Chemical Composition of the Red Sea Green Algae Ulva lactuca: Isolation and In Silico Studies of New Anti-COVID-19 Ceramides

Coronavirus disease 2019 (COVID-19) is the disease caused by the virus SARS-CoV-2 responsible for the ongoing pandemic which has claimed the lives of millions of people. This has prompted the scientific research community to act to find treatments against the SARS-CoV-2 virus that include safe antiviral medicinal compounds. The edible green algae U. lactuca. is known to exhibit diverse biological activities such as anti-influenza virus, anti-Japanese encephalitis virus, immunomodulatory, anticoagulant, antioxidant and antibacterial activities. Herein, four new ceramides in addition to two known ones were isolated from Ulva lactuca. The isolated ceramides, including Cer-1, Cer-2, Cer-3, Cer-4, Cer-5 and Cer-6 showed promising antiviral activity against SARS-CoV-2 when investigated using in silico approaches by preventing its attachment to human cells and/or inhibiting its viral replication. Cer-4 and Cer-5 were the most effective in inhibiting the human angiotensin converting enzyme (hACE)–spike protein complex which is essential for the virus to enter the human host. In addition to this, Cer-4 also showed an inhibition of the SARS-CoV-2 protease (Mpro) that is responsible for its viral replication and transcription. In this study, we also used liquid chromatography coupled to electrospray ionization high-resolution mass spectroscopy (LC–ESI–HRMS) to identify several metabolites of U. lactuca, including metabolites such as fatty acids, their glyceride derivatives, terpenoids, sterols and oxysterols from the organic extract. Some of these metabolites also possessed promising antiviral activity, as previously reported.

Structure elucidation of the novel carotenoid gemmatoxanthin from the photosynthetic complex of Gemmatimonas phototrophica AP64

Gemmatimonas phototrophica AP64 is the first phototrophic representative of the bacterial phylum Gemmatimonadetes. The cells contain photosynthetic complexes with bacteriochlorophyll a as the main light-harvesting pigment and an unknown carotenoid with a single broad absorption band at 490 nm in methanol. The carotenoid was extracted from isolated photosynthetic complexes, and purified by liquid chromatography. A combination of nuclear magnetic resonance (1H NMR, COSY, 1H-13C HSQC, 1H-13C HMBC, J-resolved, and ROESY), high-resolution mass spectroscopy, Fourier-transformed infra-red, and Raman spectroscopy was used to determine its chemical structure. The novel linear carotenoid, that we have named gemmatoxanthin, contains 11 conjugated double bonds and is further substituted by methoxy, carboxyl and aldehyde groups. Its IUPAC-IUBMB semi-systematic name is 1′-Methoxy-19′-oxo-3′,4′-didehydro-7,8,1′,2′-tetrahydro- Ψ, Ψ carotene-16-oic acid. To our best knowledge, the presence of the carboxyl, methoxy and aldehyde groups on a linear C40 carotenoid backbone is reported here for the first time.

Kokosanolide D: A New Tetranortriterpenoid from Fruit Peels of Lansium domesticum Corr. cv Kokossan

A novel tetranortriterpenoid named kokosanolide D has been isolated from fruit peels of Lansium domesticum. The structure of kokosanolide D was elucidated primarily on the basis of spectroscopic data including infrared, 1D and 2D-NMR, as well as high resolution mass spectroscopy analysis and comparison with related compounds previously reported.

Synthesis and Characterization of Nickel(II) Homogeneous and Supported Complexes for the Hydrogenation of Furfural to Furfuryl Alcohol

Nickel(II) complexes have been synthesized and characterized using nuclear magnetic resonance (NMR), infrared spectroscopy, high resolution mass spectroscopy, and elemental analysis. The complexes were evaluated as pre-catalysts in the direct hydrogenation of furfural to furfuryl alcohol. The pre-catalysts C1 and C4 gave higher furfural conversion (97% and 96%, respectively), as a result, they were also evaluated in the transfer hydrogenation of furfural using formic acid as the hydrogen source where higher furfural conversion (93%) was obtained and selectivity (100%) toward the formation of furfuryl alcohol at 4 h. The catalyst C1 was recycled three times with and it was observed that the catalytic activity might be due to a mixture of both molecular catalysis and nanoparticles, as evidenced by the decrease in activity in mercury poisoning experiments. The hydrogenation reactions were also extended to alpha-β unsaturated substrates and were selective toward saturation of the carbonyl functionality over alkene groups.

