Metabolic Profiling, GC-MS, LC-ESI-MS/MS Analysis, Phenolics Isolation and Biological Evaluation of the Aerial Parts Extracts of Felicia abyssinica L.

Felicia abyssinica L., family Asteraceae, is widely used in folk medicine. This represents the first study to investigate its phytoconstituents and pharmacological effects. Phytoconstituents identified by GC-MS, LC-ESI-MS/MS-based metabolomics, and NMR (1D & 2D). GC-MS of the (FAMEs) revealed mainly the identification of 55 fatty acids. LC-ESI-MS/MS analysis resulted in the tentative identity of 13 compounds representing flavonoids, phenolics, and fatty acids. Ethyl acetate fraction exhibited the highest total flavonoids 66.19 mg/mL Rutin equivalent, while the methanolic fraction showed the highest phenolics 87.70 mg/mL gallic acid equivalent, and the total condensed tannins were 64.35 µg CE/mg catechins equivalent. A flavonoid and a cinnamic acid derivative were identified as quercetin 3-O-(2'''-O-acetyl) rutinoside (Mumikotin A) (1) and Methyl sinapate (2). Biological evaluation of antioxidant and cytotoxic activities was carried out. Cytotoxicity was examined on HepG-2 cell lines where the average cell viability was 91.42 % and 52.48 % for concentrations 10 and 100 µg/mL respectively. Methylene chloride and methanolic fractions showed the highest antioxidant activity 225 µg/mL Ascorbic acid equivalents. It is hypothesized that high phenolics, flavonoid content, and oxygenated identified compounds contribute to the antioxidant activity and can be regarded as a promising species for nutraceuticals active antioxidants with potential value for remedy.

Cladamide: a new ceramide from the endophytic fungus Cladosporium cladosporioides.

A new ceramide, named cladamide (1), in addition to cinnamic acid (2), para-coumaric acid (3), stigmasterol-3-O-ß-D-glucoside (4), and uracil (5), was isolated from the white beans culture of Cladosporium cladosporioides, a marine-derived endohpytic fungus isolated from the leaves of the mangrove, Avicennia marina (Forssk.) Vierh. Structure elucidation of compound 1 was established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with HR-ESI-MS. The ability of the isolated compounds to inhibit acetylcholine esterase was evaluated. Compound 3 showed the highest acetylcholine esterase inhibitory activity (IC50 = 0.057 ± 0.003 µM), followed by compound 4 (IC50 = 0.068 ± 0.003 µM) and compound 1 (IC50 = 0.099 ± 0.005 µM) compared to donepezil, the positive control, (IC50 = 0.044 ± 0.002 µM). Compounds 2 and 5 showed lower activity (IC50 = 0.182 ± 0.009 and 0.236 ± 0.012 µM, respectively). The results were further validated by molecular docking study.

In vitro and in silico studies of SARS-CoV-2 main protease Mpro inhibitors isolated from Helichrysum bracteatum.

