Evaluation of antimicrobial activity of glycinate and carbonate derivatives of cholesterol: Synthesis and characterization

Synthesis and antitumor activity of some cholesterol-based selenocyanate compounds

The introduction of selenium-containing functional groups into steroids to study the biological activities of related derivatives is rarely reported in the literature. In the present study, using cholesterol as raw material, four cholesterol-3-selenocyanoates and eight B-norcholesterol selenocyanate derivatives were synthesized, respectively. The structures of the compounds were characterized by NMR and MS. The results of the in vitro antiproliferative activity test showed that the cholesterol-3-selenocyanoate derivatives did not exhibit obvious inhibitory on the tested tumor cell lines. However, the B-norcholesterol selenocyanate derivatives obtained by structural modification of cholesterol showed good inhibitory activity against the proliferation of tumor cell. Among them, compounds 9b-c, 9f and 12 showed similar inhibitory activity against tested tumor cells as positive control 2-methoxyestradiol, and better than Abiraterone. At the same time, these B-norcholesterol selenocyanate derivatives displayed a strong selective inhibitory against Sk-Ov-3 cell line. Except for compound 9g, the IC₅₀ value of all B-norcholesterol selenocyanate compounds against Sk-Ov-3 cells was less than 10 µM, and compound 9d was 3.4 µM. In addition, Annexin V-FITC/PI double staining was used to analyze the cell death mechanism. The results showed that compound 9c could induce Sk-Ov-3 cells to enter programmed apoptosis in a dose-dependent manner. Furthermore, the in vivo antitumor experiments of compound 9f against zebrafish xenograft tumor showed that 9f displayed obvious inhibitory effect on the growth of human cervical cancer (HeLa) xenograft tumor in zebrafish. Our results provide new thinking for the study of such compounds as new antitumor drugs.

Antihypertensive potential of Brassica rapa leaves: An in vitro and in silico approach

Aim: Plants contain many essential constituents and their optimization can result in the discovery of new medicines. One such plant is Brassica rapa that is commonly used as a vegetable to fulfill daily food requirements worldwide. This study intends to screen the phytochemicals, antihypertensive potential, GC-MS, and in silico analysis of the leaves of Brassica rapa.

Methods: Powdered leaves were subjected to proximate analysis followed by estimation of primary metabolites. Extracts were obtained by hot and cold extraction and investigated for secondary metabolites. All crude extracts were screened for their antihypertensive potential using an angiotensin-converting enzyme (ACE) inhibition assay. GC-MS analysis was carried out to standardize the extract, and an antihypertensive metabolite was confirmed using an in silico approach.

Results: Physicochemical evaluation resulted in moisture content (9.10% ± 0.1), total ash value (18.10% ± 0.6), and extractive values (water 9.46% ± 0.5 and alcohol soluble 4.99% ± 0.1), while phytochemical investigation revealed primary metabolites (total proteins 11.90 mg/g ± 0.9; total fats 3.48 mg/g ± 0.5; and total carbohydrates 57.45 mg/g ± 1.2). Methanol extract showed the highest number of secondary metabolites including polyphenols 93.63 mg/g ± 0.6; flavonoids 259.13 mg/g ± 0.6; and polysaccharides 56.63 mg/g ± 1.4, while water extract (70 mg/g ± 2) was rich in glycosaponins. Methanol extract showed the highest antihypertensive potential by inhibiting ACE (79.39%) amongst all extracts, compared to the standard drug captopril, which inhibited 85.81%. Standardization of methanol extract via GC-MS analysis revealed potent phytoconstituents, and a molecular docking study confirmed that oleic acid is the main antihypertensive metabolite.

Conclusion: We conclude that leaves of Brassica rapa can successfully lower hypertension by inhibiting ACE, however; in vivo investigations are required to confirm this antihypertensive activity.

Natural-product-based pesticides: Semisynthesis, structural elucidation, and evaluation of new cholesterol-matrine conjugates as pesticidal agents

To develop new potential pesticide candidates from low value-added natural bioactive products, a series of new cholesterol-matrine conjugates (I(a-e)-IV(a-e)) were prepared from two lead compounds cholesterol and matrine. Against Mythimna separata Walker, compound IVa exhibited 3.0 and 2.6 folds promising insecticidal activity of cholesterol and matrine, respectively; against Aphis citricola Van der Goot, compound IVd showed 4.3 and 2.2 folds potent aphicidal activity of their precursors; notably, it also showed good control effects in the greenhouse; against Plutella xylostella Linnaeus at a dose of 20 μg/nymph, compound IIIe exhibited 2.8 and 2.0 folds oral toxicity of cholesterol and matrine, respectively. Compounds IIIe, IVd and IVe can be used as the leads for further structural optimization as the insecticidal and aphicidal agents.

