Analogues of neurohypophyseal hormones, oxytocin and arginine vasopressin, conformationally restricted in the N-terminal part of the molecule

Secondary hemophagocytic syndrome in an acquired immunodeficiency syndrome and Alpha-thalassemia patient infected with Talaromyces marneffei: A case report and literature review

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease characterized by a hyperinflammatory syndrome and impairment of multiple organ systems. Talaromycosis marneffei (TSM) is an opportunistic infection mostly found in immunosuppressed populations, such as those with acquired immunodeficiency syndrome (AIDS), and is prevalent in southern China. However, HLH secondary to TSM is extremely rare and has only been reported in isolated cases. A 30-year-old patient with recurrent high fever and progressive cytopenia was diagnosed with HLH secondary to disseminated TSM with AIDS and Alpha-thalassemia. The patient remained in sustained remission without recurrence after effective treatment with antifungals and glucocorticoids.

Vasopressin and Its Analogues: From Natural Hormones to Multitasking Peptides

Human neurohormone vasopressin (AVP) is synthesized in overlapping regions in the hypothalamus. It is mainly known for its vasoconstricting abilities, and it is responsible for the regulation of plasma osmolality by maintaining fluid homeostasis. Over years, many attempts have been made to modify this hormone and find AVP analogues with different pharmacological profiles that could overcome its limitations. Non-peptide AVP analogues with low molecular weight presented good affinity to AVP receptors. Natural peptide counterparts, found in animals, are successfully applied as therapeutics; for instance, lypressin used in treatment of diabetes insipidus. Synthetic peptide analogues compensate for the shortcomings of AVP. Desmopressin is more resistant to proteolysis and presents mainly antidiuretic effects, while terlipressin is a long-acting AVP analogue and a drug recommended in the treatment of varicose bleeding in patients with liver cirrhosis. Recently published results on diverse applications of AVP analogues in medicinal practice, including potential lypressin, terlipressin and ornipressin in the treatment of SARS-CoV-2, are discussed.

Preclinical Efficacy of [V4 Q5 ]dDAVP, a Second Generation Vasopressin Analog, on Metastatic Spread and Tumor-Associated Angiogenesis in Colorectal Cancer

Purpose

Control of metastatic spread of colorectal cancer (CRC) remains as a major therapeutic challenge. [V4 Q5 ]dDAVP is a vasopressin peptide analog with previously reported anticancer activity against carcinoma tumors. By acting as a selective agonist of arginine vasopressin type 2 membrane receptor (AVPR2) present in endothelial and tumor cells, [V⁴Q⁵]dDAVP is able to impair tumor aggressiveness and distant spread. Our aim was to evaluate the potential therapeutic benefits of [V⁴Q⁵]dDAVP on highly aggressive CRC disease using experimental models with translational relevance.

Materials and Methods

Murine CT-26 and human Colo-205 AVPR2-expressing CRC cell lines were used to test the preclinical efficacy of [V⁴Q⁵]dDAVP, both in vitro and in vivo.

Results

In syngeneic mice surgically implanted with CT-26 cells in the spleen, sustained intravenous treatment with [V⁴Q⁵]dDAVP (0.3 µg/kg) dramatically impaired metastatic progression to liver without overt signs of toxicity, and also reduced experimental lung colonization. The compound inhibited in vivo angiogenesis driven by Colo-205 cells in athymic mice, as well as in vitro endothelial cell migration and capillary tube formation. [V⁴Q⁵]dDAVP exerted AVPR2-dependent cytostatic activity in vitro (IC₅₀ 1.08 µM) and addition to 5-fluorouracil resulted in synergistic antiproliferative effects both in CT-26 and Colo-205 cells.

Conclusion

The present preclinical study establishes for the first time the efficacy of [V⁴Q⁵]dDAVP on CRC. These encouraging results suggest that the novel second generation vasopressin analog could be used for the management of aggressive CRC as an adjuvant agent during surgery or to complement standard chemotherapy, limiting tumor angiogenesis and metastasis and thus protecting the patient from CRC recurrence.

Structure-activity relationship of 1-desamino-8-D-arginine vasopressin as an antiproliferative agent on human vasopressin V2 receptor-expressing cancer cells

The synthetic nonapeptide 1‑desamino‑8‑D‑arginine vasopressin (dDAVP) can reduce tumor cell growth through agonist action on the vasopressin V2 receptor. A structure‑antiproliferative activity relationship analysis of dDAVP was performed using the alanine scanning technique on the aggressive MDA‑MB‑231 human breast carcinoma cell line. The results from this analysis demonstrated that the amino acids located at the loop of dDAVP are important for the antiproliferative activity of dDAVP, highlighting the key role of the N‑terminal region of the peptide in the interaction with the tumor cell surface receptor. The findings from this study present novel strategies for designing improved compounds with enhanced stability for cancer therapy.

Revisiting oxytocin through the medium of isonitriles

The reaction of thioamino acids and N-terminal peptides, mediated by hindered isonitriles and hydroxybenzotriazole, gives rise to peptide bonds. In one pathway, oxytocin was synthesized by eight such reiterative amidations. In another stereospecific track, oxytocin was constructed by native chemical ligation, wherein the two building blocks were assembled by thioacid amine amidation. The NMR spectra of oxytocin and dihydrooxytocin suggest a high level of preorganization in the latter, perhaps favoring oxidative folding.

Design, synthesis and biological activity of new neurohypophyseal hormones analogues conformationally restricted in the N-terminal part of the molecule. Highly potent OT receptor antagonists

In this study we present the synthesis and some pharmacological properties of fourteen new analogues of neurohypophyseal hormones conformationally restricted in the N-terminal part of the molecule. All new peptides were substituted at position 2 with cis-1-amino-4-phenylcyclohexane-1-carboxylic acid (cis-Apc). Moreover, one of the new analogues: [cis-Apc(2), Val(4)]AVP was also prepared in N-acylated forms with various bulky acyl groups. All the peptides were tested for pressor, antidiuretic, and in vitro uterotonic activities. We also determined the binding affinity of the selected compounds to human OT receptor. Our results showed that introduction of cis -Apc(2) in position 2 of either AVP or OT resulted in analogues with high antioxytocin potency. Two of the new compounds, [Mpa(1),cis-Apc(2)]AVP and [Mpa(1),cis-Apc(2),Val(4)]AVP, were exceptionally potent antiuterotonic agents (pA(2) = 8.46 and 8.40, respectively) and exhibited higher affinities for the human OT receptor than Atosiban (K (i) values 5.4 and 9.1 nM). Moreover, we have demonstrated for the first time that N -terminal acylation of AVP analogue can improve its selectivity. Using this approach, we obtained compound Aba[cis-Apc(2),Val(4)]AVP (XI) which turned out to be a moderately potent and exceptionally selective OT antagonist (pA(2) = 7.26).