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The recent coronavirus disease 2019 (COVID-19) pandemic is a global threat for healthcare management and the economic system, and effective treatments against the pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus responsible for this disease have not yet progressed beyond the developmental phases. As drug refinement and vaccine progression require enormously broad investments of time, alternative strategies are urgently needed. In this study, we examined phytochemicals extracted from Avicennia officinalis and evaluated their potential effects against the main protease of SARS-CoV-2. The antioxidant activities of A. officinalis leaf and fruit extracts at 150 µg/mL were 95.97% and 92.48%, respectively. Furthermore, both extracts displayed low cytotoxicity levels against Artemia salina. The gas chromatography–mass spectroscopy analysis confirmed the identifies of 75 phytochemicals from both extracts, and four potent compounds, triacontane, hexacosane, methyl linoleate, and methyl palminoleate, had binding free energy values of −6.75, −6.7, −6.3, and −6.3 Kcal/mol, respectively, in complexes with the SARS-CoV-2 main protease. The active residues Cys145, Met165, Glu166, Gln189, and Arg188 in the main protease formed non-bonded interactions with the screened compounds. The root-mean-square difference (RMSD), root-mean-square fluctuations (RMSF), radius of gyration (Rg), solvent-accessible surface area (SASA), and hydrogen bond data from a molecular dynamics simulation study confirmed the docked complexes′ binding rigidity in the atomistic simulated environment. However, this study′s findings require in vitro and in vivo validation to ensure the possible inhibitory effects and pharmacological efficacy of the identified compounds.

NAC (NAM, ATAF1/2, CUC2) transcription factors (TFs) constitute a plant-specific gene family. It is reported that NAC TFs play important roles in plant growth and developmental processes and in response to biotic/abiotic stresses. Nevertheless, little information is known about the functional and evolutionary characteristics of NAC TFs in mangrove plants, a group of species adapting coastal intertidal habitats. Thus, we conducted a comprehensive investigation for NAC TFs in Avicennia marina, one pioneer species of mangrove plants. We totally identified 142 NAC TFs from the genome of A. marina. Combined with NAC proteins having been functionally characterized in other organisms, we built a phylogenetic tree to infer the function of NAC TFs in A. marina. Gene structure and motif sequence analyses suggest the sequence conservation and transcription regulatory regions-mediated functional diversity. Whole-genome duplication serves as the driver force to the evolution of NAC gene family. Moreover, two pairs of NAC genes were identified as positively selected genes of which AmNAC010/040 may be imposed on less constraint toward neofunctionalization. Quite a few stress/hormone-related responsive elements were found in promoter regions indicating potential response to various external factors. Transcriptome data revealed some NAC TFs were involved in pneumatophore and leaf salt gland development and response to salt, flooding and Cd stresses. Gene co-expression analysis found a few NAC TFs participates in the special biological processes concerned with adaptation to intertidal environment. In summary, this study provides detailed functional and evolutionary information about NAC gene family in mangrove plant A. marina and new perspective for adaptation to intertidal habitats.Key messageThis study provides comprehensive functional and evolutionary information for NAC transcription factor in the genome of mangrove plants Avicennia marina and new perspectives from the regulatory mechanisms for adaptation to intertidal habitats.

Avicennia marina, commonly known as the grey mangrove, is a salt-tolerant species widely distributed in coastal and estuarine ecosystems. Traditionally, it has been used in folk medicine to treat skin diseases, rheumatism, and ulcers due to its anti-inflammatory and antimicrobial properties. However, comprehensive studies on the chemical constituents and their pharmacological effects remain limited. The dried powder of the aerial parts of A. marina (3.6 kg) was successfully extracted three times with methanol (20 L × 3, each for 2 h) using a multifunctional ultrasonic cleaner operated at 25 °C with a 50% amplitude setting. In this study, the methanolic extract of the aerial parts of A. marina led to the isolation of eight compounds, including two previously unreported iridoid glycosides—avicenosides A and B (1 and 2)—and six known compounds: techtochrysin (3), 7,4′-di-O-methyl-apigenin (4), luteolin (5), kaempferol (6), trans-caffeic acid (7), and 3,4-dihydroxybenzoic acid (8). Their chemical structures were elucidated using nuclear magnetic resonance (NMR) spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and compared with previously published data. Moreover, the absolute configuration of the sugar moieties in the new compounds was also identified. All isolated compounds were evaluated for their cytotoxicity against HepG2 and A549 cancer cell lines. The results indicate potential cytotoxicity of the secondary metabolites from A. marina and provide evidence of their promising role as lead compounds for the development of novel anticancer agents.

