RESUMO
Natural product studies explore potential and interesting new compounds to discover innovative drugs. Nigella sativa (N. sativa) (Ranunculaceae) is traditionally used to treat diabetes. Flavonoids and triterpenoid mostly show anti-diabetic activity. The current study aim to identify new compounds by a systematic study of the anti-oxidant and anti-diabetic activity of aerial parts of N. sativa concerning. Phytochemicals were isolated from the methanolic extract of aerial parts of the plant by column chromatography and identified by nuclear magnetic resonance spectroscopy and mass spectroscopy. A new triterpenoid saponin glycoside was isolated along with flavonoids. The anti-diabetic study was carried out by DPPH, ABTS, α -glucosidase, and protein tyrosine phosphatase 1B assays at doses of 12.5 to 250 µM. The isolated phytochemicals were identified as 3-O-(ß-d-xylopyranosyl-(1-3)-α-l-rhamnopyrnaosyl-(1-2)-α-l-arabinopyranosyl]-28-O-(α-l-rhamno-pyranosyl-(1-4)-ß-d-glucopyranosyl-(1-6)-ß-d-glucopyranosyl] hederagenin (1), flaccidoside III (2), catechol (3), quercetin-3-gentiobiosides (4), magnoflorine (5), nigelflavonoside B (6), nigelloside (7), quercetin sphorotrioside (8), kaempferol-3, 7-diglucoside (9), kaempferol 3-O-rutinoside (10), rutin (11), 3-O-[α-l-rhamnopyranosyl-(1â2)-α-l-arabinopyranpsylhederagenin (12), 3ß,23,28-trihydroxyolean-12-ene-3-O-α-l-arabinopyranoside(1â4)-a-rhamnopyranosyl,(1â4)-ß-d-gluco-pyranoside (13), 3-O-α-l-rhamnopyranosyl-(1â2)-α-l-arabinopyranpsyl]-28-O-ß-d-gluco-pyranosyl hederagenin (14), and α-hederin (15). These were isolated and are reported for the first time in this study. Compared 13 was identified as a new compound. Compound 2 was isolated for first time from the genus Nigella. Compound 6 was found to be the most active in the DPPH, and ABTS assays and compound 10 was found to be the most active in the α-glucosidase assay, with IC50 32.7 ± 0.1, 95.18 ± 0.9, 214.5 ± 0.0 µΜ, respectively. Compound 12, at a dose of 125 µΜ, showed anti-diabetic activity in a PTP1B assay with IC50 91.30 ± 2.5 µΜ. In conclusion, the anti-diabetic activity of N. sativa is due to its flavonoids and TTSGs. Therefore, our studies suggest that the aerial parts of N. sativa are also a valuable and alternate source of valuable phytochemicals that could be used to develop anti-oxidant and anti-diabetic medicines.
Assuntos
Antioxidantes/análise , Diabetes Mellitus/tratamento farmacológico , Nigella sativa/química , Ácido Oleanólico/análogos & derivados , Componentes Aéreos da Planta/química , Extratos Vegetais/análise , Saponinas/análise , Antioxidantes/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Benzotiazóis/química , Compostos de Bifenilo/química , Cromatografia Líquida de Alta Pressão , Flavonoides/análise , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Inibidores de Glicosídeo Hidrolases/farmacologia , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Estrutura Molecular , Nigella sativa/enzimologia , Ácido Oleanólico/análise , Ácido Oleanólico/química , Ácido Oleanólico/isolamento & purificação , Ácido Oleanólico/farmacologia , Picratos/química , Componentes Aéreos da Planta/enzimologia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Proteínas Tirosina Fosfatases/antagonistas & inibidores , Saponinas/química , Saponinas/isolamento & purificação , Saponinas/farmacologia , Ácidos Sulfônicos/química , Triterpenos/análise , Triterpenos/isolamento & purificação , Triterpenos/farmacologiaRESUMO
Hydroponically cultivated Nigella sativa L. plants treated with methyl jasmonate (MeJA) showed a twelve-fold increase in levels of the monodesmosidic triterpene saponins alpha-hederin and kalopanaxsaponin I (KsI) in the leaves. We will demonstrate that these two saponins accounted for approximately 10% of the dry plant matter, of which 93% was KsI and 7% alpha-hederin. To address the molecular basis of saponin induction by MeJA, we cloned and characterized the beta-amyrin synthase gene (NsbetaAS1) encoding one of the key enzymes in triterpene saponin biosynthesis. As expected, NsbetaAS1 transcription was induced by MeJA and led to the production of beta-amyrin when over-expressed in yeast.