Six new diterpenoids with anti-inflammatory and cytotoxic activity from Isodon serra.

Diterpenoids occupy an important slot of the natural products diversity space with wide ranges of bioactivities and complex structures, providing potential applications for the development of therapeutics. In this study, we reported four new abietane-type diterpenoids viroxocin B-E (1-4), a new totarane-type diterpenoid viroxocin F (5), and a new sempervirane-type diterpenoid viroxocin G (6) along with four known compounds (7-10), isolated and identified from a widely used Traditional Chinese Medicine, Isodon serra (I. serra). Their structures were established by spectroscopic data analysis, experimental and calculated electronic circular dichroism (ECD) data, as well as X-ray diffraction analysis. Compounds 2, 5, 7, 8 and 10 exhibited promising anti-inflammatory activities in lipopolysaccharide (LPS)-induced RAW 267.4 cells, and their inhibition rates on NO production were more than 60% at 10 µM. Compound 7 showed cytotoxicity against human renal cell carcinoma 769P at 20 µM, the inhibition rate was 52.66%.

Manzamine A reduces androgen receptor transcription and synthesis by blocking E2F8-DNA interactions and effectively inhibits prostate tumor growth in mice.

The androgen receptor (AR) is the main driver in the development of castration-resistant prostate cancer, where the emergence of AR splice variants leads to treatment-resistant disease. Through detailed molecular studies of the marine alkaloid manzamine A (MA), we identified transcription factor E2F8 as a previously unknown regulator of AR transcription that prevents AR synthesis in prostate cancer cells. MA significantly inhibited the growth of various prostate cancer cell lines and was highly effective in inhibiting xenograft tumor growth in mice without any pathophysiological perturbations in major organs. MA suppressed the full-length AR (AR-FL), its spliced variant AR-V7, and the AR-regulated prostate-specific antigen (PSA; also known as KLK3) and human kallikrein 2 (hK2; also known as KLK2) genes. RNA sequencing (RNA-seq) analysis and protein modeling studies revealed E2F8 interactions with DNA as a potential novel target of MA, suppressing AR transcription and its synthesis. This novel mechanism of blocking AR biogenesis via E2F8 may provide an opportunity to control therapy-resistant prostate cancer over the currently used AR antagonists designed to target different parts of the AR gene.

A Toxic Sterolysin From a 1950s Culture of Gymnodinium Veneficum Ballantine.

In 1957 Abbott and Ballentine described a highly toxic activity from a dinoflagellate isolated from the English Channel. in 1949 by Mary Park. From a culture maintained at Plymouth Laboratory since 1950, we have been able to isolate two toxic molecules (Abbotoxin and 59-E-Chloro-Abbotoxin), determine the planar structures by analysis of HRMS and 1D and 2D NMR spectra and found them to be karlotoxin (KmTx) congeners. Both toxins kill larval zebrafish with symptoms identical to that described by Abbot and Ballantine for gobies (Gobius virescens). Using surface plasma resonance the sterol binding specificity of karlotoxins is shown to require desmethyl sterols. Our results with black lipid membranes indicate that karlotoxin forms large-conductance channels in the lipid membrane, which are characterized by large ionic conductance, poor ionic selectivity, and a complex gating behavior that exhibits strong voltage dependence and multiple gating patterns. In addition, we show that KmTx 2 pore formation is a highly targeted mechanism involving sterol-specificity. This is the first report of the functional properties of the membrane pores formed by karlotoxins and are consistent with the intial observations of Abbott and Ballentine from 1957.

Manzamine-A Alters In Vitro Calvarial Osteoclast Function.

