Naturally occurring phenylethanoids and phenylpropanoids: antimalarial potential.

Malaria as an infectious disease is one of the world's most dangerous parasitic diseases. There is an urgent need for the development of new antimalarial drugs. Natural products are a very rich source of new bioactive compounds. Our research aims to shed light on the recent studies which demonstrated the antimalarial potential of phenylpropanoids as a major natural-products class. This study involves an in silico analysis of naturally-occurring phenylpropanoids and phenylethanoids which showed 25 compounds with moderate to strong binding affinity to various amino acid residues lining the active site; P. falciparum kinase (PfPK5), P. falciparum cytochrome bc1 complex (cyt bc1), and P. falciparum lysyl-tRNA synthetase (PfKRS1); of Plasmodium falciparum parasite, a unicellular protozoan which causes the most severe and life-threatening malaria. Furthermore, the study was augmented by the assessment of antiplasmodial activity of glandularin, a naturally occurring dibenzylbutyrolactolic lignan, against chloroquine-sensitive 3D7 strain of P. falciparum using SYBR green I-based fluorescence assay, which showed high antimalarial activity with IC50 value of 11.2 µM after 24 hours of incubation. Our results highlight phenylpropanoids and glandularin in particular as a promising chemical lead for development of antimalarial drugs.

The inhibition of inducible nitric oxide production in lipopolysaccharide-stimulated rat macrophages and in silico studies by flavonoids from Iris spuria L. rhizomes.

ETHNOPHARMACOLOGICAL RELEVANCE: Iris is the largest genus in the family Iridaceae. Iris plants are distributed in tropical regions of the world. They are used as ornamentals and traditionally used to treat a variety of ailments. AIM: This study aimed to evaluate the anti-inflammatory effect of flavonoids isolated from Iris spuria L. MATERIALS AND METHODS: The isolated flavonoids (1-4) were identified on the basis of different spectroscopic methods (1D- and 2D-NMR) and co-TLC with authentic samples. The anti-inflammatory effect was tested on lipopolysaccharide (LPS)-induced nitric oxide (NO) production from rat-isolated peritoneal macrophages. Modeling and docking simulations of the compounds were performed using Molecular Operating Environment software and the crystal structure of the murine inducible nitric oxide synthase (iNOS). RESULTS: Four flavonoids (1-4) had been isolated from the rhizomes of Iris spuria L. (Hocka Hoona) for the first time. They were characterized as 5,7,2'-trihydroxy-6-methoxyflavanone (1), tectorigenin 7-O-ß-D-glucopyranoside (2), tectorigenin 4'-O-ß-D-glucopyranoside (3), and tectorigenin 4'-O-[ß-D-glucopyranosyl(1 â†’ 6)-ß-D-glucopyranoside] (4). The selective inducible NO synthase inhibitor; aminoguanidine was used as a positive control. The production of nitric oxide (NO) was inhibited in a dose-dependent manner of the isolated compounds along with isoflavonoids (5-9) previously isolated from Iris spuria L. (Calizona). A concentration of 60 µg/ml of all tested compounds showed a significant inhibitory effect compared to media with LPS. Molecular modeling experiments supported the obtained biological data. CONCLUSION: Our results reveal that flavonoids isolated from I. spuria L. (Hocka Hoona) and I. spuria L. (Calizona) appear to have a potential anti-inflammatory effect via inhibition of iNOS.

Natural coumarins as potential anti-SARS-CoV-2 agents supported by docking analysis.

COVID-19 is a global pandemic first identified in China, causing severe acute respiratory syndrome. One of the therapeutic strategies for combating viral infections is the search for viral spike proteins as attachment inhibitors among natural compounds using molecular docking. This review aims at shedding light on the antiviral potential of natural products belonging to the natural-products class of coumarins up to 2020. Moreover, all these compounds were filtered based on ADME analysis to determine their physicochemical properties, and the best 74 compounds were selected. Using virtual-screening methods, the selected compounds were investigated for potential inhibition of viral main protease (Mpro), viral methyltransferase (nsp16/10 complex), viral recognition binding domain (RBD) of S-protein, and human angiotensin-converting enzyme 2 (ACE2), which is the human receptor for viral S-protein targets, using molecular-docking studies. Promising potential results against SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) and methyltransferase (nsp16) are presented.

Chemosystematically valuable triterpenoid saponins from Glandularia x hybrida.

Phytochemical investigation of the ethanolic extract of Glandularia x hybrida roots resulted in the isolation and identification of five previously undescribed saponins, 3-O-ß-ᴅ-xylopyranosyl-hederagenin-28-O-ß-ᴅ-glucopyranosyl (1→2)-O-ß-ᴅ-glucopyranosyl ester, 3-O-ß-ᴅ-xylopyranosyl-hederagenin-28-O-ß-ᴅ-glucopyranosyl (1→2)-[ß-ᴅ-glucopyranosyl (1→6)]-ß-ᴅ-glucopyranosyl ester, hederagenin-28-O-ß-ᴅ-glucopyranosyl (1→2)-[ß-ᴅ-glucopyranosyl (1→6)]-ß-ᴅ-glucopyranosyl ester, 23-O-acetyl-3-O-ß-ᴅ-xylopyranosyl-pomolic acid-28-O-ß-ᴅ-glucopyranosyl ester, and 23-O-acetyl-pomolic acid-3-O-ß-ᴅ-xylopyranoside, along with eleven structurally diverse compounds. The structural characterizations of the isolated compounds were determined using physical data, comprehensive 1D and 2D NMR spectral analysis, and HRESIMS. All isolated saponins are hederagenin or pomolic acid glycosides conjugated with differentiable sugar units bound to C-3 and/or C-28 of the aglycone through ether and/or ester glycosidic linkages, respectively. Structural diversity of these isolated secondary metabolites would have a great impact on the future chemosystematic studies of this plant. Four saponins, obtained in good yield were evaluated for their anti-inflammatory activities in a rat model using the carrageenan-induced paw edema protocol. Two of these exhibited significant anti-inflammatory activities demonstrated through inhibition of the paw edema by 64 and 60%.

