An improved water-soluble/stereospecific biotransformation of aporphine alkaloids in Stephania epigaea to 4 R -hydroxyaporphine alkaloids by Clonostachys rogersoniana

Detoxification Mechanism of Hinokitiol by Alternaria alternata and Its Application in Agricultural Antifungal Control

Alternaria alternata is a common plant pathogen that can infect crops and reduce their production. In this work, an antagonism experiment between A. alternata and the essential oil of arborvitae (Platycladus orientalis) was performed, and it was proven that A. alternata had developed resistance to this plant-derived fungicide. A. alternata facilitated the biotransformation of hinokitiol (1), the main antifungal compound in the essential oil of arborvitae, into (R)-2-hydroxy-β-methylbenzeneethanol (2), which does not have antifungal activity against A. alternata. This biotransformation is an unusual ring-contraction reaction that was verified to be catalyzed by P450 enzyme hydroxylation and Baeyer-Villiger oxidation. In addition, the P450 enzyme inhibitors 1-aminobenzotriazole and piperonyl butoxide effectively prevented the destruction of the hinokitiol structure by A. alternata, and the combined use of these P450 enzyme inhibitors significantly increased the antifungal activity of hinokitiol. This work provides a theoretical reference for the further development of botanical fungicides.

Terpenes modulate bacterial and fungal growth and sorghum rhizobiome communities

Terpenes are among the oldest and largest class of plant-specialized bioproducts that are known to affect plant development, adaptation, and biological interactions. While their biosynthesis, evolution, and function in aboveground interactions with insects and individual microbial species are well studied, how different terpenes impact plant microbiomes belowground is much less understood. Here we designed an experiment to assess how belowground exogenous applications of monoterpenes (1,8-cineole and linalool) and a sesquiterpene (nerolidol) delivered through an artificial root system impacted its belowground bacterial and fungal microbiome. We found that the terpene applications had significant and variable impacts on bacterial and fungal communities, depending on terpene class and concentration; however, these impacts were localized to the artificial root system and the fungal rhizosphere. We complemented this experiment with pure culture bioassays on responsive bacteria and fungi isolated from the sorghum rhizobiome. Overall, higher concentrations (200 µM) of nerolidol were inhibitory to Ferrovibrium and tested Firmicutes. While fungal isolates of Penicillium and Periconia were also more inhibited by higher concentrations (200 µM) of nerolidol, Clonostachys was enhanced at this higher level and together with Humicola was inhibited by the lower concentration tested (100 µM). On the other hand, 1,8-cineole had an inhibitory effect on Orbilia at both tested concentrations but had a promotive effect at 100 µM on Penicillium and Periconia. Similarly, linalool at 100 µM had significant growth promotion in Mortierella, but an inhibitory effect for Orbilia. Together, these results highlight the variable direct effects of terpenes on single microbial isolates and demonstrate the complexity of microbe-terpene interactions in the rhizobiome. IMPORTANCE Terpenes represent one of the largest and oldest classes of plant-specialized metabolism, but their role in the belowground microbiome is poorly understood. Here, we used a "rhizobox" mesocosm experimental set-up to supply different concentrations and classes of terpenes into the soil compartment with growing sorghum for 1 month to assess how these terpenes affect sorghum bacterial and fungal rhizobiome communities. Changes in bacterial and fungal communities between treatments belowground were characterized, followed by bioassays screening on bacterial and fungal isolates from the sorghum rhizosphere against terpenes to validate direct microbial responses. We found that microbial growth stimulatory and inhibitory effects were localized, terpene specific, dose dependent, and transient in time. This work paves the way for engineering terpene metabolisms in plant microbiomes for improved sustainable agriculture and bioenergy crop production.

Multi-Level Optimization and Strategies in Microbial Biotransformation of Nature Products

Continuously growing demand for natural products with pharmacological activities has promoted the development of microbial transformation techniques, thereby facilitating the efficient production of natural products and the mining of new active compounds. Furthermore, due to the shortcomings and defects of microbial transformation, it is an important scientific issue of social and economic value to improve and optimize microbial transformation technology in increasing the yield and activity of transformed products. In this review, the aspects regarding the optimization of fermentation and the cross-disciplinary strategy, leading to the microbial transformation of increased levels of the high-efficiency process from natural products of a plant or microbial origin, were discussed. Additionally, due to the increasing craving for targeted and efficient methods for detecting transformed metabolites, analytical methods based on multiomics were also discussed. Such strategies can be well exploited and applied to the production of more efficient and more natural products from microbial resources.

