Unprecedented antioxidative cyclic ether from the red seaweed Kappaphycus alvarezii with anti-cyclooxygenase and lipoxidase activities

Structure-based pharmacophore modeling and DFT studies of Indian Ocean-derived red algal compounds as PI3Kα inhibitors

Phosphoinositide kinases (PIKs) are a type of lipid kinase that acts as an upstream activator of oncogenic signaling. Presently accessible therapeutic compounds have downsides, such as toxicity and dubious efficacy, as well as lengthy treatment durations, which have bred resistance. Here we attempt to screen the Indian Ocean-derived red algal compounds to be used as a promising lead for PI3Kα inhibitor development. Experimental structure of the PI3K alpha Isoform-Specific Inhibitor alpelisib complex-based pharmacophore model was constructed and used as key to mark off the suitable lead compounds from the pool of marine-derived red algal compounds of Indian Ocean. Besides, the study encompasses pharmacophore scaffold screening as well as physicochemical and pharmacokinetic parameter assessment. We employed molecular docking and molecular dynamics simulation to assess the binding type and stability of 21 red algal derivatives. Twelve compounds demonstrated a sustained binding mode within the PI3Kα binding pocket with an optimal protein backbone root-mean-square deviation, also prompted hydrogen bonding throughout the simulations, and also implies that these MNPs have firmly mediated the interaction with prime hinge region residues in the PI3Kα ATP binding pocket. DFT studies revealed that proposed compounds had the greatest occupied molecular orbital electrophilicity index, basicity, and dipole moment, all of which attributed their stability as well as binding affinity at the PI3Kα active site. Our study's findings revealed that CMNPD31054, CMNPD4798, CMNPD27861, CMNPD4799, CMNPD27860, CMNPD9533, CMNPD3732, CMNPD4221, CMNPD31058, CMNPD31052, CMNPD29281, and CMNPD31055 can be used as lead compounds for PI3KΑ isoform inhibitors design.

Red Seaweed-Derived Compounds as a Potential New Approach for Acne Vulgaris Care

Acne vulgaris (AV) is a chronic skin disease of the pilosebaceous unit affecting both adolescents and adults. Its pathophysiology includes processes of inflammation, increased keratinization, sebum production, hormonal dysregulation, and bacterial Cutibacterium acnes proliferation. Common AV has been treated with antibiotics since the 1960s, but strain resistance has emerged and is of paramount concern. Macroalgae are known producers of substances with bioactive properties, including anti-viral, antibacterial, antioxidant, and anti-inflammatory properties, among several others. In particular, red algae are rich in bioactive compounds such as polysaccharides, phenolic compounds, lipids, sterols, alkaloids, and terpenoids, conferring them antioxidant, antimicrobial, and anti-inflammatory activities, among others. Thus, the exploration of compounds from marine resources can be an appealing approach to discover new treatment options against AV. The aim of this work is to provide an overview of the current knowledge of the potentialities of red macroalgae in the treatment of AV by reviewing the main therapeutic targets of this disease, and then the existence of compounds or extracts with bioactive properties against them.

Novel Furanyl-Substituted Isochromanyl Class of Anti-Inflammatory Turbinochromanone from Brown Seaweed Turbinaria conoides

Organic extract of the brown seaweed Turbinaria conoides (Sargassaceae) was chromatographically fractionated to yield an undescribed furanyl-substituted isochromanyl metabolite, named as turbinochromanone, which was characterized as methyl 4-[(3S)-8-{[(3R)-4-ethyl-2,3-dihydrofuran-3-yl]methyl}-1-oxo-3,4-dihydro-1H-2-benzopyran-3-yl]butanoate. The isochromanyl derivative possessed comparable attenuation potential against 5-lipoxygenase (IC₅₀ 3.70 μM) with standard 5-lipoxygenase inhibitor drug zileuton (IC₅₀ 2.41 μM). Noticeably, the index of anti-inflammatory selectivity of turbinochromanone (∼1.7) was considerably greater than that exhibited by the standard agent diclofenac (1.06). Antioxidant properties of turbinochromanone against oxidants (IC₅₀ ∼24 μM) further supported its potential anti-inflammatory property. Greater electronic properties (topological polar surface area of 61.8) along with comparatively lesser docking parameters of the studied compound with aminoacyl residues of targeted enzymes (cyclooxygenase-2 and 5-lipoxygenase) (binding energy of -11.05 and -9.40 kcal mol^-1 , respectively) recognized its prospective anti-inflammatory potential. In an aim to develop seaweed-based natural anti-inflammatory leads, the present study isolated turbinochromanone as promising 5-lipoxygenase and cyclooxygenase-2 inhibitor, which could be used for pharmaceutical and biotechnological applications.

Metabolites with Antioxidant Activity from Marine Macroalgae

Reactive oxygen species (ROS) attack biological molecules, such as lipids, proteins, enzymes, DNA, and RNA, causing cellular and tissue damage. Hence, the disturbance of cellular antioxidant homeostasis can lead to oxidative stress and the onset of a plethora of diseases. Macroalgae, growing in stressful conditions under intense exposure to UV radiation, have developed protective mechanisms and have been recognized as an important source of secondary metabolites and macromolecules with antioxidant activity. In parallel, the fact that many algae can be cultivated in coastal areas ensures the provision of sufficient quantities of fine chemicals and biopolymers for commercial utilization, rendering them a viable source of antioxidants. This review focuses on the progress made concerning the discovery of antioxidant compounds derived from marine macroalgae, covering the literature up to December 2020. The present report presents the antioxidant potential and biogenetic origin of 301 macroalgal metabolites, categorized according to their chemical classes, highlighting the mechanisms of antioxidative action when known.