Discovering SARS-CoV-2 inhibitors from natural sources is still a target that has captured the interest of many researchers. In this study, the compounds (1-18) present in the methanolic extract of Helichrysum bracteatum were isolated, identified, and their in vitro inhibitory activities against SARS-CoV-2 main protease (Mpro) was evaluated using fluorescence resonance energy transfer assay (FRET-based assay). Based on 1D and 2D spectroscopic techniques, compounds (1-18) were identified as 24-ß-ethyl-cholesta-5(6),22(23),25(26)-triene-3-ol (1), α-amyrin (2), linoleic acid (3), 24-ß-ethyl-cholesta-5(6),22(23),25(26)-triene-3-O-ß-d-glucoside (4), 1,3-propanediol-2-amino-1-(3',4'-methylenedioxyphenyl) (5), (-)-(7R,8R,8'R)-acuminatolide (6), (+)-piperitol (7), 5,7,4'-trihydroxy-8,3'-dimethoxy flavanone (8), 5,7,4'-trihydroxy-6-methoxy flavanone (9), 4',5-dihydroxy-3',7,8-trimethoxyflavone (10), 5,7-dihydroxy-3',4',5',8-tetramethoxy flavone (11), 1,3-propanediol-2-amino-1-(4'-hydroxy-3'-methoxyphenyl) (12), 3',5',5,7-tetrahydroxy-6-methoxyflavanone (13), simplexoside (piperitol-O-ß-d-glucoside) (14), pinoresinol monomethyl ether-ß-d-glucoside (15), orientin (16), luteolin-3'-O-ß-d-glucoside (17), and 3,5-dicaffeoylquinic acid (18). Compounds 6, 12, and 14 showed comparable inhibitory activities against SARS-CoV-2 Mpro with IC50 values of 0.917 ± 0.05, 0.476 ± 0.02, and 0.610 ± 0.03 µM, respectively, compared with the control lopinavir with an IC50 value of 0.225 ± 0.01 µM. The other tested compounds showed considerable inhibitory activities. The molecular docking study for the tested compounds was carried out to correlate their binding modes and affinities for the SARS-CoV-2 Mpro enzyme with the in vitro results. Analyzing the results of the in vitro assay together with the obtained in silico results led to the conclusion that phenylpropanoids, lignans, and flavonoids could be considered suitable drug leads for developing anti-COVID-19 therapeutics. Moreover, the phenylpropanoid skeleton oxygenated at C3, C4 of the phenyl moiety and at C1, C3 of the propane parts constitute an essential core of the SARS-CoV-2 Mpro inhibitors, and thus could be proposed as a scaffold for the design of new anti-COVID-19 drugs.

Westalsan: A New Acetylcholine Esterase Inhibitor from the Endophytic Fungus Westerdykella nigra.

A new cytochalasan alkaloid, westalsan (1), along with two known cytochalasan compounds, phomacin B (2) and 19-hydroxy-19,20-dihydrophomacin C (3), were isolated from the solid rice culture of Westerdykella nigra, a marine-derived endophytic fungus, isolated from the roots of mangrove Avicennia marina (Forssk.) Vierh. The structures of compounds 1-3 were established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with HR-ESI-MS. The ability of the isolated compounds to inhibit acetylcholine esterase activity was evaluated. Compound 3 showed the highest acetylcholine esterase inhibitory activity (IC50 0.056±0.003 µM), followed by compound 1 (IC50 0.088±0.005 µM) and compound 2 (IC50 0.140±0.007 µM) compared to donepezil (IC50 0.035±0.002 µM). This was further confirmed by molecular docking experiment.

New prenylated flavonoid and neuroprotective compounds from Tephrosia purpurea subsp. dunensis.

Continuation of the phytochemical investigation of the aerial parts of Tephrosia purpurea subsp. dunensis resulted in the isolation and structural elucidation of a new prenylated flavonoid demeapollinin (1), glabratephrinol (2) and a mixture (3) of tephroapollin G (3a) and epi-tephroapollin G (3b). The neuroprotective activity of compounds (1-3) besides the previously isolated compounds; dunensin (4), pseudosemiglabrin (6), glabratephrin (7), apollinin (5), kampferol 3, 7-O-α-L-dirhamnoside (8) and quercetin 3, 7-O-α-L-dirhamnoside (9) was examined. Molecular docking, acetylcholine esterase inhibitory assay and protection against both H2O2 and induced neurotoxicity were used to evaluate their neuroprotective effect. Compound 2 showed the highest acetylcholine esterase inhibitory activity (IC50 4.31 ± 0.75 µM) compared to galantamine (IC50 1.64 ± 0.32 µM), compounds 4 and 3 exhibited potent protective effect against induced neurotoxicity (IC50 7.70 ± 5.23 and 10.91 ± 6.27 µM, respectively) compared to standard epigallocatechin gallate (IC50 18.36 ± 6.22 µM).

Melanogenesis Inhibitors from the Endophytic Fungus Aspergillus amstelodami.

Two new compounds, named 3,4-dimethoxyphenyl α-d-ribofuranoside (1) and 3ß-(ß-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.

Acetylcholine esterase inhibitors and melanin synthesis inhibitors from Salvia officinalis.

