Sarita Singh

Quaternary alkaloids of Argemone mexicana

Four quaternary isoquinoline alkaloids, dehydrocorydalmine, jatrorrhizine, columbamine, and oxyberberine, have been isolated from the whole plant of Argemone mexicana Linn. (Papaveraceae) and their structures established by spectral evidence. This is the first report of these alkaloids (dehydrocorydalmine, jatrorrhizine, columbamine, and oxyberberine) from Argemone mexicana and the Argemone genus.

Alkaloids and flavonoids of Argemone mexicana

A new protopine alkaloid, protomexicine and a new isoflavonoid, mexitin, together with 8-methoxydihydrosanguinarine, 13-oxoprotopine, rutin and quercetrin have been isolated from the aerial part of the methanolic extract of Argemone mexicana. The structures of these compounds have been established by various spectral data. The structure of protomexicine was further confirmed by heteronuclear multiple bond correlation experiment. Protomexicine and mexitin are new compounds, and other compounds are first reported from A. mexicana and genus Argemone.

A new benzylisoquinoline alkaloid from Argemone mexicana

A new benzylisoquinoline alkaloid, argemexirine, together with two known protoberberine alkaloids, dl-tetrahydrocoptisine and dihydrocoptisine, have been isolated from the methanolic extract of the whole plant of Argemone mexicana L. The compounds were identified by spectral and chemical evidence. This is the first report of these alkaloids in this plant species.

Antifungal activity of the mixture of quaternary alkaloids isolated from Argemone mexicana against some phytopathogenic fungi

The anti-fungal activity of a mixture of quaternary alkaloids of Argemone mexicana was observed at different concentrations (1000, 2000, 3000, 4000 and 5000 μl/ml) against 10 fungi, viz., Ustilago cynodontis, Cercospora cajani, Sphaerotheca sp., Cercospora sp., Alternaria solani, Bipolaris sp., Helminthosporium sp., Curvularia sp., Fusarium udum and Alternaria cajani. Spore germination was inhibited at 2000, 3000, 4000, 5000 μg/ml. Analysis of phenolics by high performance liquid chromatography (HPLC) recorded 11 peaks in the alkaloids but only three could be identified, viz., tannic, caffeic and ferulic acids. The significant efficacy of the alkaloid under in vitro conditions may open the possibility of its use by farmers under field conditions for controlling some crop diseases.

A new indole alkaloid from Alstonia scholaris

A new indole alkaloid, N-formylscholarine, together with picrinine, strictamine and nareline has been isolated from the fruit pods of Alstonia scholaris, and their structures were established by various spectral data. This is the first report of these alkaloids in A. scholaris fruit pods.

New alkaloids from Corydalis species

A new alkaloid, chaerophylline (1), together with known alkaloids (−)-corypalmine, berberine chloride, (−)-isocorypalmine, (−)-corydalmine and (+)-bicuculline have been isolated from the crude base fraction of Corydalis chaerophylla. The crude base fractions of Corydalis longipes gave a new alkaloid, longicine (4), together with known alkaloids (±)-α-hydrastine, (±)-β-hydrastine, N-methylhydrasteine hydroxylactam, 1-methoxyberberine chloride and berberinium hydroxide. These alkaloids are reported for the first time from the above species and their structures were established by chemical and spectroscopic evidence.

Antifungal Activity of Securinine against Some Plant Pathogenic Fungi

The alkaloid securinine was assessed against spore germination of some plant pathogenic and saprophytic fungi (Alternaria alternata, Alternaria brassicae, Alternaria brassicicola, Curvularia lunata, Curvularia maculans, Curvularia pallenscens, Colletotrichum musae, Colletotrichum sp., Erysiphe pisi, Helminthosporium echinoclova, Helminthosporium spiciferum, Heterosporium sp.). Spore germinations of all the tested fungi were inhibited. Alternaria brassicicola, C. lunata, C. pallenscens and H. spiciferum were highly sensitive as complete inhibition of spore germination was observed at very low concentrations (200 ppm).

A new chalcone glycoside from Rhamnus nipalensis

A new chalcone glycoside, chalcone-2′,4-dihydroxy-4′-O-β-D-glucoside has been isolated from Rhamnus nipalensis together with sitosterol, lupeol, di-O-methyldaidzein, kaempferol-4′-methylether, quercetin, physcion, sitosterol glucoside, emodin and their structures established by spectroscopic data. Isolation of these compounds are the first report from this plant.

Cytotoxicity of alkaloids isolated from Argemone mexicana on SW480 human colon cancer cell line

Abstract Context: Argemone mexicana Linn. (Papaveraceae) has been used as traditional medicine in India and Taiwan for the treatment of skin diseases, inflammations, bilious, fever, etc. Some alkaloids of A. mexicana have been screened for their cytotoxicity on different cancer cell lines. Objective: The study investigates potential cytotoxic effects of alkaloids isolated from aerial part of A. mexicana on SW480 human colon cancer cell line. Materials and methods: Six alkaloids, 13-oxoprotopine, protomexicine, 8-methoxydihydrosanguinarine, dehydrocorydalmine, jatrorrhizine, and 8-oxyberberine were isolated from the methanol extract of A. mexicana. Cytotoxicity of these alkaloids was studied on SW480 human colon cancer cell line at 1, 25, 50, 75, 100, 125, 150, and 200 µg/mL for 24 and 48 h. Cells were seeded in a 96-well micro-plate at a concentration of 2 × 104 cells per well and MTS assay was performed to assess cytotoxicity in terms of cell viability. Results: At 200 µg/mL, protomexicine and 13-oxoprotopine showed mild cytotoxicity (∼24–28%) whereas dehydrocorydalmine exhibited moderate cytotoxicity (∼48%). 8-Oxyberberine was mildly cytotoxic (∼27%) at 24 h but was more potent (∼76%) at 48 h. Jatrorrhizine and 8-methoxydihydrosanguinarine were most potent (∼95–100%) in inhibiting the human colon cancer cell proliferation showing complete reduction in cell viability. Discussion and conclusion: This is the first study on the effect of these alkaloids on SW480 human colon cancer cell line. This study indicates that some alkaloids of A. mexicana strongly inhibit the cell proliferation in human colon cancer cells, and it might be a basis for future development of a potent chemotherapeutic drug.

Two new 14-membered cyclopeptide alkaloids from Zizyphus xylopyra

The phytochemical investigation of the bark of Zizyphus xylopyra resulted in the isolation of two new 14-membered ring cyclopeptide alkaloids, xylopyrine-G and xylopyrine H. Their structures have been established by chemical and spectral evidences.