Inhibition of calmodulin-dependent calcium-ATPase and phosphodiesterase by various cyclopeptides and peptide alkaloids from the Zizyphus species

Plant peptides - redefining an area of ribosomally synthesized and post-translationally modified peptides

Covering 1965 to February 2024Plants are prolific peptide chemists and are known to make thousands of different peptidic molecules. These peptides vary dramatically in their size, chemistry, and bioactivity. Despite their differences, all plant peptides to date are biosynthesized as ribosomally synthesized and post-translationally modified peptides (RiPPs). Decades of research in plant RiPP biosynthesis have extended the definition and scope of RiPPs from microbial sources, establishing paradigms and discovering new families of biosynthetic enzymes. The discovery and elucidation of plant peptide pathways is challenging due to repurposing and evolution of housekeeping genes as both precursor peptides and biosynthetic enzymes and due to the low rates of gene clustering in plants. In this review, we highlight the chemistry, biosynthesis, and function of the known RiPP classes from plants and recommend a nomenclature for the recent addition of BURP-domain-derived RiPPs termed burpitides. Burpitides are an emerging family of cyclic plant RiPPs characterized by macrocyclic crosslinks between tyrosine or tryptophan side chains and other amino acid side chains or their peptide backbone that are formed by copper-dependent BURP-domain-containing proteins termed burpitide cyclases. Finally, we review the discovery of plant RiPPs through bioactivity-guided, structure-guided, and gene-guided approaches.

Catharanthine, an anticancer vinca alkaloid: an in silico and in vitro analysis of the autophagic system as the major mechanism of cell death in liver HepG2 cells

Catharanthine, a component of the anticancer drug vinblastine along with vindoline, disrupts the cell cycle by interfering with mitotic spindle formation. Apart from their antioxidant properties, vinca alkaloids like catharanthine inhibit phosphodiesterase activity and elevate intracellular cAMP levels. The aim of this study was to investigate how catharantine affects apoptosis and autophagy. This study conducted experiments on HepG2 liver carcinoma cells with varying doses of catharanthine to evaluate cell death rates and viability and determine the IC50 concentration via MTT assays. The apoptotic and autophagic effects of catharanthine were assessed using flow cytometry with annexin V and PI staining, while the expression of autophagy-related genes was analyzed through quantitative PCR. Additionally, molecular docking and molecular dynamics simulations were employed to further investigate catharanthine's impact on autophagy mechanisms. The study showed that catharanthine reduced oxidative stress and triggered apoptosis in HepG2 cells in a dose-dependent manner. Catharanthine also upregulated the expression of autophagy-related genes like LC3, Beclin1, and ULK1. Notably, catharanthine increased sirtuin-1 levels, a known autophagy inducer, while decreasing Akt expression compared to untreated cells. Molecular docking results indicated rapamycin had a stronger binding affinity with FRB (-10.7 KJ/mol-1) than catharanthine (-7.3 KJ/mol-1). Additionally, molecular dynamics simulations revealed that catharanthine interacted effectively with the FRB domain of mTOR, displaying stability and a strong binding affinity, although not as potent as rapamycin. In summary, besides its cytotoxic and pro-apoptotic effects, catharanthine activates autophagy signaling pathways and induces autophagic necrosis by inhibiting mTOR.

Sour Jujube (Ziziphus jujuba var. spinosa): A Bibliometric Review of Its Bioactive Profile, Health Benefits and Trends in Food and Medicine Applications

Research on the comprehensive utilization of sour jujube and its beneficial properties to human health has attracted extensive attention. This study aims to conduct a bibliometric analysis of the bioactive profile of sour jujube and future trends in applications. The research advancements within this field from 2000 to 2023 were addressed using the Web of Science database and VOSviewer. Among the 322 results, the most frequent keywords of bioactivity are flavonoids, antioxidants, saponins, insomnia, polyphenols, terpenoids and anti-inflammatory; the most studied parts of sour jujube are seeds, fruits and leaves; the published articles with high citations mainly focus on identification, biological effects and different parts distribution of bioactive compounds. The bioactivity of various parts of sour jujube was reviewed considering their application potential. The seeds, rich in flavonoids, saponins and alkaloids, exhibit strong effects on central nervous system diseases and have been well-developed in pharmacology, healthcare products and functional foods. The pulp has antioxidant properties and is used to develop added-value foods (e.g., juice, vinegar, wine). The leaves can be used to make tea and flowers are good sources of honey; their extracts are rich sources of flavonoids and saponins, which show promising medicinal effects. The branches, roots and bark have healing properties in traditional folk medicine. Overall, this study provides a reference for future applications of sour jujube in food and medicine fields.