The expansion of black mangrove Avicennia germinans into historically smooth cordgrass Spartina alterniflora-dominated marshes with warming temperatures heralds the migration of the marsh-mangrove ecotone northward in the northern Gulf of Mexico. With this shift, A. germinans is expected to outcompete S. alterniflora where it is able to establish, offering another prevalent food source to first order consumers. In this study, we find A. germinans leaves to be preferable to chewing herbivores, but simultaneously, chewing herbivores cause more damage to S. alterniflora leaves. Despite higher nitrogen content, A. germinans leaves decomposed slower than S. alterniflora leaves, perhaps due to other leaf constituents or a different microbial community. Other studies have found the opposite in decomposition rates of the two species' leaf tissue. This study provides insights into basic trophic process, herbivory and decomposition, at the initial stages of black mangrove colonization into S. alterniflora salt marsh.

Colorectal cancer (CRC) remains a significant global health challenge, with the current therapies often being inadequate. This study investigates the potential of Avicennia alba ( A. alba ), a mangrove plant, as a source of new anticancer drug candidates. We employed a network pharmacology, bioinformatics approach, and in vitro experimental to explore the molecular mechanisms of action and validating activity of A. alba in CRC treatment. Cytotoxicity effect was also evaluated using MTT assay. Four constituents of A. alba —Avicenol B, Avicenol C, Avicequinone B, and Avicequinone C—were verified, leading to the identification of 10 hub genes (i.e., EGFR , PIK3CA , JAK2 , MTOR , JUN , ERBB2 , IGF2 , SRC , MDM2 , and PARP1 ) associated with CRC. Molecular docking and molecular dynamics simulations indicated that Avicequinone C exhibited the best docking scores and stable interactions with the top three hub genes ( EGFR , PIK3CA , and JAK2 ). The interactions were characterized by π-sigma, alkyl, and conventional hydrogen bonds. A. alba exhibited cytotoxic activity against WiDr cell lines with an IC 50 of 205.96 ± 24.05 μg/mL after treatment for 48 h. Our findings highlight potential therapeutic targets for A. alba in CRC treatment and demonstrate that integrating network pharmacology, bioinformatics, and molecular docking with in vitro experimental validation is an effective strategy for discovering new therapeutic targets in drug development.

Overlying water, sediment, rhizosphere sediment and mangrove seedlings in the Futian mangrove forest were analyzed for heavy metals. The results showed that mangrove plant acidified sediment and increased organic matter contents. Except for chromium (Cr), nickel (Ni) and copper (Cu) in Aegiceras corniculatum sediment, heavy metals in all sediments were higher than in overlying water, rhizosphere sediment and mangrove root. Heavy metals in Avicennia marina sediments were higher than other sediments. The lower heavy metal biological concentration factors (BCFs) and translocation factors (TFs) indicated that mangrove plant adopted exclusion strategy. The geo-accumulation index, potential ecological risk index and risk assessment code (RAC) demonstrated that heavy metals have posed a considerable ecological risk, especially for cadmium (Cd). Heavy metals (Cr, Ni, Cu and Cd) mainly existed in the reducible fractions. These findings provide actual heavy metal accumulations in sediment-plant ecosystems in mangrove forest, being important in designing the long-term management and conservation policies for managers of mangrove forest.

Plant salt glands are nature's desalination devices that harbour potentially useful information pertaining to salt and water transport during secretion. As part of the program toward deciphering secretion mechanisms in salt glands, we used shotgun proteomics to compare the protein profiles of salt gland-enriched (isolated epidermal peels) and salt gland-deprived (mesophyll) tissues of the mangrove species Avicennia officinalis. The purpose of the work is to identify proteins that are present in the salt gland-enriched tissues. An average of 2189 and 977 proteins were identified from the epidermal peel and mesophyll tissues, respectively. Among these, 2188 proteins were identified in salt gland-enriched tissues and a total of 1032 selected proteins were categorized by Gene Ontology (GO) analysis. This paper reports for the first time the proteomic analysis of salt gland-enriched tissues of a mangrove tree species. Candidate proteins that may play a role in the desalination process of the mangrove salt glands and their potential localization were identified. Information obtained from this study paves the way for future proteomic research aiming at elucidating the molecular mechanism underlying secretion in plant salt glands. The data have been deposited to the ProteomeXchange with identifier PXD000771.

