Discovery of Anti-Hypercholesterolemia Agents Targeting LXRα from Marine Microorganism-Derived Natural Products.

A strategy integrating in silico molecular docking with LXRα and phenotypic assays was adopted to discover anti-hypercholesterolemia agents in a small library containing 205 marine microorganism-derived natural products, collected by our group in recent years. Two fumitremorgin derivatives, 12R,13S-dihydroxyfumitremorgin C (1) and tryprostatin A (3), were identified as potential LXRα agonists, by real-time qPCR and Western blot (WB) analysis, together with a surface plasmon resonance (SPR) assay. The anti-hypercholesterolemic effects of 1 and 3, together with their mechanisms, were investigated in depth using different cell and mouse models, among which the study of LXRα is of crucial importance. Compound 1 or 3 exhibited the capacity to effectively reverse excessive lipid accumulation in a hepatic steatosis cell model and significantly reduce liver damage and blood cholesterol levels in high cholesterol diet (HCD)-fed wild-type mice, whereas those beneficial effects were completely nullified in HCD-fed LXRα-knockout mice. Furthermore, 1 and 3 outperformed common LXRα agonists by suppressing the expression of sterol regulatory element-binding protein 1 (SREBP1) in HCD-fed mice, mitigating lipotoxicity. Thus, this study highlights the discovery of two marine microorganism-derived anti-hypercholesterolemia agents targeting LXRα.

Avellanin A Has an Antiproliferative Effect on TP-Induced RWPE-1 Cells via the PI3K-Akt Signalling Pathway.

Cyclic pentapeptide compounds have garnered much attention as a drug discovery resource. This study focused on the characterization and anti-benign prostatic hyperplasia (BPH) properties of avellanin A from Aspergillus fumigatus fungus in marine sediment samples collected in the Beibu Gulf of Guangxi Province in China. The antiproliferative effect and molecular mechanism of avellanin A were explored in testosterone propionate (TP)-induced RWPE-1 cells. The transcriptome results showed that avellanin A significantly blocked the ECM-receptor interaction and suppressed the downstream PI3K-Akt signalling pathway. Molecular docking revealed that avellanin A has a good affinity for the cathepsin L protein, which is involved in the terminal degradation of extracellular matrix components. Subsequently, qRT-PCR analysis revealed that the expression of the genes COL1A1, COL1A2, COL5A2, COL6A3, MMP2, MMP9, ITGA2, and ITGB3 was significantly downregulated after avellanin A intervention. The Western blot results also confirmed that it not only reduced ITGB3 and FAK/p-FAK protein expression but also inhibited PI3K/p-PI3K and Akt/p-Akt protein expression in the PI3K-Akt signalling pathway. Furthermore, avellanin A downregulated Cyclin D1 protein expression and upregulated Bax, p21WAF1/Cip1, and p53 proapoptotic protein expression in TP-induced RWPE-1 cells, leading to cell cycle arrest and inhibition of cell proliferation. The results of this study support the use of avellanin A as a potential new drug for the treatment of BPH.

New Polyene Macrolide Compounds from Mangrove-Derived Strain Streptomyces hiroshimensis GXIMD 06359: Isolation, Antifungal Activity, and Mechanism against Talaromyces marneffei.

Mangrove-derived actinomycetes represent a rich source of novel bioactive natural products in drug discovery. In this study, four new polyene macrolide antibiotics antifungalmycin B-E (1-4), along with seven known analogs (5-11), were isolated from the fermentation broth of the mangrove strain Streptomyces hiroshimensis GXIMD 06359. All compounds from this strain were purified using semi-preparative HPLC and Sephadex LH-20 gel filtration while following an antifungal activity-guided fractionation. Their structures were elucidated through spectroscopic techniques including UV, HR-ESI-MS, and NMR. These compounds exhibited broad-spectrum antifungal activity against Talaromyces marneffei with minimum inhibitory concentration (MIC) values being in the range of 2-128 µg/mL except compound 2. This is the first report of polyene derivatives produced by S. hiroshimensis as bioactive compounds against T. marneffei. In vitro studies showed that compound 1 exerted a significantly stronger antifungal activity against T. marneffei than other new compounds, and the antifungal mechanism of compound 1 may be related to the disrupted cell membrane, which causes mitochondrial dysfunction, resulting in leakage of intracellular biological components, and subsequently, cell death. Taken together, this study provides a basis for compound 1 preventing and controlling talaromycosis.

