Molecular mechanism of HNTX-I activates the intermediate-conductance Ca2+-activated K+ (IK) channels.

The IK channel, a potassium ion channel regulated by calcium ions and voltages in a bidirectional manner, has been implicated in a range of diseases. However, there are currently few compounds available that can target the IK channel with high potency and specificity. Hainantoxin-I (HNTX-I) is the first peptide activator of IK channel discovered so far, but its activity is not ideal, and the underlying mechanism interaction between HNTX-I toxin and IK channel remains unclear. Thus, our study aimed to enhance the potency of IK channel activating peptides derived from HNTX-I and elucidate the molecular mechanism underlying the interaction between HNTX-I and the IK channel. By employing virtual alanine scanning mutagenesis, we generated 11 HNTX-I mutants using site-directed mutagenesis to pinpoint specific residues crucial for the HNTX-I and IK channel interaction. Subsequently, we identified key residues on the IK channel that are involved in the interaction with HNTX-I. Additionally, molecular docking was employed to guide the molecular engineering process and clarify the binding interface between HNTX-I and the IK channel. Our results demonstrate that HNTX-I primarily acts on the IK channel via the N-terminal amino acid, and its interaction with the IK channel is mediated by electrostatic and hydrophobic interactions, specifically the amino acid residues at positions 1, 3, 5, and 7 on HNTX-I. This study provides valuable insights into the peptide toxins that may serve as potential templates for the development of activators with enhanced potency and selectivity for the IK channel.

Synthesis and Characterization of Novel Chickpea Protein Hydrolysate-Vanadium Complexes Having Cell Inhibitory Effects on Lung Cancer A549 Cells Lines.

Designing new types of drugs with preferred properties against cancer is a great issue for scientists dealing with synthesis and study of biological activity. Several organometallic compounds used in chemotherapy reveal side effects. Peptides from edible sources having no side effects may play a transport role in the delivery of anticancer metal ions into targeted tumor cells. For the last two decades, peptide-metal complexes have been considered as potential anticancer agents. In this work, oxovanadium complexes of peptides from Chickpea (Cicer arietinum L.) seeds' protein hydrolysate were investigated. The albumin fraction of Chickpea seeds protein was hydrolyzed with a combination of enzymes papain, trypsin, and alcalase. The hydrolysate was combined with vanadyl ions and obtained oxovanadium complexes were studied by FTIR, SEM-EDX, and TG-DSC analyses, and cell inhibition activity against A549 cells was detected by MTT Assay. In a result, activity of the complexes (IC50 = 14.39 µg/mL) increased 1.7-fold compared to the activity of inorganic salt of vanadium (IC50 = 24.75 µg/mL) against A549 cells. The complexes (CPH-V) were fractionated through Sephadex G-15, and the second active fraction, named CPH-V G15-II was studied by nano-Q-TOF LC/MS. Nine peptides with a molecular mass range of 437-1864 Da were identified. Seven of them were theoretically considered as cell-penetrating peptides. These results could serve first steps for deeper fundamental research on food-derived peptide-vanadium complexes.

Effects of trypsin-induced limited hydrolysis on the structural, functional, and bioactive properties of sericin.

The effects of trypsin-induced hydrolysis on the structural, functional, and antioxidant properties of sericin were studied. The structural properties of sericin and its hydrolysates were characterized by using SDS-PAGE, SEC-HPLC, surface hydrophobicity, and circular dichroism. Antioxidative properties were evaluated based on quenching capacity against hydroxyl, DPPH, and ABTS, and metal (Fe2+, Cu2+) chelating activity. The enzymatic hydrolysis raised the flexibility, changed emulsifying and foaming properties, and improved the solubility and antioxidant activity of sericin. Meanwhile, the hydrolysis led to a decline in gelation capacity, oil holding capacity, and water holding capacity. Sericin and its hydrolysates exhibited excellent function with regard to oil holding, emulsifying, and foaming. Sericin and its hydrolysates had clear effects on the growth of both Enterococcus faecalis and Lactobacillus bulgaricus strains.

A designed antifungal peptide with therapeutic potential for clinical drug-resistant Candida albicans.

