Skeletal protein protection: the mode of action of an anti-osteoporotic marine alkaloid, norzoanthamine

Metabolic bone disorders and the promise of marine osteoactive compounds

Metabolic bone disorders and associated fragility fractures are major causes of disability and mortality worldwide and place an important financial burden on the global health systems. These disorders result from an unbalance between bone anabolic and resorptive processes and are characterized by different pathophysiological mechanisms. Drugs are available to treat bone metabolic pathologies, but they are either poorly effective or associated with undesired side effects that limit their use. The molecular mechanism underlying the most common metabolic bone disorders, and the availability, efficacy, and limitations of therapeutic options currently available are discussed here. A source for the unmet need of novel drugs to treat metabolic bone disorders is marine organisms, which produce natural osteoactive compounds of high pharmaceutical potential. In this review, we have inventoried the marine osteoactive compounds (MOCs) currently identified and spotted the groups of marine organisms with potential for MOC production. Finally, we briefly examine the availability of in vivo screening and validation tools for the study of MOCs.

Osteoprotective effect of the marine alkaloid norzoanthamine on an osteoporosis model in ovariectomized rat

Norzoanthamine (NZ), an alkaloid that has been isolated from the marine cnidiaria Zoanthus sp., has been shown an interesting anti-osteoporotic activity. Although its mechanism of action is not yet clear, it seems that it is different from those of currently used drugs making it particularly interesting. Previous studies have been carried out mostly in vitro. Herein, we present an in vivo study that allows to check the real potential of NZ as a protector substance by direct application into ovariectomized rat bone using a sustained delivery system. Histological and histomorphometric results in ovariectomized rats showed higher bone quality as a result of greater number of trabeculae and osteogenic activity in the group implanted with NZ, compared to controls. In contrast with the untreated controls, NZ-treated groups showed a balanced osteoblast/osteoclast number ratio, similar to that found in the normal bone. These results suggest that NZ could be useful as adjunct to other osteoporosis treatments, but probably its main therapeutic role would be as preventive therapy against bone deterioration.

Marine Macroalgal Polygalactan-Built Nanoparticle Construct for Osteogenesis

Naturally derived polysaccharide biopolymer-based nanoparticles with their size and drug release potentials have appeared as promising biomaterials for osteogenic differentiation. A metallic nanoparticle (GS-AgNP) prepared from a sulfated polygalactan characterized as →3)-2-O-methyl-O-6-sulfonato-β-d-galactopyranosyl-(1 → 4)-2-O-methyl-3,6-anhydro-α-d-galactopyranose-(1→ isolated from the marine macroalga Gracilaria salicornia exhibited a prospective osteogenic effect. Upon treatment with the studied GS-AgNP, alkaline phosphatase activity (88.9 mU/mg) was significantly elevated in human mesenchymal osteoblast stem cells (hMSCs) compared to that in the normal control (33.7 mU/mg). A mineralization study of GS-AgNPs demonstrated an intense mineralized nodule formation on the hMSC surface. A fluorescence-activated cell sorting study of osteocalcin and bone morphogenic protein-2 (BMP-2) expression resulted in an increased population of osteocalcin (78.64%) and BMP-2-positive cells (46.10%) after treatment with GS-AgNPs (250 μg/mL) on M2 macrophages. A time-dependent cell viability study of GS-AgNPs exhibited its non-cytotoxic nature. The studied polygalactan-built nanoparticle could be developed as a promising bioactive pharmacophore against metabolic bone disorder and the treatment for osteogenesis therapy.

Effect of echinalkamide identified from Echinacea purpurea (L.) Moench on the inhibition of osteoclastogenesis and bone resorption

Plant cell cultures have been exploited to provide stable production and new secondary metabolites for better pharmacological activity. Fractionation of adventitious root cultures of Echinacea purpurea resulted in the isolation of eleven constituents, including three new compounds. The structures of the three new compounds were determined to be an alkylamide (1), a polyacetylene (2) and a lignan (3) on the basis of combined spectroscopic analysis. To discover new types of antiresorptive agents, we screened for new compounds that regulate osteoclast differentiation, and survival. Among three new compounds, echinalkamide (compound 1) had considerably inhibitory effects on RANKL-induced osteoclast differentiation, and on proliferation of osteoclasts and efficiently attenuated osteoclastic bone resorption without toxicity. In addition, echinalamide treatment inhibited the osteoclast—specific gene expression level. Echinalkamide achieved this inhibitory effect by disturbing phosphorylation of MAPK and activation of osteoclast transcription factors c-Fos and NFATc1. Conclusionally, our study investigated that echinalkamide remarkably inhibited osteoclast differentiation and osteoclast specific gene expression through repression of the MAPK–c-Fos–NFATC1 cascade.