New Cyclic Pentapeptides from the Mangrove-Derived Aspergillus fumigatus GXIMD 03099.

Four new cyclic pentapeptides, avellanins D-G (1-4), together with four known compounds (5-8), were isolated from a mangrove-derived Aspergillus fumigatus GXIMD 03099 fungus from Acanthus ilicifolius L. Their structures were elucidated by analysis of HRESIMS, NMR, and ESI-MS/MS data. Their absolute configurations were determined by X-ray diffraction analysis and Marfey's method. Compounds 1-8 were screened for insecticidal and antibacterial activities. Compound 2 showed insecticidal activity against newly hatched larvae of Culex quinquefasciatus with an LC50 value of 86.6 µM; compound 4 had weak activity against Vibrio harveyi with an MIC value of 5.85 µM.

New Alkaloids and Steroids from Hydranth of Goniopora columna Corals and Their Inhibiting Lung Cancer Cell Activities.

A new alkaloids, aplysingoniopora A (1), and new configuration pregnane type steroid compound, 9,17-α-pregn-1,4,20-en-3-one (2), and two known pregnane type steroid compounds (3 and 4) were isolated from hydranth of Goniopora columna corals. The compounds structures and absolute configurations were determined by extensive spectroscopic analysis, MS data, single-crystal X-ray diffraction analysis and quantum chemical calculation. The anticancer effect of the compounds were explored in human non-small-cell lung cancer (NSCLC) A549 cell lines. As the results, the compound 3 and 4 induces toxicity and has proliferation inhibitory effects on A549 cells (IC50=58.99 µM and 58.77 µM, respectively) in vitro.

Proteomic Identification of Plasma Components in Tachypleus tridentatus and Their Effects on the Longitudinal Bone Growth Rate in Rats.

Tachypleus tridentatus (T. tridentatus) is a marine animal and traditional Chinese medicine. T. tridentatus plasma is a valuable resource for important medical and health-based functions. In this experiment, in order to evaluate the effect and mechanism of T. tridentatus plasma with respect to the promotion of bone tissue growth in rats, the processes of ultrafiltration and mass spectrometry were first used to separate and identify the components of T. tridentatus plasma. Then, a comparison of the effects of the T. tridentatus plasma samples, which each possessed different molecular weights, regarding the growth of the long bones of rats was conducted. Finally, transcriptomics, proteomics, and bioinformatics were all used to analyze the biological functions and related signaling pathways of the T. tridentatus plasma in order to promote rat bone growth. The results showed that the contents of amino acid residues in peptides are related to the growth promotion that was contained in the 10-30 kDa plasma group. Moreover, the T. tridentatus plasma samples were found to be higher in this respect than those in the whole plasma group. In addition, the 10-30 kDa plasma group could significantly promote bone growth activity in rats. The proteomic analysis showed that the proteins that were differentially expressed in the 10-30 kDa plasma group were mainly enriched in the PI3K-AKT signal pathway. Our study suggested that the T. tridentatus plasma possesses promising potential for the purposes of clinical use, whereby it can serve the role of a growth-promoting agent.

Stappia sediminis sp. nov., isolated from rhizosphere soil of coastal herb Zoysia matrella within the Beibu Gulf.

A bacterial isolate (BGMRC 2046T) was isolated from the rhizosphere soil of Zoysia matrella collected from the Beibu Gulf of China. The results of a polyphasic taxonomic study revealed that this strain belongs to a member of the genus Stappia with the characteristics of Gram-stain-negative, catalase- and oxidase-positive, motile, short rod-shaped. The strain grew at 20-37 °C (optimal, 28 °C), pH 6.0-9.0 (optimal, pH 7.0), and 1-7% (w/v) optimal, NaCl (1-3%). A phylogenetic evaluation based on 16S rRNA gene sequence analysis revealed that this strain fall into the family Stappiaceae, being most closely related to Stappia indica CGMCC 1A01226T (95.8% sequence similarity), Stappia stellulata DSM 5886T (95.1%), and Stappia taiwanensis DSM 23284T (94.4%). The major cellular fatty acid, respiratory quinone and polar lipids were all detected from new species (BGMRC 2046T), that shows the chemical characteristics of BGMRC 2046T. The major polar lipids were two unidentified ninhydrin positive phospholipids, four unidentified phospholipids, and one unidentified lipid. Genome sequencing revealed a genome size of 4.78 Mbp and a G + C content of 60.8%. Pairwise comparison of the genomes of the new strain BGMRC 2046T and the three most closely related strains resulted in gANI values was lower than 75% and a digital DNA-DNA hybridization values was lower than 24%. The strain possessed genes encoding choline uptake and conversion to betaine gene clusters. The results of the polyphasic taxonomic study showed that strain BGMRC 2046T represents a new species of the genus Stappia. The name Stappia sediminis sp. nov. is proposed for the species with the type strain BGMRC 2046T (= KCTC52115T = CGMCC1.17425T).

