Characterization of a sesquiterpene cyclase from the glandular trichomes of Leucosceptrum canum for sole production of cedrol in Escherichia coli and Nicotiana benthamiana

Synergistic treatment of androgenetic alopecia with follicular co-delivery of minoxidil and cedrol in metal-organic frameworks stabilized by covalently cross-linked cyclodextrins

Androgenetic alopecia seriously affects the physical and mental health of patients. The main clinical therapeutic agent, minoxidil tincture, is challenged by solvent irritation and dose-dependent side effects. Our recent work has identified a biosafety natural product, cedrol, that is synergistic in combination with minoxidil, thereby improving medication safety by substantially reducing the clinical dose of minoxidil. In addition, ccross-linked CD-MOF were designed as carriers for hair follicle delivery, and γ-CD in the carriers was cross-linked by diphenyl carbonate with covalent bonds to protect the CD-MOF from rapid disintegration in an aqueous environment. This improved nanocarrier has a drug loading of 25%, whereas nanocarriers increased drug delivery to the hair follicles through ratchet effect, and increased human dermal papilla cells uptake of drugs via endocytosis pathways mainly mediated by lattice proteins, energy-dependent active transport, and lipid raft-dependent, thus improved cell viability, proliferation, and migration, followed by significantly enhancing the anti-androgenetic alopecia effect, with cedrol focusing on inhibiting 5α-reductase and activating Shh/Gli pathway, and minoxidil, which up-regulated VEGF, down-regulated TGF-β, and activated ERK/AKT pathway. This drug combination provides a new therapeutic strategy for androgenetic alopecia, while the newly developed cross-linked CD-MOF has been shown to serve as a promising follicular delivery vehicle.

The component of the Chamaecyparis obtusa essential oil and insecticidal activity against Tribolium castaneum (Herbst)

Tribolium castaneum (Herbst) is a worldwide grain storage pest controlled by chemical control methods of phosphine fumigation, which results in many hazards, damages human health, makes pests resistant to pesticides, and pollutes the environment. In recent years, the popularity of botanical insecticides has continued to rise, and plant essential oils (EO) are considered potential alternatives for developing insecticides. In the current study, we selected the Chamaecyparis obtusa EO to determine its insecticidal effects and component analysis on T. castaneum. Through gas chromatography-ion mobility spectrometry (GC-IMS) technology, cedrol was the most obvious compound in the signal peak of the volatile components detected in the C. obtusa EO. The results of the bioassay showed that the C. obtusa EO had certain contact activity against T. castaneum, and the LD50 was 52.54 μg/adult. At three concentrations (0.41,1.62, 2.83 uL/cm2), the repellent rates of C. obtusa EO against T. castaneum were all above 80% at 15, 30, 60, and 120 min, respectively, indicating that the repellent effect was strong. Meanwhile, the C. obtusa EO exhibited fumigant toxicity against T. castaneum with LC50 values of 7.09 μg/L air. In addition, C. obtusa EO significantly increased the activity of AChE, CarE, POD, CAT, T-SOD, and chitinase in T. castaneum. Finally, the mechanism of C. obtusa EO on T. castaneum adults was explored based on transcriptome sequencing. We found that the DEGs focused on the chitin metabolic process and some aging genes in T. castaneum. Therefore, C. obtusa EO could be used as potential eco-friendly candidates for stored grain pest management.

A new sesquiterpene synthase catalyzing the formation of (R)-β-bisabolene from medicinal plant Colquhounia coccinea var. mollis and its anti-adipogenic and antibacterial activities

The sesquiterpene β-bisabolene possessing R and S configurations is commonly found in plant essential oils with antimicrobial and antioxidant activities. Here, we report the cloning and functional characterization of a (R)-β-bisabolene synthase gene (CcTPS2) from a Lamiaceae medicinal plant Colquhounia coccinea var. mollis. The biochemical function of CcTPS2 catalyzing the cyclization of farnesyl diphosphate to form a single product (R)-β-bisabolene was characterized through an engineered Escherichia coli producing diverse polyprenyl diphosphate precursors and in vitro enzyme assay, indicating that CcTPS2 was a high-fidelity (R)-β-bisabolene synthase. The production of (R)-β-bisabolene in an engineered E. coli strain harboring the exogenous mevalonate pathway, farnesyl diphosphate synthase and CcTPS1 genes was 17 mg/L under shaking flask conditions. Ultimately, 120 mg of purified (R)-β-bisabolene was obtained from the engineered E. coli, and its structure was elucidated by detailed spectroscopic analyses (including 1D and 2D NMR, and specific rotation). Four chimeric enzymes were constructed through domain swapping, which altered the product outcome, indicating the region important for substrate and product specificity. In addition, (R)-β-bisabolene exhibited anti-adipogenic activity in the model organism Caenorhabditis elegans and antibacterial activity selectively against Gram-positive bacteria.

