Activation and inhibition effects of some natural products on human cytosolic CAI and CAII

Chemical profile of the Anatolian Sideritis species with bioactivity studies

CONTEXT

The genus Sideritis L. (Lamiaceae) is represented by 46 species in Turkey with an 79% endemism ratio, 42 of 46 belonging to the section Empodoclia.

OBJECTIVE

In this review article, Sideritis species growing in Turkey have been evaluated for phytochemical constituents and biological activities.

METHODS

The data for the isolates, components and extracts of the Anatolian Sideritis species and their bioactivity studies were retrieved from the main databases WoS, Scopus and PubMed from 1975 until 31 December 2022.

RESULTS

In this review article, terpenoids, flavonoids, phenolics and other secondary metabolites isolated from Turkish Sideritis species were reported. Anatolian Sideritis species, which primarily consist of monoterpenes and sesquiterpenes, were studied in detail. Sideritis plants are represented by 46 species in Turkey, and 25 of them were investigated for their diterpenoids through isolation or LC-MS studies. Most of the diterpenoids of Turkish Sideritis species have ent-kaurene skeleton, among them linearol, siderol, 7-epicandicandiol and sideridiol were found to be the main compounds. Exceptionally, labdane, pimarane and beyerene diterpenoids were only found in a few species. For phenolics and flavonoids, only 12 species were investigated until now, and they were found to be rich in phenylethanoid glycosides and flavonoid glycosides. In terms of activity, most of the species were tested for antioxidant activity, followed by antimicrobial and anti-ulcer/anti-inflammatory activities. Their cytotoxic, enzyme inhibitory, antinociceptive and antistress activities were less frequently studied.

CONCLUSIONS

Sideritis species should be considered promising therapeutic agents in the treatment of upper respiratory tract and ulcer/inflammatory diseases.

Cell extraction method coupled with LC-QTOF MS/MS analysis for predicting neuroprotective compounds from Polygonum tinctorium

The cell extraction method coupled with LC-QTOF-MS/MS is a biological screening technique in which cells are incubated with extracts of natural products, which results in potential bioactive compounds selectively combining with various extracellular and intracellular targets. Although the neuroprotective effects of the plant Polygonum tinctorium are unknown, the ethyl acetate (EtOAc) fraction exhibits significant neuroprotective effects against ʟ-glutamate-induced cytotoxicity in HT22 cells. In this study, we attempted to identify the neuroprotective compounds in the EtOAc fraction of P. tinctorium using the cell extraction method coupled with LC-QTOF MS/MS. Potential neuroprotective components derived from P. tinctorium were combined selectively with HT22 cells, and cell-derived metabolites were identified. A new flavonoid compound, 3,5,3',4'-tetrahydroxy-6,7-methylendioxyflavone-3-O-β-ᴅ-glucopyranoside (1), and 14 known compounds (2-15), with compounds 2, 3, 8, 13, and 15 detected by the cell extraction method, were isolated from the EtOAc fraction of P. tinctorium. Compounds 2, 8, 12, and 14 showed strong neuroprotective effects, with compounds 2 and 14 identified in this plant for the first time in this study. Our results indicate that the cell extraction method coupled with LC-QTOF MS/MS is a useful tool for screening and identifying neuroprotective compounds in natural products.

Antibacterial properties and carbonic anhydrase inhibition profiles of azido sulfonyl carbamate derivatives

Aim: The aim of this study was to identify inhibition of carbonic anhydrase I and II (CA I and II) isozymes by azido sulfonyl carbamates through both in vitro and in silico approaches and also to determine the drug-likeness properties and antibacterial activities of azido sulfonyl carbamates. Methods & Results: In vitro inhibition and molecular docking studies of azido sulfonyl carbamate derivatives (1-4) on isozymes were performed. Except for derivative 4, all derivatives inhibited human CA I and II. Almost all compounds had antibacterial effects. The docking results showed that compound 3 had the best results, with binding energy of -8.20 kcal/mol for human CA I and -8.24 kcal/mol for human CA II. Conclusion: Molecule 4 inhibited only CA I. Its usage as a potential chemotherapeutic agent specific to the CA I isozyme may be considered.

