vivo against rice sheath blight. Porcine succinate dehydrogenase (SDH) enzymatic inhibitory assay revealed that A23 is a potent inhibitor of SDH, with a half-maximal inhibitory concentration of 0.0425 μm. Docking study within R. solani SDH indicated that A23 effectively binds into the ubiquinone site mainly through hydrogen-bonds, and cation-π and π-π interactions.

CONCLUSION

The identified β-ketonitrile compound A23 containing diphenyl ether moiety is a potent SDH inhibitor, which might be a good lead for novel fungicide research and optimization. © 2024 Society of Chemical Industry.

URJC-1: Stable and Efficient Catalyst for O-Arylation Cross-Coupling

The design of metal-organic frameworks (MOFs) allows the definition of properties for their final application in small-scale heterogeneous catalysis. Incorporating various catalytic centers within a single structure can produce a synergistic effect, which is particularly intriguing for cross-coupling reactions. The URJC-1 material exhibits catalytic duality: the metal centers act as Lewis acid centers, while the nitrogen atoms of the organic ligand must behave as basic centers. The impact of reaction temperature, catalyst concentration, and basic agent concentration was evaluated. Several copper-based catalysts, including homogeneous and heterogeneous MOF catalysts with and without the presence of nitrogen atoms in the organic ligand, were assessed for their catalytic effect under optimal conditions. Among the catalysts tested, URJC-1 exhibited the highest catalytic activity, achieving complete conversion of 4-nitrobenzaldehyde with only 3% mol copper concentration in one hour. Furthermore, URJC-1 maintained its crystalline structure even after five reaction cycles, demonstrating remarkable stability in the reaction medium. The study also examined the impact of various substituents of the substrate alcohol on the reaction using URJC-1. The results showed that the reaction had high activity when activating substituents were present and for most cyclic alcohols rather than linear ones.

Atroposelective Synthesis of Axially Chiral Diaryl Ethers by N-Heterocyclic-Carbene-Catalyzed Sequentially Desymmetric/Kinetic Resolution Process

We describe herein an N-heterocyclic-carbene-catalyzed atroposelective synthesis of axially chiral diaryl ethers. Through a sequentially enantioselective desymmetric process and a kinetic resolution process, the products could be constructed in good yields with excellent enantiopurities. Both alcohols and phenols were compatible with this catalytic system. The axially chiral carboxylic acids derived from the esters were proven to be potential chiral ligands for asymmetric synthesis, for example, Rh(III)-catalyzed enantioselective C-H functionalization.

Design, synthesis, and biological evaluation of novel quinoxaline aryl ethers as anticancer agents

We designed and synthesized thirty novel quinoxaline aryl ethers as anticancer agents, and the structures of final compounds were confirmed with various analytical techniques like Mass, 1 H NMR, 13 C NMR, FTIR, and elemental analyses. The compounds were tested against three cancer cell lines: colon cancer (HCT-116), breast cancer (MDA-MB-231), prostate cancer (DU-145), and one normal cell line: human embryonic kidney cell line (HEK-293). The obtained results indicate that two compounds, FQ and MQ, with IC50 values < 16 μM, were the most active compounds. Molecular docking studies revealed the binding of FQ and MQ molecules in the active site of the c-Met kinase (PDB ID: 3F66, 1.40 Å). Furthermore, QikProp ADME prediction and the MDS analysis preserved those critical docking data of both compounds, FQ and MQ. Western blotting was used to confirm the impact of the compounds FQ and MQ on the inhibition of the c-Met kinase receptor. The apoptosis assays were performed to investigate the mechanism of cell death for the most active compounds, FQ and MQ. The Annexin V/7-AAD assay indicated apoptosis in MDA-MB-231 cells treated with FQ and MQ, with FQ (21.4%) showing a higher efficacy in killing MDA-MB-231 cells than MQ (14.25%). The Caspase 3/7 7-AAD assay further supported these findings, revealing higher percentages of apoptotic cells for FQ-treated MDA-MB-231 cells (41.8%). The results obtained from the apoptosis assay conclude that FQ exhibits better anticancer activity against MDA-MB-231 cells than MQ.