Cobalt(I)-Catalyzed [6π + 2π] Cycloaddition of 1,2-Dienes and 1,3-Diynes to N-Carbocholesteroxyazepine in the Synthesis of Previously Undescribed Heterofunctional 9-Azabicyclo[4.2.1]nonadi(tri)enes

Promising heterofunctional (E)-9-azabicyclo[4.2.1]nona-2,4-dienes (79-92%) and 9-azabicyclo[4.2.1]nona-2,4,7-trienes (77-90%) containing a cholesterol fragment in the structure have been synthesized for the first time through the [6π + 2π] cycloaddition reaction of terminal 1,2-dienes and symmetric 1,3-diynes with N-carbocholesteroxyazepine under the action of the Co(acac)₂(dppe)/Zn/ZnI₂ three-component catalytic system.

Construction of Cholesterol Oxime Ether Derivatives Containing Isoxazoline/Isoxazole Fragments and Their Agricultural Bioactive Properties/Control Efficiency

To explore natural-product-based pesticidal candidates and high value-added application of cholesterol in agriculture, oximinoether derivatives of cholesterol-containing isoxazoline/isoxazole fragments (I-1∼I-16 and II-1∼II-18) were semiprepared by structural optimization of cholesterol. Their structures were characterized by optical rotation, high-resolution mass spectrometry (HRMS), IR, and ¹H NMR spectroscopy. Particularly, the Z configurations of oxime fragments at the C-7 position of target compounds were undoubtedly determined by X-ray crystallography. Against Mythimna separata Walker, compounds 3e, I-8, I-14, and II-3 showed 2.4-2.7-fold growth inhibitory activity of the precursor cholesterol. Against Plutella xylostella Linnaeus, compounds I-6, I-7, and I-9 showed 2.4-2.7-fold oral toxicity of cholesterol. Against Aphis citricola Van der Goot, compounds 2e and II-15 exhibited 4.9 and 5.8-fold aphicidal activity of cholesterol, respectively. Notably, they showed good control effects (3.0-5.0-fold promising control efficiency of 1) against A. citricola in the greenhouse. Structure-activity relationships (SARs) suggested that the C-3 hydroxyl group and the C-7 position of cholesterol are two important modification sites. It will pave the way for future structural optimization and application of cholesterol derivatives as potential pesticidal agents in agriculture.

Synthesis of New Functionally Substituted 9-Azabicyclo[4.2.1]nona-2,4,7-trienes by Cobalt(I)-Catalyzed [6π + 2π]-Cycloaddition of N-Carbocholesteroxyazepine to Alkynes

Catalytic [6π + 2π]-cycloaddition of N-carbocholesteroxyazepine with functionally substituted terminal alkynes and 1,4-butynediol was performed for the first time under the action of the Co(acac)2(dppe)/Zn/ZnI2 three-component catalytic system. The reaction gave previously undescribed but promising 9-azabicyclo[4.2.1]nona-2,4,7-trienes (in 79-95% yields), covalently bound to a natural metabolite, cholesterol. The structure of the synthesized azabicycles was confirmed by analysis of one- and two-dimensional (1H, 13C, DEPT 13C, COSY, NOESY, HSQC, HMBC) NMR spectra.

Antimicrobial activity of Asteraceae species against bacterial pathogens isolated from postmenopausal women

Purpose

Investigation of the antibacterial action of aqueous extracts of Bidens sulphurea, Bidens pilosa, and Tanacetum vulgare, species of Asteraceae family that are popularly used for the treatment of genito-urinary infection.

Methods

The minimum inhibitory concentration (MIC) and minimal bacterial concentration (MBC) of the extracts against standard strains of Staphylococcus aureus (ATCC25923), Enterococcus faecalis (ATCC29212), Escherichia coli (ATCC25922), and Pseudomonas aeruginosa (ATCC27853) and against bacteria that were isolated from cultures of vaginal secretions and urine from menopausal women with a diagnosis of recurrent urinary tract infections (rUTI) were determined by broth microdilution.

Results

The MIC values of the three extracts against Gram-positive and Gram-negative standard bacterial strains ranged from 7.81 to 125.00 mg ml^-1, and the MBC values ranged from 7.81 to 500.00 mg ml^-1. However, B. sulphurea was more efficient. In the urine samples, the three extracts inhibited the growth of coagulase-negative Staphylococcus spp., and the B. pilosa was the most active extract against E. coli compared with the other ones. For the vaginal secretion samples, no significant differences in the inhibition of coagulase-positive Staphylococcus spp. and P. mirabilis were found among the extracts. T. vulgare and B. sulphurea were more effective in inhibiting coagulase-negative Staphylococcus spp. compared with B. pilosa. E. coli was more susceptible to the B. sulphurea extract compared with the B. pilosa and T. vulgare extracts.

Conclusion

The present results suggested the potential medicinal use of Asteraceae species, especially B. sulphurea, as therapeutic agents against rUTI-related bacteria.