Efficient microwave-assisted prenylation of pinostrobin and biological evaluation of its derivatives as antitumor agents

Valorisation of liquorice (Glycyrrhiza) roots: antimicrobial activity and cytotoxicity of prenylated (iso)flavonoids and chalcones from liquorice spent (G. glabra, G. inflata, and G. uralensis)

Prenylated phenolics are antimicrobials found in liquorice (Glycyrrhiza spp.).

Tailored Functionalization of Natural Phenols to Improve Biological Activity

Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols' anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

Molecular docking of novel 5-O-benzoylpinostrobin derivatives as wild type and L858R/T790M/V948R mutant EGFR inhibitor

Background Previous studies have shown that 5-O-benzoylpinostrobin derivatives is a potential anti-breast cancer, with the highest potential being the HER2 inhibitors, is a protein's member of the epidermal growth factor receptor (EGFR) family. Overexpression of EGFR itself is known to be one of the causes of other cancer, including non-small cell lung cancer (NSCLC). Thus, it is possible that 5-O-benzoylpinostrobin derivatives can also inhibit the overexpression of EGFR in NSCLC. In the case of NSCLC, mutations of EGFR are often found in several amino acids, such as L858R, T790M, and V948R. This study aimed to determine the potential of 5-O-benzoylpinostrobin derivatives as an inhibitor of wild type and L858R/T790M/V948R-mutant EGFR. Methods Docking was performed using AutoDock Vina 1.1.2 on both wild type and L858R/T790M/V948R-mutant EGFR. Parameters observed, consisted of free energy of binding (ΔG) and amino acid interactions of each ligand. Results Docking results showed that all 5-O-benzoylpinostrobin derivatives showed a lower ΔG for both wild type and L858R/T790M/V948R-mutant EGFR, with the lowest ΔG shown by 4-methyl-5-O-benzoylpinostrobin and 4-trifluoromethyl-5-O-benzoylpinostrobin. Both the ligands have the similarity of interacting amino acids compared to reference ligands between 76.47 and 88.24%. Specifically, the ΔG of all test ligands was lower in mutant EGFR than in the wild type, which indicates the potential of the ligand as EGFR inhibitors where a mutation to EGFR occurs. Conclusions These results confirm that 5-O-benzoylpinostrobin derivatives have the potential to inhibit EGFR in both wild type and L858R/T790M/V948R-mutant.

ADMET properties of novel 5-O-benzoylpinostrobin derivatives

Background Prediction of the properties of absorption, distribution, metabolism, excretion, and toxicity (ADMET) from a compound is essential, especially for modified novel compounds. Previous research has successfully designed several modified compounds of 5-O-benzoyl derivatives from pinostrobin, a flavanone that has cytotoxic activity. This study aims to describe the properties of ADMET from the 5-O-benzoylpinostrobin derivative. Methods Prediction of the properties of ADMET was carried out using three web servers consisting of SwissADME, pkCSM, and ProTox-II. The observed parameters are divided into ADMET parameters. Results In general, absorption parameters indicate that the 5-O-benzoylpinostrobin derivative has lower water solubility than the parent pinostrobin. Distribution parameters show mixed results for distribution through the blood-brain barrier. Metabolism parameters showed different results with generally inhibitory activity shown in CYP2C19, CYP2C9, and CYP3A4. The excretion parameters showed a higher total clearance than pinostrobin except in the trifluoromethyl derivative. The toxicity parameters showed both pinostrobin and the 5-O-benzoylpinostrobin derivatives, including the class IV toxicity category with the lowest LD50 value indicated by the nitro derivative of 1500, with the possible target of the androgen receptor and prostaglandin G/H synthase 1. Conclusions Overall, the 5-O-benzoylpinostrobin derivative has the predicted ADMET profile that is relatively similar to pinostrobin, with the most noticeable difference being shown in the absorption parameters where all 5-O-benzoylpinostrobin derivatives have lower water solubility than pinostrobin.

