In the current investigation, a series of heterocyclic derivatives of boswellic acids were prepared along with new monomers of 3-O-acetyl-11-keto-β-boswellic acid (AKBA, 1) 11-keto-β-boswellic acid (KBA, 2) and several new bis-AKBA and KBA homodimers and AKBA-KBA heterodimers. The effects of these compounds on the proliferation of different human cancer cell lines, viz., FaDu (pharynx carcinoma), A2780 (ovarian carcinoma), HT29 (colon adenocarcinoma), and A375 (malignant melanoma), have been evaluated. Thus, KBA homodimer 21 effectively inhibited the growth of FaDu, A2780, HT29, and A375 cells with EC50 values below 9 μM. In addition, compounds 7, 8, 11, 12, 15, 16, and 17 also exhibited cytotoxic effects for A2780, HT29, and A375 cancer cells. In particular, the pyrazine analog 8 was highly cytotoxic for A375 cancer cells with an EC50 value of 2.1 μM.

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Herbs of the Umbelliferae family are popular spices valued worldwide for their many nutritional and health benefits. Herein, five chief umbelliferous fruits viz., cumin, fennel, anise, coriander and caraway were assessed for its secondary metabolites diversity along with compositional changes incurring upon roasting as analyzed via ultra-high performance liquid chromatography coupled to photodiode array and electrospray ionization mass detectors UHPLC-qToF/MS. A total of 186 metabolites were annotated, according to metabolomics society guidelines, belonging mainly to flavonoids, fatty acids and phenolic acids. Multivariate models viz., PCA, HCA and OPLS-DA were further employed to assess fruits\' heterogeneity in an untargeted manner and determine mechanistic changes in bioactive makeup post roasting viz., glycosidic cleavage, lipid degradation and Maillard reaction. Finally, the fruits\' antioxidant activity showed decline upon roasting and in correlation with its total phenolic content. This study presents the first complete map of umbelliferous fruit metabolome, compositional differences and its roasting effect.

Glandular trichomes are epidermal outgrowths that are the site of biosynthesis and storage of large quantities of specialized metabolites. Besides their role in the protection of plants against biotic and abiotic stresses, they have attracted interest owing to the importance of the compounds they produce for human use; for example, as pharmaceuticals, flavor and fragrance ingredients, or pesticides. Here, we review what novel concepts investigations on glandular trichomes have brought to the field of specialized metabolism, particularly with respect to chemical and enzymatic diversity. Furthermore, the next challenges in the field are understanding the metabolic network underlying the high productivity of glandular trichomes and the transport and storage of metabolites. Another emerging area is the development of glandular trichomes. Studies in some model species, essentially tomato, tobacco, and Artemisia, are now providing the first molecular clues, but many open questions remain: How is the distribution and density of different trichome types on the leaf surface controlled? When is the decision for an epidermal cell to differentiate into one type of trichome or another taken? Recent advances in gene editing make it now possible to address these questions and promise exciting discoveries in the near future.

Flower organ abscission in Arabidopsis is regulated by a peptide hormone that is released from its precursor by a network of redundant subtilases. An exciting new study describes how drought-induced flower abscission in tomato is regulated similarly, but distinctly via a single, different subtilase that releases a very different peptide hormone.

Industrialized tomato production faces a decrease in flavors and nutritional value due to conventional breeding. Moreover, tomato production heavily relies on nitrogen and phosphate fertilization. Phosphate uptake and improvement of fruit quality by arbuscular mycorrhizal (AM) fungi are well-studied. We addressed the question of whether commercially used tomato cultivars grown in a hydroponic system can be mycorrhizal, leading to improved fruit quality. Tomato plants inoculated with Rhizophagus irregularis were grown under different phosphate concentrations and in substrates used in industrial tomato production. Changes in fruit gene expression and metabolite levels were checked by RNAseq and metabolite determination, respectively. The tests revealed that reduction of phosphate to 80% and use of mixed substrate allow AM establishment without affecting yield. By comparing green fruits from non-mycorrhizal and mycorrhizal plants, differentially expressed genes (DEGs) were found to possibly be involved in processes regulating fruit maturation and nutrition. Red fruits from mycorrhizal plants showed a trend of higher BRIX values and increased levels of carotenoids in comparison to those from non-mycorrhizal plants. Free amino acids exhibited up to four times higher levels in red fruits due to AM, showing the potential of mycorrhization to increase the nutritional value of tomatoes in industrialized production.