BACKGROUND: Salvia officinalis is a traditionally used herb with a wide range of medicinal applications. Many phytoconstituents have been isolated from S. officinalis, mainly phenolic diterpenes, which possess many biological activities. PURPOSE: This study aimed to evaluate the ability of the phenolic diterpenes of S. officinalis to inhibit acetylcholine esterase (AChE) as well as their ability to inhibit melanin biosynthesis in B16 melanoma cells. METHODS: The phenolic diterpenes isolated from the aerial parts of S. officinalis were tested for their effect on melanin biosynthesis in B16 melanoma cell lines. They were also tested for their ability to inhibit AChE using Ellman's method. Moreover, a molecular docking experiment was used to investigate the binding affinity of the isolated phenolic diterpenes to the amino acid residues at the active sites of AChE. RESULTS: Seven phenolic diterpenes-sageone, 12-methylcarnosol, carnosol, 7b-methoxyrosmanol, 7a-methoxyrosmanol, isorosmanol and epirosmanol-were isolated from the methanolic extract of the aerial parts of S. officinalis. Isorosmanol showed a melanin-inhibiting activity as potent as that of arbutin. Compounds 7a-methoxyrosmanol and isorosmanol inhibited AChE activity by 50% and 65%, respectively, at a concentration of 500 µM. CONCLUSIONS: The results suggest that isorosmanol is a promising natural compound for further studies on development of new medications which might be useful in ageing disorders such as the declining of cognitive functions and hyperpigmentation.

New ent-kaurane diterpenoid dimer from Pulicaria inuloides.

A new naturally occurring ent-kaurane diterpenoid dimer, 15ß, 15'ß-oxybis (ent-kaur-16-en-19-oic acid) (1) along with six known compounds, 15ß-hydroxy-ent-kaur-16-en-19-oic acid (2), 15ß-hydroxy-ent-kaur-16-en-19-oate-ß-d-glucopyranoside (3), 6-hydroxykaempferol-3, 7-dimethyl ether (4), quercetagetin 3, 7, 3'-trimethyl ether (5), ß-sitosterol (6) and ß-sitosterol glucoside (daucosterol) (7) were isolated from the aerial parts of Pulicaria inuloides DC. Compounds 2-5 were isolated for the first time from genus Pulicaria. The structures of compounds 1-7 were established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with ESI-MS. The antimicrobial activity of the isolated compounds was evaluated against Staphylococcus aureus, Escherichia coli and Candida albicans. Sulphorhodamine B cytotoxic assay against HepG2 (liver cancer) cell line and ABTS antioxidant assay were carried out.

Diterpenoids from Fagonia mollis.

A new acyclic diterpenoid (1) and a new erythroxan diterpenoid (2), together with 4 erythroxan diterpenoids and 3 triterpenoids, have been isolated from the aerial parts of Fagonia mollis. Their structures were elucidated on the basis of 1D and 2D NMR data. The cytotoxic activity of the isolated compounds was investigated against HL-60 cancer cells.

Essential oil of Daucus glaber Forssk.

The composition of the essential oil of the fruits, leaves and stems of Daucus glaber Forssk has been studied by GC/MS. It was found that, the essential oil of the fruits consists of monoterpene hydrocarbons (limonene and sylvestrene are the majors) and phenylpropanoids (elemicin is the major). Sylvestrene has never been reported before in the essential oil of any Daucus species. The study of the essential oil of the leaves revealed the presence of monoterpene hydrocarbons; limonene and gamma-terpinene are the majors and a small amount of sylvestrene. The essential oil of stems consists of monoterpene hydrocarbons (gamma-terpinene is the major), terpene alcohols (mainly 4-terpineol) and phenylpropanoids (myristicin and elemicin are the majors). It is interesting that, the essential oil of the fruits is free from any oxygenated terpenes while that of the stems is free from limonene and sylvestrene which are present in the essential oil of the fruits and leaves in fairly large amounts The essential oil of the fruits, leaves and stems shows broad antimicrobial activities against both gram positive and gram negative bacteria. In addition, the volatile oil of the stem, particularly, show activities against Candida albicans (yeast). Also, the prepared oils have variable cytotoxic activities with LC50 21.52, 36.01 and 42.34 microg/ml, respectively.