Characterization of the Aminosugar Biosynthetic and Regulatory Genes of Vicenistatin in Monodonata labio-Associated Streptomyces parvus SCSIO Mla-L010.

Vicenistatin (1) is a potent polyketide antitumor antibiotic composed of a 20-membered macrolactam core appended to a unique aminosugar, vicenisamine. In this study, vicenistatin was isolated and its biosynthetic gene cluster identified from Monodonata labio-associated Streptomyces parvus SCSIO Mla-L010. A set of five genes, vicC, vicD, vicE, vicF, and vicG, was confirmed to be involved in the biosynthesis of the aminosugar by gene inactivations. VicG was characterized as an N-methyltransferase that catalyzes the methylation of the 4'-amino group in the last step of the aminosugar biosynthetic pathway; the N-demethyl intermediate 4'-N-demethylvicenistatin (2) was isolated from the ΔvicG mutant strain. In addition, vicR1 was characterized as a positive pathway-specific regulatory gene. Notably, N-demethyl compound 2 was found to exert impressive antibacterial activities, with MIC values spanning 0.06-4 µg/mL, against a panel of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, Gram-negative Helicobacter pylori, and mycobacterium Mycobacterium smegmatis and the fungal pathogen Candida albicans. Compound 2 was also found to display reduced cytotoxicities relative to vicenistatin, especially against noncancerous human cell lines.

Sonneradon A Extends Lifespan of Caenorhabditis elegans by Modulating Mitochondrial and IIS Signaling Pathways.

Aging is related to the lowered overall functioning and increased risk for various age-related diseases in humans. Sonneradon A (SDA), a new compound first extracted from the edible fruits of mangrove Sonneratia apetala, showed remarkable antiaging activity. However, the role of SDA in antiaging remains unclear. In this article, we studied the function of SDA in antiaging by using the animal model Caenorhabditis elegans. Results showed that SDA inhibited production of reactive oxygen species (ROS) by 53%, and reduced the accumulation of aging markers such as lipids and lipofuscins. Moreover, SDA also enhanced the innate immune response to Pseudomonas aeruginosa infection. Genetic analysis of a series of mutants showed that SDA extended the lifespan of the mutants of eat-2 and glp-1. Together, this effect may be related to the enhanced resistance to oxidative stress via mitochondrial and insulin/insulin-like growth factor-1 signaling (IIS) pathways. The results of this study provided new evidence for an antiaging effect of SDA in C. elegans, as well as insights into the implication of antiaging activity of SDA in higher organisms.

Martelella alba sp. nov., isolated from mangrove rhizosphere soil within the Beibu Gulf.

Strain BGMRC 2036T was isolated from rhizosphere soil of Bruguiear gymnorrhiza collected from the Beibu Gulf of China. Optimum growth occurred at 28 °C, pH 7.0, and under the conditions of 3-5% (w/v) NaCl. The phylogenetic comparisons of 16S rRNA gene sequences displayed that strain BGMRC 2036T was closely related to Martelella limonii NBRC109441T (96.6% sequence similarity), M. mediterranea CGMCC 1.12224T (96.5%), M. lutilitoris GH2-6T (96.5%), M. radicis BM5-7T (96.2%), and M. mangrove BM9-1T (95.9%), M. suaedae NBRC109440T (95.8%). The phylogenomic tree based on the up-to-date bacterial core gene set indicated that the strain BGMRC 2036T form a clade formed with members of the genera Martelella. The major polar lipids include phosphatidylmethylethanolamine, phosphatidylglycerol, phosphatidylcholine, phosphotidylinositol, two unidentified phospholipids, and three unidentified ninhydrin positive phospholipids. The major respiratory quinone is Q-10, which is similar to those of genera Martelella. The main cellular fatty acids are C18:1 ω7c, C16:0, and C12:0 aldehyde. Genome sequencing revealed a genome size of 4.99 Mbp and a G + C content of 62.3 mol%. Pairwise comparison of the genomes of the new strain BGMRC 2036T and the three reference strains M. endophytica YC 6887T, M. mediterranea CGMCC 1.12224T, and M. mangrovi USBA-857 indicated that gANI value was lower than 81% and a digital DNA-DNA hybridization value was lower than 27%. The strain BGMRC 2036T possessed genes putatively encoding riboflavin synthesis and flavodoxin A polyphasic taxonomic study suggested that strain BGMRC 2036T represented a novel species belonging to the genus Martelella, and it was named Martelella alba sp. nov. The type strain is BGMRC 2036T (=KCTC 52121T =NBRC 111908T).