The mangrove ecosystems are known to efficiently sequester trace metals both in sediments and plant biomass. However, less is known about the chemistry of rare earth elements (REE) in the coastal environments, especially in the world’s largest mangrove province, the Sundarban. Here, the concentration of REE in the sediment and plant organs of eight dominant mangrove species (mainly Avicennia sp.) in the Indian Sundarban was measured to assess REE sources, distribution, and bioaccumulation state. Results revealed that light REE (LREE) were more concentrated than the heavy REE (HREE) (128–144 mg kg −1 and 12–15 mg kg −1 , respectively) in the mangrove sediments, with a relatively weak positive europium anomaly (Eu/Eu* = 1.03–1.14) with respect to North American shale composite. The primary source of REE was most likely linked to aluminosilicate weathering of crustal materials, and the resultant increase in LREE in the detritus. Vertical distribution of REE in one of the long cores from Lothian Island was altered by mangrove root activity and dependent on various physicochemical properties in the sediment (e.g., Eh, pH, organic carbon, and phosphate). REE uptake by plants was higher in the below-ground parts than in the above-ground plant tissues (root = 3.3 mg kg −1 , leaf + wood = 1.7 mg kg −1 ); however, their total concentration was much lower than in the sediment (149.5 mg kg −1 ). Species-specific variability in bioaccumulation factor and translocation factor was observed indicating different REE partitioning and varying degree of mangrove uptake efficiency. Total REE stock in plant (above + live below ground) was estimated to be 168 g ha −1 with LREE contributing ~ 90% of the stock. This study highlighted the efficiency of using REE as a biological proxy in determining the degree of bioaccumulation within the mangrove environment.

China’s rapid economic growth has been accompanied by increasing environmental pollution. Mangrove ecosystems are now facing greater pollution pressures due to elevated chemical discharges from various land-based sources. Data on the levels of heavy metals and organic pollutants in mangrove compartments (sediments, plants, zoobenthos, and fish) in China over the past 20 years have been summarized to evaluate the current pollution status of the mangrove ecosystem. Overall, the Pearl River and Jiulong River estuaries were severely polluted spots. Concentrations of Cu, Zn, Cd, and Pb in mangrove sediments of Guangdong, Fujian, and Hong Kong were higher than those from Guangxi and Hainan. The pollution status was closely linked to industrialization and urbanization. The highest concentrations of polycyclic aromatic hydrocarbons (PAHs) were found in mangrove sediments from Hong Kong, followed by Fujian and Guangdong. Mangrove plants tend to have low-enriched ability for heavy metals and organic pollutants. Much higher levels of Pb, Cd, and Hg were observed in mollusks.

Purpose: Medical halophytes plants are potent sources of bioactive secondary metabolite components used against different diseases. Avicenniamarina one of the typical halophytes plant species used in folk medicine to treat smallpox, rheumatism, and ulcer. Despite the richness of A.marina with polyphenolic, flavonoids, terpenoid, and terpene, contents remain poorly investigated against cancer types. Consequently, to explore the function-composition relationship of A.marina hexane leaves crude extract, the current study designed to investigate the cytotoxicity, apoptotic and antiproliferative impacts on the colon (HCT-116), liver (HepG2), and breast (MCF-7) cancer cell lines. Materials and Methods: Therefore, the cytotoxicity impact screening carried out by Sulforhodamine-B assay. While, the initiation of the apoptosis evaluated by chromatin condensing, early apoptosis, late apoptosis and the formation and appearance of apoptotic bodies. On the other hand, the flow cytometry used to identify the phase of inhibition where the determined IC50 value used. While, the chemical composition of the hexane extract was detected using liquid chromatography-mass spectrometry/mass spectrometry. Results: Revealed that hexane extract showed a weak induction of apoptosis despite the formation of apoptotic bodies and the high cell inhibitory effect on all tested cell lines with IC50 values (23.7 ± 0.7, 44.9 ± 0.93, 79.55 ± 0.57) μg/ml on HCT-116, HepG2, and MCF-7, respectively. Furthermore, it showed the ability to inhibit cell cycle in G0/G1 for HCT-116, S phase for HepG2, and MCF-7. Conclusion: In the light of these results, the current study suggests that A.marina leaves hexane extract may be considered as a candidate for further anticancer drug development investigations.