13C NMR spectroscopic data of aporphine alkaloids

This study involves aporphine alkaloids identified through ¹³C Nuclear Magnetic Resonance (NMR) spectroscopic data. For the present publication, articles were selected from several databases on aporphine alkaloids from 1994 to 2021. In this class, more than 700 compounds have been registered, with 221 were included in this section, among which 122 were characterized for the first time in the investigated period. The study also addresses their biosynthetic pathways, classifying substances according to their structural characteristics based on established literature. Furthermore, pharmacological activities related to the aporphine alkaloids highlighted in this section are also presented, giving an overview of the various applications of these compounds.

Stephapierrines A-H, new tetrahydroprotoberberine and aporphine alkaloids from the tubers of Stephania pierrei Diels and their anti-cholinesterase activities

Eight new alkaloids, which are four new tetrahydroprotoberberine alkaloids, stephapierrines A-D (1-4), and four new aporphine alkaloids, stephapierrines E-H (5-8), together with three new naturally occurring alkaloids (9-11) and thirty-four known alkaloids (12-45) were isolated from the tubers of Stephania pierrei Diels. The structures of the new compounds were elucidated by spectroscopic analysis and physical properties. The structures of the known compounds were characterized by comparison of their spectroscopic data with those previously reported. Compound 42 exhibited the strongest acetylcholinesterase (AChE) inhibitory activity, which was more active than galanthamine, the reference drug. Compound 23 showed the highest butyrylcholinesterase (BuChE) inhibitory activity, which was also more active than galanthamine. Molecular docking studies are in good agreement with the experimental results.

Biotransformation of 1,8-Dihydroxyanthraquinone into Peniphenone under the Fermentation of Aleurodiscus mirabilis

The present study verified that 1,8-dihydroxyanthraquinone (1), a common component in some industrial raw materials and dyes, could be converted into peniphenone (2), which possesses immunosuppressive activity and other medicinal potential, by Aleurodiscus mirabilis fermentation. The yield of peniphenone (2) after 7 days of fermentation was 11.05 ± 2.19%. To reveal the transformation mechanism, two secondary metabolites, emodin (3) and monodictyphenone (4), were isolated from the fermentation broth of A. mirabilis, implying that polyketide metabolic pathways from emodin (3) to monodictyphenone (4) might exist in A. mirabilis. 1,8-Dihydroxyanthraquinone (1) was suspected to be converted into peniphenone (2) via the same pathway since emodin (3) and 1,8-dihydroxyanthraquinone (1) share very similar skeletons. The P450 enzyme and Baeyer-Villiger oxidase in A. mirabilis were confirmed to catalyze this biotransformation on the basis of ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis. This novel investigation could shed light on the mechanism and therefore development of peniphenone production from 1,8-dihydroxyanthraquinone by microbial fermentation.

Biotransformation of α-terpineol by Alternaria alternata

α-Terpineol (1), the main volatile constituent in some traditional Chinese medicines, has been reported to be metabolized to 4R-oleuropeic acid by the larvae of common cutworms. The present study verified that α-terpineol could be converted to 4R-oleuropeic acid (2) and (1S,2R,4R)-p-menthane-1,2,8-triol (3) by Alternaria alternata fermentation. Using shortened fermentation times, 7-hydroxy-α-terpineol (2a) was identified as an oxidative intermediate, which was consistent with the hypothesis put forward by previous studies. Cytochrome P450 enzymes were also confirmed to catalyze this biotransformation. This is the first study on the biotransformation of α-terpineol by microbial fermentation.

A new menthane-type monoterpenoid from fermented Illigera aromatica with Clonostachys rogersoniana 828H2

A new menthane-type monoterpenoid, illigerate E (1), as well as two known ones, (1R^*,3R^*,4S^*,6R^*)-6,8-dihydroxymenthol (2) and cis-4-hydroxy-5-(1-hydroxy-1-methylethyl)-2-methyl-2-cyclohexene-1-one (3), were isolated from fermented Illigera aromatica with Clonostachys rogersoniana 828H2. Their structures were identified by HRESIMS and 1D/2D NMR spectra. Their inhibitory effects of NO production in RAW 264.7 macrophages were estimated.

