Applications of Antioxidant Secondary Metabolites of Sargassum spp.

Sargassum is one of the largest and most diverse genus of brown seaweeds, comprising of around 400 taxonomically accepted species. Many species of this genus have long been a part of human culture with applications as food, feed, and remedies in folk medicine. Apart from their high nutritional value, these seaweeds are also a well-known reservoir of natural antioxidant compounds of great interest, including polyphenols, carotenoids, meroterpenoids, phytosterols, and several others. Such compounds provide a valuable contribution to innovation that can translate, for instance, into the development of new ingredients for preventing product deterioration, particularly in food products, cosmetics or biostimulants to boost crops production and tolerance to abiotic stress. This manuscript revises the chemical composition of Sargassum seaweeds, highlighting their antioxidant secondary metabolites, their mechanism of action, and multiple applications in fields, including agriculture, food, and health.

Overview of Phlorotannins' Constituents in Fucales.

Fucales are an order within the Phaeophyceae that include most of the common littoral seaweeds in temperate and subtropical coastal regions. Many species of this order have long been a part of human culture with applications as food, feedand remedies in folk medicine. Apart from their high nutritional value, these seaweeds are also a well-known reservoir of multiple bioactive compounds with great industrial interest. Among them, phlorotannins, a unique and diverse class of brown algae-exclusive phenolics, have gathered much attention during the last few years due to their numerous potential health benefits. However, due to their complex structural features, combined with the scarcity of standards, it poses a great challenge to the identification and characterization of these compounds, at least with the technology currently available. Nevertheless, much effort has been taken towards the elucidation of the structural features of phlorotannins, which have resulted in relevant insights into the chemistry of these compounds. In this context, this review addresses the major contributions and technological advances in the field of phlorotannins extraction and characterization, with a particular focus on Fucales.

Coordination Compounds As Multi-Delivery Systems for Osteoporosis.

Osteoporosis therapies leveraging bisphosphonates and mineral components (e.g., magnesium, calcium, and strontium) have been raising attention because of their potential for managing this ever-growing disease. The administration of multicomponent therapeutics (combined therapy) in elderly patients is complex and suffers from low patient adherence. Herein, we report an all-in-one combination of four antiosteoporotic components into a new family of coordination complexes: [M2(H4alen)4(H2O)2]·1.5H2O [where M2+ = Mg2+ (1), (Mg0.535Ca0.465)2+ (2) and (Mg0.505Ca0.450Sr0.045)2+ (3)]. These solid-state complexes were prepared, for the first time, through microwave-assisted synthesis. It is demonstrated that the compounds are capable of releasing their antiosteoporotic components, both in conditions that mimic the path along the gastrointestinal tract and in long periods under physiological conditions (pH ∼7.4). More importantly, when administered in low concentrations, the compounds did not elicit a cytotoxic effect toward liver, kidney, and osteoblast-like cell lines. Besides, it is important to highlight the unique coordination complex with four bone therapeutic components, [(Mg0.505Ca0.450Sr0.045)2(H4alen)4(H2O)2]·1.5H2O (3), which significantly promoted osteoblast metabolic activity up to ca. 1.4-fold versus the control group. These findings bring this type of compounds one-step closer to be considered as an all-in-one and more effective treatment for managing chronic bone diseases, prompting further research on their therapeutic properties.

Chitosan nanoparticles as a promising tool in nanomedicine with particular emphasis on oncological treatment.

The study describes the current state of knowledge on nanotechnology and its utilization in medicine. The focus in this manuscript was on the properties, usage safety, and potentially valuable applications of chitosan-based nanomaterials. Chitosan nanoparticles have high importance in nanomedicine, biomedical engineering, discovery and development of new drugs. The manuscript reviewed the new studies regarding the use of chitosan-based nanoparticles for creating new release systems with improved bioavailability, increased specificity and sensitivity, and reduced pharmacological toxicity of drugs. Nowadays, effective cancer treatment is a global problem, and recent advances in nanomedicine are of great importance. Special attention was put on the application of chitosan nanoparticles in developing new system for anticancer drug delivery. Pre-clinical and clinical studies support the use of chitosan-based nanoparticles in nanomedicine. This manuscript overviews the last progresses regarding the utilization, stability, and bioavailability of drug nanoencapsulation with chitosan and their safety.