Manzamine-A is a marine-derived alkaloid that has demonstrated antimalarial and antiproliferative properties and is an emerging drug lead compound as a possible intervention in certain cancers. This compound has been found to modulate SIX1 gene expression, a target that is critical for the proliferation and survival of cells via various developmental pathways. As yet, little research has focused on manzamine-A and how its use may affect tissue systems including bone. Here we hypothesized that manzamine-A, through its interaction with SIX1, would alter precursor cells that give rise to the bone cell responsible for remodeling: the osteoclast. We further hypothesized reduced effects in differentiated osteoclasts, as these cells are generally not mitotic. We interrogated the effects of manzamine-A on preosteoclasts and osteoclasts. qrtPCR, MTS cell viability, Caspase 3/7, and TRAP staining were used as a functional assay. Preosteoclasts show responsiveness to manzamine-A treatment exhibited by decreases in cell viability and an increase in apoptosis. Osteoclasts also proved to be affected by manzamine-A but only at higher concentrations where apoptosis was increased and activation was reduced. In summary, our presented results suggest manzamine-A may have significant effects on bone development and health through multiple cell targets, previously shown in the osteoblast cell lineage, the cell responsible for mineralized tissue formation, and here in the osteoclast, the cell responsible for the removal of mineralized tissue and renewal via precipitation of bone remodeling.

Platanosides from Platanus × acerifolia: New molecules, SAR, and target validation of a strong lead for drug-resistant bacterial infections and the associated sepsis.

Three undescribed (1-3) and nine known (4-12) platanosides were isolated and characterized from a bioactive extract of the May leaves of Platanus × acerifolia that initially showed inhibition against Staphylococcus aureus. Targeted compound mining was guided by an LC-MS/MS-based molecular ion networking (MoIN) strategy combined with conventional isolation procedures from a unique geographic location. The novel structures were mainly determined by 2D NMR and computational (NMR/ECD calculations) methods. Compound 1 is a rare acylated kaempferol rhamnoside possessing a truxinate unit. 6 (Z,E-platanoside) and 7 (E,E-platanoside) were confirmed to have remarkable inhibitory effects against both methicillin-resistant S. aureus (MIC: ≤ 16 µg/mL) and glycopeptide-resistant Enterococcus faecium (MIC: ≤ 1 µg/mL). These platanosides were subjected to docking analyses against FabI (enoyl-ACP reductase) and PBP1/2 (penicillin binding protein), both of which are pivotal enzymes governing bacterial growth but not found in the human host. The results showed that 6 and 7 displayed superior binding affinities towards FabI and PBP2. Moreover, surface plasmon resonance studies on the interaction of 1/7 and FabI revealed that 7 has a higher affinity (KD = 1.72 µM), which further supports the above in vitro data and is thus expected to be a novel anti-antibacterial drug lead.

Informatics and Computational Approaches for the Discovery and Optimization of Natural Product-Inspired Inhibitors of the SARS-CoV-2 2'-O-Methyltransferase.

The urgent need for new classes of orally available, safe, and effective antivirals─covering a breadth of emerging viruses─is evidenced by the loss of life and economic challenges created by the HIV-1 and SARS-CoV-2 pandemics. As frontline interventions, small-molecule antivirals can be deployed prophylactically or postinfection to control the initial spread of outbreaks by reducing transmissibility and symptom severity. Natural products have an impressive track record of success as prototypic antivirals and continue to provide new drugs through synthesis, medicinal chemistry, and optimization decades after discovery. Here, we demonstrate an approach using computational analysis typically used for rational drug design to identify and develop natural product-inspired antivirals. This was done with the goal of identifying natural product prototypes to aid the effort of progressing toward safe, effective, and affordable broad-spectrum inhibitors of Betacoronavirus replication by targeting the highly conserved RNA 2'-O-methyltransferase (2'-O-MTase). Machaeriols RS-1 (7) and RS-2 (8) were identified using a previously outlined informatics approach to first screen for natural product prototypes, followed by in silico-guided synthesis. Both molecules are based on a rare natural product group. The machaeriols (3-6), isolated from the genus Machaerium, endemic to Amazonia, inhibited the SARS-CoV-2 2'-O-MTase more potently than the positive control, Sinefungin (2), and in silico modeling suggests distinct molecular interactions. This report highlights the potential of computationally driven screening to leverage natural product libraries and improve the efficiency of isolation or synthetic analog development.

The anti-proliferative effects of a frankincense extract in a window of opportunity phase ia clinical trial for patients with breast cancer.