Cedrol, a Ginger-derived sesquiterpineol, suppresses estrogen-deficient osteoporosis by intervening NFATc1 and reactive oxygen species

Osteoporosis is a prevalent bone metabolic disease in menopause, and long-term medication is accompanied by serious side effects. Ginger, a food spice and traditional medicine with ancient history, exhibits the potential to alleviate osteoporosis in preclinical experiments, whereas its complex composition leads to ambiguous pharmacological mechanisms. The purpose of this study was to investigate the effect and mechanism of Ced in estrogen-deficient osteoporosis, a sesquiterpene alcohol recently discovered from Ginger with multiple pharmacological properties. RANKL was stimulated BMM (bone marrow macrophages) differentiation into osteoclasts in vitro. And the osteoclast activity and number were assessed by TRAcP and SEM. We found that Ced mitigated RANKL-induced osteoclastogenesis by descending the ROS content and obstructing NFATc1, NF-κB, and MAPK signaling. Also, Ced-mediated anti-osteolytic property was found in ovariectomized mice by Micro-CT scanning and histological staining. Summarily, our works demonstrated the anti-osteoporotic potential of Cedrol in Ginger for the first time, which also offered more pharmacological evidence for Ginger as food or medicine used for bone metabolic disease.

AabHLH112, a bHLH transcription factor, positively regulates sesquiterpenes biosynthesis in Artemisia annua

The bHLH transcription factors play important roles in the regulation of plant growth, development, and secondary metabolism. β-Caryophyllene, epi-cedrol, and β-farnesene, three kinds of sesquiterpenes mainly found in plants, are widely used as spice in the food industry and biological pesticides in agricultural production. Furthermore, they also have a significant value in the pharmaceutical industry. However, there is currently a lack of knowledge on the function of bHLH family TFs in β-caryophyllene, epi-cedrol, and β-farnesene biosynthesis. Here, we found that AabHLH112 transcription factor had a novel function to positively regulate β-carophyllene, epi-cedrol, and β-farnesene biosynthesis in Artemisia annua. Exogenous MeJA enhanced the expression of AabHLH112 and genes of β-caryophyllene synthase (CPS), epi-cedrol synthase (ECS), and β-farnesene synthase (BFS), as well as sesquiterpenes content. Dual-LUC assay showed the activation of AaCPS, AaECS, and AaBFS promoters were enhanced by AabHLH112. Yeast one-hybrid assay showed AabHLH112 could bind to the G-box (CANNTG) cis-element in promoters of both AaCPS and AaECS. In addition, overexpression of AabHLH112 in A. annua significantly elevated the expression levels of AaCPS, AaECS, and AaBFS as well as the contents of β-caryophyllene, epi-cedrol, and β-farnesene, while suppressing AabHLH112 expression by RNAi reduced the expression of the three genes and the contents of the three sesquiterpenes. These results suggested that AabHLH112 is a positive regulator of β-caryophyllene, epi-cedrol, and β-farnesene biosynthesis in A. annua.

Design and biocatalytic applications of genetically fused multifunctional enzymes

Fusion proteins, understood as those created by joining two or more genes that originally encoded independent proteins, have numerous applications in biotechnology, from analytical methods to metabolic engineering. The use of fusion enzymes in biocatalysis may be even more interesting due to the physical connection of enzymes catalyzing successive reactions into covalently linked complexes. The proximity of the active sites of two enzymes in multi-enzyme complexes can make a significant contribution to the catalytic efficiency of the reaction. However, the physical proximity of the active sites does not guarantee this result. Other aspects, such as the nature and length of the linker used for the fusion or the order in which the enzymes are fused, must be considered and optimized to achieve the expected increase in catalytic efficiency. In this review, we will relate the new advances in the design, creation, and use of fused enzymes with those achieved in biocatalysis over the past 20 years. Thus, we will discuss some examples of genetically fused enzymes and their application in carbon‑carbon bond formation and oxidative reactions, generation of chiral amines, synthesis of carbohydrates, biodegradation of plant biomass and plastics, and in the preparation of other high-value products.