Marine natural products from zoantharians: bioactivity, biosynthesis, systematics, and ecological roles

The dazzling marine zoantharians represent a reservoir of chemical diversity that remains to be unveiled. These fragile animals have so far been found to harbour the highly bioactive palytoxins or zoanthamines but also the harmless ecdysteroids or zoanthozanthins.

Bioactive Compounds from Marine Organisms: Potential for Bone Growth and Healing

Marine organisms represent a highly diverse reserve of bioactives which could aid in the treatment of a wide range of diseases, including various musculoskeletal conditions. Osteoporosis in particular would benefit from a novel and effective marine-based treatment, due to its large disease burden and the inefficiencies of current treatment options. Osteogenic bioactives have been isolated from many marine organisms, including nacre powder derived from molluscan shells and fucoidan—the sulphated polysaccharide commonly sourced from brown macroalgae. Such extracts and compounds are known to have a range of osteogenic effects, including stimulation of osteoblast activity and mineralisation, as well as suppression of osteoclast resorption. This review describes currently known soluble osteogenic extracts and compounds from marine invertebrates and algae, and assesses their preclinical potential.

Sequential activation of the AKT pathway in human osteoblasts treated with Oscarvit: a bioactive product with positive effect both on skeletal pain and mineralization in osteoblasts

Background

Oscarvit (OSC) is an in-house preparation consisting of calcium, magnesium, phosphorus, strontium, Vitamin D, and eggshell membrane hydrolysate containing naturally occurring glycosaminoglycans and sulfated glycoproteins. OSC has been used both in an open-label human study and in vitro in osteoblasts.

Methods

Fifteen patients divided into three groups received oral OSC 0.6 g three times daily for 20 days. The main outcome measures were regional skeletal pain over the treatment period. For the in vitro experiments eight primary human osteoblasts cultures were established from trabecular bone, six of them from the femoral head, and two from the tibia. Cells were cultured for five to 20 days in the presence of 20 μg/ml OSC. Immunocytochemistry and RT-PCR were used to detect molecular alterations involved in the mineralization process. Calcium concentration was measured by means of a colorimetric assay and cell viability was analyzed using the LDH cytotoxicity assay. To investigate whether the osteoblasts response to OSC is associated with signaling processes the ERK1/2 and AKT signal transduction pathways were analyzed.

Results

Open label human study: OSC, 0.6 g three times daily, resulted in a significant positive effect on pain alleviation of 42% after 5 days (p < 0.001), 57% after 10 days and 68% after 20 days (p < 0.0001; for both time points), with no side-effects being reported. In vitro analysis: In osteoblasts, growing in OSC-supplemented media significant overexpression of bone γ-carboxylglutamic acid-containing protein, secreted phosphoprotein-1, integrin binding sialoprotein, and dentin matrix phosphoprotein genes could be detected when compared to control osteoblasts grown in the absence of OSC. Moreover, OSC-treated osteoblasts produced over the study period vast extracellular calcium deposits without any loss of cellular integrity or signs of cellular toxicity. In addition OSC promotes osteoblast differentiation and activates the AKT signaling pathway.

Conclusion

This open label study provides preliminary evidence of the efficacy of OSC. Despite the limitations (small heterogeneous patient group) the findings can be viewed as a necessary investigation that supports further clinical trials with a double-blind controlled design. Experiments at cellular and molecular level provide supplementary information about OSC that increases mineralization in osteoblasts and activation of the AKT pathway.

Trial registration

DRKS00013233, 06th November 2017, retrospectively registered.

New oxidized zoanthamines from a Canary Islands Zoanthus sp

Three new norzoanthamine-type alkaloids, named 2-hydroxy-11-ketonorzoanthamide B (1), norzoanthamide B (2) and 15-hydroxynorzoanthamine (3), were isolated from Zoanthus sp. specimens collected at the Canary Islands. Their structures were determined by interpretation of NMR and HR-ESIMS data. Relative configurations of their chiral centers were proposed on the basis of ROESY spectra and by comparison of their spectroscopic data with those of the well-known compound, norzoanthamine.