PURPOSE: Boswellic acids, active components of frankincense, suppress tumor proliferation in vitro with a strong clinical trial safety profile in patients with inflammatory diseases. We performed a Phase Ia window of opportunity trial of Boswellia serrata (B. serrata) in patients with breast cancer to evaluate its biologic activity and safety. METHODS: Patients with invasive breast cancer were treated pre-operatively with B. Serrata (2400 mg/day PO) until the night before surgery for a median of 11 days (SD 6 days; range: 5-23 days). Paraffin-embedded sections from pretreatment diagnostic core biopsies and post-treatment surgical excisions were evaluated using a tunnel assay and immunohistochemistry staining with Ki-67 antibodies. A non-intervention retrospective control arm consisting of core and surgical tissue specimens from untreated patients was used to compare patients treated with B. Serrata. The change in proliferation and apoptosis between diagnostic core specimens and surgical specimens was compared between the control and treatment groups using a two-tailed paired t-test. RESULTS: Twenty-two patients were enrolled, of which 20 received treatment, and 18 had sufficient tissue for IHC. There was an increase in percent change in proliferation from core biopsy to surgical excision in the control group (n = 18) of 54.6 ± 21.4%. In the B. serrata-treated group there was a reduction in proliferation between core biopsy and excision (n = 18) of 13.8 ± 11.7%. This difference was statistically significant between the control and B. serrata-treated groups (p = 0.008). There was no difference in change in apoptosis. There were no serious adverse events related to the drug. CONCLUSION: Boswellia serrata inhibited breast cancer proliferation and was well-tolerated in a Phase Ia window of opportunity trial.

Profiling Prokaryotic Communities and Aaptamines of Sponge Aaptos suberitoides from Tulamben, Bali.

Sponges (Porifera) harbor a diversity of microorganisms that contribute largely to the production a vast array of bioactive compounds. The microorganisms associated with sponge have an important impact on the chemical diversity of the natural products. Herein, our study focuses on an Aaptos suberitoides commonly found in Indonesia. The objective of this study was to investigate the profile of prokaryotic community and the presence of aaptamine metabolites in sponge Aaptos suberitoides. Sponges were collected from two site locations (Liberty Wreck and Drop Off) in Tulamben, Bali. The sponges were identified by barcoding DNA cytochrome oxidase subunit I (COI) gene. The profile of prokaryotic composition was investigated by amplifying the 16S rRNA gene using primers 515f and 806r to target the V4 region. The metabolites were analyzed using LC-MS, and dereplication was done to identify the aaptamines and its derivates. The barcoding DNA of the sponges confirmed the identity of samples as Aaptos suberitoides. The prokaryotic communities of samples A. suberitoides were enriched and dominated by taxa Proteobacteria, Chloroflexi, Actinobacteria, and Acidobacteria. The chemical analysis showed that all sponges produce aaptamine and isoaaptamine except A. suberitoides S2421 produce analog of aaptamines. This is the first report on the profile of prokaryotic community and the aaptamine of tropical marine sponges, A. suberitoides, from Tulamben, Bali.

In-Silico Approaches for the Screening and Discovery of Broad-Spectrum Marine Natural Product Antiviral Agents Against Coronaviruses.

The urgent need for SARS-CoV-2 controls has led to a reassessment of approaches to identify and develop natural product inhibitors of zoonotic, highly virulent, and rapidly emerging viruses. There are yet no clinically approved broad-spectrum antivirals available for beta-coronaviruses. Discovery pipelines for pan-virus medications against a broad range of betacoronaviruses are therefore a priority. A variety of marine natural product (MNP) small molecules have shown inhibitory activity against viral species. Access to large data caches of small molecule structural information is vital to finding new pharmaceuticals. Increasingly, molecular docking simulations are being used to narrow the space of possibilities and generate drug leads. Combining in-silico methods, augmented by metaheuristic optimization and machine learning (ML) allows the generation of hits from within a virtual MNP library to narrow screens for novel targets against coronaviruses. In this review article, we explore current insights and techniques that can be leveraged to generate broad-spectrum antivirals against betacoronaviruses using in-silico optimization and ML. ML approaches are capable of simultaneously evaluating different features for predicting inhibitory activity. Many also provide a semi-quantitative measure of feature relevance and can guide in selecting a subset of features relevant for inhibition of SARS-CoV-2.

Prenylated flavonoids with significant anti-hepatoma activity from Daphne giraldii and effects on Fibroblast Growth Factor Receptor 1 (FGFR1).