First report of substituted 2H-pyranoids from brown seaweed Turbinaria conoides with antioxidant and anti-inflammatory activities

The organic extract of Turbinaria conoides, a brown seaweed harvested from the Gulf of Manner region of Indian peninsular was chromatographically fractionated to yield three substituted 2H-pyranoids, namely methyl-21-yl-[5', 6'- dihydro-5'-yl-{54-(4-hydroxybenzoyl)-oxy-(52-methylbutyl)}-3'-methyl-2H-pyran]-21-methyl butanoate (1), 11-[(3', 6'-dihydro-4'-methyl-2'-oxo-2H-pyran-3'-yl)methyl]-10-methylhexyl benzoate (2), and [6-ethyl-3,4-dimethyl-(tetrahydro-2', 2', 6'-trimethyl-2H-pyran-3'-yl)-2,5-cycloheptadiene]-1-propanoate (3). The compounds 1 and 2 bearing 2H-pyranyl-4-hydroxybenzoyl and 2H-pyranyl-10-methylhexylbenzoate moieties exhibited potential antioxidant activities (IC50 0.54-0.69 mg mL-1) as commercial antioxidant (α-tocopherol IC50 0.63-0.73 mg mL-1). Likewise, potential bioactivity of the 2H-pyran derivative, 1 against 5-lipoxygenase (IC50 ∼ 1 mg mL-1) along with higher index of selectivity (COX-1 inhibitoryIC50/COX-2 inhibitoryIC50 1.88) indicated their selective anti-inflammatory properties against inducible inflammatory mediators than that displayed by commercially available non-steroidal anti-inflammatory drug (ibuprofen, 0.44). Structure activity relationship analysis of the studied compounds showed that the antioxidative and anti-inflammatory properties were directly proportional to their electronic properties. The previously undescribed 2H-pyranoids might constitute as potential antioxidative and anti-inflammatory pharmacophores for medicinal applications. [Formula: see text].

First report of spiro-compounds from marine macroalga Gracilaria salicornia: prospective natural anti-inflammatory agents attenuate 5-lipoxygenase and cyclooxygenase-2

The inflammation pathology is an orchestrated biological process and the dual inhibition of pro-inflammatory enzymes 5-lipoxygenase and cyclooxygenase-2 has been found to be an effective approach against inflammation. This study involves the characterisation of two previously undescribed spiro[5.5]undecanes, 3-(hydroxymethyl)-7-(methoxymethyl)-3,11-dimethyl-9-oxospiro[5.5]undec-4-en-10-methylbutanoate (1) and 4-ethoxy-11,11-dimethyl-7-methylene-8-(propionyloxy)spiro[5.5]undec-2-en-10⁴,10⁶-dihydroxytetrahydro-2H-pyran-10-carboxylate (2) with potential anti-inflammatory properties, from seaweed Gracilaria salicornia by extensive-spectroscopic-experiments. These metabolites recorded prospective bioactivities against 5-lipoxygenase (IC₅₀ < 2.80 mM), whereas their selectivity indices were significantly greater (∼1) than ibuprofen (0.89) (p < 0.05), which attributed selective anti-inflammatory potencies of the studied spiro[5.5]undecane derivatives against inducible cyclooxygenase-2 than constitutive cyclooxygenase-1. Radical scavenging potential of spiro[5.5]undec-2-en-10⁴,10⁶-dihydroxytetrahydro-2H-pyran-10-carboxylate analogue (2) against oxidants, 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3 ethylbenzothiozoline-6-sulfonic acid were found to be greater (IC₅₀ < 1.25 mM) than commercial standard, α-tocopherol (IC₅₀ 1.42-1.79 mM). The greater hydrogen-bonding interactions and binding affinity of 2 (-10.13 kcal/mol) with 5-LOX appropriately corroborated its prospective anti-inflammatory activity.

Marine natural products

Covering: January to December 2017This review covers the literature published in 2017 for marine natural products (MNPs), with 740 citations (723 for the period January to December 2017) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1490 in 477 papers for 2017), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. Geographic distributions of MNPs at a phylogenetic level are reported.

Isolation, structural elucidation and antiplasmodial activity of fucosterol compound from brown seaweed, Sargassum linearifolium against malarial parasite Plasmodium falciparum

The brown seaweed, Sargassum linearifolium (Turner) C. Agardh, 1820 is commonly available along the south-east coast of India. Its compound fucosterol was isolated and confirmed through spectral characterisation and chemical transformation methods. The antiplasmodial effect of the isolated fucosterol was investigated against the 3D7 chloroquine sensitive Plasmodium falciparum strain, parasitaemia percentage was determined at 48 h and morphological change was studied through microscopic examination after Giemsa staining. A perceptible antiplasmodial effect was produced by fucosterol compound against the P. falciparum and positive control, chloroquine with the IC50 values (μg/mL) of 7.48 and 12.81, respectively. Fucosterol showed higher antiplasmodial activity as compared to chloroquine. It is inferred that both the fucosterol and chloroquine could have inhibited the schizont stage of the parasite during the intra-erythrocyte asexual development. The findings underline the usefulness of the seaweed-based fucosterol and further studies are warranted.