Edible: By grafting natural peptide antagonists onto the cyclotide kalata B1, orally active peptides were engineered, which are potentially useful therapeutics for the treatment of inflammatory pain. For example, the entire loop 6 of kalata B1 was replaced with the peptidic bradykinin B1 receptor antagonist DALK (red in scheme) to obtain the cyclic bradykinin antagonist ckb‐kal.

A total synthesis of daptomycin, the first natural product antibiotic launched in a generation, was achieved. This convergent synthesis relies on an efficient macrocyclization via a serine ligation to assemble the 31-membered cyclic depsipeptide. The difficult esterification by the nonproteinogenic amino acid kynurenine was accomplished via the esterification of a threonine residue by a suitably protected Trp ester, followed by ozonolysis. This synthesis provides a foundation and framework to prepare varied analogues of daptomycin to establish its structure-activity profile.

Significance: Pulmonary hypertension is a devastating disorder without any available treatment strategies that satisfactorily promote the survival of patients. The identification of new therapeutic strategies to treat patients with pulmonary hypertension is warranted. Recent Advances: Human studies have provided evidence that there is increased oxidative stress (lipid peroxidation, protein oxidation, DNA oxidation, and the depletion of smallmolecule antioxidants) in patients with pulmonary hypertension. A variety of compounds with antioxidant properties have been shown to have beneficial therapeutic effects in animal models of pulmonary hypertension, possibly supporting the hypothesis that reactive oxygen species (ROS) are involved in the progression of pulmonary hypertension. Thus, understanding the molecular mechanisms of ROS actions could contribute to the development of optimal, antioxidant-based therapy for human pulmonary hypertension. One such mechanism includes action as a second messenger during cell-signaling events, leading to the growth of pulmonary vascular cells and right ventricular cells. Critical Issues: The molecular mechanisms behind promotion of cell signaling for pulmonary vascular cell growth and right ventricular hypertrophy by ROS are not well understood. Evidence suggests that iron-catalyzed protein carbonylation may be involved. Future Directions: Understanding precise mechanisms of ROS actions should be useful for designing preclinical animal experiments and human clinical trials of the use of antioxidants and/or other redox compounds in the treatment of pulmonary hypertension.

Making heads or tails of it: A strategy involving a head‐to‐tail imine‐captured ring closure followed by ring contraction was used to synthesize otherwise difficult cyclic tetrapeptides. Compared with the direct lactamization process, the estimated activation energies for the cyclic imine formation and the ring contraction were lowered by 7.3 and 7.6 kcal mol−1, respectively, which enables cyclization.

Background: Cyclotides are plant-derived cyclic peptides that are divided into Möbius and bracelet subfamilies. Currently, only four linear variants of the Möbius subfamily have been isolated. Results: We discovered hedyotide B2 as the first linear representative of the bracelet subfamily. Conclusion: Hedyotide B2 shares the same connectivity as conventional cyclotides. Its linear structure is genetically predetermined. Significance: Our study broadens our knowledge of linear cyclotides.