Phenolic compounds from Senecio scandens

A New Quinazolinone Alkaloid along with Known Compounds with Seed-Germination-Promoting Activity from Rhodiola tibetica Endophytic Fungus Penicillium sp. HJT-A-6

A new quinazolinone alkaloid named peniquinazolinone A (1), as well as eleven known compounds, 2-(2-hydroxy-3-phenylpropionamido)-N-methylbenzamide (2), viridicatin (3), viridicatol (4), (±)-cyclopeptin (5a/5b), dehydrocyclopeptin (6), cyclopenin (7), cyclopenol (8), methyl-indole-3-carboxylate (9), 2,5-dihydroxyphenyl acetate (10), methyl m-hydroxyphenylacetate (11), and conidiogenone B (12), were isolated from the endophytic Penicillium sp. HJT-A-6. The chemical structures of all the compounds were elucidated by comprehensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS. The absolute configuration at C-13 of peniquinazolinone A (1) was established by applying the modified Mosher's method. Compounds 2, 3, and 7 exhibited an optimal promoting effect on the seed germination of Rhodiola tibetica at a concentration of 0.01 mg/mL, while the optimal concentration for compounds 4 and 9 to promote Rhodiola tibetica seed germination was 0.001 mg/mL. Compound 12 showed optimal seed-germination-promoting activity at a concentration of 0.1 mg/mL. Compared with the positive drug 6-benzyladenine (6-BA), compounds 2, 3, 4, 7, 9, and 12 could extend the seed germination period of Rhodiola tibetica up to the 11th day.

LC-ESI/MS-phytochemical profiling with antioxidant and antiacetylcholinesterase activities of Algerian Senecio angulatus L.f. extracts

Senecio angulatus L.f. is a flowering plant from the Asteraceae family that is native to South Africa and which was observed recently in the north and the east of Algeria. This study was aimed for the first time, to evaluate concomitantly phytochemical profiles, using LC-ESI/MS analysis, following by testing and assessing in vitro antioxidant and antiacetylcholinesterase activities of these specific species. The results indicated that the hydromethanolic and the acetate extracts have shown remarkable potent inhibitory effects on AChE with IC₅₀ of (6.04 ± 0.05; 6.72 ± 0.10 µg/mL) respectively along with antioxidant potential of acetate for FRAP and phenanthroline methods with A_0.5 of (11.15 ± 0.72; 5.72 ± 0.13 µg/mL) successively. Moreover, a high amount of cynarin and trans-ferulic acid was found in this extract whilst butanolic extract has recorded the highest amount of chlorogenic acid. Indeed phenolic compounds usually have a hydroxyl in their structure which may contribute significantly to the antioxidant activity.

Neuroprotective activity of natural products isolated from Senecio graciliflorus DC against corticosterone-induced impairment in SH-SY5Y cells

Senecio graciliflorus DC root extract was studied for secondary metabolite composition following the bioactivity-guided isolation technique. The ethyl acetate extract of Senecio graciliflorus root yielded nine chemical constituents: 3,4-di-tert-butyl toluene, stigmasterol, β-sitosterol, 2β-(angeloyloxy)furanoeremophilane, gallic acid, 2β-{[(Z)-2-hydroxymethylbut-2-enoyl]oxy}furanoeremophilane, 1-hydroxypentan-2-yl-4-methylbenzoate, sarcinic acid, and sitosterol 3-O-β-D-glucopyranoside. The structures of the chemical constituents were elucidated on the basis of spectral data analysis in the light of literature. All the compounds are being reported for the first time from this plant. The isolated constituents were screened for neuroprotective effects against corticosterone-induced impairment in neuroblastoma cell lines (SH-SY5S cells). The viability of SH-SY5S cells was determined using MTT assay. Among various isolated compounds, three natural products (sarcinic acid, gallic acid, and β-sitosterol) displayed robust neurotropic activity. The compounds increased neuronal cell survival in differentiated neuroblastoma cells (SH-SY5Y) from high-dose corticosterone (400 µM)-induced cell death. All the three constituents showed maximum AKT/ERK pathway activation at 20 µM concentration. The studies are aimed to explore small molecules for treating neurodegeneration underlying various neurological disorders to restore neuronal cell plasticity.

