New phenolic compounds from the seeds of Nigella glandulifera and their inhibitory activities against human cancer cells

Screening of Monoamine Oxidase Inhibitors from Seeds of Nigella glandulifera Freyn et Sint. by Ligand Fishing and Their Neuroprotective Activity

Nigella glandulifera is a traditional medicinal plant used to treat seizures, insomnia, and mental disorders among the Tibetan and Xinjiang people of China. Recent pharmacological research indicates that the seeds of this plant have a neuroprotective effect; however, the chemical components responsible for this effect are unknown. Monoamine oxidase B (MAO-B) has been recognized as a target for developing anti-Parkinson's disease drugs. In this work, MAO-B functionalized magnetic nanoparticles were used to enrich the enzyme's ligands in extracts of N. glandulifera seeds for rapid screening of MAO-B inhibitors coupled with HPLC-MS. Tauroside E and thymoquinone were found to inhibit the enzyme with IC₅₀ values of 35.85 μM and 25.54 μM, respectively. Both compounds exhibited neuroprotective effects on 6-OHDA-induced PC-12 cells by increasing the cell viability to 52% and 58%, respectively, compared to 50% of the injured cells. Finally, molecular docking indicated strong interactions of both inhibitors with the enzyme. This work shows that MAO-B functionalized magnetic nanoparticles are effective for rapid screening of anti-PD inhibitors from complex herbal mixtures and, at the same time, shows the promising potential of this plant's seeds in developing anti-PD drugs.

Chemical constituents from the seeds of Nigella glandulifera and their hypoglycemic activities

The seeds of Nigella glandulifera Freyn et Sint. are traditional Uygur medicine used for the treatment of diabetes. However, the active anti-diabetic constituents in the seeds of N. glandulifera remain unclear. In the present study, a new delabellane-type diterpene, 8-denicotinoylnigellamine A1 (1), and a new acyclic sesquiterpene, 2,6,10-trimethyl-6,7,12-trihydroxy-dodec-2-ene (3), together with eight known compounds including alkaloids (2 and 7), triterpenoid saponins (4–6), and phenolic compounds (8–10), were isolated from the seeds of N. glandulifera. Their structures were determined by extensive spectroscopic analyses and quantum chemical calculations. We evaluated the potential protective effects of the isolated compounds on an insulin resistant HepG2 (IR-HepG2) cell model. The results showed that compounds 2, 4–8, and 10 could promote the consumption of glucose in IR-HepG2 cells. Those compounds might be responsible for the anti-diabetic effects of the seeds of N. glandulifera.

The seed of Nigella glandulifera Freyn et Sint. is a traditional Uygur medicine used for the treatment of diabetes.

Saponins from Nigella glandulifera seeds attenuate collagen-induced rheumatoid arthritis in rats via the OPG/RANKL/NF-κB and Ang/Tie-2 pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Nigella glandulifera Freyn et Sint. (N. glandulifera) seeds are widely used in traditional Uyghur medicine for a variety of immuno-inflammatory diseases. The total saponins from N. glandulifera seeds (TSNGS) have been shown to have analgesic, antioxidant, and anti-inflammatory effects that can alleviate joint pain and swelling.

AIM OF THE STUDY

Rheumatoid arthritis (RA) is a chronic and progressive, debilitating autoimmune disease for which current treatments are not sufficiently effective and result in unsatisfactory side effects. This study aimed to mechanistically investigate the therapeutic effects of TSNGS on RA.

MATERIALS AND METHODS

Qualitative analysis of TSNGS was performed using ultra-high-performance liquid chromatography-Q-Orbitrap-high-resolution mass spectrometry. Rats with collagen-induced arthritis (CIA), IL-1β-induced HFLS-RAs, and VEGF-induced HUVECs were analyzed to determine the efficacy and mechanism of TSNGS on RA.

RESULTS

Twenty-one compounds were identified in TSNGS. TSNGS (10, 50, or 250 mg/kg) reduced the severity of arthritis, indicated by a lower arthritis score, reduced paw swelling, and body weight in rats with CIA. TSNGS ameliorated histopathological changes involving inflammatory infiltration, bone degeneration, and angiogenesis in knee and ankle joints. TSNGS improved the immuno-inflammatory response by restoring the levels of the cytokines IFN-γ, TNF-α, IL-1β, IL-6, IL-17A, IL-4, and IL-10, and increasing the number of CD4⁺CD25⁺ Tregs in the peripheral circulation and Foxp3 levels in knee joints in rats with CIA. Furthermore, TSNGS increased the OPG/RANKL ratio and downregulated p-p65 in serum and joint synovia. Inhibition of angiogenesis by TSNGS was associated with recovery of the angiogenesis-related Ang/Tie-2 signaling pathway.