Regio- and Stereoselective Intermolecular 1,2-Difunctionalization of Terminal Alkynes: An Approach to Access (Z)-β-Amidovinylsulfones

We have developed the first I2/base-catalyzed regio- and stereoselective intermolecular β-amidosulfonylation of terminal alkynes using sodium sulfinates and quinoxalinone derivatives. The present methodology is compatible with a broad spectrum of various heterocyclic amides, terminal alkynes, and sodium sulfinates. It provides rapid access to valuable (Z)-β-amidovinyl sulfones at mild conditions. Moreover, the synthetic application of this methodology was demonstrated by the late-stage functionalization of numerous bioactive molecules.

Synthesis and Biological Activities of Novel Pyrazole Carboxamides Containing an Aryloxypyridyl Ethylamine Module

Pyrazole carboxamide is widely utilized in agricultural crop protection. In this research, we synthesized two classes of compounds, namely, pyrazole-5-carboxamide (4a) and pyrazole-4-carboxamide (4b), which are distinguished by the inclusion of the N-1-(6-aryloxypyridin-3-yl) ethylamine skeleton. This design was inspired by the frequent occurrence of diaryl ether modules in pesticide molecules. The bioassay results revealed that some compounds 4a exhibit higher insecticidal activity (IA) than 4b, while some compounds 4b display stronger fungicidal activity compared to 4a. This suggests that pyrazolyl plays a crucial role in determining the selectivity of these compounds toward different biological species. Notably, compound 4a-14 not only retains the potent activity of tolfenpyrad, the exact lead compound of 4a, against Lepidoptera pest Plutella xylostella and Thysanoptera pest Frankliniella occidentalis but also shows excellent IA against pests with piercing-sucking mouthparts, such as Aphis craccivora Koch and Nilaparvata lugens. This research has important implications for the control of pests with piercing-sucking mouthparts and the development of new insecticides and fungicides. The findings highlight the potential of inhibitory complex I as an effective control target for these pests, particularly those that have developed resistance to traditional insecticides. Additionally, it sheds light on the binding mode of 4b-11 and complex II, which serves as a negative reference for the design of SDHI fungicides. The study emphasizes the significance of pyrazolyl in determining selectivity in biological species and identifies avenues for future research in enhancing the biological activity of amino modules. The discovery of (S)-4a-14 not only presents a promising candidate compound for pesticide development but also provides valuable insights into the inhibitory effect of a respiratory chain complex on piercing-sucking insect pests. These findings have important implications in both theory and practice, offering new directions for pest control strategies and pesticide and fungicide development.

Rhodium-Catalyzed C(sp2)-O Cross Couplings of Diazo Quinones with Phenols to Construct Diaryl Ethers

The diaryl ether represents a prevalent structural motif found in numerous biologically active molecules. Herein, we describe a dirhodium-catalyzed C(sp2)-O cross coupling reaction between diazo quinones and phenols for the construction of diaryl ethers in moderate to high yields. The reaction proceeds under mild and neutral conditions and is tolerant of various functional groups. The synthetic method has been successfully applied to the concise synthesis of a Navl.7 inhibitor.

The Bis(indolylmethyl) ethers: Design, Prototypical Synthesis, and Scope Studies

The design, prototypical synthesis, isolation, and characterization of bis(indolylmethyl) ethers from corresponding indolylcarbinols is described. This approach involves very mild conditions and exhibits good scope for indolylcarbinols (both N-electron withdrawing group and N-electron donating group). Cross etherification between two electronically different indolylcarbinols is also demonstrated for the generation of unsymmetrical ethers. For the first time, the intermediacy of the bis(indolylmethyl) ethers for the formation of bis(indolyl)methanes from indolylcarbinols is proved experimentally and by 1H NMR analysis.