Bioactive compounds from Cudrania tricuspidata: A natural anticancer source

The tumor is becoming a critical threat to our lives in these years. Searching for antitumor substances from natural products is a great interest of scientists. Cudrania tricuspidata (C. tricuspidata) is a regional plant containing 158 flavonoids and 99 xanthones, and others ingredients with favorable bioactivity. This review comprehensively analyzes the antitumor compounds from C. tricuspidata against different tumors, and 78 flavonoids plus xanthones are considered as underlying antineoplastic. Importantly, the structure of preylation groups is the primary source of antitumor activity among 45 flavonoids plus xanthones, which could be a direction of structural modification for a better antitumor ability. Additionally, the fruits are also preferable sources of antitumor compounds compared to the roots and barks due to the abundant isoflavones and sustainability. However, many studies only focused on the cells viability inhibition of the compounds, the underlying molecular mechanisms, and the intracellular targets remain ambiguous. In conclusion, C. tricuspidata has a great potential for anti-tumor prevention or therapy, but more attention should be paid to deeper research in vitro and in vivo models.

Total Synthesis of (±)-Isoperbergins and Correction of the Chemical Structure of Perbergin

On the basis of its reported chemical structure, perbergin, a Rhodococcus fascians virulence quencher from the bark of Dalbergia pervillei, and its isomer were synthesized in nine steps with a 13.5% yield. However, the NMR spectra of the synthetic products were inconsistent with those reported in the literature. Re-evaluation of the 1D and 2D NMR spectra of the natural product perbergin revealed that the geranyl moiety of this compound is located at C-6 and has an E-configuration, instead of the reported C-8 geranylation with a Z-configuration. Interestingly, the synthetic isoperbergins demonstrated good antibacterial activity against R. fascians, Mycobacterium smegmatis, and Staphylococcus aureus, but not against the Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli.

A review on biological sources, chemistry and pharmacological activities of pinostrobin

Pinostrobin, a dietary bioflavonoid discovered more than 6 decades ago in the heart-wood of pine (Pinus strobus), has depicted many pharmacological activities including anti-viral, anti-oxidant, anti-leukaemic, anti-inflammatory and anti-aromatase activities. It is an inhibitor of sodium channel and Ca(2+) signalling pathways and also inhibits intestinal smooth muscle contractions. In spite of the fact that pinostrobin has an application as functional foods, till-to-date no comprehensive review on pinostrobin has been carried out. Hence, the present review deals with the biological sources, chemistry and pharmacological activities of pinostrobin.

Synthesis of icariin from kaempferol through regioselective methylation and para-Claisen-Cope rearrangement

The hemisynthesis of the naturally occurring bioactive flavonoid glycoside icariin (1) has been accomplished in eleven steps with 7% overall yield from kaempferol. The 4′-OH methylation of kaempferol, the 8-prenylation of 3-O-methoxymethyl-4′-O-methyl-5-O-prenyl-7-O-benzylkaempferol (8) via para-Claisen–Cope rearrangement catalyzed by Eu(fod)₃ in the presence of NaHCO₃, and the glycosylation of icaritin (3) are the key steps.

Development and extraction optimization of baicalein and pinostrobin from Scutellaria violacea through response surface methodology

Objective:

To develop a process that involves optimization of the amount of baicalein and pinostrobin from the hydro-methanolic extract of the leaves of Scutellaria violacea by response surface methodology (RSM).

Materials and Methods:

The combinatorial influence of various extraction parameters on the extraction yield was investigated by adopting Box–Behnken experimental design. Preliminary experiments carried out based on the traditional one variable at a time optimization revealed four such operational parameters to play a crucial role by influencing the yield. These four process parameters at three levels were considered to obtain the Box–Behnken experimental design.

