Antioxidant drimane-type sesquiterpenoid from muricid gastropod Chicoreus ramosus attenuates pro-inflammatory 5-lipoxygenase and carbolytic enzymes

The muricid gastropod, Chicoreus ramosus, is a nutrient-enriched food source available along the coastal peninsular of the Indian subcontinent. This study was aimed at bioactivity-directed chromatographic fractionation of the organic extract of C. ramosus to isolate an unprecedented drimane-type sesquiterpenoid Ramosane, characterized as 3-hydroxy-7,9b-dimethyl-5-methylene-8-pentyl-octahydro-1H-cyclopenta[a]naphthalen-9(2H)-one. The compound possessed potential antioxidant activities {2, 2'-diphenyl-1-picryl hydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activities of IC₅₀ 1.42 mM and 1.72 mM, respectively} and was proportionate with those (IC₅₀ 1.39 and 1.69 mM, respectively) exhibited by α-tocopherol. The studied sesquiterpenoid exhibited potential attenuation property countering the pro-inflammatory 5-lipoxygenase (IC₅₀  ~ 4 mM), and its activity was analogous with that exhibited by the anti-inflammatory ibuprofen (IC₅₀ 4.36 mM), whereas its carbolytic α-amylase activity (IC₅₀ 0.96 mM) was commensurate with that displayed by acarbose (IC₅₀ 0.43 mM). The isolated metabolite might anticipate as potential naturally derived bioactive constituent in functional food and pharmaceutical applications. PRACTICAL APPLICATIONS: The edible marine muricid gastropod C. ramosus is a prominently available gastropod species of commercial significance in the coastal regions of Indian Peninsula. An unprecedented drimane-type sesquiterpenoid Ramosane was isolated through the bioactivity-directed chromatographic fractionation of the organic extract of muricidae C. ramosus displaying potential anti-inflammatory and anti-diabetic properties. The present study apprehended the prospective of drimane-type sesquiterpenoid derivative Ramosane purified from C. ramosus as a naturally derived pharmacophore with anti-diabetic and anti-inflammatory potential for utilization in functional food and pharmaceutical formulations to minimize the likelihood of inflammation and hyperglycemic pathologies.

Antioxidative oxygenated terpenoids with bioactivities against pro-inflammatory inducible enzymes from Indian squid, Uroteuthis (Photololigo) duvaucelii

Cephalopod squid, Uroteuthis (Photololigo) duvaucelii is consumed as culinary delicacy along the southwest part of Asian continent. Ethyl acetate:methanol extract of U. duvaucelii was chromatographically fractionated to yield C₁₉ furano-norditerpenoid (1) along with irregular C₁₅ sesquiterpenoid (2) and C₂₀ diterpenoid compounds (3). In vitro anti-inflammatory and antioxidant analyses were utilised to evaluate their bio-potentials. The C₁₉ furano-norditerpenoid was reported for significantly effective 2,2-diphenyl-1-picrylhydrazyl radical inhibition (IC₅₀ 0.60 mg/mL) than other compounds and α-tocopherol (IC₅₀ ≥ 0.64 mg/mL). The 2,2'-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid inhibition and ferrous ion chelating potentials were higher for compounds 1 and 2 (IC₅₀ ∼ 0.69 and ∼0.84 mg/mL, respectively) compared to α-tocopherol (IC₅₀ 0.76-0.95 mg/mL). The studied compounds displayed comparable inhibitory activities with synthetic ibuprofen against pro-inflammatory inducible 5-lipoxygenase (IC₅₀ ∼ 0.92 mg/mL). The lower hydrophobicity and steric variables were directly correlated with their antioxidative and anti-inflammatory properties. The studied compounds could be utilised as natural antioxidants and anti-inflammatory functional food ingredients.

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.