Improving the acetylcholinesterase inhibitory effect of Illigera aromatica by fermentation with Clonostachys rogersoniana

Illigera aromatica was fermented by Clonostachys rogersoniana. The acetylcholinesterase (AChE) inhibitory effects of unfermented and fermented I. aromatica revealed that C. rogersoniana-fermented I. aromatica (CFIA) induced significantly more AChE inhibitory activity (IC₅₀: 35.4 ± 2.1 μg/mL). The biotransformation of actinodaphnine (1) into (4R,6aS)-4-hydroxyactinodaphnine (2) was found during the fermentation, which played an important role in the improvement of the AChE inhibitory activity of I. aromatica. Subsequently, the fermentation conditions-including the solid-liquid ratio, fermentation temperature, and fermentation time-were optimized. I. aromatica immersed in 100-200% water and fermented with C. rogersoniana at ambient temperature for 30 days was conducive to the biotransformation of actinodaphnine (1) and improved the AChE inhibitory activity of I. aromatica. The present study provides a novel approach for improving the pharmacological effect of I. aromatica and suggests that CFIA may be used as an alternative AChE inhibitor.

(-)-Grandiflorimine, a new dibenzopyrrocoline alkaloid with cholinesterase inhibitory activity from Illigera grandiflora

A new dibenzopyrrocoline alkaloid, (-)-grandifloramine (1), together with five known ones, actinodaphnine (2), N-methyllaurotetanine (3), boldine (4), lindcarpine (5), and (+)-norboldine (6), were isolated from Illigera grandiflora W. W. Sm. et J. F. Jeff. The structure of 1 was identified by HRESIMS, 1D/2D NMR, and electronic circular dichroism (ECD) spectra. Compound 1 and 2 exhibited the moderate inhibitory activity against acetylcholinesterase and 3 showed moderate butyrylcholinesterase inhibitory activity. This is the first report of the chemical constituents of I. grandiflora.

Configurational Study of an Aporphine Alkaloid from Annona purpurea

Purpureine (1), norpurpureine (2), and 3-hydroxyglaucine (4) were isolated from the leaves of Annona purpurea. A vibrational circular dichroism study for the absolute configuration determination of 1 provides evidence for the mutually dependent atropisomerism, local chirality of the sole stereogenic center, and the geometry of the tetrahedral nitrogen atom in aporphine alkaloids. The observed change in the optical rotation sign between 2 and its hydrochloride 3 might explain why this compound has been reported as dextrorotatory and levorotatory from the same botanical source. Furthermore, 1H and 13C NMR spectra of 1, 2 and 4 were fully assigned for the first time.

Fermentation of Illigera aromatica with Clonostachys rogersoniana producing novel cytotoxic menthane-type monoterpenoid dimers

Five novel menthane-type monoterpenoid dimers were isolated from non-fermented and Clonostachys rogersoniana fermented Illigera aromatica.

Monoterpene esters and aporphine alkaloids from Illigera aromatica with inhibitory effects against cholinesterase and NO production in LPS-stimulated RAW264.7 macrophages

Three new monoterpene phenylpropionic acid esters, illigerates A-C (1-3), and one new aporphine alkaloid, illigeranine (4), as well as four known ones, actinodaphnine (5), nordicentrine (6), 8-hydroxy carvacrol (7), and 3-hydroxy-α,4-dimethyl styrene (8), were isolated from the tubers of Illigera aromatica. The structures of 1-4 were identified by HRESIMS, 1D and 2D NMR, and electronic circular dichroism spectra. Compound 1 potently inhibited NO production in LPS-stimulated RAW264.7 cells with an IC₅₀ value of 18.71 ± 0.85 μM; compound 1, 3, and 4 showed moderate butyrylcholinesterase inhibitory activities with the IC₅₀ values of 46.86 ± 0.65, 53.51 ± 0.71, and 31.62 ± 1.15 μM, respectively. Compound 4 showed weak AChE inhibitory activity with an IC₅₀ value of 81.69 ± 2.07 μM, and compounds 5 and 6 possessed moderate AChE inhibitory activities with the IC₅₀ values of 47.74 ± 1.66 and 40.28 ± 2.73 μM, respectively. This paper provides a chemical structure and bioactive foundation for using I. aromatica as an herbal medicine.