Strategies to Broaden the Applications of Olive Biophenols Oleuropein and Hydroxytyrosol in Food Products.

Oleuropein (OLE) and hydroxytyrosol (HT) are olive-derived phenols recognised as health-promoting agents with antioxidant, anti-inflammatory, cardioprotective, antifungal, antimicrobial, and antitumor activities, providing a wide range of applications as functional food ingredients. HT is Generally Recognised as Safe (GRAS) by the European Food Safety Authority (EFSA) and the Food and Drug Administration (FDA), whereas OLE is included in EFSA daily consumptions recommendations, albeit there is no official GRAS status for its pure form. Their application in food, however, may be hindered by challenges such as degradation caused by processing conditions and undesired sensorial properties (e.g., the astringency of OLE). Among the strategies to overcome such setbacks, the encapsulation in delivery systems and the covalent and non-covalent complexation are highlighted in this review. Additionally, the synthesis of OLE and HT derivatives are studied to improve their applicability. All in all, more research needs however to be carried out to investigate the impact of these approaches on the sensory properties of the final food product and its percussions at the gastrointestinal level, as well as on bioactivity. At last limitations of these approaches at a scale of the food industry must also be considered.

Inclusion Complex of Resveratrol with γ-Cyclodextrin as a Functional Ingredient for Lemon Juices.

Microencapsulated resveratrol (RSV) is a pertinent ingredient in functional foods to be used in the prevention and management of cardiovascular diseases. Gamma-cyclodextrin (γ-CD) was evaluated for its RSV inclusion ability. Inclusion procedures comprised mixing equal concentration of an aqueous solution of γ-CD with an ethanol solution of RSV and freeze-drying to obtain a solid material. Solid-state characterization by vibrational spectroscopy, thermogravimetry, and powder X-ray diffraction (PXRD) confirmed the formation of the γ-CD·RSV complex in a ratio of 1:1. PXRD suggested that cyclodextrin molecules in the complex are stacked in infinite channels holding the RSV inside, with a wide inter-channel space where 14 water molecules are retained. Fresh lemon juices supplemented with 0.625 mg/mL of RSV in its free (RSV-juice) or complexed (γ-CD·RSV-juice) form were stored along 28 days under dark and room temperature or at 4 °C. Initially, the RSV level in γ-CD·RSV-juice was about nine times higher than in RSV-juice (43.1% and 4.8%, respectively), suggesting that the RSV complexation promoted its solubility in the lemon juice, a fact that was still noticed after 28 days of storage. Moreover, regardless the fact that the antioxidant capacity was similar among the juices, the loss of antiradical ABTS•+ capacity in γ-CD·RSV-juice was reduced compared to that of the RSV-juice. Overall, this study allowed concluding that γ-CD can serve as a carrier of RSV, promoting its solubility and eventually protecting its antioxidant stability in lemon juices for at least 28 days.

Bone Tissue Disorders: Healing Through Coordination Chemistry.

Osteoporosis, Paget's disease and osteosarcoma are a few examples of bone tissue disorders that affect millions of people worldwide. These conditions can strictly limit the lifestyle of patients and may even lead to their demise. To prevent this or, at least, try to manage the situation, there are several treatments available on the market. Notwithstanding, research has been driven by the possibility to improve the existing therapies, as well as to find new approaches that could better respond to these diseases. In this Review the path is shown through which, in recent years, coordination compounds have been prepared and manufactured to be applied in the management of bone tissue disorders. Starting with the design and preparation of the coordination compounds with various dimensionalities, two approaches have been used: (1) they are prepared as three-dimensional cages that can act as delivery systems for therapeutic substances, or (2) they are constructed/prepared from compounds with intrinsic therapeutic properties. Following this, several strategies have been explored to manufacture the effective delivery to the patients. The versatility of coordination compounds has allowed their use in the preparation of drug tablets, coatings for titanium implants, or even scaffolds for bone tissue engineering. In the end, it becomes clear that these compounds can be a valuable approach to reach a better treatment for bone tissue disorders. Nonetheless, along the road, a few bumps have appeared concerning the therapeutic profile, such as the effect of the structural arrangement or particle size.

Solid γ-Cyclodextrin Inclusion Compound with Gingerols, a Multi-Component Guest: Preparation, Properties and Application in Yogurt.