Results:

RSM based model fitted to the resulting experimental data suggested that 52.3% methanol/water, 12.46:1 solvent-solid ratio, 285 rpm agitation and 6.07 h of extraction time are the optimal conditions which yielded a maximized amount of baicalein and pinostrobin of 2.9 and 4.05 mg/g DM. Analysis of variance revealed a high correlation coefficient (R² = 0.999 for baicalein and 0.994 for pinostrobin), signifying a good fit between the regression model (second order) and the experimental observations.

Conclusion:

The present study signifies that both the metabolites have been extracted from S. violacea for the first time. Further, this study developed an optimized extraction procedure to obtain maximum yield of the metabolites, which is unique and better than conventional extraction methodology. The operational parameters under optimized conditions accounts for the lowest cost in extraction process thus, providing an efficient, rapid and cost-effective method for isolation and scale up of these commercially vital flavonoids.

A comparative analysis on the binding characteristics of various mammalian albumins towards a multitherapeutic agent, pinostrobin

The interaction of pinostrobin (PS), a multitherapeutic agent with serum albumins of various mammalian species namely, goat, bovine, human, porcine, rabbit, sheep and dog was investigated using fluorescence quench titration and competitive drug displacement experiments. Analysis of the intrinsic fluorescence quenching data revealed values of the association constant, K_a in the range of 1.49 – 6.12 × 10⁴ M⁻¹, with 1:1 binding stoichiometry. Based on the PS–albumin binding characteristics, these albumins were grouped into two classes. Ligand displacement studies using warfarin as the site I marker ligand correlated well with the binding data. Albumins from goat and bovine were found to be closely similar to human albumin on the basis of PS binding characteristics.

Synthesis and evaluation of 3-salicyloylpyridine derivatives as cytotoxic mitochondrial apoptosis inducers

A series of novel 3-salicyloylpyridines (4a-h) were synthesized with good yield by modified Knoevenagel-Stobbel method; o-allylation with allyl bromide lead to formation of compounds (5a-h). The synthesized compounds were characterized by spectroscopic techniques and evaluated for cytotoxic activity against human cancer cell lines. Compounds bearing hydroxyl group displayed high cytotoxicity (4a-h) as compared to o-allylated molecules (5a-h). The most active compound 4b was selected for further investigation to look for mechanism of cell death in prostate cancer (PC-3) cells. The apoptotic bodies induced by 4b in PC-3 cells were scanned by confocal microscopy and confirmed by scanning electron microscopy (SEM). Further results obtained from spectrofluorimetric determination of mitochondrial membrane potential (ΔΨm) and intracellular reactive oxygen species (ROS) in treated PC-3 cells revealed that mitochondria dependent apoptosis was involved in the cell death.

Synthesis of 4-aryl-6-indolylpyridine-3-carbonitriles and evaluation of their antiproliferative activity

A novel class of 6-indolypyridine-3-carbonitrilile derivatives were synthesized and evaluated for antiproliferative activities to establish structure-activity relationship. The synthesis was carried out through one-pot multicomponent reaction of 3-acetylindole, aromatic aldehydes, ethyl cyanoacetate, and ammonium acetate in the presence of piperidine as a catalyst, using a microwave irradiation method or a traditional thermal method. This was followed by chlorination for compounds 13a-e and subsequent nucleophilic substitution of the chlorine group by ethylenediamine at C2 position of the pyridine ring. The antiproliferative activity of these new nicotinonitriles was evaluated against human ovarian adenocarcinoma (SK-OV-3), breast adenocarcinoma (MCF-7), and cervix adenocarcinoma (HeLa) cells. Among all compounds, 2-((2-aminoethyl)amino)-4-aryl-6-indolylnicotinonitriles series (15a, 15b, 15d, and 15e) exhibited higher antiproliferative activity cells with IC50 values of 4.1-13.4 μM.

Subtle Mitsunobu couplings under super-heating: the role of high-throughput continuous flow and microwave strategies

Fragile Mitsunobu reaction can efficiently be performed under super-heating.