Chemical profile and biological activities of the aerial parts of Senecio acaulis (L.f.) Sch.Bip

Abstract

Background: Genus Senecio is known by its phenolic constituents, terpenoids, essential oil (EO), and pyrrolizidine alkaloids. No previous reports could be traced about the phytochemical study of Senecio acaulis. Objectives: To investigate the chemical composition and biological potentiality of EO of S. acaulis aerial parts and to study the phytoconstituents of the plant extract and its spasmolytic activity. Materials and Methods: The EO was obtained by hydrodistillation and its chemical composition was analyzed by gas chromatography coupled to mass spectrometry. In-vitro screen of antimicrobial, antimalarial, and antileishmanial activities was determined against positive controls. Column chromatography was used to isolate the phytoconstituents from chloroform and ethyl acetate fractions; their structures were elucidated using physical and spectral methods. Spasmolytic activity was measured before and after K+-induced contractions on isolated rabbit jejunum. DNA-fingerprint was established by RAPD-PCR technique using 12 primers. Results: The study of EO revealed the detection of 22 compounds representing 81.08% of the oil composition. The major constituents were D-limonene (13.32%), β-pinene (11.54%), and sabinene (10.79%). Eight compounds were isolated from the plant extract and identified as β-amyrin, β-sitosterol, lupeol, oleanolic acid, β-amyrin-3-O-β-glucopyranoside, isorhamnetin 3-O-β-glucopyranoside, isoquercitrin, and quercitrin. The oil exhibited moderate antimalarial activity against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. The oil showed a significant antimicrobial activity against methicillin-resistant Staphylococcus aureus and Cryptococcus neoformans and weak antileishmanial activity. In isolated rabbit jejunum, the ethanol extract produced a relaxation of spontaneous and moderate effect against high K+ (80 mM)-induced contractions. Amplification of DNA yielded 87 RAPD fragments. Conclusion: Senecio acaulis (L.f.) Sch.Bip essential oil can be used as antimicrobial agent against Staphylococcus aureus and Cryptococcus neoformans. In addition, the spasmolytic activity of its ethanolic extract suggests its incorporation in antidiarrheal preparations. Further clinical trials are required to evaluate these effects on humans. Identification of twenty two compounds in its essential oil, isolation of eight compounds for the first time as well as authentication of the plant via DNA finger print may play an important role in its chemotaxonomic classification. Abbreviations Used: EO: Essential oil, GC: Gas Chromatography, GC-MS: Gas Chromatography-Mass Spectrophotometry, ETOAc: Ethyl acetate, SEM: Standard error mean, RRI: Relative retention indices, SI: Selectivity Index, D6: chloroquine sensitive Plasmodium falciparum, W2: chloroquine resistant Plasmodium falciparum. SI: selectivity index, IC50, IC90: concentration that affords 50 and 90% inhibition, respectively, 1H-NMR: Proton Nuclear magnetic resonance, 13C-NMR: Carbon-13 Nuclear magnetic resonance.