Methanol Extract of Euchelus asper Prevents Bone Resorption in Ovariectomised Mice Model

Marine molluscs are widely distributed throughout the world and many bioactive compounds exhibiting antiviral, antitumor, antileukemic, and antibacterial activity have been reported worldwide. The present study was designed to investigate the beneficial effect of methanol extract of Euchelus asper (EAME) on estrogen deficiency induced osteoporosis in ovariectomised mice model. Forty-two female Swiss albino mice were randomly assigned into Sham operated (Sham) group and six ovariectomised (OVX) subgroups such as OVX with vehicle (OVX); OVX with estradiol (2 mg/kg/day); OVX with EAME of graded doses (25, 50, 100, and 200 mg/kg/day). Bone turnover markers like serum alkaline phosphatase (ALP), serum acid phosphatase (ACP), serum calcium, and histological investigations of tibia and uterus were analysed. Metaphyseal DNA content of the femur bone was also studied. Antiosteoclastogenic activity of EAME was examined. Administration of EAME was able to reduce the increased bone turnover markers in the ovariectomised mice. Histomorphometric analysis revealed an increase in bone trabeculation and restoration of trabecular separation by EAME treatment. Metaphyseal DNA content of the femur of the OVX mice was increased by EAME administration. EAME also showed a potent antiosteoclastogenic behaviour. Thus, the present study reveals that EAME was able to successfully reduce the estrogen deficiency induced bone loss.

Marine invertebrate natural products for anti-inflammatory and chronic diseases

The marine environment represents a relatively available source of functional ingredients that can be applied to various aspects of food processing, storage, and fortification. Moreover, numerous marine invertebrates based compounds have biological activities and also interfere with the pathogenesis of diseases. Isolated compounds from marine invertebrates have been shown to pharmacological activities and are helpful for the invention and discovery of bioactive compounds, primarily for deadly diseases like cancer, acquired immunodeficiency syndrome (AIDS), osteoporosis, and so forth. Extensive research within the last decade has revealed that most chronic illnesses such as cancer, neurological diseases, diabetes, and autoimmune diseases exhibit dysregulation of multiple cell signaling pathways that have been linked to inflammation. On the basis of their bioactive properties, this review focuses on the potential use of marine invertebrate derived compounds on anti-inflammatory and some chronic diseases such as cardiovascular disease, osteoporosis, diabetes, HIV, and cancer.

Enantioselective synthesis of the ABC ring motif of norzoanthamine based on asymmetric Robinson annulation reactions

An enantioselective strategy for the synthesis of tetracyclic motif 5, representing the northern fragment of norzoanthamine, is presented. Key to the strategy is the use of two asymmetric Robinson annulation reactions that produce the tricyclic ABC ring system with excellent stereoselectivity. Further functionalization at the periphery of the C ring produces compound 5 containing six contiguous stereocenters of the natural product.

Osteoporosis treatment: marine algal compounds

Osteoporosis is one of the most common bone diseases that occur due to imbalance during bone formation and bone resorption. About half of all women over the age of 50 will have a fracture on the hip, wrist, or vertebra. Research and treatment of osteoporosis are challenging for researchers and physicians. There are several types of treatments for osteoporosis including most famous bisphosphonates, estrogen agonists/antagonists, parathyroid hormone, estrogen therapy, hormone therapy, and recently developed RANKL inhibition. In the recent days, much attention has been paid for marine algal extracts and compounds for osteoporosis treatment. In this chapter, we extensively deal with marine algae compounds and their rich mineral constituents for osteoporosis treatment.

Distribution and possible function of the marine alkaloid, norzoanthamine, in the zoanthid Zoanthus sp. using MALDI imaging mass spectrometry

The role of the marine alkaloid, norzoanthamine, in the colonial zoanthid Zoanthus sp. was previously unknown. High concentrations of norzoanthamine are present in the epidermal tissue of Zoanthus sp., as determined using protonated molecular ion peak mapping of norzoanthamine by matrix-assisted laser desorption/ionization mass spectrometry and high-performance liquid chromatography quantification. Sodium dodecylsulfate polyacrylamide gel electrophoresis experiments indicate that norzoanthamine increases the resistance of collagen to damage from UV light, probably not via UV light absorption, but by strengthening collagen itself, thus suggesting that collagen strengthening may be the function of norzoanthamine in Zoanthus sp.