Wild Jujube (Ziziphus jujuba var. spinosa): A Review of Its Phytonutrients, Health Benefits, Metabolism, and Applications

Wild jujube, Ziziphus jujuba Mill. var. spinosa (Bunge) Hu ex H. F. Chou, as a food and health supplement worldwide, has rich nutritional value. It contains nutrients such as nucleosides, amino acids, polysaccharides, and fatty oils. The fruits, seeds, and leaves of wild jujube can all be used for food, medicine, or health care purposes. Among these, the fruits play many roles, such as antioxidant, antibacterial, and anti-inflammatory functions, and can be used as a natural nutritional supplement to prevent aging. Simultaneously, the mature seed of wild jujube exhibits beneficial effects on central nervous system diseases and is often used for the treatment of insomnia and as a functional food for improving sleep quality and enhancing learning and memory. This review presents an overview of research progress relevant to the phytonutrients, biological functions, metabolism of bioactive compounds, and applications of wild jujube and aims to provide a scientific reference for the development and utilization of this plant.

Natural Molecules as Talented Inhibitors of Nucleotide Pyrophosphatases/Phosphodiesterases (PDEs)

BACKGROUND

Phosphodiesterases (PDEs) are a wide group of enzymes with multiple therapeutic actions, including vasorelaxation, cardiotonic, antidepressant, anti-inflammatory, antithrombotic, anti-spasmolytic, memory-enhancing, and anti-asthmatic. PDEs with eleven subtypes from PDE-1 to PDE-11 typically catalyze the cleavage of the phosphodiester bond and, hence, degrades either cyclic adenosine monophosphate (cAMP) or cyclic guanosine monophosphate (cGMP).

OBJECTIVE

Several selective or non-selective inhibitors of the PDE subtypes are used clinically, i.e. sildenafil, rolipram, cysteine, etc. Recently, interest in plant-based pharmacologically bioactive compounds having potent PDEs inhibitory potential has increased. Purposely, extensive research has been carried out on natural products to explore new inhibitors of various PDEs. Therefore, this review summarizes the published data on natural PDEs inhibitors and their potential therapeutic applications.

METHODS

For this purpose, natural compounds with PDE inhibitory potential have been surveyed through several databases, including PubMed, Web of Sciences (WoS), Scopus, and Google Scholar.

RESULTS

According to a detailed literature survey, the most promising class of herbal compounds with PDE-inhibiting property has been found to belong to phenolics, including flavonoids (luteolin, kaempferol, icariin, etc.). Many other encouraging inhibitors from plants have also been identified, such as coumarins (23, 24) (licoarylcoumarin and glycocoumarin,), saponins ( agapanthussaponins), lignans (31, 33) [(±)-schizandrin and kobusin], terpenes (28, 29, 31) (perianradulcin A, quinovic acid, and ursolic acid), anthraquinones (18, 19) (emodin and chrysophanol), and alkaloids (Sanjoinine-D) (36).

CONCLUSION

In this review, studies have revealed the PDE-inhibitory potential of natural plant extracts and their bioactive constituents in treating various diseases; however, further clinical studies comprising synergistic use of different therapies (synthetic & natural) to acquire multi-targeted results might also be a promising option.

Ziziphus spinosa seeds for insomnia: A review of chemistry and psychopharmacology

BACKGROUND

In Chinese medicine, Ziziphus jujuba Mill. var. spinosa (Bunge) Hu ex H. F. Chou is widely used for the treatment of insomnia.

PURPOSE/SECTIONS

This paper summarises the chemistry, psychopharmacology, and compares the pharmaceutical effects of the seeds of Ziziphus jujuba plant, Ziziphus spinosa (ZS) seeds, with benzodiazepines. Whole extracts and constituent compounds have been evaluated in preclinical and clinical studies.

CONCLUSIONS

ZS secondary metabolites modulate GABAergic activity and the serotonergic system. The actual therapeutic agents require further confirmation/identification so that new insomnia phytomedicines can be discovered.

Cu-mediated enamide formation in the total synthesis of complex peptide natural products

Cu-mediated C(sp(2))-N bond formation has received intense interest recently, and has been applied to the total synthesis of a wide variety of structurally complex natural products. This review covers the synthetic assembly of peptide natural products in which Cu-mediated enamide formation is the key transformation. The total syntheses of cyclopeptide alkaloids, pacidamycin D, and yaku'amide A exemplify the versatility of the Cu-catalyzed cross-coupling reaction in comparison to other synthetic methods.