Discovery of Novel Isoxazoline Derivatives Containing Diaryl Ether against Fall Armyworms

With the continuous evolution of insect resistance, it is a tremendous challenge to control the fall armyworm (Spodoptera frugiperda) with traditional insecticides. To solve this pending issue, a series of novel isoxazoline derivatives containing diaryl ether structures were designed and synthesized, and most of the target compounds exhibited excellent insecticidal activity. Based on the three-dimensional quantitative structure-activity relationship (3D-QSAR) model analysis, we further optimized the molecular structure with compound L35 obtained and tested for its activity. Compound L35 (LC₅₀ = 1.69 mg/L) exhibited excellent insecticidal activity against S. frugiperda, which was better than those of commercial fipronil (LC₅₀ = 70.78 mg/L) and indoxacarb (LC₅₀ = 5.37 mg/L). The enzyme-linked immunosorbent assay showed that L35 could upregulate the levels of GABA in insects. In addition, molecular docking and transcriptomic results also indicated that compound L35 may affect the nervous system of S. frugiperda by acting on GABA receptors. Notably, through high-performance liquid chromatography (HPLC), we were able to obtain the two enantiomers of compound L35, and the insecticidal activity test revealed that S-(+)-L35 was 44 times more active than R-(-)-L35 against S. frugiperda. This study established the chemistry basis and mechanistic foundations for the future development of pesticide candidates against fall armyworms.

Synthesis and Antiproliferative Activity of Steroidal Diaryl Ethers

Novel 13α-estrone derivatives have been synthesized via direct arylation of the phenolic hydroxy function. Chan-Lam couplings of arylboronic acids with 13α-estrone as a nucleophilic partner were carried out under copper catalysis. The antiproliferative activities of the newly synthesized diaryl ethers against a panel of human cancer cell lines (A2780, MCF-7, MDA-MB 231, HeLa, SiHa) were investigated by means of MTT assays. The quinoline derivative displayed substantial antiproliferative activity against MCF-7 and HeLa cell lines with low micromolar IC₅₀ values. Disturbance of tubulin polymerization has been confirmed by microplate-based photometric assay. Computational calculations reveal significant interactions of the quinoline derivative with the taxoid binding site of tubulin.

Advancement of Phenoxypyridine as an Active Scaffold for Pesticides

Phenoxypyridine, the bioisostere of diaryl ethers, has been widely introduced into bioactive molecules as an active scaffold, which has different properties from diaryl ethers. In this paper, the bioactivities, structure-activity relationships, and mechanism of compounds containing phenoxypyridine were summarized, which may help to explore the lead compounds and discover novel pesticides with potential bioactivities.

Organosulphur and organoselenium compounds as emerging building blocks for catalytic systems for O-arylation of phenols, a C-O coupling reaction

Diaryl ethers form an important class of organic compounds. The classic copper-mediated Ullmann diaryl ether synthesis has been known for many years and involves the coupling of phenols with aryl halides. However, the use of high reaction temperature, high catalyst loading and expensive ligands has created a need for the development of alternative catalytic systems. In the recent past, organosulphur and organoselenium compounds have been used as building blocks for developing homogeneous, heterogeneous and nanocatalysts for this C-O coupling reaction. Homogeneous catalytic systems include preformed complexes of metals with organosulphur and organoselenium ligands. The performance of such complexes is influenced dramatically by the nature of the chalcogen (S or Se) donor site of the ligand. Nanocatalytic systems (including Pd₁₇Se₁₅, Pd₁₆S₇ and Cu_1.8S) have been designed using a single-source precursor route. Heterogeneous catalytic systems contain either metal (Cu or Pd) or metal chalcogenides (Pd₁₇Se₁₅ or Cu_1.8S) as catalytically active species. This article aims to cover the simple and straightforward methodologies and approaches that are adopted for developing catalytically relevant organosulfur and organoselenium ligands, their homogeneous metal complexes, heterogeneous and nanocatalysts. The effects of chalcogen (S or Se) donor, halogen (Cl/Br/I) of aryl halide, nature (electron withdrawing or electron donating) of substituents present on the aromatic ring of aryl halides or substituted phenols and position (ortho or para) of substitution on the results of catalytic reactions have been critically analyzed and summarized. The effect of composition (Pd₁₇Se₁₅ or Pd₁₆S₇) on the performance of nanocatalytic systems is also highlighted. Substrate scope has also been discussed in all three types of catalysis. The superiority of heterogeneous catalytic systems (e.g., Pd₁₇Se₁₅ immobilised on graphene oxide) indicates the bright future possibilities for the development of efficient catalytic systems using similar or tailored ligands for this reaction.

