Changes in Yield-Related Traits, Phytochemical Composition, and Antioxidant Activity of Pepper (Capsicum annuum) Depending on Its Variety, Fruit Position, and Ripening Stage

The Multifaceted Chemistry of Chili Peppers: A Biodiversity Treasure for Nutrition and Biomedicine

Due to its biodiversity, traditional medicine has been recognized worldwide for centuries and continues to affect the development of complementary and alternative therapies. A wide variety of spices, herbs, and trees are known for their curative effects. Chili pepper (Ch-p), a spice-utilizing fruit, is rich in natural medicinally bioactive compounds, such as flavonoids, capsaicinoids, and many other phytochemicals and phytonutrients. Operating in synergy and consortium, these compounds demonstrate their functionality, in comparison to lonely treatment, as active agents in handling many disorders. These may include abnormal coagulation, oxidative stress, obesity, diabetes, inflammation, cancer, and microbe-inducing diseases. Recently, capsaicinoids, particularly capsaicin, have been shown to manage the symptoms of significant viral diseases, including COVID-19. Capsaicin also has the potential to be an effective anesthetic agent and enables Ch-p to be expandedly employed as a topical preparation in relieving pain as well. The phytochemicals of Ch-p are not only beneficial and inexpensive phyto-alternatives in disease management, but they can also be used as scaffolds for the production of novel medicines. The study also substantiates the role of the TRPV1 receptor in the mitigation of chronic diseases in conjunction with capsaicin. Nevertheless, the consumption of Ch-p is the subject of limited medicinal research, necessitating the confirmation of the results from animal studies. The nutritional and biomedical prospection of Ch-p-derived products has been addressed in an accessible format in this artifact, with the potential to precisely enhance and enrich our pharmaceutical industries in the pursuit of human well-being.

Characterization of leucine aminopeptidase (LAP) activity in sweet pepper fruits during ripening and its inhibition by nitration and reducing events

KEY MESSAGE

Pepper fruits contain two leucine aminopeptidase (LAP) genes which are differentially modulated during ripening and by nitric oxide. The LAP activity increases during ripening but is negatively modulated by nitration. Leucine aminopeptidase (LAP) is an essential metalloenzyme that cleaves N-terminal leucine residues from proteins but also metabolizes dipeptides and tripeptides. LAPs play a fundamental role in cell protein turnover and participate in physiological processes such as defense mechanisms against biotic and abiotic stresses, but little is known about their involvement in fruit physiology. This study aims to identify and characterize genes encoding LAP and evaluate their role during the ripening of pepper (Capsicum annuum L.) fruits and under a nitric oxide (NO)-enriched environment. Using a data-mining approach of the pepper plant genome and fruit transcriptome (RNA-seq), two LAP genes, designated CaLAP1 and CaLAP2, were identified. The time course expression analysis of these genes during different fruit ripening stages showed that whereas CaLAP1 decreased, CaLAP2 was upregulated. However, under an exogenous NO treatment of fruits, both genes were downregulated. On the contrary, it was shown that during fruit ripening LAP activity increased by 81%. An in vitro assay of the LAP activity in the presence of different modulating compounds including peroxynitrite (ONOO-), NO donors (S-nitrosoglutathione and nitrosocyteine), reducing agents such as reduced glutathione (GSH), L-cysteine (L-Cys), and cyanide triggered a differential response. Thus, peroxynitrite and reducing compounds provoked around 50% inhibition of the LAP activity in green immature fruits, whereas cyanide upregulated it 1.5 folds. To our knowledge, this is the first characterization of LAP in pepper fruits as well as of its regulation by diverse modulating compounds. Based on the capacity of LAP to metabolize dipeptides and tripeptides, it could be hypothesized that the LAP might be involved in the GSH recycling during the ripening process.