We report here the orchestration of molecular ion networking (MoIN) and a set of computational and informatics assisted structural elucidation approaches in the discovery of 23 new prenyl-flavonoids and 13 known molecules from Daphne giraldii Nitsche (Thymelaeaceae), some of which possess significant bioactivity against hepatoma carcinoma. Daphnegiratriprenylone A (DPTP-A) represents the class of polyprenyl-flavonoids possessing a triprenyl substitution, and was identified with the guidance of mass spectrometry and nuclear magnetic resonance combined with computational approaches. This approach illustrates a paradigm shift in the application of computational tools for the direct assignment of new natural product structures and it was demonstrated to be reliable compared to conventional 2D-NMR techniques. Seventeen compounds exhibited potent and selective activity against Hep3B cells (IC50 ranging from 0.42 to 7.08 µM). Tyrosine kinase FGFR1 has emerged as a potential target of polyprenyl-flavonoids by a reverse pharmacophore mapping approach. We validated that the prenyl-flavonoids effectively inhibit FGFR1 using the Mobility Shift Assay, Western blot and molecular dynamics simulations, and the results suggest significant potency of the compounds towards FGFR1. These findings provide a new chemical class with strong links to traditional medicines, possessing reasonable safety for developing potential therapeutic agents for FGFR1-related diseases.

Assessment of microplastic bioconcentration, bioaccumulation and biomagnification in a simple coral reef food web.

Plastics, and more specifically, microplastics (MPs, <5 mm) are considered a marine contaminant of emerging concern. To accurately assess the ecological risk of MPs, it is critical to first understand the relationship between MP contamination in organisms with that in their surrounding environment. The goal of this study was to examine the ecological risk of MPs in coral reef ecosystems by assessing the MP contamination found within a simple food web against contamination in the surrounding environment. Taxa representing three trophic levels (zooplankton, benthic crustaceans, and reef fish), as well as the distinct environmental matrices which they inhabit (i.e., mid-column water and sediment) were collected from two mid-shelf reefs in the central Great Barrier Reef, Australia. Microplastics were isolated using validated clarification techniques, visually characterised (i.e., shape, colour, size) by microscopy, chemically confirmed by Fourier transform infrared spectroscopy and recorded in all three trophic levels and all abiotic samples. MPs were found to bioconcentrate, with similar concentrations, polymer types, sizes, shapes, and colours at each trophic level compared to their surrounding environment. However, MP contamination varied across the three trophic levels, with no evidence of bioaccumulation. Further, MP concentrations did not increase up the food web, discounting MP biomagnification. Regardless, given the heterogeneity of MPs found in the marine environment, and the complexity of marine food webs, trophic transfer represents a prominent pathway of exposure from lower to higher trophic levels.

Commemorative Issue in Honor of Professor Paul J. Scheuer.

This Special Issue is dedicated to the memory of Professor Paul J [...].

Manzamine-A Alters In Vitro Calvarial Osteoblast Function.

Manzamine-A is a marine-derived alkaloid which has anti-viral and anti-proliferative properties and is currently being investigated for its efficacy in the treatment of certain viruses (malaria, herpes, HIV-1) and cancers (breast, cervical, colorectal). Manzamine-A has been found to exert effects via modulation of SIX1 gene expression, a gene critical to craniofacial development via the WNT, NOTCH, and PI3K/AKT pathways. To date little work has focused on Manzamine-A and how its use may affect bone. We hypothesize that Manzamine-A, through SIX1, alters bone cell activity. Here, we assessed the effects of Manzamine-A on cells that are responsible for the generation of bone, pre-osteoblasts and osteoblasts. PCR, qrtPCR, MTS cell viability, Caspase 3/7, and functional assays were used to test the effects of Manzamine-A on these cells. Our data suggests Six1 is highly expressed in osteoblasts and their progenitors. Further, osteoblast progenitors and osteoblasts exhibit great sensitivity to Manzamine-A treatment exhibited by a significant decrease in cell viability, increase in cellular apoptosis, and decrease in alkaline phosphatase activity. In silico binding experiment showed that manzamine A potential as an inhibitor of cell proliferation and survival proteins, i.e., Iκb, JAK2, AKT, PKC, FAK, and Bcl-2. Overall, our data suggests Manzamine-A may have great effects on bone health overall and may disrupt skeletal development, homeostasis, and repair.