First report of chromenyl derivatives from spineless marine cuttlefish Sepiella inermis: Prospective antihyperglycemic agents attenuate serine protease dipeptidyl peptidase-IV

Spineless marine cuttlefish Sepiella inermis has been considered as a popular dietary cephalopod species in Asian and Mediterranean coasts. Bioassay-directed purification of organic extract of S. inermis ensued in the characterization of two chromenyl derivatives. The studied compounds exhibited significantly greater antioxidant potencies (IC₅₀  ≤ 0.5 mg/ml) when compared with α-tocopherol. The substituted 1H-isochromenyloxy-11-hydroxyethyl pentanoate isoform (compound 1) efficiently inhibited the carbolytic enzymes along with key regulator of insulin secretion dipeptidyl peptidase-IV (IC₅₀ 0.16 mg/ml). The molecular docking simulations displayed optimum binding affinity of the compound 1 (-10.01 kcal/mol) with dipeptidyl peptidase-IV and lesser inhibition constant (K_i 46.41 nM), which along with its permissible hydrophobic-hydrophilic balance (log P_ow  ~ 2) appeared to play significant roles in its greater antihyperglycemic activity compared to other studied chromenyl isoform. The greater antioxidant and antidiabetic properties of compound 1 could be utilized as an important natural lead against hyperglycemic-related disorders. PRACTICAL APPLICATIONS: The edible spineless marine cuttlefish Sepiella inermis are ubiquitously available in Asian and Mediterranean coasts. The sequential chromatographic purification of the organic extract of S. inermis led to the identification of two pure chromenyl chemotypes. The metabolites with substituted 1H-isochromenyloxy-11-hydroxyethyl pentanoate isoform (compound 1) displayed potential antioxidative and antihyperglycemic activities compared to the chemotype (2) bearing 3H-isochromen-5-yl moiety. The attenuating potential of chromenyl chemotype 1 against carbohydrate hydrolyzing enzymes and insulin secretion regulator attributed towards its efficiency as an important natural lead against postprandial hyperglycemia and incretin hormone regulation to maintain glucose homeostasis in the biological system. The chromenyl metabolites isolated from S. inermis could be utilized as a functional food ingredient in the nutraceutical formulations against hyperglycemic-related disorders.

First report of a lactonic disecosteroid from the buccinid gastropod Babylonia spirata

A lactonic steroid with an unprecedented 1, 10: 8, 9-disecoergostane framework was identified from the ethyl acetate-methanol extract of buccinid gastropod mollusk, Babylonia spirata collected from the southwestern coast of Indian peninsular region. The compound was characterized as 1, 10: 8, 9-disecoergosta-8-en-A-homo-6a-oxa-1-one by exhaustive spectroscopic methods including two-dimensional nuclear magnetic resonance and mass spectroscopic investigations. The disecosteroid displayed moderate carbolytic enzyme inhibition activity as distinguished by its inhibitive effects against α-amylase and α-glucosidase (IC₅₀ 0.40 and 0.54 mg/mL, respectively). The anti-inflammatory (5-lipoxidase inhibitory) activity of the titled secondary metabolite was found to be superior (IC₅₀ < 0.85 mg/mL) than the commercial anti-inflammatory drug (ibuprofen IC₅₀ > 0.85 mg/mL). However, significantly greater antioxidant property was recorded for the studied disecosteroid as evaluated by in vitro 2, 2-diphenyl-1-picrylhydrazyl radical inhibition potential (IC₅₀ 0.30 mg/mL) than that of standard, α-tocopherol (IC₅₀ > 0.50 mg/mL). The in silico molecular docking studies were conducted to explain the anti-5-lipoxidase and anti-α-amylase properties of the isolated compound. The molecular binding interactions of the ligands with the pro-inflammatory 5-lipoxidase and the carbolytic enzyme α-amylase, demonstrated that their binding energies/docking scores were positively associated with their in vitro bioactivities. A plausible pathway for the biosynthetic origin of lactonic disecosteroid in B. spirata was proposed from an ergosterol precursor. Structure-activity correlation study demonstrated that the biological activities of the disecosteroid were directly proportional to their electronic properties allied with lesser steric restrictions.

