Synthesis and biological activities of novel pyrazolomatrine derivatives

Expedient discovery of novel oxime ester derivatives of piperine/piperine analogs as potent pesticide candidates and their mode of action against Tetranychus cinnabarinus Boisduval

BACKGROUND

Nowadays, pest infestation and resistance have appeared as a consequence of repeated and extensive use of pesticides. Thus, development of new effective pesticide candidates in crop protection is highly desirable. Herein, a series of new piperine derivatives containing oxime ester scaffolds were regioselectively and stereoselectively prepared as pesticidal agents.

RESULTS

Steric configurations of compounds 2, 5z and 13e were definitively determined by single-crystal X-ray diffraction. Against Tetranychus cinnabarinus, notably, compounds 5f [median lethal concentration (LC50 ) = 0.14 mg mL-1 ] and 5v (LC50  = 0.13 mg mL-1 ) showed >107-fold greater acaricidal activity than piperine (LC50  = 15.02 mg mL-1 ), which were comparable to the commercial acaricide spirodiclofen. Against Aphis citricola, compound 5d (LD50  = 19.12 ng aphid-1 ) exhibited 6.1-fold more potent aphicidal activity than piperine (LD50  = 116.06 ng aphid-1 ). Additionally, through scanning electron microscopy, the toxicology study suggested that the acaricidal activity of piperine derivatives may be related to damage of the cuticle layer crest of T. cinnabarinus.

CONCLUSION

The structure-activity relationships suggested that 3,4-dioxymethylene of piperine was crucial for its acaricidal activity; and introduction of a certain length of aliphatic chain at the C-2 position was beneficial to the aphicidal and acaricidal activities. Compounds 5f and 5v are potential leads for further structural modification as acaricidal agents. © 2023 Society of Chemical Industry.

Quinolizidine-Type Alkaloids: Chemodiversity, Occurrence, and Bioactivity

Quinolizidine alkaloids (QAs) are nitrogen-containing compounds produced naturally as specialized metabolites distributed in plants and animals (e.g., frogs, sponges). The present review compiles the available information on the chemical diversity and biological activity of QAs reported during the last three decades. So far, 397 QAs have been isolated, gathering 20 different representative classes, including the most common such as matrine (13.6%), lupanine (9.8%), anagyrine (4.0%), sparteine (5.3%), cytisine (6.5%), tetrahydrocytisine (4.3%), lupinine (12.1%), macrocyclic bisquinolizidine (9.3%), biphenylquinolizidine lactone (7.1%), dimeric (7.1%), and other less known QAs (20.9%), which include several structural patterns of QAs. A detailed survey of the reported information about the bioactivities of these compounds indicated their potential as cytotoxic, antiviral, antimicrobial, insecticidal, anti-inflammatory, antimalarial, and antiacetylcholinesterase compounds, involving favorable putative drug-likeness scores. In this regard, research progress on the structural and biological/pharmacological diversity of QAs requires further studies oriented on expanding the chemical space to find bioactive scaffolds based on QAs for pharmacological and agrochemical applications.

Synthesis and Evaluation of 11-Butyl Matrine Derivatives as Potential Anti-Virus Agents

Matrine derivatives were reported to have various biological activities, especially the ester, amide or sulfonamide derivatives of matrine deriving from the hydroxyl or carboxyl group at the end of the branch chain after the D ring of matrine is opened. In this work, to investigate whether moving away all functional groups from the C-11 branch chain could have an impact on the bioactivities, such as anti-tobacco mosaic virus (TMV), insecticidal and fungicidal activities, a variety of N-substituted-11-butyl matrine derivatives were synthesized. The obtained bioassay result showed that most N-substituted-11-butyl matrine derivatives had obviously enhanced anti-TMV activity compared with matrine, especially many compounds had good inhibitory activity close to that of commercialized virucide Ningnanmycin (inhibition rate 55.4, 57.8 ± 1.4, 55.3 ± 0.5 and 60.3 ± 1.2% at 500 μg/mL; 26.1, 29.7 ± 0.2, 24.2 ± 1.0 and 27.0 ± 0.3% at 100 μg/mL, for the in vitro activity, in vivo inactivation, curative and protection activities, respectively). Notably, N-benzoyl (7), N-benzyl (16), and N-cyclohexylmethyl-11-butyl (19) matrine derivatives had higher anti-TMV activity than Ningnanmycin at both 500 and 100 μg/mL for the four test modes, showing high potential as anti-TMV agent. Furthermore, some compounds also showed good fungicidal activity or insecticidal activity.

The Advances on Bioactivities, Mechanisms of Action, and Structural Optimizations of Matrine and Its Derivatives

Matrine, a tetracyclo-quinolizidine alkaloid, is isolated from the industrial crop plant Sophora flavescens. Due to a wide range of pharmacological and agricultural properties, the research on the phytochemistry, pharmacology, toxicology and mechanisms of action of matrine and its derivatives has received much attention. On the other hand, to improve their biological activities, the study on structural optimizations and structure-activity relationships of matrine and its derivatives has also attached more and more importance. In this review article, the update advances on bioactivities, mechanisms of action, structural modifications and structure-activity relationships of matrine and its derivatives from 2017 to 2020 are presented. We hope that this review will provide a reference for the development and application of matrine and its derivatives as drugs or pesticides in the future.

Double asymmetric intramolecular aza-Michael reaction: a convenient strategy for the synthesis of quinolizidine alkaloids

A new methodology to access the quinolizidine skeleton in an asymmetric fashion was devised. It involves two consecutive intramolecular aza-Michael reactions of sulfinyl amines bearing a bis-enone moiety, in turn generated by a monodirectional cross metathesis reaction. The sequence, which takes place with excellent yields and diastereocontrol, was applied to the total synthesis of alkaloids lasubine I and myrtine.

Agrochemical properties evaluation of some imines alkaloids of matrine/oxymatrine

To discover non-food renewable forest bioactive products as new potential pesticidal alternatives for crop protection, a series of C15-imines alkaloids were obtained by structural modification of matrine and oxymatrine. Compounds Id, Ih, Ii and IIg (>2-3 folds of their precursors) showed the most potent antifeedant activity against armyworm. Against red spider mite, compounds Ie, Il, IIb, IIc and IIg displayed 1.8-3.1 folds acaricidal activity of their precursors. Notably, compound IIg exhibiting the most pronounced pesticidal activities, can be used as a promising bio-sourced agrochemical agent. The study of stress responses showed that the nAChR subunit α5 and VGSC might be the targets of action of matrine, oxymatrine and IIg against red spider mite.