CONCLUSIONS

It was established that TSNGS provides a therapeutic effect on RA by alleviating synovitis, bone degeneration, and angiogenesis via the OPG/RANKL/NF-κB and Ang/Tie-2 pathways and may be used for the treatment of RA.

Nigella Plants - Traditional Uses, Bioactive Phytoconstituents, Preclinical and Clinical Studies

Nigella is a small genus of the family Ranunculaceae, which includes some popular species due to their culinary and medicinal properties, especially in Eastern Europe, Middle East, Western, and Central Asia. Therefore, this review covers the traditional uses and phytochemical composition of Nigella and, in particular, Nigella sativa. The pharmacological studies reported in vitro, in vivo, and in humans have also been reviewed. One of the main strength of the use of Nigella is that the seeds are rich in the omega-6 fatty acid linoleic acid and provide an extra-source of dietary phytochemicals, including the bioactive thymoquinone, and characteristics saponins, alkaloids, and flavonoids. Among Nigella species, N. sativa L. is the most studied plant from the genus. Due to the phytochemical composition and pharmacological properties, the seed and seed oil from this plant can be considered as good candidates to formulate functional ingredients on the basis of folklore and scientific knowledge. Nonetheless, the main limations are that more studies, especially, clinical trials are required to standardize the results, e.g. to establish active molecules, dosage, chemical profile, long-term effects and impact of cooking/incorporation into foods.

Recent Progress on Chemical Constituents and Pharmacological Effects of the Genus Nigella

Seeds of the genus Nigella plants as folk medicine are often used to prevent and treat asthma, diarrhea, dyslipidemia, and other diseases around the world. Pharmacological researches showed that seed extract and seed oil have antibacterial, antioxidant, hypoglycemic, and hepatoprotective effects which attributed to their bioactive constituents such as alkaloids, saponins, flavones, and phenols. This paper has covered recent progresses on chemical and pharmacological researches on these plants, including their compounds and pharmacological effects. It was found that the chemical component researches were focused on the seed oil. Therefore, more attention should be paid to the profile of the whole constituents in the seeds.

Microbial metabolites of proanthocyanidins reduce chemical carcinogen-induced DNA damage in human lung epithelial and fetal hepatic cells in vitro

Seven selected microbial metabolites of proanthocyanidins (MMP), 3-phenylpropionic, 4-hydroxyphenyl acetic, 3-(4-hydroxyphenyl) propionic, p-coumaric, benzoic acid, pyrogallol (PG), and pyrocatechol (PC) were evaluated for their ability to reduce chemical carcinogen-induced toxicity in human lung epithelial cells (BEAS-2B) and human fetal hepatic cells (WRL-68). Cells pre-treated with MMP were exposed to a known chemical carcinogen, 4-[(acetoxymethyl) nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc) to assess MMP-mediated cytoprotection and reduction of DNA damage. PG in BEAS-2B and PC in WRL-68 cells mitigated the NNKOAc-induced cytotoxicity. Pre-incubation of PG depicted significant protection against NNKOAc-induced DNA damage in BEAS-2B cells. PC in WRL-68 cells showed similar activity. To understand the mechanisms of PG- and PC-mediated DNA damage reduction, the effect on DNA damage response (DDR) proteins, cellular reactive oxygen species (ROS), total antioxidant capacity (TAC), glutathione peroxidase (GPx), and caspase activity were studied. PG and PC alter the DDR and may promote ATR-Chk1 and ATM-Chk2 pathways, respectively. Cellular oxidative stress induced by NNKOAc was mitigated by PG and PC through enhanced GPx expression and TAC. PG and PC suppressed the activation of the extrinsic apoptotic pathway (caspase 3 and 8) provoked by NNKOAc. MMP are beneficial in chemoprevention by reducing cellular DNA damage.

Nigegladines A-C, Three Thymoquinone Dimers from Nigella glandulifera

Nigegladines A-C (1-3), three thymoquinone dimers, were isolated from the seeds of Nigella glandulifera. Racemic 1 possesses a unique tricyclo[5.4.0.1^2,6]dodecane carbon skeleton, and compounds 2 and 3 are two unusual diterpenoid alkaloids with indole cores. Their structures were determined by extensive spectroscopic analyses, and that of 1 was confirmed by single-crystal X-ray diffraction. Both (+)-1 and (-)-1 exhibited significant protective effects against hypoxia/reoxygenation-induced H9c2 myocardial cell injury.