Bruguierivorax albus gen. nov. sp. nov. Isolated from Mangrove Sediment and Proposal of Bruguierivoracaceae fam. nov.

A novel Gram-negative, motile, aerobic rod-shaped bacterium designated BGMRC 2031T was isolated from mangrove sediment collected from Guangxi Province, China. Optimal growth occurred at 28 °C and pH 7.0-8.0 in the presence of 1% (w/v) NaCl. Alignment based on 16S rRNA gene sequences indicated that strain BGMRC 2031T is most closely related to Sodalis praecaptivus HS1T (95.6%, sequence similarity), followed by Biostraticola tofi DSM 19580T (95.5%), Sodalis glossinidius DSM 16929T (95.4%), and Brenneria goodwinii FRB141T (94.9%) sequence similarity. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain BGMRC 2031T formed a distinct branch in a robust cluster and revealed that strain BGMRC 2031T, genera Biostraticola and Sodalis, formed a novel family-level clade in the order Enterobacterales. The novel strain showed an average nucleotide similarity of 74.7%, 74.2%, and 73.1% for S. praecaptivus HS1T, S. glossinidius DSM 16929T, and B. tofi DSM 19580T, respectively. The genomes of the BGMRC 2031T shared the presence of a riboflavin synthesis gene cluster. The menaquinones of strain BGMRC 2031T were MK-8 and Q-8, which were similar to those of genus Biostraticola. The major fatty acids (> 10%) were C16:0 (19.9%), summed feature 2 (iso-C16:1 and/or C14:0 3-OH, 18.10%), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c, 15.3%), C12:0 (13.9%), C17:0 cyclo (11.4%), and C14:0 (10.4%). The main polar lipids were phosphatidyl methylethanolamine, phosphatidyl glycerol, diphosphatidyl glycerol, phosphatidyl inositol, one unidentified phospholipid, and one unknown polar lipid. The G+C content of strain BGMRC 2031T was 55.4%. Strain BGMRC 2031T could extend the mean lifespan and maximum lifespan of Caenorhabditis elegans by 4.5% and 12.5%, respectively. Overall, the results of this study indicate that BGMRC 2031T is a novel species in a new genus, for which the name Bruguierivorax albus gen. nov. sp. nov. is proposed, and the type of strain is designated as BGMRC 2031T (= NBRC 111907T = KCTC 52119T). In addition, a novel family, Bruguierivoracaceae fam. nov., is proposed to accommodate the genera Bruguierivorax, Biostraticola, and Sodalis.

Pararhizobium mangrovi sp. nov., Isolated From Aegiceras corniculatum Stem.

A novel Gram-stain-negative, catalase- and oxidase-positive, motile, short rod-shaped bacterium designated BGMRC 6574T was isolated from stems of Aegiceras corniculatum collected from Hainan province, China. The strain grew at 25-37 °C (optimal at 28 °C), pH 5.0-10.0 (pH 7.0), and 3-8% (w/v) NaCl (3%). Based on the 16S rRNA phylogenetic analysis, the strain was closely related to Pararhizobium haloflavum MCCC 1K03228T (96.45% sequence similarity). The novel strain showed an average nucleotide identity value and a digital DNA-DNA hybridization of 72.62 and 27.1%, respectively, to P. haloflavum MCCC 1K03228T based on draft genome sequences. The G+C content of the genomic DNA was 64.7 mol%. The major respiratory quinone was Q-10. The strain possessed genes putatively encoding choline uptake and conversion to betaine gene clusters. The extract significantly delayed the lifespan of Caenorhabditis elegans compared to the control (P < 0.05). The major polar lipids were phosphatidylcholine, seven unidentified phospholipids, three unidentified ninhydrin-positive phospholipids, and two unidentified lipids. The major cellular fatty acid was C19:0 cyclo ω8c. The results of a polyphasic taxonomic study showed that strain BGMRC 6574T represents a new species of the genus Pararhizobium, and it was named Pararhizobium mangrovi sp. nov. The type strain is BGMRC 6574T (=KCTC 72636T = CGMCC 1.16783).