Gingerols from the rhizome of fresh ginger (Zingiber officinale) were obtained by a simple extraction, followed by purification. The gingerols extract was composed of 6-gingerol (54%), 8-gingerol (20%), and 10-gingerol (26%). It was included into γ-cyclodextrin by classic co-dissolution procedures. Solid-state characterisation of γ-cyclodextrin·gingerols shows that this inclusion compound features 1:1 host-to-guest stoichiometry and that it is a microcrystalline powder with a crystalline cell that belongs to the tetragonal space group 4212, having the host molecules stacked in infinite channels where the gingerols are accommodated. In chimico studies with ABTS•+ scavenging, NO• scavenging, ß-carotene peroxidation, and 5-LOX inhibition show that γ-cyclodextrin is a suitable carrier for gingerols, because it does not alter their reactivity towards these substances. Yogurt was tested as a matrix for the incorporation of gingerols and γ-cyclodextrin·gingerols into foodstuff. The colour of the fortified yogurt suffered little alterations. In the case of yogurt with the inclusion compound, γ-cyclodextrin·gingerols, as fortificant, these alterations were not perceptible to the naked eye. Moreover, yogurt with γ-cyclodextrin·gingerols showed a good antioxidant activity, thus being suitable for use in nutraceutical applications.

Fluorescent Light-up Probe for the Detection of Protein Aggregates.

A fluorescent dye was decorated with water-soluble pyridinium groups in order to be applied in the detection of cyclodextrins or DNA. The dye displays an enhancement of its emission intensity when the internal rotations are restricted due to the formation of an inclusion complex with cyclodextrins or upon interaction with DNA. In vivo, the fluorescent probe can stain protein aggregates with a selectivity comparable to the widely used Proteostat®.

Preformulation Studies of the γ-Cyclodextrin and Montelukast Inclusion Compound Prepared by Comilling.

Montelukast (MLK), an oral antiasthmatic drug with growing use, requires special care in formulation and storage to avoid its degradation by action of light and water. This work investigates the increase in the stability of montelukast as the effect of molecular encapsulation with gamma-cyclodextrin (γ-CD) by means of a solvent-free method, cogrinding. As a first step, a 1:1 preferred stoichiometry is established for this hostguest system using a combination of molecular modeling and the continuous variation method. The solid 1:1 inclusion compound, γ-CD·MLK, is obtained by 2 comilling procedures. For comparison purposes, γ-CD·MLK is also prepared by a classical codissolution procedure and isolated by freeze-drying. Products were characterized by powder X-ray diffraction, 13C{1H} CP-MAS NMR, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetry, and differential scanning calorimetry, which confirm inclusion, demonstrate the formation of amorphous products by comilling, and highlight the importance of the amorphous nature of the starting materials for the stability of the comilled final product. The dissolution profile of montelukast when released from the comilled products shows equivalent concentrations to those obtained with the same mass of the pure drug, with the extra advantage of keeping the solution stability (unaltered concentration) for longer periods.

Solid-state studies and antioxidant properties of the γ-cyclodextrin·fisetin inclusion compound.

Fisetin is a natural antioxidant with a wide range of nutraceutical properties, including antidiabetic, neuroprotecting, and suppression or prevention of tumors. The present work describes the preparation of a water-soluble, solid inclusion compound of fisetin with gamma-cyclodextrin (γ-CD), a cyclic oligosaccharide approved for human consumption. A detailed physicochemical analysis of the product is carried out using elemental analysis, powder X-ray diffraction (PXRD), Raman, infrared and 13C{1H} CP-MAS NMR spectroscopies, and thermal analysis (TGA) to verify fisetin inclusion and to present a hypothetical structural arrangement for the host-guest units. The antioxidant activity of the γ-CD·fisetin inclusion compound is evaluated by the DPPH assay.

Association of aescin with ß- and γ-cyclodextrins studied by DFT calculations and spectroscopic methods.