Structure elucidation of the novel carotenoid gemmatoxanthin from the photosynthetic complex of Gemmatimonas phototrophica AP64

Gemmatimonas phototrophica AP64 is the first phototrophic representative of bacterial phylum Gemmatimonadetes. The cells contain photosynthetic complexes with bacteriochlorophyll a as the main light-harvesting pigment. In addition, the complexes contain a carotenoid with a single broad absorption band at 490 nm in methanol. A combination of nuclear magnetic resonance, high-resolution mass spectroscopy and Fourier-transformed infra-red spectroscopy was used to determine the chemical structure of G. phototrophica light-harvesting carotenoid that we have named gemmatoxanthin. It is a novel linear carotenoid containing 11 conjugated double bonds and further substituted by methoxy, carboxyl and aldehyde group. Its IUPAC-IUBMB semi-systematic name is 1’-Methoxy-19’-oxo-3’,4’-didehydro-7,8,1’,2’-tetrahydro- Ψ, Ψ carotene-16-oic acid. To our best knowledge, the presence of the carboxyl, methoxy and aldehyde groups on a linear C40 carotenoid backbone is reported here for the first time.

Untargeted analysis of first trimester serum to reveal biomarkers of pregnancy complications: a case–control discovery phase study

Understanding of causal biology and predictive biomarkers are lacking for hypertensive disorders of pregnancy (HDP) and preterm birth (PTB). First-trimester serum specimens from 51 cases of HDP, including 18 cases of pre-eclampsia (PE) and 33 cases of gestational hypertension (GH); 53 cases of PTB; and 109 controls were obtained from the Global Alliance to Prevent Prematurity and Stillbirth repository. Metabotyping was conducted using liquid chromatography high resolution mass spectroscopy and nuclear magnetic resonance spectroscopy. Multivariable logistic regression was used to identify signals that differed between groups after controlling for confounders. Signals important to predicting HDP and PTB were matched to an in-house physical standards library and public databases. Pathway analysis was conducted using GeneGo MetaCore. Over 400 signals for endogenous and exogenous metabolites that differentiated cases and controls were identified or annotated, and models that included these signals produced substantial improvements in predictive power beyond models that only included known risk factors. Perturbations of the aminoacyl-tRNA biosynthesis, l-threonine, and renal secretion of organic electrolytes pathways were associated with both HDP and PTB, while pathways related to cholesterol transport and metabolism were associated with HDP. This untargeted metabolomics analysis identified signals and common pathways associated with pregnancy complications.

3-Hydroxy-8,14-secogammacera-7,14-dien-21-one: A New Onoceranoid Triterpenes from Lansium domesticum Corr. cv kokossan

A new onoceranoid triterpenes, namely 3-hydroxy-8,14-secogammacera-7,14-dien-21-one (1), has been isolated from the fruit peels of Lansium domesticum Corr. cv kokossan. The structure of 1 was determined on the basis of spectroscopic data including infrared, 1D and 2D-NMR, as well as high resolution mass spectroscopy analysis. Compound 1 showed a weak activity against MCF-7 breast cancer cell lines.

5,5′-Oxybis(1,3,7-trihydroxy-9H-xanthen-9-one): A New Xanthone from the Stem Bark of Garcinia porrecta (Clusiaceae)

A new polyoxygenated dimer-type xanthone, namely 5,5′-oxybis(1,3,7-trihydroxy-9H-xanthen-9-one (1), has been isolated from the stem bark of Garcinia porrecta. The structure of 1 was determined based on spectroscopic data, including 1D and 2D-NMR as well as high resolution mass spectroscopy analysis.