Compounds from the fruits of mangrove Sonneratia apetala: Isolation, molecular docking and antiaging effects using a Caenorhabditis elegans model.

The chemical investigation of the fruits of a mangrove Sonneratia apetala collected from the Beibu Gulf led to the isolation of four new compounds, sonneradons A-D (1-4), as well as 18 known compounds (5-22). The structures of the new compounds were elucidated based on extensive spectroscopic analysis, and the structures of the known compounds were established by comparison of their spectroscopic data with those of related metabolites. The antiaging activities of all isolates were evaluated using the nematode Caenorhabditis elegans as a model organism. The results showed that 10 compounds could protect C. elegans by extending its lifespan. Compound 1 possessed the most potent effect in the anti-heat stress assay and significantly attenuated aging-related decreases in the pumping and bending of the nematodes in the healthspan assay. Molecular docking studies suggested that compound 1 was bound to the DNA binding domain of HSF-1 and promoted the conformation of HSF-1, thus strengthening the interaction between the HSF-1 and related DNA. GLN49, ASN-74, and LYS-80 of the binding region might be the key amino residues during the interaction.

Marinoid J, a phenylglycoside from Avicennia marina fruit, ameliorates cognitive impairment in rat vascular dementia: a quantitative iTRAQ proteomic study.

CONTEXT: Fruit of Avicennia marina (Forsk.) Vierh. (Acanthaceae) is used as a Chinese herb. Studies have found that it contains marinoid J, a novel phenylethanoid glycoside (PG) compound, but its neuroprotective functions are largely unknown. OBJECTIVE: This study evaluated the effects of marinoid J on vascular dementia (VD) and determined its potential mechanisms of action. MATERIALS AND METHODS: The VD model was established by the ligation of the bilateral common carotid artery in Sprague-Dawley rats, who received daily intragastrically administration of saline, marinoid J (125 or 500 mg/kg body weight/d), or oxiracetam (250 mg/kg body weight/d) for 14 days (20 rats in each group). The Morris water maze (MWM) was used to evaluate cognitive performance. The hippocampus was subjected to histological and proteomic analyses. RESULTS: Marinoid J shortened the escape latency of VD rats (31.07 ± 3.74 s, p < 0.05). It also decreased malondialdehyde (MDA) (27.53%) and nitric oxide (NO) (20.41%) while increasing superoxide dismutase (SOD) (11.26%) and glutathione peroxidase (GSH-Px) (20.38%) content in hippocampus tissues. Proteomic analysis revealed 45 differentially expressed proteins (DEPs) in marinoid J-treated VD rats, which included angiotensin-converting enzyme (ACE), keratin 18 (KRT18), cluster of differentiation 34 (CD34), and synaptotagmin II (SYT2). CONCLUSIONS: Marinoid J played a role in protecting hippocampal neurons by regulating a set of proteins that influence oxidative stress and apoptosis, this effect may thereby alleviate the symptoms of VD rats. Thus, pharmacological manipulation of marinoid J may offer a novel opportunity for VD treatment.

Nocardioides kandeliae sp. nov., an endophytic actinomycete isolated from leaves of Kandelia candel.