Cyclopeptide alkaloids from Scutia buxifolia Reiss

Scutianene E (1), 3,4,28-tris-epi-scutiaene E (2), 28-epi-scutianene E (3) and scutianene L (4), four neutral cyclopeptide alkaloids, were isolated from Scutia buxifolia Reiss, together with four known cyclopeptide alkaloids, scutianines B, C, D and E. Scutianenes 1-3 are diastereoisomeric compounds, with 3-hydroxyleucine as a β-hydroxy amino acid unit, which is connected to the styryl fragment via an ether bridge, β-phenylserine, as a common ring-bonded amino acid residue. Attached to the amino group of β-hydroxyamino acid is a side chain [trans-CH=CH-Ph]. The structures of the peptides were elucidated by means of spectroscopic analysis, including extensive 2D NMR studies. The stereochemistry for the diastereomeric 3,4,28-tris-epi-scutiaene E and 28-epi-scutianene E was confirmed by X-ray diffraction analysis of their O-acetyl derivatives.

Identification and inhibitory properties of multifunctional peptides from pea protein hydrolysate

Pea protein isolate was hydrolyzed with alcalase, and the hydrolysate passed through a 1 kDa cutoff ultrafiltration membrane. The permeate was freeze-dried and fractionated on a cationic solid-phase extraction (SPE) column. All fractions were tested for their inhibitory activities against angiotensin-converting enzyme (ACE), renin, and calmodulin-dependent phosphodiesterase 1 (CaMPDE). With the exception of the first eluted fraction, inhibitory properties of the SPE fractions against CaMPDE (but not ACE and renin) were directly related to cationic character (residence time on the column). However, the fraction that eluted with 1% ammonium hydroxide (SPE 1%) had the highest peptide yield and was subsequently fractionated using two consecutive rounds of reversed-phase high-performance liquid chromatography to obtain three peaks with major peptides identified as IR, KF, and EF by ultra performance liquid chromatography-tandem mass spectrometry. The three dipeptides showed weak inhibitory properties toward CaMPDE but strong inhibitions (IC50 values <25 mM) of ACE and renin. In general, the peptides had higher potency against ACE than against renin. It is indicated from our results that these peptides may be used as potential ingredients to formulate multifunctional food products and nutraceuticals.

Antinociceptive effects of 14-membered cyclopeptide alkaloids

The analgesic potential of six 14-membered-ring cyclopeptide alkaloids, namely, franganine (1), discarine B (2), scutianines B (3), C (4), and D (5), and adouetine X (6), have been investigated. Among the compounds tested, only franganine (1) and adouetine X (6) produced antinociceptive effects in a mouse model of acute pain, without inducing undesirable side effects. Furthermore, compound 6 also exhibited a pronounced analgesic effect in a chronic neuropathic pain model in mice. It has been found that adouetine X (6) can decrease the activities of Ca(2+)-ATPase and Na(+)/K(+)-ATPase in vitro. Thus, the present findings have demonstrated that adouetine X (6) is a promising analgesic agent.

Amino Acid Derived Macrocycles—An Area Driven by Synthesis or Application?

The synthesis, structure, and physical properties of macrocycles have fascinated chemists for many years. Their inherent properties make them useful in areas as diverse as ion transport across membranes, development of new antibiotics, and catalysis. In this Review, the authors examine the chemistry of macrocycles containing non-peptidic amino acid derived molecules; the analysis is discussed in terms of function, rather than structure or synthesis. It is revealed that the diverse and imaginative structures created by synthetic chemists are not being fully exploited in application-driven endeavors.

Inhibition of calmodulin-dependent protein kinase II by cyclic and linear peptide alkaloids fromZizyphus species

The effects of sedative peptide alkaloids from Zizyphus species on calmodulin- dependent protein kinase II were investigated. Protein kinase II activity was assayed on the basis of its ability to activate tryptophan 5-monooxygenase as its substrate in the presence of calmodulin. All thirteen alkaloids tested were stronger inhibitors than chlorpromazine (IC50, 98 microM) on calmodulin-dependent protein kinase II. Among them, the most potent inhibitor was daechuine S27 (IC50 2.95 microM), which was stronger than pimozide (IC50, 15.0 microM).

Cyclopeptide alkaloids: chemistry and biology

Recent progress in the synthesis and investigation of the biological activities of cyclopeptide alkaloids is reviewed. New strategies have been devised to overcome some of the synthetic challenges inherent in the formation of strained paracyclophanes. However, issues remain which offer opportunities for the application of catalytic enantioselective organometallic reactions. Members of this class of natural products have been isolated from various parts of a wide variety of plants and researchers will likely continue to show great interest in their formation and function. The biological properties of certain members of this class warrant further investigation. To gain additional insight into these areas, continuing development of synthetic methodology will be essential.