Background: Aescin, a natural mixture of saponins occurring in Aesculus hippocastanum, exhibits important flebotonic properties, being used in the treatment of chronic venous insufficiency in legs. The inclusion of aescin into cyclodextrins (CDs) is a technical solution for its incorporation into the textile of stockings, but details of the physicochemistry of these host-guest systems are lacking. This work investigates the inclusion of aescin into the cavities of two native cyclodextrins, ß-CD and γ-CD. Results: The continuous variation method applied to aqueous-phase 1H nuclear magnetic resonance (1H NMR) has demonstrated that the preferred CD/aescin inclusion stoichiometries are 2:1 with ß-CD and 1:1 with γ-CD. The affinity constant calculated for γ-CD·aescin was 894 M-1, while for 2ß-CD·aescin it was estimated to be 715 M-1. Density functional theory (DFT) calculations on the interaction of aescin Ib with CDs show that an inclusion can indeed occur and it is further demonstrated that the wider cavity of γ-CD is more adequate to accommodate this large guest. ROESY spectroscopy is consistent with the formation of a complex in which the triterpenic moiety of aescin is included into the cavity of γ-CD. The higher stability of this geometry was confirmed by DFT. Furthermore, DFT calculations were applied to determine the chemical shifts of the protons H3 and H5 of the CDs in the optimised structures of the inclusion complexes. The calculated values are very similar to the experimental data, validating the approach made in this study by NMR. Conclusion: The combination of experimental data from aqueous-state NMR measurements and theoretical calculations has demonstrated that γ-CD is the most suitable host for aescin, although the inclusion also occurs with ß-CD. The geometry of the γ-CD·aescin complex is characterised by the inclusion of the triterpene segment of aescin into the host cavity.

Carriers for metal complexes on tumour cells: the effect of cyclodextrins vs CNTs on the model guest phenanthroline-5,6-dione trithiacyclononane ruthenium(II) chloride.

The complex [Ru[9]aneS3(pdon)Cl]Cl (pdon = 1,10-phenanthroline-5,6-dione) was readily obtained from the stoichiometric reaction of Ru[9]aneS3(dmso)Cl2 with pdon. Recrystallisation in ethanol using salicylic acid as a co-crystallisation helper afforded single-crystals suitable for the collection of X-ray diffraction data which afforded a reasonable structural description. Two different kinds of molecular carriers were tested as vehicles for this complex: carbon nanotubes (CNTs) and cyclodextrins. CNTs had an insufficient loading rate for the ruthenium complex at CNT concentrations deemed non-cytotoxic on cultured cells. The cyclodextrin (CD) carriers, ß-CD and TRIMEB (standing for permethylated ß-CD), were able to form two adducts, studied by powder X-ray diffraction, thermogravimetric analysis (TGA), (13)C{(1)H} CP/MAS NMR and FT-IR spectroscopies. The DNA thermal denaturation studies showed that the complex 1 is able to intercalate with DNA. The in vitro cytotoxicity of the free complex [Ru[9]aneS3(pdon)Cl]Cl (1) and of its two CD adducts (2 and 3) was assessed on both rodent and human cell lines. By using the mouse K1735-M2 melanoma cell line and the non-tumour rat H9c2 cardiomyoblasts, the results showed that 1 and 2 significantly inhibited the growth of the tumour cell line while displaying a good safety profile on cardiomyoblasts. Compound 3 at 100 µM inhibited the proliferation of both cell lines, with a higher activity towards the melanoma cell line. The cytotoxicity of the compounds 1-3 was further assessed on human breast cancer cell lines. Against the MDA-MB-231 line, growth inhibition occurred only with 1 and 3 at the incubation time of 96 h, both with approximate inhibition rates of 50 %; against the MCF-7 line, mild cytotoxicity was observed at 48 h of incubation, with IC50 values calculated above 100 µM for 1, 2 and 3.

Analysis of the microcrystalline inclusion compounds of triclosan with ß-cyclodextrin and its tris-O-methylated derivative.

Solid 1:1 inclusion compounds of triclosan with native and permethylated ß-cyclodextrin (ß-CD and TRIMEB) were prepared by co-crystallisation and co-evaporation, respectively, and studied by FT-IR and (13)C{(1)H} CP/MAS NMR spectroscopies, thermogravimetric analysis, X-ray diffraction and theoretical calculations. Results showed that triclosan inclusion into TRIMEB afforded an amorphous solid, whilst ß-CD·triclosan is composed of microcrystals belonging to two different phases. In the phase featuring larger crystals, X-ray diffraction was carried out and the ß-CD host units, packing head-to-head in infinite channels, were refined; the geometry for the included but highly disordered triclosan molecules was assessed by theoretical calculations. The bacterial growth inhibitory action of the inclusion compounds was studied in comparison to that of pure triclosan on Gram-negative (Salmonella, Escherichia) and Gram-positive strains (Bacillus, Listeria, Enterococcus and Staphylococcus) typically associated with human pathologies, and also on environmental bacteria isolated from different soil and water sources. The antimicrobial activities obtained in the present work showed that, of the two CD hosts, TRIMEB brings the most favourable carrier effect: it reduced the toxicity of triclosan against some of the environmental strains and afforded slightly higher action against virulent strains.