Investigation of in vitro and in silico effects of some novel carbazole Schiff bases on human carbonic anhydrase isoforms I and II

Carbonic anhydrases (CAs, EC4.2.1.1) are metalloenzymes that catalyse reversible hydration reaction of carbon dioxide to bicarbonate and protons. In recent years, there has been a great interest in inhibitors/activators of carbonic anhydrase isoenzymes. Therefore, we investigated the effects of four different carbazole Schiff base derivatives, which are believed to have a potential to be used as a drug, on human carbonic anhydrase (hCA) isoenzymes I and II under in vitro conditions. The IC₅₀ values of carbazole Schiff base derivatives were found to be in the range of 32.09-151.2 μM for hCA isoenzyme I and 21.82-40.54 μM for hCA isoenzyme II. Among all compounds, (E)-3-(((9-Octyl-9H-carbazole-3-yl)imino)methyl)benzene-1,2-diol (C3) had the strongest inhibitory effect on hCA isoenzyme II. It was determined that 2,3,4-trimethoxy and 4-hydroxy phenyl containing carbazole compounds have selective inhibition against hCA II isoenzyme. Docking studies were performed against hCA I and II receptors using induced-fit docking method. The compounds had affinity scores varying from -7.74 ± 0.27 to -6.27 ± 0.07 kcal/mol for hCA I and from -8.04 ± 0.17 to -7.27 ± 0.18 kcal/mol for hCA II.Communicated by Ramaswamy H. Sarma.

Probing 4-(diethylamino)-salicylaldehyde-based thiosemicarbazones as multi-target directed ligands against cholinesterases, carbonic anhydrases and α-glycosidase enzymes

With the fading of 'one drug-one target' approach, Multi-Target-Directed Ligands (MTDL) has become a central idea in modern Medicinal Chemistry. The present study aimed to design, develop and characterize a novel series of 4-(Diethylamino)-salicylaldehyde based thiosemicarbazones (3a-p) and evaluates their biological activity against cholinesterase, carbonic anhydrases and α-glycosidase enzymes. The hCA I isoform was inhibited by these novel 4-(diethylamino)-salicylaldehyde-based thiosemicarbazones (3a-p) in low nanomolar levels, the Ki of which differed between 407.73 ± 43.71 and 1104.11 ± 80.66 nM. Against the physiologically dominant isoform hCA II, the novel compounds demonstrated K_is varying from 323.04 ± 56.88 to 991.62 ± 77.26 nM. Also, these novel 4-(diethylamino)-salicylaldehyde based thiosemicarbazones (3a-p) effectively inhibited AChE, with Ki values in the range of 121.74 ± 23.52 to 548.63 ± 73.74 nM. For BChE, Ki values were obtained with in the range of 132.85 ± 12.53 to 618.53 ± 74.23 nM. For α-glycosidase, the most effective Ki values of 3b, 3k, and 3g were with Ki values of 77.85 ± 10.64, 96.15 ± 9.64, and 124.95 ± 11.44 nM, respectively. We have identified inhibition mechanism of 3b, 3g, 3k, and 3n on α-glycosidase AChE, hCA I, hCA II, and BChE enzyme activities. Hydrazine-1-carbothioamide and hydroxybenzylidene moieties of compounds play an important role in the inhibition of AChE, hCA I, and hCA II enzymes. Hydroxybenzylidene moieties are critical for inhibition of both BChE and α-glycosidase enzymes. The findings of in vitro and in silico evaluations indicate 4-(diethylamino)-salicylaldehyde-based thiosemicarbazone scaffold to be a promising hit for drug development for multifactorial diseases like Alzheimer's disease.

Microsecond Simulation of the Proteoglycan-like Region of Carbonic Anhydrase IX and Design of Chemical Inhibitors Targeting pH Homeostasis in Cancer Cells

Carbonic anhydrase IX (CAIX) is a membrane-bound enzyme associated with tumor hypoxia and found to be over expressed in various tumor conditions. Targeting CAIX catalytic activity is proven to be efficient modality in modulating pH homeostasis in cancer cells. Proteoglycan-like (PG) region is unique to CAIX and is proposed to serve as an antenna enhancing the export of protons in conjunction with facilitated efflux of lactate ions via monocarboxylate transporters. Moreover, the PG region is also reported to contribute to the assembly and maturation of focal adhesion links during cellular attachment and dispersion on solid supports. Thus, drug targeting of this region shall efficiently modulate pH homeostasis and cell adhesion in cancer cells. As the PG region is intrinsically disordered, the complete crystal structure is not elucidated. Hence, in this study, we intend to sample the conformational landscape of the PG region at microsecond scale simulation in order to sample the most probable conformations that shall be utilized for structure-based drug design. In addition, the sampled conformations were subjected to high-throughput virtual screening against NCI and Maybridge datasets to identify potential hits based on consensus scoring and validation by molecular dynamics simulation. Further, the identified hits were experimentally validated for efficacy by in vitro and direct enzymatic assays. The results reveal 5-(2-aminoethyl)-1,2,3-benzenetriol to be the most promising hit as it showed significant CAIX inhibition at all levels of in silico and experimental validation.