Phytochemistry, biological activities and in silico molecular docking studies of Oxalis pes-caprae L. compounds against SARS-CoV-2

Phytochemicals are directly involved in therapeutic treatment or precursors to synthesize useful drugs. The current study was aimed to evaluate the phytocompounds and their biopotentials using methanolic and n-hexane extracts of various parts of Oxalis pes-caprae. For the phytochemical analysis, standard procedures were used, whereas Aluminum Chloride reagent and Follin-ciocalteau reagent methods were used to determine total flavonoid and phenolic contents. Radical scavenging DPPH, phosphomolybdenum reduction, and reducing power assays were used to assess antioxidative potentials. Antibacterial potential was determined by applying disc diffusion method while cytotoxicity was determined employing brine shrimp assay. FT-IR (Fourier-transform infrared) analysis was utilized to gather spectral information, while molecular docking tools were employed to look at how O. pes-caprae plant-based ligands interact with the target protein COVID-19 3CLPro (PDB:6LU7). Phenols, flavonoids, alkaloids and saponins were tested positive in preliminary phytochemical studies. TPC and TFC in different extracts ranging from (38.55 ± 1.72) to (65.68 ± 0.88) mg/g GAE/g and (24.75 ± 1.80) to (14.83 ± 0.92) mg/g QUE/g were used respectively. IC₅₀ value (24.75 ± 0.76 g/mL) by OXFH, total antioxidant capacity (55.89 ± 1.75) mg/g by OXLM, reducing potential (34.98 ± 1.089) mg/g by OXSM, maximum zone of inhibition against B. subtilis (24 ± 0.65 mm) by OXLM and maximum cytotoxicity 96% with LD₅₀ 19.66 (μg/mL) by OXSM were the best calculated values among all extracts. Using molecular docking, it was found that Caeruleanone A, 2',4'-Dihydroxy-2″-(1-hydroxy-1-methylethyl) dihydrofuro [2,3-h] flavanone and Vadimezan demonstrated best affinity with the investigated SARS CoV-2 Mpro protein. This work provide justification about this plant as a source of effective phytochemicals and their potential against microbes could lead to development of biosafe drugs for the welfare of human being. In future, different in vitro and in vivo biological studies can be performed to further investigate its biomedical potentials.

Anti-barnacle biofouling coatings for the protection of marine vessels: synthesis and progress

Marine biofouling has gnawed both mobile and non-mobile marine structures since time immemorial, leading to the deterioration of designed operational capabilities as well as a loss of valuable economic revenues. Mitigation of biofouling has been the primary focus of researchers and scientists from across the globe to save billions of dollars wasted due to the biological fouling of marine structures. The availability of an appropriate environment along with favorable substrata initiates biofilm formation within a few minutes. The crucial element in establishing a gelatinous biofilm is the excreted metabolites of destructive nature and exopolymeric substances (EPSs). These help in securing as well as signaling numerous foulants to establish themselves on this substrate. The larvae of various benthic invertebrates adhere to these suitable surfaces and transform from juveniles to adult barnacles depending upon the environment. Despite biofouling being characteristically witnessed for a month or lengthier timeframe, the preliminary phases of the fouling process typically transpire on a much lesser timescale. A few natural and synthetic additives had demonstrated excellent non-toxic anti barnacle establishment capability; however, further development into commercial products is still far-fetched. This review collates the specific anti-barnacle coatings, emphasizing natural additives, their sources of extraction, general life cycle analysis, and concluding future perspectives of this niche product.

Chemical Review of Gorgostane-Type Steroids Isolated from Marine Organisms and Their 13C-NMR Spectroscopic Data Characteristics

Gorgostane steroids are isolated from marine organisms and consist of 30 carbon atoms with a characteristic cyclopropane moiety. From the pioneering results to the end of 2021, isolation, biosynthesis, and structural elucidation using ¹³C-NMR will be used. Overall, 75 compounds are categorized into five major groups: gorgost-5-ene, 5,6-epoxygorgostane, 5,6-dihydroxygorgostane, 9,11-secogorgostane, and 23-demethylgorgostane, in addition to miscellaneous gorgostane. The structural diversity, selectivity for marine organisms, and biological effects of gorgostane steroids have generated considerable interest in the field of drug discovery research.