Due to the increasing drug-resistant of Candida albicans (C. albicans), there is an urgent need to develop a novel therapeutic agent for C. albicans induced inflammatory disease treatment. Antimicrobial peptides (AMPs) are regarded as one of the most promising antifungal drugs. However, most of the designed AMPs showed side-effects. In the present study, 10 novel peptides were designed based on the sequence of frog skin secretions peptide (Ranacyclin AJ). Among them, AKK8 (RWRFKWWKK) exhibited the strongest antifungal effect against both standard and clinically isolated drug-resistant C. albicans. AKK8 killed C. albicans (within 30 min), and the antifungal effect lasted for 24 h, showed an efficient and long lasted antifungal effect against C. albicans. Notably, AKK8 showed low toxicity to human red blood cells and high stability in human serum. Moreover, AKK8 administration showed therapeutic effects on systemic infections mice induced by the clinical drug-resistant C. albicans, in a dose-depended manner. These findings suggested that AKK8 may be a potential candidate for the anti-inflammation treatments for diseases caused by clinical drug-resistant C. albicans.

Endophytic Bacteria Associated with Medicinal Plant Vernonia anthelmintica: Diversity and Characterization.

Increasing evidence shows that endophytic bacteria living inside plant tissue may possess similar biological activity and produce similar metabolites to their hosts. This study aimed to determine the diversity of endophytic bacteria associated with Vernonia anthelmintica and to evaluate their biological activity. The bacteria were isolated from the plant tissue using culture-dependent techniques. Comparison of the 16S rRNA gene sequences of endophytic bacteria isolated from V. anthelmintica showed that isolates belong to the species Micrococcus endophyticus VERA1, Bacillus megaterium VERA2, Pseudomonas chlororaphis VERA3, P. kilonensis VERA4, Stenotrophomonas pavanii VERA5, B. endophyticus VERA6, S. maltophilia VERA7, Pantoea ananatis VERA8, B. atrophaeus VERA9 and M. flavus VERA10. Activity studies showed that the endophytic bacteria share several similar biological properties with their host plant including antimicrobial, anti-vitiligo and antidiabetic activities. These findings indicate that plant phytochemical compounds and activity play an important role in the physiological properties of their endophytes.

Optimization of Scorpion Protein Extraction and Characterization of the Proteins' Functional Properties.

Scorpion has long been used in traditional Chinese medicine, because whole scorpion body extract has anti-cancer, analgesic, anti-thrombotic blood anti-coagulation, immune modulating, anti-epileptic, and other functions. The purpose of this study was to find an efficient extraction method and investigate some of physical and chemical parameters, like water solubility, emulsification, foaming properties, and oil-holding capacity of obtained scorpion proteins. Response surface methodology (RSM) was used for the determination of optimal parameters of ultrasonic extraction (UE). Based on single factor experiments, three factors (ultrasonic power (w), liquid/solid (mL/g) ratio, and extraction time (min)) were used for the determination of scorpion proteins (SPs). The order of the effects of the three factors on the protein content and yield were ultrasonic power > extraction time > liquid/solid ratio, and the optimum conditions of extraction proteins were as follows: extraction time = 50.00 min, ultrasonic power = 400.00 w, and liquid/solid ratio = 18.00 mL/g. For the optimal conditions, the protein content of the ultrasonic extraction and yield were 78.94% and 24.80%, respectively. The solubility, emulsification and foaming properties, and water and oil holding capacity of scorpion proteins were investigated. The results of this study suggest that scorpion proteins can be considered as an important ingredient and raw material for the creation of water-soluble supramolecular complexes for drugs.

Optimization of ultrasonic-assisted extraction, characterization and biological activities of polysaccharides from Orchis chusua D. Don (Salep).

In the present study, ultrasonic-assisted extraction (UAE) of polysaccharides from Orchis chusua D. Don (salep) was optimized by response surface methodology (RSM) combined with a Box-Behnken design (BBD), the optimum conditions were determined to be: ultrasonic power of 390 W, extraction temperature of 60 °C, extraction time of 50 min and water/raw material ratio of 40 mL/g. Based on it, 48.30 ±â€¯0.6% yield of crude polysaccharide was obtained. After purification, the chemical compositions, physicochemical and structural property was investigated based on the GC-MS, TGA, XRD, SEM and Congo red test. The results showed that USP-U and USP-N were hetero-polysaccharides, mainly composed of mannose and glucose, and the average molecular weight was 25.57 kDa and 11.64 kDa, respectively. FT-IR spectra and NMR results indicated that the presence of α-linkage glycopyranose via typical peaks. Furthermore, reducing power and antioxidant activities of both purified fractions showed a relatively high ability to scavenge free radicals. Lastly, the cytotoxicity assay showed that purified polysaccharides have no obvious cytotoxicity against RAW267.4 and L6 cells at their effective concentration and had potent anti-inflammatory activity in a concentration-dependent manner. Salep polysaccharide is expected to be developed as a new efficacy factor in the pharmaceutical and food industry.