Discovery of Novel Cytochrome bc1 Complex Inhibitor Based on Natural Product Neopeltolide

Background:

Natural products (NPs) are important sources for the design of new drugs and agrochemicals. Neopeltolide, a marine NP, has been identified as a potent Qo-site inhibitor of cytochrome bc1 complex.

Methods:

In this study, a series of neopeltolide derivatives was designed and synthesized by the simplification of its 14-membered macrolactone ring with a diphenyl ether fragment. The enzymatic inhibition bioassays and mycelium growth inhibition experiments against a range of fungi were performed to determine their fungicidal activities.

Results:

The derivatives have potent activity against the porcine bc1 complex. Compound 8q showed the best activity with an IC50 value of 24.41 nM, which was 8-fold more effective than that of positive control azoxystrobin. Compound 8a exhibited a 100% inhibitory rate against Zymoseptoria tritici and Alternaria solani at a 20 mg/L dose.

Conclusion:

Computational results indicated that compounds with suitable physicochemical properties, as well as those forming a hydrogen bond with His161, would have good fungicidal activity. These data could be useful for the design of bc1 complex inhibitors in the future.

Formal dual C(sp2)–H cross-dehydrogenative C–O bond formation to construct highly functionalized diaryl ethers with O2

A formal dual C(sp2)–H cross-dehydrogenative C–O bond formation reaction between phenols and naphthylamine derivatives to construct diaryl ethers has been developed under mild conditions.

A review on synthetic chalcone derivatives as tubulin polymerisation inhibitors

Microtubules play an important role in the process of cell mitosis and can form a spindle in the mitotic prophase of the cell, which can pull chromosomes to the ends of the cell and then divide into two daughter cells to complete the process of mitosis. Tubulin inhibitors suppress cell proliferation by inhibiting microtubule dynamics and disrupting microtubule homeostasis. Thereby inducing a cell cycle arrest at the G2/M phase and interfering with the mitotic process. It has been found that a variety of chalcone derivatives can bind to microtubule proteins and disrupt the dynamic balance of microtubules, inhibit the proliferation of tumour cells, and exert anti-tumour effects. Consequently, a great number of studies have been conducted on chalcone derivatives targeting microtubule proteins. In this review, synthetic or natural chalcone microtubule inhibitors in recent years are described, along with their structure-activity relationship (SAR) for anticancer activity.

Synthesis and biological evaluation of halogenated phenoxychalcones and their corresponding pyrazolines as cytotoxic agents in human breast cancer

Novel halogenated phenoxychalcones 2a–f and their corresponding N-acetylpyrazolines 3a–f were synthesised and evaluated for their anticancer activities against breast cancer cell line (MCF-7) and normal breast cell line (MCF-10a), compared with staurosporine. All compounds showed moderate to good cytotoxic activity when compared to control. Compound 2c was the most active, with IC₅₀ = 1.52 µM and selectivity index = 15.24. Also, chalcone 2f showed significant cytotoxic activity with IC₅₀ = 1.87 µM and selectivity index = 11.03. Compound 2c decreased both total mitogen activated protein kinase (p38α MAPK) and phosphorylated enzyme in MCF-7 cells, suggesting its ability to decrease cell proliferation and survival. It also showed the ability to induce ROS in MCF-7 treated cells. Compound 2c exhibited apoptotic behaviour in MCF-7 cells due to cell accumulation in G2/M phase and elevation in late apoptosis 57.78-fold more than control. Docking studies showed that compounds 2c and 2f interact with p38alpha MAPK active sites.