Platanosides, a Potential Botanical Drug Combination, Decrease Liver Injury Caused by Acetaminophen Overdose in Mice.

Oxidative stress plays an important role in acetaminophen (APAP)-induced hepatotoxicity. Platanosides (PTSs) isolated from the American sycamore tree (Platanus occidentalis) represent a potential new four-molecule botanical drug class of antibiotics active against drug-resistant infectious disease. Preliminary studies have suggested that PTSs are safe and well tolerated and have antioxidant properties. The potential utility of PTSs in decreasing APAP hepatotoxicity in mice in addition to an assessment of their potential with APAP for the control of infectious diseases along with pain and pyrexia associated with a bacterial infection was investigated. On PTS treatment in mice, serum alanine aminotransferase (ALT) release, hepatic centrilobular necrosis, and 4-hydroxynonenal (4-HNE) were markedly decreased. In addition, inducible nitric oxide synthase (iNOS) expression and c-Jun-N-terminal kinase (JNK) activation decreased when mice overdosed with APAP were treated with PTSs. Computational studies suggested that PTSs may act as JNK-1/2 and Keap1-Nrf2 inhibitors and that the isomeric mixture could provide greater efficacy than the individual molecules. Overall, PTSs represent promising botanical drugs for hepatoprotection and drug-resistant bacterial infections and are effective in protecting against APAP-related hepatotoxicity, which decreases liver necrosis and inflammation, iNOS expression, and oxidative and nitrative stresses, possibly by preventing persistent JNK activation.

Temporal patterns of plastic contamination in surface waters at the SS Yongala shipwreck, Great Barrier Reef, Australia.

Plastic pollution is ubiquitous within the marine environment, including surface waters, water column and benthic sediments. Marine plastic contamination is expected to increase if future projections of increased plastic production eventuate. Conversely, national and international efforts are aiming to reduce marine plastic contamination. In this context, scientists, managers and the general public are increasingly interested in understanding the status and temporal trends of plastic contamination in the marine environment. Presented here is the first temporal assessment of plastic contamination in surface waters of the Great Barrier Reef (GBR), Australia. Specifically, duplicate surface seawater samples (n = 66) were collected at the SS Yongala shipwreck (Central GBR) monthly from September 2016 to September 2019 and analysed for plastic presence and abundance. The processing workflow involved density separation, followed by filtration, visual identification and sizing of putative plastics using stereomicroscopy, and chemical characterisation using Fourier transform infrared spectroscopy. A total of 533 plastic items were identified across all tows, consisting of macro-, meso- and microplastic fragments and fibres, with polypropylene and polyethylene being the most common polymers. Plastic contamination was detected in every replicate tow, bar one. Plastic concentrations fluctuated and spiked every three months, although contamination did not significantly alter across the three-year period. Wind speed, salinity and river discharge volume, but not surface current speed nor sea surface temperature, had a significant influence on the levels of plastic contamination. This study reveals, for the first time, the chronic presence of plastic debris in the surface waters of the GBR highlighting the need for long-term and on-going monitoring of the marine environment for plastic contamination.

Impacts of artificial light at night in marine ecosystems-A review.

The globally widespread adoption of Artificial Light at Night (ALAN) began in the mid-20th century. Yet, it is only in the last decade that a renewed research focus has emerged into its impacts on ecological and biological processes in the marine environment that are guided by natural intensities, moon phase, natural light and dark cycles and daily light spectra alterations. The field has diversified rapidly from one restricted to impacts on a handful of vertebrates, to one in which impacts have been quantified across a broad array of marine and coastal habitats and species. Here, we review the current understanding of ALAN impacts in diverse marine ecosystems. The review presents the current state of knowledge across key marine and coastal ecosystems (sandy and rocky shores, coral reefs and pelagic) and taxa (birds and sea turtles), introducing how ALAN can mask seabird and sea turtle navigation, cause changes in animals predation patterns and failure of coral spawning synchronization, as well as inhibition of zooplankton Diel Vertical Migration. Mitigation measures are recommended, however, while strategies for mitigation were easily identified, barriers to implementation are poorly understood. Finally, we point out knowledge gaps that if addressed would aid in the prediction and mitigation of ALAN impacts in the marine realm.