(2,2'-Bipyridine-κN,N')bromido(1,4,7-trithia-cyclo-nonane-κS,S',S'')ruthenium(II) hexa-fluoridophosphate.

The title compound, [RuBr(C(10)H(8)N(2))(C(6)H(12)S(3))]PF(6) or [RuBr(bpy)([9]aneS(3))]PF(6) ([9]aneS(3) is 1,4,7-trithia-cyclo-nonane and bpy is 2,2'-bipyridine), exhibits a very similar octahedral coordination geometry for the Ru(2+) atom to that of its [RuCl(bpy)([9]aneS(3))](+) analogue, with only the chloride ligand being substituted by a bromide ligand. The presence of a PF(6) (-) anion (alongside with the coordinated bromide ligand) promotes the existence of an extensive network of weak C-H⋯X (X = F, Br) inter-actions.

Arcyriaflavin A monohydrate.

The asymmetric unit of the title compound comprises the monohydrated form of the natural product arcyriaflavin A [systematic name: 12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione monohydrate], C(20)H(11)N(3)O(2)·H(2)O. Individual molecular units are engaged in hydrogen-bonding interactions, forming two-dimensional zigzag supramolecular layers parallel to the (102) plane. The close packing of the layers is mediated by strong co-operative π-π stacking interactions, in tandem with interlayer hydrogen bonds involving the solvent water molecule.

Diaqua-bis(ethyl-enediamine-κN,N')copper(II) bis-(4-phenyl-benzoate) 2.66-hydrate.

In the title complex, [Cu(C(2)H(8)N(2))(2)(H(2)O)(2)](C(13)H(9)O(2))(2)·2.66H(2)O, the Cu(II) centre (located at an inversion centre) is coordinated by two bidentate ethyl-enediamine (en) ligands and two water O atoms in a typical Jahn-Teller distorted octahedral geometry. The amino groups and the water mol-ecules are disordered over two distinct crystallographic positions with occupancies of 1/3 and 2/3. In the crystal, the cations and anions are disposed in alternating layers. One of the water mol-ecules of crystallization is disordered and the other has a fractional occupation. In the 2/3 occupancy component, water mol-ecules are organized into a chain composed of hexa-meric units inter-connected by carboxyl-ate bridges.

Bis(µ-4-phenyl-pyridine N-oxide-κO:O)bis-[bis-(1,1,1,5,5,5-hexa-fluoro-pentane-2,4-dionato)copper(II)].

The asymmetric unit of the title compound, [Cu(2)(C(5)HF(6)O(2))(4)(C(11)H(9)NO)(2)], contains one half of the centrosymmetric dinuclear complex. The coordination geometry of the Cu(II) atom is octa-hedral, exhibiting a typical Jahn-Teller distortion. One trifluoro-methyl group is rotationally disordered between two orientations in a 1:1 ratio.

(2,2'-Bipyridine-κN,N')chlorido(1,4,7-trithia-cyclo-nonane-κS,S',S'')ruthenium(II) nitrate monohydrate.

In the title compound, [RuCl(C(10)H(8)N(2))(C(6)H(12)S(3))]NO(3)·H(2)O or [RuCl(bpy)([9]aneS(3))]NO(3)·H(2)O, ([9]aneS(3) is 1,4,7-tri-thia-cyclo-nonane and bpy is 2,2'-bipyridine), the Ru(II) cation has a slightly distorted octa-hedral environment composed of three facially coordinated S atoms from ([9]aneS(3)), two N atoms from bpy and a chloride anion. The nitrate counter-ion and the water mol-ecule of crystallization are engaged in O-H⋯O hydrogen-bonding inter-actions, leading to a supra-molecular chain running parallel to the c axis.