Identification of Pigmented Substances in Black Honey from Leucosceptrum canum: Novel Quinonoids Contribute to Honey Color

Leucosceptrum canum (Lamiaceae) honey (LCH) is a rare and high-value honey with an unusual dark brown color. Its pigments may be related to the purported health benefits of the honey and could serve as indicators of authentic LCH. Here, we purified the pigmented substances contributing to LCH's color and identified them using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. The major pigmented substances were 1-[4-(3-carboxy-propylamino)-3,6-dioxo-cyclohexa-1,4-dienyl]-pyrrolidine-2-carboxylic acid (GPBQ), 1-[4-(3-carboxy-propylamino)-3,6-dioxo-cyclohexa-1,4-dienyl]-pyrrolidine-2-carboxylic acid. (GAPBQ), and 2,5-di-(N-prolyl)-para-benzoquinone (DPBQ). According to UHPLC-DAD data recorded at 370 nm, GPBQ, GAPBQ, and DPBQ contents ranged from 2.58 to 5.13, 2.93 to 4.96, and 4.26 to 9.22 mg/kg, respectively. These amino acid-quinone conjugates, found here for the first time, are pigments that can serve as markers to control the quality of LCH.

A Cryptic Plant Terpene Cyclase Producing Unconventional 18- and 14-Membered Macrocyclic C25 and C20 Terpenoids with Immunosuppressive Activity

A versatile terpene synthase (LcTPS2) producing unconventional macrocyclic terpenoids was characterized from Leucosceptrum canum. Engineered Escherichia coli and Nicotiana benthamiana expressing LcTPS2 produced six 18-/14-membered sesterterpenoids including five new ones and two 14-membered diterpenoids. These products represent the first macrocyclic sesterterpenoids from plants and the largest sesterterpenoid ring system identified to date. Two variants F516A and F516G producing approximately 3.3- and 2.5-fold, respectively, more sesterterpenoids than the wild-type enzyme were engineered. Both 18- and 14-membered ring sesterterpenoids displayed significant inhibitory activity on the IL-2 and IFN-γ production of T cells probably via inhibition of the MAPK pathway. The findings will contribute to the development of efficient biocatalysts to create bioactive macrocyclic sesterterpenoids, and also herald a new potential in the well-trodden territory of plant terpenoid biosynthesis.

An extremely promiscuous terpenoid synthase from the Lamiaceae plant Colquhounia coccinea var. mollis catalyzes the formation of sester-/di-/sesqui-/mono-terpenoids

Terpenoids are the largest class of natural products with complex structures and extensive bioactivities; their scaffolds are generated by diverse terpenoid synthases (TPSs) from a limited number of isoprenoid diphosphate precursors. Promiscuous TPSs play important roles in the evolution of terpenoid chemodiversity, but they remain largely unappreciated. Here, an extremely promiscuous terpenoid synthase (CcTPS1) of the TPS-b subfamily was cloned and functionally characterized from a leaf-specific transcriptome of the Lamiaceae plant Colquhounia coccinea var. mollis. CcTPS1 is the first sester-/di-/sesqui-/mono-TPS identified from the plant kingdom, accepting C25/C20/C15/C10 diphosphate substrates to generate a panel of sester-/di-/sesqui-/mono-terpenoids. Engineered Escherichia coli expressing CcTPS1 produced three previously unreported terpenoids (two sesterterpenoids and a diterpenoid) with rare cyclohexane-containing skeletons, along with four sesquiterpenoids and one monoterpenoid. Their structures were elucidated by extensive nuclear magnetic resonance spectroscopy. Nicotiana benthamiana transiently expressing CcTPS1 also produced the diterpenoid and sesquiterpenoids, demonstrating the enzyme's promiscuity in planta. Its highly leaf-specific expression pattern combined with detectable terpenoid products in leaves of C. coccinea var. mollis and N. benthamiana expressing CcTPS1 suggested that CcTPS1 was mainly responsible for diterpenoid and sesquiterpenoid biosynthesis in plants. CcTPS1 expression and the terpenoid products could be induced by methyl jasmonate, suggesting their possible role in plant-environment interaction. CcTPS1 was localized to the cytosol and may differ from mono-TPSs in subcellular compartmentalization and substrate tolerance. These findings will greatly aid our understanding of plant TPS evolution and terpenoid chemodiversity; they also highlight the enormous potential of transcriptome mining and heterologous expression for the exploration of unique enzymes and natural products hidden in plants.

Metabolic engineering strategies for sesquiterpene production in microorganism

Sesquiterpenes are a large variety of terpene natural products, widely existing in plants, fungi, marine organisms, insects, and microbes. Value-added sesquiterpenes are extensively used in industries such as: food, drugs, fragrances, and fuels. With an increase in market demands and the price of sesquiterpenes, the biosynthesis of sesquiterpenes by microbial fermentation methods from renewable feedstocks is acquiring increasing attention. Synthetic biology provides robust tools of sesquiterpene production in microorganisms. This review presents a summary of metabolic engineering strategies on the hosts and pathway engineering for sesquiterpene production. Advances in synthetic biology provide new strategies on the creation of desired hosts for sesquiterpene production. Especially, metabolic engineering strategies for the production of sesquiterpenes such as: amorphadiene, farnesene, bisabolene, and caryophyllene are emphasized in: Escherichia coli, Saccharomyces cerevisiae, and other microorganisms. Challenges and future perspectives of the bioprocess for translating sesquiterpene production into practical industrial work are also discussed.