Electrochemical Organic Synthesis of Electron-Rich Biaryl Scaffolds: An Update

Biaryl scaffolds are widely spread in biologically important natural products, in numerous therapeutic agents, but they are also considered a privileged class of ligands and (organo)catalysts; therefore, the development of efficient alternative methodologies to prepare such compounds is always attracting much attention. The present review discusses the organic electrosynthesis of biaryls starting from phenols, anilines, naphthols, and naphthylamines. The most significant examples of the works reported in the last decade are presented and classified according to the single class of molecules: after the introduction, the first three sections relate to the reactions of phenols, naphthols, and anilines, respectively; the other two sections refer to cross-coupling and miscellaneous reactions.

The Fellowship of Privileged Scaffolds-One Structure to Inhibit Them All

Over the past few years, the application of privileged structure has emerged as a powerful approach to the discovery of new biologically active molecules. Privileged structures are molecular scaffolds with binding properties to the range of different biological targets. Moreover, privileged structures typically exhibit good drug-like properties, thus assuring more drug-like properties of modified compound. Our main objective is to discuss the privileged structures used for the development of antiviral agents.

Catalytic Reductive Alcohol Etherifications with Carbonyl-Based Compounds or CO2 and Related Transformations for the Synthesis of Ether Derivatives

Ether derivatives have myriad applications in several areas of chemical industry and academia. Hence, the development of more effective and sustainable protocols for their production is highly desired. Among the different methodologies reported for ether synthesis, catalytic reductive alcohol etherifications with carbonyl-based moieties (aldehydes/ketones and carboxylic acid derivatives) have emerged in the last years as a potential tool. These processes constitute appealing routes for the selective production of both symmetrical and asymmetrical ethers (including O-heterocycles) with an increased molecular complexity. Likewise, ester-to-ether catalytic reductions and hydrogenative alcohol etherifications with CO2 to dialkoxymethanes and other acetals, albeit in less extent, have undergone important advances, too. In this Review, an update of the recent progresses in the area of catalytic reductive alcohol etherifications using carbonyl-based compounds and CO2 have been described with a special focus on organic synthetic applications and catalyst design. Complementarily, recent progress made in catalytic acetal/ketal-to-ether or ester-to-ether reductions and other related transformations have been also summarized.

Synthesis and Electrochemistry of Novel Dumbbell-Shaped Bis-pyrazolino[60]fullerene Derivatives Formed Using Microwave Radiation

The design of covalently linked [60]fullerene dimers has gained increased attention, as the linked electron donors or acceptors are in close proximity to the surface of the C60, providing a valuable approach to novel molecular electronic devices. Herein, new compounds involving C60 dumbbells covalently connected by the π-conjugated system from azobenzene and diaryl ether linkers were synthesized following the bifunctional cycloaddition reactions to C60 using microwave radiation. The structural identity of the fullerene dimers has been determined using spectroscopic techniques including Fourier transform infrared (FT-IR), matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF), and NMR spectroscopy, and the photophysical and the electrochemical properties for the new dumbbells have been examined using UV-vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and square wave voltammetry. Both new dimers show electronic interaction with the fullerene cage and higher electron affinity than the pristine C60.

Electro-oxidative C(sp2)–H/O–H cross-dehydrogenative coupling of phenols and tertiary anilines for diaryl ether formation

The selective electrochemical oxidation of tertiary anilines in the presence of phenolic reactants leads to diaryl ether products.