In Vitro Antioxidant, Cytotoxic Activities, and Phenolic Profile of Senecio glaucus from Saudi Arabia

Current treatments for complex diseases have remarkable side effects that negatively impact patients' quality of life. Thus, natural compounds with fewer side effects represent a promising source for safe drugs. The genus Senecio is widely used in folk medicine due to its various pharmacological properties. In the present study, the total phenolic content of Senecio glaucus, which is grown in Saudi Arabia, was assessed using the Folin-Ciocalteau colorimetric method. Scavenging DPPH and ABTS assays were utilized to determine the antioxidant properties of S. glaucus fractions, and MTT assay was used to screen the cytotoxic activity of S. glaucus against various cancer cells. In addition, HPLC-UV was utilized to detect the presence of two phenolic acids, namely, vanillic acid (VA) and gallic acid (GA). Among all fractions tested, S. glaucus chloroform fraction (SGCF) yielded the highest value (125.3 mg·GA/g) in terms of total phenolic content. SGCF also exhibited the highest scavenging activities (76.7 and 74.1%) on both DPPH and ABTS assays, respectively. Similarly, SGCF also possessed the most potent cytotoxic activity against the MCF-7 cell line, with an IC₅₀ value of 41.8 μg/ml. The validated HPLC method confirmed the presence of VA (4.8 μg/mg DW) and GA (3.9 μg/mg DW) in SGCF. Overall, our data show that S. glaucus had antioxidant and cytotoxic properties. A developed validated HPLC method which could be helpful for quantifying phenolic compounds in S. glaucus was established.

Senecipyrrolidine, an unusual pyrrolidine alkaloid isolated from Jacobaea gigantea (Desf.) Pelser (Asteraceae)

Alkaloids and phenolic compounds are among the most biologically active natural products from the Jacobaea/Senecio genera (Asteraceae). To isolate original natural products directly from Jacobaea gigantea crude polar extracts, centrifugal partition chromatography (CPC) was used. Previously, we reported the phytochemical study of J. gigantea (syn. Senecio giganteus) n-butanol extract using various classical chromatographical techniques combined with CPC. Herein major constituents from the J. gigantea crude ethyl acetate extract and further compounds from the n-butanol extract were purified in only one step using this technique. A new pyrrolidine alkaloid, named senecipyrrolidine was isolated along with thirteen known compounds - chiro-inositol, three phenolic acids, six flavonoids, two quinones and emiline, another pyrrolidine alkaloid - from crude n-butanol or ethyl acetate extracts. Pyrrolidine alkaloids were isolated for the first time in the Jacobaea/Senecio genera and were probably biogenetically related to the two isolated quinones derivatives jacaranone and 3a-hydroxy-3,3a,7,7a-tetrahydrobenzofuran-2,6-dione, isolated in this species.

Essential Oil Composition and Antibacterial Activity of Monticalia greenmaniana (Asteraceae)

The essential oils from fresh aerial parts of Monticalia greenmaniana (Hieron) C. Jeffrey (Asteraceae) collected in March, were analyzed by GC/MS. Oil yields (w/v) of 0.1% (flowers), 0.07%, (stems) and 0.1% (leaves) were obtained by hydrodistillation. Thirteen, sixteen and eighteen components, respectively, were identified by comparison of their mass spectra with those in the Wiley GC-MS Library data base. The major components of the flower and stem oils were 1-nonane (38.8% flowers; 33.5% stems), α-pinene (29.0% flowers; 14.8% stems) and germacrene D (15.6% flowers; 18.6% stems). However, in the leaf oil, germacrene D was observed at 50.7%, followed by β-cedrene at 8.4 %. The leaf essential oil showed a broad spectrum of antibacterial activity against the important human pathogenic Gram-positive and Gram-negative bacteria Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 19433), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Klebsiella pneumoniae (ATCC 25955) with MIC values ranging from 75 to 6000 ppm.