Structure and Antimicrobial Activity of Rare Lactone Lipids from the Sooty Mold (Scorias spongiosa).

Two new lactone lipids, scoriosin (1) and its methyl ester (2), with a rare furylidene ring joined to a tetrahydrofurandione ring, were isolated from Scorias spongiosa, commonly referred to as sooty mold. The planar structure of these compounds was assigned by 1D and 2D NMR. The conformational analysis of these molecules was undertaken to evaluate the relative and absolute configuration through GIAO NMR chemical shift analysis and ECD calculation. In addition to the potent antimicrobial activities, compound 2 strongly potentiated the activity of amphotericin B against Cryptococcus neoformans, suggesting the potential utility of this compound in combination therapies for treating cryptococcal infections.

Recent advances and limitations in the application of kahalalides for the control of cancer.

Since the discovery of the kahalalide family of marine depsipeptides in 1993, considerable work has been done to develop these compounds as new and biologically distinct anti-cancer agents. Clinical trials and laboratory research have yielded a wealth of data that indicates tolerance of kahalalides in healthy cells and selective activity against diseased cells. Currently, two molecules have attracted the greates level of attention, kahalalide F (KF) and isokahalalide F (isoKF, Irvalec, PM 02734, elisidepsin). Both compounds were originally isolated from the sarcoglossan mollusk Elysia rufescens but due to distinct structural characteristics it has been hypothesized and recently shown that the ultimate origin of the molecules is microbial. The search for their true source has been a subject of considerable research in the anticipation of finding new analogs and a culturable expression system that can produce sufficient material through fermentation to be industrially relevant.

Non-enzymatic glycoxidation linked with nutrition enhances the tumorigenic capacity of prostate cancer epithelia through AGE mediated activation of RAGE in cancer associated fibroblasts.

The molecular implications of food consumption on cancer etiology are poorly defined. The rate of nutrition associated non-enzymatic glycoxidation, a reaction that occurs between reactive carbonyl groups on linear sugars and nucleophilic amino, lysyl and arginyl groups on fats and proteins, is rapidly increased by food cooking and manufacturing processes. In this study, we assign nutrition-associated glycoxidation with significant oncogenic potential, promoting prostate tumor growth, progression, and metastasis in vivo. Advanced glycation end products (AGEs) are the final irreversible product of non-enzymatic glycoxidation. Exogenous treatment of prostate tumor cells with a single AGE peptide replicated glycoxidation induced tumor growth in vivo. Mechanistically, receptor for AGE (RAGE) deficiency in the stroma inhibited AGE mediated tumor growth. Functionally, AGE treatment induced RAGE dimerization in activated fibroblasts which sustained and increased the migratory potential of tumor epithelial cells. These data identify a novel nutrition associated pathway that can promote a tissue microenvironment conducive for aggressive tumor growth. Targeted and/or interventional strategies aimed at reducing AGE bioavailability as a consequence of nutrition may be viewed as novel chemoprevention initiatives.

TLC-Based Fingerprinting Analysis of the Geographical Variation of Melastoma malabathricum in Inland and Archipelago Regions: A Rapid and Easy-to-Use Tool for Field Metabolomics Studies.

Melastoma malabathricum is an Indo-Pacific herb that has been used traditionally to treat numerous ailments such as wounds, dysentery, diarrhea, toothache, and diabetes. The objective of this study was to evaluate the variability of the metabolic profiles of M. malabathricum across its geographic distribution. By employing thin layer chromatography (TLC), specimens collected from six terrestrial and archipelago regions of Indonesia were analyzed by densitometry for metabolomic fingerprinting analysis combined with chemometric tools: principal component analysis (PCA) and hierarchical cluster analysis (HCA). Two PCAs were identified as PC1 and PC2 with 41.90% and 20.36%, respectively. Our results indicate the importance of considering geographic distribution during field-collection efforts since they demonstrate regional metabolic variation in secondary metabolites of M. malabathricum, as illustrated by TLC and their biological activities.