Antioxidant and antiinflammatory secondary metabolites from the Asian green mussel Perna viridis

The Asian green mussel, Perna viridis is a nutritious health food in the estuarine and coastal sea beds of the Arabian Sea along the west coast of India. In the present study, bioactivity-guided purification of the chloroform fraction of the methanolic extract of P. viridis was carried out. The isolated secondary metabolites were characterized by spectroscopic experiments, and their antioxidative/antiinflammatory properties were evaluated. The titled compounds were characterized as 3-hydroxy-13-vinyl-dodecahydro-11-phenanthrenone (1), 4,4,9-trimethyl-13-vinyl-dodecahydro-2-phenanthrenone (2), 11,20-dihydroxy-6,6-dimethyl-decahydro-5H-benzo[h]naphtho[1,2-c]chromene-16-carbaldehyde (3), 16-acetyl-20-hydroxy-6,6-dimethyl-dodecahydro-5H-benzo[h]naphtho[1,2-c]chromen-12-one (4), cholest-5-en-3β-3-yl-(30-hydroxy-3-methyl-36-methyleneundeca-30E,34E-dienoate) (5), and cholest-5-en-3β-3-yl-((E)-33-oxooct-31-enoate) (6). No significant differences in the antioxidant activities of the compounds with chromene-16-carbaldehyde (3) and chromen-12-one (4) functionalities (IC₅₀ 0.52-0.68 mg/ml) vis-à-vis the positive control, α-tocopherol (IC₅₀ 0.65-0.76 mg/ml) were registered. The studied compounds, 1-4, displayed potential antiinflammatory activities against pro-inflammatory 5-lipoxygenase (5-LOX) (IC₅₀  < 1 mg/ml). The balanced hydrophilic-lipophilic properties and lower steric values of the studied compounds, 1-4, were correlated with their bioactive potentials. PRACTICAL APPLICATIONS: The edible bivalve green mussels, P. viridis, are broadly available in the estuarine and coastal regions of the Indian Peninsula. The sequential chromatographic purification of the chloroform fraction of the methanolic extract of P. viridis led to the identification of six pure secondary metabolites. The metabolites with substituted chromene-16-carbaldehyde and chromen-12-one functionalities displayed potential antioxidative and antiinflammatory activities compared to other studied compounds. These bioactive metabolites could be used in functional food formulations and as antioxidant leads in medicinal food applications.

Previously undescribed antioxidative O-heterocyclic angiotensin converting enzyme inhibitors from the intertidal seaweed Sargassum wightii as potential antihypertensives

Four previously undescribed antioxidative O-heterocyclic analogues, characterized as 3″-isopropyl-3c-{3b-[(2-oxo-3,4-dihydro-2H-chromen-3-yl) methyl] butyl}-2″-butenyl-3'-hydroxy-2'-(2'b-methoxy-2'-oxoethyl)-3', 4'-dihydro-2H-pyran-4'-carboxylate (1), 2c-methylbutyl-6-[6c-(benzoyloxy)propyl]-6-methyl-tetrahydro-2H-pyran-2-carboxylate (2), 6-{6b-[3'-(5'a-methyl propyl)-3', 4'-dihydro-2H-pyran-6'-yl] ethyl}-tetrahydro-2H-pyran-2-one (3) and 7-(7c-methylpentyl)-hexahydro-2H-chromen-2-one (4) were isolated from the ethylacetate:methanol fraction of the brown seaweed Sargassum wightii. Nuclear magnetic resonance and mass spectroscopic experiments unambiguously attributed their structural identities. Antihypertensive activities of the studied compounds were determined in terms of their angiotensin converting enzyme (ACE) inhibitory potential. The 2H-pyranylcarboxylate derivative (1) displayed comparable activity (IC50 0.08 mg/mL) with standard antihypertensive agent captopril (IC50 0.07 mg/mL). The O-heterocyclic derivatives bearing 2H-pyran-4'-carboxylate (1) and 2H-pyran-2-carboxylate (2) frameworks showed significantly greater (p < 0.05) 1, 1-diphenyl-2-picryl-hydrazil radical quenching potential {IC50 (1) 0.34 and IC50 (2) 0.45 mg/mL} compared to the standard antioxidant α-tocopherol (IC50 0.63 mg/mL). Structure-activity relationship analyses demonstrated that the electronic and lipophilic descriptors might significantly contribute towards the target bioactivities of 2H-pyranylcarboxylates (1 and 2). Molecular docking simulations were carried out for ACE inhibition, and the binding energy obtained for the compounds (~7.04-8.48 kcal/mol) demonstrated their potential enzyme-ligand interactions. The potential of hitherto undescribed O-heterocyclic derivatives as natural antioxidant and antihypertensive functional food supplements and their utilization as therapeutic leads in the antihypertensive management were described in the present study.