Characterization of a Sesquiterpene Synthase Catalyzing Formation of Cedrol and Two Diastereoisomers of Tricho-Acorenol from Euphorbia fischeriana

A sesquiterpene synthase gene was identified from the transcriptome of Euphorbia fischeriana Steud, and the function of its product EfTPS12 was characterized by in vitro biochemical experiments and synthetic biology approaches. EfTPS12 catalyzed conversion of farnesyl diphosphate into three products, including cedrol (1) and eupho-acorenols A (2) and B (3) (two diastereoisomers of tricho-acorenol), thereby being named EfCAS herein. The structures of 2 and 3 were determined by spectroscopic methods and comparison of experimental and calculated electronic circular dichroism spectra. EfCAS is the first example of a plant-derived sesquiterpene synthase that is capable of synthesizing acorane-type alcohols. This study also documents that synthetic biology approaches enable large-scale preparation of volatile terpenes and thereby substantially facilitate characterization of corresponding terpene synthases and elucidation of the structures of their products.

Production of the Inaccessible Sesquiterpene (-)-5-Epieremophilene by Metabolically Engineered Escherichia coli

(-)-5-Epieremophilene, an epimer of the versatile sesquiterpene (+)-valencene, is an inaccessible natural product catalyzed by three sesquiterpene synthases (SmSTPSs1-3) of the Chinese medicinal herb Salvia miltiorrhiza, and its biological activity remains less explored. In this study, three metabolically engineered Escherichia coli strains were constructed for (-)-5-epieremophilene production with yields of 42.4-76.0 mg/L in shake-flask culture. Introducing an additional copy of farnesyl diphosphate synthase (FDPS) gene through fusion expression of SmSTPS1-FDPS or dividing the FDP synthetic pathway into two modules resulted in significantly improved production, and ultimately 250 mg of (-)-5-epieremophilene were achieved. Biological assay indicated that (-)-5-epieremophilene showed significant antifeedant activity against Helicoverpa armigera (EC₅₀ =1.25 μg/cm² ), a common pest of S. miltiorrhiza, implying its potential defensive role in the plant. The results provided an ideal material supply for studying other potential biological activities of (-)-5-epieremophilene, and also a strategy for manipulating terpene production in engineered E. coli using synthetic biology.

Cedrol attenuates collagen-induced arthritis in mice and modulates the inflammatory response in LPS-mediated fibroblast-like synoviocytes

Ginger has been used as a flavouring agent and traditional medicine for a long time in Asian countries.

Enhancing epi-cedrol production in Escherichia coli by fusion expression of farnesyl pyrophosphate synthase and epi-cedrol synthase

Terpene synthase catalyses acyclic diphosphate farnesyl diphosphate into desired sesquiterpenes. In this study, a fusion enzyme was constructed by linking Santalum album farnesyl pyrophosphate synthase (SaFPPS) individually with terpene synthase and Artemisia annua Epi-cedrol synthase (AaECS). The stop codon at the N-terminus of SaFPPS was removed and replaced by a short peptide (GSGGS) to introduce a linker between the two open reading frames. This fusion clone was expressed in Escherichia coli Rosseta DE3 cells. The fusion enzyme FPPS-ECS produced sesquiterpene 8-epi-cedrol from substrates isopentenyl pyrophosphate and dimethylallyl pyrophosphate through sequential reactions. The K _m values for FPPS-ECS for isopentyl diphosphate was 4.71 µM. The fusion enzyme carried out the efficient conversion of IPP to epi-cedrol, in comparison to single enzymes SaFPPS and AaECS when combined together in enzyme assay over time. Further, the recombinant E. coli BL21 strain harbouring fusion plasmid successfully produced epi-cedrol in fermentation medium. The strain having fusion plasmid (pET32a-FPPS-ECS) produced 1.084 ± 0.09 mg/L epi-cedrol, while the strain harbouring mixed plasmid (pRSETB-FPPS and pET28a-ECS) showed 1.002 ± 0.07 mg/L titre in fermentation medium by overexpression and MEP pathway utilization. Structural analysis was done by I-TASSER server and docking was done by AutoDock Vina software, which suggested that secondary structure of the N- C terminal domain and their relative positions to functional domains of the fusion enzyme was greatly significant to the catalytic properties of the fusion enzymatic complex than individual enzymes.