The Chloride Intracellular Ion Channel (CLIC) family consists of six evolutionarily conserved proteins in humans. Members of this family are unusual, existing as both monomeric soluble proteins and as integral membrane proteins where they function as chloride selective ion channels, however no function has previously been assigned to their soluble form. Structural studies have shown that in the soluble form, CLIC proteins adopt a glutathione S-transferase (GST) fold, however, they have an active site with a conserved glutaredoxin monothiol motif, similar to the omega class GSTs. We demonstrate that CLIC proteins have glutaredoxin-like glutathione-dependent oxidoreductase enzymatic activity. CLICs 1, 2 and 4 demonstrate typical glutaredoxin-like activity using 2-hydroxyethyl disulfide as a substrate. Mutagenesis experiments identify cysteine 24 as the catalytic cysteine residue in CLIC1, which is consistent with its structure. CLIC1 was shown to reduce sodium selenite and dehydroascorbate in a glutathione-dependent manner. Previous electrophysiological studies have shown that the drugs IAA-94 and A9C specifically block CLIC channel activity. These same compounds inhibit CLIC1 oxidoreductase activity. This work for the first time assigns a functional activity to the soluble form of the CLIC proteins. Our results demonstrate that the soluble form of the CLIC proteins has an enzymatic activity that is distinct from the channel activity of their integral membrane form. This CLIC enzymatic activity may be important for protecting the intracellular environment against oxidation. It is also likely that this enzymatic activity regulates the CLIC ion channel function.

Cannabidiol (CBD), derived from the cannabis plant, has gained significant attention due to its potential therapeutic benefits. However, one of the challenges associated with CBD administration is its low bioavailability, which refers to the fraction of an administered dose that reaches systemic circulation. This limitation necessitates the exploration of various approaches to enhance the bioavailability of CBD, thus helping to maximize its therapeutic potential. A variety of approaches are now emerging, including nanoemulsion-based systems, lipid-based formulations, prodrugs, nanocarriers, and alternative routes of administration, which hold promise for improving the bioavailability of CBD and pave the way for novel formulations that maximize the therapeutic potential of CBD in various medical conditions. This opinion piece presents the current understanding surrounding CBD bioavailability and considers strategies aimed at improving both its absorption and its bioavailability.

The antibacterial and antioxidant activities of different parts of local seeded banana fruit were investigated in vitro. Dried peels, pulps and seeds of the fruit were extracted with hexane, ethyl acetate and ethanol. Antibacterial property of the extracts was evaluated against four Gram positive and four Gram negative bacteria using disc diffusion technique. Ethyl acetate and ethanol extract of both pulp and peel exhibited antibacterial activity with zone of inhibition ranging from 9 to 24 mm. On the other hand, only ethyl acetate extract of seeds showed antibacterial activity and the zone of inhibition ranged from 8.5 to 10 mm; interestingly, none of the hexane extracts of the three banana parts exhibited zone of inhibition. Antioxidant activity of the extracts was evaluated by total phenolic content determination and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Total phenolic content expressed as gallic acid equivalents (GAE) was found to be highest in ethyl acetate extract of banana seed (19.46 mg GAE/g extract) followed by the same extract of banana pulp (15.78 mg GAE/g extract) and peel (11.23 mg GAE/g extract). High free radical scavenging activity was observed with ethyl acetate extracts of banana seed, peel and pulp with an ascorbic acid equivalent antioxidant capacity (AEAC) value of 1238.33, 1011.43 and 588.03 mg AA/ 100 g extract, respectively. Key words: Seedy banana, antibacterial, antioxidant, phenolic content.

Cholesterol’s effects on Na⁺,K⁺-ATPase reconstituted in phospholipid vesicles have been extensively studied. However, previous studies have reported both cholesterol-mediated stimulation and inhibition of Na⁺,K⁺-ATPase activity. Here, using partial reaction kinetics determined via stopped-flow experiments, we studied cholesterol’s effect on Na⁺,K⁺-ATPase in a near-native environment in which purified membrane fragments were depleted of cholesterol with methyl-β-cyclodextrin (mβCD). The mβCD-treated Na⁺,K⁺-ATPase had significantly reduced overall activity and exhibited decreased observed rate constants for ATP phosphorylation (ENa⁺₃ → E2P, i.e. phosphorylation by ATP and Na⁺ occlusion from the cytoplasm) and K⁺ deocclusion with subsequent intracellular Na⁺ binding (E2K⁺₂ → E1Na⁺₃). However, cholesterol depletion did not affect the observed rate constant for K⁺ occlusion by phosphorylated Na⁺,K⁺-ATPase on the extracellular face and subsequent dephosphorylation (E2P → E2K⁺₂). Thus, partial reactions involving cation binding and release at the protein’s intracellular side were most dependent on cholesterol. Fluorescence measurements with the probe eosin indicated that cholesterol depletion stabilizes the unphosphorylated E2 state relative to E1, and the cholesterol depletion-induced slowing of ATP phosphorylation kinetics was consistent with partial conversion of Na⁺,K⁺-ATPase into the E2 state, requiring a slow E2 → E1 transition before the phosphorylation. Molecular dynamics simulations of Na⁺,K⁺-ATPase in membranes with 40 mol% cholesterol revealed cholesterol interaction sites that differ markedly among protein conformations. They further disclosed state-dependent effects on membrane shape, with the E2 state being likely disfavored in cholesterol-rich bilayers relative to the E1P state because of a greater hydrophobic mismatch. In summary, cholesterol extraction from membranes significantly decreases Na⁺,K⁺-ATPase steady-state activity.