A new pentacyclic triterpenoid from the leaves of Lantana montevidensis (Spreng.) Briq.

A new pentacyclic triterpenoid, 3ß,25-epoxy-3α,22ß,23α-trihydroxy-olean-12-en-28-oic acid (1), together with seven known compounds, including five triterpenoids, ß-amyrin (2), lantadene B (3), lantanilic acid (4), lantanolic acid (5) and ursolic acid (6) in addition to ß-sitosterol (7) and benzoic acid (8) has been isolated from the leaves of Lantana montevidensis. Their chemical structures were elucidated by spectroscopic analysis and by comparison with the literature data and/or authentic samples. Compound 1 showed moderate to weak antibacterial activity against Staphylococcus aureus and Escherichia coli.

Cinnamyl alcohols and methyl esters of fatty acids from Wedelia prostrata callus cultures.

Two methyl esters of fatty acids, namely octadecanoic acid methyl ester (methyl stearate) and hexadecanoic acid methyl ester (methyl palmitate), in addition to four cinnamyl alcohol derivatives, sinapyl alcohol, coniferyl alcohol, p-coumaryl alcohol and coniferyl alcohol 4-O-glucoside (coniferin), were isolated from callus cultures of Wedelia prostrata. The structure of coniferin was established by spectroscopic and chemical methods, while the other compounds were identified by gas chromatography-mass spectrometry and thin layer chromatography in comparison with standards.

New isoflavone glycosides from Iris spuria L. (Calizona) cultivated in Egypt.

Two new isoflavone glycosides, tectorigenin 7-O-beta-D-glucopyranoside-4'-O-[beta-D-glucopyranosyl-(1''''-->6''')-beta-D-glucopyranoside] (1) and iristectorigenin B 4'-O-[beta-D-glucopyranosyl-(1'' --> 6'')-beta-D-glucopyranoside] (2), together with 11 known compounds, including six isoflavones, tectorigenin 7-O-beta-D-glucopyranoside-4'-O-beta-D-glucopyranoside (3), tectorigenin 4'-O-[beta-D-glucopyranosyl-(1'''--> 6'')-beta-D-glucopyranoside] (4), tectorigenin 7-O-beta-D-glucopyranoside (5), genistein 7-O-beta-D-glucopyranoside (6), tectorigenin 4'-O-beta-D-glucopyranoside (7), and tectorigenin (8); two phenolic acid glycosides, vanillic acid 4-O-beta-D-glucopyranoside (9) and glucosyringic acid (10); a phenylpropanoid glycoside, E-coniferin (11); an auronol derivative, maesopsin 6-O-beta-D-glucopyranoside (12); and a pyrrole derivative, 4-(2-formyl-5-hydroxymethylpyrrol-1-yl) butyric acid (13), were isolated from fresh Iris spuria (Calizona) rhizomes. The structures of these compounds were established on the basis of spectroscopic and chemical evidence. Inhibitory effects on the activation of Epstein-Barr virus early antigen were examined for compounds 1-8 and 12.

Fructose-amino acid conjugate and other constituents from Cyperus rotundus L.

Further phytochemical study on the aerial parts of Cyperus rotundus L. led to the isolation of a fructose-amino acid conjugate, N-(1-deoxy-alpha-D-fructos-1-yl)-L-tryptophan (16) and its tautomers, in addition to n-butyl-beta-D-fructopyranoside (1), ethyl-alpha-D-glucopyranoside (2), adenosine (3), (-)-(E)-caffeoylmalic acid (4), vitexin (5), isovitexin (6), orientin (7), epiorientin (8), myricetin 3-O-beta-D-galactopyranoside (9), luteolin 7-O-beta-D-glucuronopyranoside-6''-methyl ester (10), chlorogenic acid (11), luteolin 4'-O-beta-D-glucuronopyranoside (12), luteolin 7-O-beta-D-glucuronopyranoside (13), uridine (14) and ellagic acid (15). Their structures were elucidated on the basis of spectroscopic methods. Additionally, antioxidant and alpha-amylase inhibitory activities of some of the isolated phenolic compounds were carried out.

A new steroid glycoside and furochromones from Cyperus rotundus L.

Further phytochemical investigation of the aerial parts of Cyperus rotundus L. afforded a new steroid glycoside named sitosteryl (6'-hentriacontanoyl)-beta-D-galactopyranoside (4) in addition to three furochromones, khellin (2), visnagin (3) and ammiol (9). Furthermore, benzo-alpha-pyrone (coumarin) (1), salicylic acid (5), caffeic acid (6), protocatechuic acid (7), p-coumaric acid (8), tricin (10) and isorhamnetin (11) were isolated. The structures of these compounds were established by spectroscopic methods. The isolated furochromones were tested for insect antifeedant activity against larvae Spodoptera littoralis when incorporated in artificial diet and offered to larvae in a chronic feeding bioassay. Also, visnagin, khellin and sitosteryl (6'-hentriacontanoyl)-beta-D-galactopyranoside showed strong cytotoxic activity against L5178y mouse lymphoma cells and were also active in the brine shrimp lethality test.