Secondary metabolites from Senecio burtonii (Compositae)

Comment on Pyrrolizidine Alkaloids and Terpenes from Senecio (Asteraceae): Chemistry and Research Gaps in Africa

The genus Senecio is one of the largest in Asteraceae. There are thousands of species across the globe, either confirmed or awaiting taxonomic delimitation. While the species are best known for the toxic pyrrolizidine alkaloids that contaminate honeys (as bees select pollen from the species) and teas via lateral transfer and accumulation from adjacent roots of Senecio in the rhizosphere, they are also associated with more serious cases leading to fatality of grazing ruminants or people by contamination or accidental harvesting for medicine. Surprisingly, there are significantly more sesquiterpenoid than pyrrolizidine alkaloid-containing species. The main chemical classes, aside from alkaloids, are flavonoids, cacalols, eremophilanes, and bisabolols, often in the form of furan derivatives or free acids. The chemistry of the species across the globe generally overlaps with the 469 confirmed species of Africa. A small number of species express multiple classes of compounds, meaning the presence of sesquiterpenes does not exclude alkaloids. It is possible that there are many species that express the pyrrolizidine alkaloids, in addition to the cacalols, eremophilanes, and bisabolols. The aim of the current communication is, thus, to identify the research gaps related to the chemistry of African species of Senecio and reveal the possible chemical groups in unexplored taxa by way of example, thereby creating a summary of references that could be used to guide chemical assignment in future studies.

GC-MS analysis of chemical composition, cytotoxicity and antioxidant activities of essential oils of Senecio glaucus under drastic conditions

This study was designed to analyze essential oils by GC-MS and to evaluate the chemical composition, cytotoxic and antioxidant activity of aerial part of plant Seniso glaucus using two methods hydro distillation and organic solvent extraction. The essential oil was analyzed by GC-MS revealed the presence of 32 compounds most of them are sesquiterpene, the main component of essential oil were, Isolongifolene, 9-one (14.4%) Longiverbenone (13.5%), (+) 4-Carene (8.39 %), O-cymene, 4.64%, and thujone were 3.54%. Cytotoxic activity of essential oil was tested against four carcinoma cell lines (A549, McF7, HepG, and HCT-16) by using (3- (4, 5- dimethyl thiazolyl-2)-2, 5-diphenyltetrazolium bromide) (MTT), the results indicate promising cytotoxic activity at the concentration (100, and50μg/ml) essential oil exhibit high cytotoxic activities against Hepg2 cell lines (83. 33 and 59.14 %) and good cytotoxicity against A549, McF-7 and HCT116 cell lines by (62.1 %, 74.40 %, and 76.60%respectively). The essential oil showed antioxidant activity with IC50 = 69.59±0.24μg/ml, using 2, 2-diphenyl-1- picrylhydrazyl (DPPH) assay the present study concluded the importance of plant Seniso glaucus as a natural antioxidant.

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.

A comparative study on phenolic components and biological activity of some Senecio species in Turkey

OBJECTIVE

The phenolic components and biological activity of nine Senecio species growing in Turkey were investigated.

METHODS

Senecio species were extracted with methanol. The content of total phenols was determined using Folin-Ciocalteu method, while individual phenolic acids and flavonoids were detected using HPLC analysis. Also, to determine the antioxidant capacity, phosphomolybdenum assay and 1,1-diphenyl picrylhydrazyl (DPPH) radical-scavenging activity assay were used. Antimicrobial activity of extract was determined using agar diffusion and broth microdilution method.

KEY FINDINGS

The total phenolic contents of the extracts were found to be highest in Senecio cilicius and Senecio mollis extracts (117.45 and 113.40 mg equivalent to gallic acid/g, respectively). S. salsuginea showed the strongest free radical-scavenging activity with IC50 (the concentration providing 50% inhibition) = 26.23 μg/ml and S. mollis showed the highest antioxidant capacity in the phosphomolybdenum method (434.48 mg equivalent to ascorbic acid/g). The extracts exerted promising antibacterial activity against most of the test bacteria (minimal inhibitory concentration = 6.25-12.5 mg/ml), but no activity was observed against Candida albicans.

CONCLUSION

The results demonstrated that nine Senecio species possess high antioxidant and antimicrobial activity in accordance with the high amount of phenolic contents in the extracts that might be natural agencies used in many areas such as food, pharmacy and alternative medicine.

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.

Chemical Composition and Antibacterial Activity of the Essential Oil of Monticalia andicola (Asteraceae) Collected in Venezuela

The essential oil from the leaves of Monticalia andicola Turcz., collected in November 2008, was analyzed by GC/MS. A yield of 0.15% oil was obtained by hydrodistillation. Thirty-six components were identified by comparison of their mass spectra with those in the Wiley GC-MS Library data base. The major components were α-pinene (19.6%), β-pinene (10.5%), α-longipinene (6.5%), δ-3-carene (6.2%), cyperene (5.4%) and β-phellandrene (5.2%). The antibacterial activity of the essential oil was evaluated against Gram- positive (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212) and Gram-negative (Escherichia coli ATCC 25992, Klebsiella pneumoniae ATCC 23357, Pseudomonas aeruginosa ATCC 27853) bacteria, using the disc diffusion agar method. The results showed a broad spectrum of activity with minimal inhibitory concentration (MIC) values ranging from 10 to150 μg/mL.

Fast Counter Current Chromatography of n-Butanolic Fraction from Senecio giganteus (Asteraceae)

Phenolic derivatives such as quinones, acid-phenols and flavonoids were successfully isolated from a n-butanolic fraction of Senecio giganteus Desf. (Asteraceae) flowers, namely jacaranone (1), 3a-hydroxy-3,3a,7,7a-tetrahydrobenzofuran-2,6-dione (2), chlorogenic acid (3), hyperoside (4), quercetin 3-O-β-D-robinobioside (5), isorhamnetin-3-O-β-D-glucuronide (6), quercetin-3-O-β-D-glucuronide (7), and isorhamnetin-3-O-β-D-glucuronide-6″-methyl ester (8). These compounds were purified through either classical polyamide filtration followed by fractionation on Si gel, or through fast centrifugal partition chromatography (FCPC). Using FCPC, the major compounds could be readily isolated from the crude n-butanolic fraction. Compounds 1-8 were identified by means of spectroscopic and spectrometric analysis (UV, 1H, 13C and 2D NMR, and MS). This work described for the first time the phytochemical composition of this endemic Algerian plant.

Chemical composition of the essential oils of the flowers, leaves and stems of two senecio polyanthemoides Sch. Bip. samples from South Africa

The essential oils of the flowers, leaves and stems of Senecio polyanthemoides Sch. Bip. Samples collected from two different localities within the city of uMhlathuze, KwaZulu-Natal Province (South Africa) were isolated by hydrodistillation and analyzed using GC and GC/MS. Twenty-six constituents were identified, representing an average of 86.0 - 99.6% of the total oil composition. The chemical profile reveals the dominance of monoterpenoid compounds, although some quantitative variance was noticed. The main constituents of the oils were limonene (3.1 - 43.0%), p-cymene (4.9-36.3%), beta-selinene (1.3-32.7%), alpha-pinene (1.8-21.4%), beta-pinene (7.6-16.5%) and 1,8-cineole (9.3-11.4%), caryophyllene oxide (4.1-13.4%) and humulene epoxide II (8.6-10.3%).