Effect of antioxidant compounds from seaweeds on storage stability of C20-22 polyunsaturated fatty acid concentrate prepared from dogfish liver oil

Ethyl acetate extracts of seaweeds were chromatographically fractionated to yield 14-methyl pentyl tetrahydro-8-hydroxy-10-methylnaphthalene-8-carboxylate (1) and tetrahydro-4-isopropyl-9-(9, 14-dimethyldec-9-enyl)-pyran-1-one (2) from Sargassum ilicifolium, whereas Padina gymnospora afforded dihydro-2-(10-(hydroxymethyl)-7,15-dimethyl-9-oxoundec-11-enyl)-2-methyl-2H-pyran-1(4H)-one (3) and 1-(decahydro-1-hydroxy-7-methyl-8-vinylnaphthalen-2-yl)ethanone (4) as major constituents. Compound 1 displayed significantly higher antioxidant activity (IC50 < 1 mg/mL, p < 0.05) comparable to other analogues (IC50 > 1 mg/mL). The C20-22 polyunsaturated fatty acid (C20-22 PUFA) concentrate (CFA) prepared from the deep-sea dogfish liver oil was added with the studied compounds and physiochemical properties and fatty acid composition during an accelerated storage were evaluated. No significant reduction in C20-22 PUFAs (∼6%) in the CFA treated with 1 as compared to that with the control (∼35%) was recorded. A greater induction time was observed for the CFA supplemented with 1 (6.8 h) than other compounds (≤6 h) and control (∼1.6 h), maintaining the oxidation indices of the CFA within desirable limits.

First report of bioactive sterols from the muricid gastropod Chicoreus ramosus

Two unusual △⁵ sterols with unprecedented skeletons were isolated from the organic extract of muricid gastropod Chicoreus ramosus collected off the Gulf of Mannar Coast. This is the first report of isolation of bioactive sterols endowed with anti-inflammatory potentials from this species. The compounds were characterized as (5Z)-24a-homo-cholesta-5,24a¹(24a²) dien-3β-ol (1) and 27(25 → 23)-abeo-(5Z)-3β-hydroxy-24-isopropyl cholesteno-26,23-lactone (2) by the interpretation of a series of spectroscopic techniques involving two-dimensional nuclear magnetic resonance and mass spectral data. The compound 1 is unusual in that it has an ethylene attachment stemming from the additional methylene group at the 24a position of the steroid side chain, whereas compound 2 has a unique side chain bearing a γ-valerolactone ring. The △⁵ sterol bearing ethylene group (1) displayed comparatively better antidiabetic activity as characterized by inhibitory effects towards α-amylase and α-glucosidase enzymes (IC₅₀ 1.97 mM and 1.78 mM, respectively), whereas the cholestenolactone analogue (2) manifested higher anti-inflammatory activity (IC₅₀ 1.42 mM) as determined by in vitro 5-lipoxygenase inhibitory potential. Structure-activity correlation study showed that the biological activities of the studied sterols were directly related to their electronic properties. The homosterol (1) exhibiting improved antidiabetic properties showed higher lipophilic character coupled with lesser steric restrictions.

Previously undisclosed bioactive sterols from corbiculid bivalve clam Villorita cyprinoides with anti-inflammatory and antioxidant potentials