Diaryl Ether: A Privileged Scaffold for Drug and Agrochemical Discovery

Diaryl ether (DE) is a functional scaffold existing widely both in natural products (NPs) and synthetic organic compounds. Statistically, DE is the second most popular and enduring scaffold within the numerous medicinal chemistry and agrochemical reports. Given its unique physicochemical properties and potential biological activities, DE nucleus is recognized as a fundamental element of medicinal and agrochemical agents aimed at different biological targets. Its drug-like derivatives have been extensively synthesized with interesting biological features including anticancer, anti-inflammatory, antiviral, antibacterial, antimalarial, herbicidal, fungicidal, insecticidal, and so on. In this review, we highlight the medicinal and agrochemical versatility of the DE motif according to the published information in the past decade and comprehensively give a summary of the target recognition, structure-activity relationship (SAR), and mechanism of action of its analogues. It is expected that this profile may provide valuable guidance for the discovery of new active ingredients both in drug and pesticide research.

Nickel-catalyzed dual C(sp2)–H activation of arenes: a new route to diaryl ethers

Diaryl ethers are synthesized directly from simple arenes for the first time through dual C(sp²)–H activation with the aid of a bidentate auxiliary by nickel catalysis. The auxiliary can be removed smoothly under mild reaction conditions.

Curdepsidones B⁻G, Six Depsidones with Anti-Inflammatory Activities from the Marine-Derived Fungus Curvularia sp. IFB-Z10

Six new depsidones, curdepsidones B-G (1-6), were obtained from the marine-derived fungus Curvularia sp. IFB-Z10. Their planar structures were determined by comprehensive analysis of HRESIMS and 1D/2D-NMR data. The absolute configuration of curdepsidones B-C (1-2) were established by synergistic use of DFT/NMR (density functional theory/nuclear magnetic resonance) and TDDFT/ECD (time-dependent density functional theory/electronic circular dichroism) calculations. Partial isolated compounds were tested for their anti-inflammatory activities in Propionibacterium acnes-induced THP-1 cells. Curdepsidone C (2) displayed significant anti-inflammatory properties with an IC50 value of 7.47 ± 0.35 μM, and reduced the P. acnes-induced phosphorylation levels of JNK and ERK in a dose-dependent mechanism. The possible anti-inflammatory mechanism of 2 was also investigated by molecular docking.

Chemoselective oxidation of aryl organoboron systems enabled by boronic acid-selective phase transfer

We report the direct chemoselective Brown-type oxidation of aryl organoboron systems containing two oxidizable boron groups. Basic biphasic reaction conditions enable selective formation and phase transfer of a boronic acid trihydroxyboronate in the presence of boronic acid pinacol (BPin) esters, while avoiding speciation equilibria. Spectroscopic investigations validate a base-promoted phase-selective discrimination of organoboron species. This phenomenon is general across a broad range of organoboron compounds and can also be used to invert conventional protecting group strategies, enabling chemoselective oxidation of BMIDA species over normally more reactive BPin substrates. We also demonstrate the selective oxidation of diboronic acid systems with chemoselectivity predictable a priori. The utility of this method is exemplified through the development of a chemoselective oxidative nucleophile coupling.

Visible-Light-Mediated Synthesis of Diaryl Ethers from Arylboronic Acids and Diaryliodonium Salts

With visible-light irradiation, a simple and metal-free photocatalytic system for the synthesis of diaryl ethers from arylboronic acids and diaryliodonium salts has been developed. The reaction proceeded in high yield for a range of different substrates in the presence of eosin Y under mild reaction conditions.

New depsidones and isoindolinones from the mangrove endophytic fungus Meyerozyma guilliermondii (HZ-Y2) isolated from the South China Sea

Three new depsidones, botryorhodines E-G (1-3), and two new isoindolinones, meyeroguillines A and B (7 and 9), along with five known compounds were isolated from an endophytic fungus Meyerozyma guilliermondii, derived from the mangrove plant Kandelia obovata. Their structures were elucidated by 1D and 2D NMR spectroscopy and high resolution mass spectrometry (HREIMS). Compounds 1-6 exhibited strong α-glucosidase inhibitory activity with IC50 values ranging from 2.1 to 13.3 μM. Moreover, kinetic studies of compounds 2 and 6 showed that both of them were noncompetitive inhibitors of α-glucosidase.