Eleven compounds were isolated from the ethyl acetate extract of
Cocos nucifera
L endocarp, jezonofol
1
, scirpusin A
2
, cassigarol G
3
, maackin A
4
, threoguiacyl glycerol-8’-vanillic acid ether
5
, erythroguiacyl glycerol-8’-vanillic acid ether
6
, apigenin-7-
O
-
β
-D-glucoside
7
, piceatannol
8
,
p
-hydroxy-benzoic acid
9
, protocatechuic acid
10
and vanillic acid
11
. Compounds
1
-
7
were isolated for the first time from the plant. The isolated compounds were virtually screened against four critical components of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), the main protease (M
pro
), papain-like protease (PL
pro
), nonstructural protein 13 (nsp13) and RNA dependent RNA polymerase (RdRp). Stilbene dimers
1-4
showed remarkable binding affinities towards the investigated targets (binding energy <−7.6 kcal/mol). Compounds
1, 3
and
4
interacted with the catalytic dyad (Cys145-His41) at the active pocket of M
pro
which is essential for achieving good inhibitory activity. Compounds
1
-
3
showed molecular interaction with the conserved ubiquitin-specific protease residues of PL
pro
, responsible for binding ability at different active sites of nsp13, which are crucial for decreasing the resistance caused by viral immune evasion. Compounds
2
and
3
showed the ability to bind at different active sites of nsp13, which is a key binding site for reducing antiviral resistance. Finally, compounds
1
-
3
showed the ability to bind with RdRp before and after RNA binding. Our findings suggested that the dimeric stilbene skeleton is a promising candidate for developing anti-COVID-19 drugs. Particularly,
1, 2
and
3
, showed a promiscuity pattern binding to multiple targets of SARS-CoV-2 replication. Herein, 20 ns molecular dynamics (MD) simulations combined with molecular mechanics-generalized Born surface area (MM-GBSA) binding energy calculations were performed to estimate the binding affinity of the most potent three compounds against the viral SARS-CoV-2 targets. MM-GBSA calculations unveiled the outshine potency of compound
1
towards PL
pro
with a binding energy of −60.7 kcal/mol. Structural and energetic analyses over 20 ns MD simulation displayed the high stability of compound
1
in complex with PL
...
Chromone glycosides comprise an important group of secondary metabolites. They are widely distributed in plants and, to a lesser extent, in fungi and bacteria. Significant biological activities, including antiviral, anti-inflammatory, antitumor, antimicrobial, etc., have been discovered for chromone glycosides, suggesting their potential as drug leads. This review compiles 192 naturally occurring chromone glycosides along with their sources, classification, biological activities, and spectroscopic features. Detailed biosynthetic pathways and chemotaxonomic studies are also described. Extensive spectroscopic features for this class of compounds have been thoroughly discussed, and detailed 13C-NMR data of compounds 1–192, have been added, except for those that have no reported 13C-NMR data.
Two new compounds, named 3,4‐dimethoxyphenyl α‐d‐ribofuranoside (1) and 3β‐(β‐d‐glucopyranosyloxy)olean‐12‐ene‐23,28,30‐trioic acid (2), together with thirteen known compounds, were isolated from the white beans culture of the marine derived endophytic fungus Aspergillus amstelodami. Structure elucidation of the new compounds was carried out by one‐, two‐dimensional spectroscopy, and high resolution electrospray ionization mass. The antimelanogenic and anti‐allergic activity of the isolated compounds were investigated. Compounds 4, 7, 1, 3, 11, 6 and 9 selectively suppressed melanin production in B16 melanoma cells, using arbutin as a positive control. Their IC50 values were 30.8±5.57, 38.5±6.08, 52.6±6.64, 98.0±1.16, 100.4±3.05, 112.0±0.22 and 144.7±2.35 μm, respectively, while that of arbutin was 151.7±1.27 μm. The tested compounds did not show any significant anti‐allergic activity in RBL‐2H3 cells, as compared to quercetin.
A new α-pyrone derivative, with a rare substitution pattern, was isolated from the solid rice media of the fungal endophyte Aspergillus versicolor associated with the fruit of the mangrove Avicennia marina. It was named allantopyrone E, after allantopyrones C and D.The aforementioned three are the only diaryl-substituted α-pyrones to be reported from nature. The unique structure was elucidated based on 1D and 2D-NMR spectroscopic data as well as high resolution mass spectroscopy. A biosynthetic scheme was proposed for the new compound. Furthermore, allantopyrone E showed cytotoxic effect on HeLa cells with IC 50 = 50.97 μM.
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