Black pepper (Piper nigrum L.) is known for the high content of piperine, a cinnamoyl amide derivative regarded as largely responsible for the pungent taste of this widely used spice. Despite its long history and worldwide use, the biosynthesis of piperine and related amides has been enigmatic up to now. In this report we describe a specific piperic acid CoA ligase from immature green fruits of P. nigrum. The corresponding enzyme was cloned and functionally expressed in E. coli. The recombinant enzyme displays a high specificity for piperic acid and does not accept the structurally related feruperic acid characterized by a similar C‐2 extension of the general C6‐C3 phenylpropanoid structure. The enzyme is also inactive with the standard set of hydroxycinnamic acids tested including caffeic acid, 4‐coumaric acid, ferulic acid, and sinapic acid. Substrate specificity is corroborated by in silico modeling which suggests a perfect fit of the substrate piperic acid to the active site of the piperic acid CoA ligase. The CoA ligase gene shows highest expression levels in immature green fruits, is also expressed in leaves and flowers, but not in roots. Virus‐induced gene silencing provided some preliminary indications that the production of piperoyl‐CoA is required for the biosynthesis of piperine in black pepper fruits.

Casein kinase 2 is a ubiquitous protein kinase that has puzzled researchers for several decades because of its pleiotropic activity. Here, we set out to identify the in vivo targets of plastid casein kinase 2 (pCK2) in Arabidopsis thaliana. Survey phosphoproteome analyses were combined with targeted analyses with wild-type and pck2 knockdown mutants to identify potential pCK2 targets by their decreased phosphorylation state in the mutant. To validate potential substrates, we complemented the pck2 knockdown line with tandem affinity tag (TAP)-tagged pCK2 and found it to restore growth parameters, as well as many, but not all, putative pCK2-dependent phosphorylation events. We further performed a targeted analysis at the end-of-night to increase the specificity of target protein identification. This analysis confirmed light-independent phosphorylation of several pCK2 target proteins. Based on the aforementioned data, we define a set of in vivo pCK2-targets that span different chloroplast functions, such as metabolism, transcription, translation and photosynthesis. The pleiotropy of pCK2 functions is also manifested by altered state transition kinetics during short-term acclimation and significant alterations in the mutant metabolism, supporting its function in photosynthetic regulation. Thus, our data expand our understanding on chloroplast phosphorylation networks and provide insights into kinase networks in the regulation of chloroplast functions.

In contrast to the myriad of methods available to produce α‐helices and antiparallel β‐sheets in synthetic peptides, just a few are known for the construction of stable, non‐cyclic parallel β‐sheets. Herein, we report an efficient on‐resin approach for the assembly of parallel β‐sheet peptides in which the N‐alkylated turn moiety enhances the stability and gives access to a variety of functionalizations without modifying the parallel strands. The key synthetic step of this strategy is the multicomponent construction of an N‐alkylated turn using the Ugi reaction on varied isocyano‐resins. This four‐component process assembles the orthogonally protected turn fragment and incorporates handles serving for labeling/conjugation purposes or for reducing peptide aggregation. NMR and circular dichroism analyses confirm the better‐structured and more stable parallel β‐sheets in the N‐alkylated peptides compared to the non‐functionalized variants.

In contrast to the myriad of methods available to produce α‐helices and antiparallel β‐sheets in synthetic peptides, just a few are known for the construction of stable, non‐cyclic parallel β‐sheets. Herein, we report an efficient on‐resin approach for the assembly of parallel β‐sheet peptides in which the N‐alkylated turn moiety enhances the stability and gives access to a variety of functionalizations without modifying the parallel strands. The key synthetic step of this strategy is the multicomponent construction of an N‐alkylated turn using the Ugi reaction on varied isocyano‐resins. This four‐component process assembles the orthogonally protected turn fragment and incorporates handles serving for labeling/conjugation purposes or for reducing peptide aggregation. NMR and circular dichroism analyses confirm the better‐structured and more stable parallel β‐sheets in the N‐alkylated peptides compared to the non‐functionalized variants.