A Gram-stain-positive, aerobic, non-spore-forming, atrichous and short rod-shaped endophytic actinomycete, designated strain BGMRC 2075T, was isolated from the leaves of Kandelia candel, and was subjected to polyphasic characterization to unravel its taxonomic position. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain BGMRC 2075T belongs to the genus Nocardioides ,showing the highest 16S rRNA gene sequence similarity to Nocardioides aestuarii JC2056T (96.1 %), Nocardioides agariphilus MSL-28T (95.1 %) andNocardioides islandiensis MSL-26T (95.1 %). The predominant cellular fatty acids of strain BGMRC 2075T were iso-C16 : 0, C17 : 1ω8c and C17 : 0. The major menaquinone was MK-8(H4). The diagnostic diamino acid in the cell-wall peptidoglycan was ll-2,6-diaminopimelic acid. The predominant cell-wall sugars were composed of ribose and glucose. The polar lipid pattern contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylcholine, five unknown phospholipids, one phospholipid of unknown structure containing glucosamine, and an unknown polar lipid. The DNA G+C content was 70.8 mol%. All these data support the allocation of the novel strain to the genus Nocardioides. The results of physiological and biochemical characterization allow the phenotypic differentiation of strain BGMRC 2075T from N. aestuarii JC2056T, N. agariphilus MSL-28T and N. islandiensis MSL-26T. Strain BGMRC 2075T represents a novel species of the genus Nocardioides, for which we propose the name Nocardioides kandeliae sp. nov. The type strain is BGMRC 2075T (=KCTC 39886T=DSM 104480T).

Four New Cyclohexylideneacetonitrile Derivatives from the Hypocotyl of Mangrove (Bruguiera gymnorrhiza).

Four new cyclohexylideneacetonitrile derivatives 1-4, named menisdaurins B-E, as well as three known cyclohexylideneacetonitrile derivatives--menisdaurin (5), coclauril (6), and menisdaurilide (7)--were isolated from the hypocotyl of a mangrove (Bruguiera gymnorrhiza). The structures of the isolates were elucidated on the basis of extensive spectroscopic analysis. Compounds 1-7 showed anti-Hepatitis B virus (HBV) activities, with EC50 values ranging from 5.1 ± 0.2 µg/mL to 87.7 ± 5.8 µg/mL.

[Study on Chemical Constituents from Hypocotyls of Mangrove Bruguiera gymnorrhiza].

OBJECTIVE: To study the chemical constituents from the hypocotyls of mangrove Bruguiera gymnorrhiza. METHODS: The chemical constituents were isolated and purified by recrystallization, silica gel column chromatography and semi-preparative HPLC. Their structures were identified by spectroscopic analysis and comparison with literatures. RESULTS: Seven compounds were isolated and their structures were identified as 3-ß-(Z)-coumaroyllupeol (1), dioslupecin (2), cholesterol (3), menisdaurillide (4), aquilegiolide (5) vomifoliol (6) and roseoside II (7). CONCLUSION: Compounds 1,2 and 4 - 7 are isolated from this plant for the first time.

An update on 2,5-diketopiperazines from marine organisms.

2,5-Diketopiperazines (2,5-DKPs) are an important category of structurally diverse cyclic dipeptides with prominent biological properties. These 2,5-DKPs have been obtained from a variety of natural resources, including marine organisms. Because of the increasing numbers and biological importance of these compounds, this review covers 90 marine originated 2,5-DKPs that were reported from 2009 to the first half-year of 2014. The review will focus on the structure characterizations, biological properties and proposed biosynthetic processes of these compounds.

New antioxidative secondary metabolites from the fruits of a Beibu Gulf mangrove, Avicennia marina.

Further chemical investigation of the fruits of the mangrove, Avicennia marina, afforded three new phenylethyl glycosides, marinoids J-L (1-3), and a new cinnamoyl glycoside, marinoid M (4). The structures of isolates were elucidated on the basis of extensive spectroscopic analysis and by comparison of the data with those of related secondary metabolites. The antioxidant activity of the isolates was evaluated using the cellular antioxidant assay (CAA), and compounds 1-4 showed antioxidant activities, with EC50 values ranging from 23.0 ± 0.71 µM to 247.8 ± 2.47 µM.

Four new Jacaranone analogs from the fruits of a Beibu Gulf mangrove Avicennia marina.

Four new jacaranone analogs, marinoids F-I (1-4), were isolated from the fruits of a Beibu Gulf mangrove Avicennia marina. The structures were elucidated based on analysis of spectroscopic data. Marinoids F and G are shown to be diastereoisomers of chlorocornoside, a new halogen containing marine secondary metabolite. The antioxidant activity of the isolates was evaluated using a cellular antioxidant assay, and 4 showed good antioxidant activity (EC50 = 26 µM).