Overcoming environmental problems of biocides: Synthetic bile acid derivatives as a sustainable alternative

Marine biofouling represents a global economic and ecological challenge. Some marine organisms produce bioactive metabolites, such as steroids, that inhibit the settlement and growth of fouling organisms. The aim of this work was to explore bile acids as a new scaffold with antifouling (AF) activity by using chemical synthesis to produce a series of bile acid derivatives with optimized AF performance and understand their structure-activity relationships. Seven bile acid derivatives were successfully synthesized in moderate to high yields, and their structures were elucidated through spectroscopic methods. Their AF activities were tested against both macro- and microfouling communities. The most potent bile acid against the settlement of Mytilus galloprovincialis larvae was the methyl ester derivative of cholic acid (10), which showed an EC₅₀ of 3.7 μM and an LC₅₀/EC₅₀ > 50 (LC₅₀ > 200 μM) in AF effectiveness vs toxicity studies. Two derivatives of deoxycholic acid (5 and 7) potently inhibited the growth of biofilm-forming marine bacteria with EC₅₀ values < 10 μM, and five bile acids (1, 5, and 7-9) potently inhibited the growth of diatoms, showing EC₅₀ values between 3 and 10 μM. Promising AF profiles were achieved with some of the synthesized bile acids by combining antimacrofouling and antimicrofouling activities. Initial studies on the incorporation of one of these promising bile acid derivatives in polymeric coatings, such as a marine paint, demonstrated the ability of these compounds to generate coatings with antimacrofouling activity.

Antifouling Compounds from Marine Invertebrates

In this review, a comprehensive overview about the antifouling compounds from marine invertebrates is described. In total, more than 198 antifouling compounds have been obtained from marine invertebrates, specifically, sponges, gorgonian and soft corals.

Marine Indole Alkaloids

Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed.

Antifouling potentials of eight deep-sea-derived fungi from the South China Sea

Marine-derived microbial secondary metabolites are promising potential sources of nontoxic antifouling agents. The search for environmentally friendly and low-toxic antifouling components guided us to investigate the antifouling potentials of eight novel fungal isolates from deep-sea sediments of the South China Sea. Sixteen crude ethyl acetate extracts of the eight fungal isolates showed distinct antibacterial activity against three marine bacteria (Loktanella hongkongensis UST950701–009, Micrococcus luteus UST950701–006 and Pseudoalteromonas piscida UST010620–005), or significant antilarval activity against larval settlement of bryozoan Bugula neritina. Furthermore, the extract of Aspergillus westerdijkiae DFFSCS013 displayed strong antifouling activity in a field trial lasting 4 months. By further bioassay-guided isolation, five antifouling alkaloids including brevianamide F, circumdatin F and L, notoamide C, and 5-chlorosclerotiamide were isolated from the extract of A. westerdijkiae DFFSCS013. This is the first report about the antifouling potentials of metabolites of the deep-sea-derived fungi from the South China Sea, and the first stage towards the development of non- or low-toxic antifouling agents from deep-sea-derived fungi.

Antifouling Indole Alkaloids from Two Marine Derived Fungi

In order to find non-toxic antifouling natural products from marine microorganisms, the chemical constituents of two marine derived fungi Penicillium sp. and Aspergillus sydowii have been investigated under bio-guided fractionation. A new indolyl diketopiperazine compound, penilloid A (1), together with 15 known ones were isolated from these two strains. The structure of 1 was elucidated on the basis of NMR and mass spectra. Some alkaloids showed significant antifouling and antibacterial activities. The results indicate that indole alkaloids could be a potential antifouling agent resource.

Marine natural products

Covering: 2010. Previous review: Nat. Prod. Rep., 2011, 28, 196. This review covers the literature published in 2010 for marine natural products, with 895 citations (590 for the period January to December 2010) 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 (1003 for 2010), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Polyhydroxylated steroids from the bamboo coral Isis hippuris

In previous studies on the secondary metabolites of the Taiwanese octocoral Isis hippuris, specimens have always been collected at Green Island. In the course of our studies on bioactive compounds from marine organisms, the acetone-solubles of the Taiwanese octocoral I. hippuris collected at Orchid Island have led to the isolation of five new polyoxygenated steroids: hipposterone M–O (1–3), hipposterol G (4) and hippuristeroketal A (5). The structures of these compounds were determined on the basis of their spectroscopic and physical data. The anti-HCMV (human cytomegalovirus) activity of 1–5 and their cytotoxicity against selected cell lines were evaluated. Compound 2 exhibited inhibitory activity against HCMV, with an EC₅₀ value of 6.0 μg/mL.