The estuarine Corbiculid bivalve black clam, Villorita cyprinoides collected from the Southwestern coastline regions of Arabian Sea are significant resources of nutritional and bioactive pluralities. The purification of ethyl acetate:methanol (EtOAc:MeOH) extract of V. cyprinoides characterized a previously undisclosed specialized abeo-pregnane-type sterol derivative 19 (10 → 5) abeo-20-methyl-pregn-10-en-3β-yl-hex-(3'E)-enoate (1) along with two cholestenols (22E),(24¹E)-24¹,24²-dihomocholesta-5,22,24¹-trien-3β-ol (2) and (22E)-24¹-homocholesta-5,22-dien-(3β,24¹β)-diol (3). These compounds were characterized by comprehensive spectroscopic investigations. The anti-inflammatory (anti-cyclooxygenase-1, 2/5-lipoxidase) activities of 1 were considerably higher (IC₅₀ < 1.10 mg/mL) than 2-3 (IC₅₀ > 1.10 mg/mL). These studied compounds registered greater selectivity indices (∼1.03) against cyclooxygenase-2 than cyclooxygenase-1. The antioxidant property of abeo-pregnane-type sterol as determined by in vitro 2,2'-azino-bis-(3-ethyl-benzthiazoline-6-sulfonic acid) quenching potential was significantly greater (IC₅₀ 0.94 mg/mL) than those of substituted dihomocholesta-trien-ol (2) and homocholesta-dien-diol (3) (IC₅₀ > 1.00 mg/mL). Structure-activity relationship studies demonstrated that bioactive potentials of the titled compounds were linearly related to their electronic factors along with optimum hydrophobic factors. In addition, molecular docking studies were performed in the active sites of COX-2 and their binding energies and docking scores were well correlated with in vitro anti-COX-2 potentials.

FAST implementation in Bangladesh: high frequency of unsuspected tuberculosis justifies challenges of scale-up

SETTING

National Institute of Diseases of the Chest and Hospital, Dhaka; Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic Disorders, Dhaka; and Chittagong Chest Disease Hospital, Chittagong, Bangladesh.

OBJECTIVE

To present operational data and discuss the challenges of implementing FAST (Find cases Actively, Separate safely and Treat effectively) as a tuberculosis (TB) transmission control strategy.

DESIGN

FAST was implemented sequentially at three hospitals.

RESULTS

Using Xpert® MTB/RIF, 733/6028 (12.2%, 95%CI 11.4-13.0) patients were diagnosed with unsuspected TB. Patients with a history of TB who were admitted with other lung diseases had more than twice the odds of being diagnosed with unsuspected TB as those with no history of TB (OR 2.6, 95%CI 2.2-3.0, P < 0.001). Unsuspected multidrug-resistant TB (MDR-TB) was diagnosed in 89/1415 patients (6.3%, 95%CI 5.1-7.7). Patients with unsuspected TB had nearly five times the odds of being diagnosed with MDR-TB than those admitted with a known TB diagnosis (OR 4.9, 95%CI 3.1-7.6, P < 0.001). Implementation challenges include staff shortages, diagnostic failure, supply-chain issues and reliance on external funding.

CONCLUSION

FAST implementation revealed a high frequency of unsuspected TB in hospitalized patients in Bangladesh. Patients with a previous history of TB have an increased risk of being diagnosed with unsuspected TB. Ensuring financial resources, stakeholder engagement and laboratory capacity are important for sustainability and scalability.

Production and Biotechnological Application of Extracellular Alkalophilic Lipase from Marine Macroalga-Associated Shewanella algae to Produce Enriched C20-22 n-3 Polyunsaturated Fatty Acid Concentrate

An extracellular alkalophilic lipase was partially purified from heterotrophic Shewanella algae (KX 272637) associated with marine macroalgae Padina gymnospora. The enzyme possessed a molecular mass of 20 kD, and was purified 60-fold with a specific activity of 36.33 U/mg. The enzyme exhibited Vmax and Km of 1000 mM/mg/min and 157 mM, respectively, with an optimum activity at 55 °C and pH 10.0. The catalytic activity of the enzyme was improved by Ca2+ and Mg2+ ions, and the enzyme showed a good tolerance towards organic solvents, such as methanol, isopropanol, and ethanol. The purified lipase hydrolyzed the refined liver oil from leafscale gulper shark Centrophorus squamosus, yielding a total C20-22 n-3 PUFA concentration of 34.99% with EPA + DHA accounting the major share (34% TFA), after 3 h of hydrolysis. This study recognized the industrial applicability of the thermostable and alkalophilic lipase from marine macroalga-associated bacterium Shewanella algae to produce enriched C20-22 n-3 polyunsaturated fatty acid concentrate.