Four new phenanthrene derivatives from Bulbophyllum retusiusculum.

Three new dihydrophenanthrenes, retusiusine D (1), retusiusine E (2), retusiusine F (3), and a new phenanthrene retusiusine G (4), together with two known dihydrophenanthrenes 4,7-dihydroxy-2,3-methylenedioxy-9,10-dihydrophenanthrene (5) and epemeranthol-A (6) were isolated from the tubers of Bulbophyllum retusiusculum. Their structures were established on the basis of extensive spectroscopic analyses. Compounds 1 and 2 exhibited potent cytotoxic activities against SMMC-7721 and weak cytotoxic activities against HL-60. Compound 4 showed moderate cytotoxic activity against SMMC-7721 and MCF-7.

New phenylpropanoids from Bulbophyllum retusiusculum.

Two new phenylpropanoids, retusiusines A (1) and B (2), and a pair of new phenylpropyl enantiomers, (±)-retusiusine C (3a and 3b), together with eight known compounds, dihydroconiferyl dihydro-p-coumarate (4), methyl 3-(4-hydroxyphenyl) propionate (5), 3-(4-hydroxyphenyl)-propanoic acid (6), dihydroferulic acid (7), methyl 3-(4-methoxyphenyl) propionate (8), 3-(3,4-dimethoxyphenyl)-2-propenal (9), trans-p-coumaric acid (10) and dihydroconiferyl alcohol (11), were isolated from the tubers of Bulbophyllum retusiusculum. The absolute configurations of the new compounds were determined by calculating their electronic circular dichroism (ECD), spectra and specific optical rotations and comparing the calculated values with the experimental data. Compound 2 exhibited potent antifungal activity against Candida albicans (16 µg/mL). Compound 3 showed moderate antibacterial activity against Bacillus subtilis (64 µg/mL).

A new phenylpropanoid glucoside and a chain compound from the roots of Allium tuberosum.

A new phenylpropanoid glucoside tuberosinine D (1) and a chain compound (Z)-11R,12S,13S-trihydroxy-9-octadecenoate (2) were isolated from the roots of Allium tuberosum. The absolute configuration of 1 was established by comparing of experimental and calculated electronic circular dichroism. The absolute configuration of 2 was determined using the modified Mosher's method for the first time.

A new flavone C-glycoside and a new bibenzyl from Bulbophyllum retusiusculum.

A new flavone C-glycoside, apigenin 6-C-α-arabinofuranosyl 8-C-α-arabinopyranoside (1) and a new bibenzyl, bulbotetusine (2), were isolated from the tubers of Bulbophyllum retusiusculum. Their structures were established on the basis of extensive spectroscopic analyses. The absolute configuration of 2 was determined by the comparison of experimental and calculated electronic circular dichroism. Compounds 1 and 2 showed no obvious cytotoxic activity against any five human tumour cell lines with IC50 values >40 µM.

New Alkaloids from Aconitum stapfianum.

Nineteen alkaloids, including a new C19-diterpenoid alkaloid stapfianine A (1) and a new benzamide derivative stapfianine B (2) were isolated from the roots of Aconitum stapfianum. Their structures were established on the basis of extensive spectroscopic analyses (IR, HRESIMS, 1D and 2D NMR).

Proaporphine and aporphine alkaloids with acetylcholinesterase inhibitory activity from Stephania epigaea.

An unusual proaporphine alkaloid bearing an isopropanenitrile group at isoquinoline nitrogen, named epiganine A (1) and a new aporphine alkaloid, epiganine B (2), together with eight known alkaloids, pronuciferine (3), dehydrodicentrine (4), romerine (5), romeline (6), N-methylcalycinine (7), phanostenine (8), dicentrine (9), and N-methyllaurotetanine (10), were isolated from the roots of Stephania epigaea. The absolute configuration of 1 was determined by calculating electronic circular dichroism (ECD) and comparing with experimental data. Compounds 2 and 4 showed strong acetylcholinesterase (AChE) inhibitory effects with the IC50 values of 4.36 and 2.98µM, respectively. Compounds 5-9 also exhibited potent AChE inhibitory activities.

Spirostanol steroids from the roots of Allium tuberosum.

Three new spirostanol saponins named tuberosines A-C (1-3), together with three known ones tuberoside O (4), 25(S)-Schidigera-saponin D5 (5), and shatavarin IV (6) were isolated from the roots of Allium tuberosum. Their structures were established on the basis of extensive spectroscopic analyses. Whereas compounds 5 and 6 exhibited potent antibacterial activities against Bacillus subtilis (32 µg/mL) and Escherichia coli (16 µg/mL), the new saponin 2 showed only moderate antibacterial activities against these pathogens. The relationship between the antibacterial activities and the structures of these saponins are described.

Diterpenoid alkaloids from Aconitum vilmorinianum.

Diterpenoid alkaloids, named vilmorines A-D, in addition to fifteen known alkaloids, were isolated from roots of Aconitum vilmorinianum. Their structures were established on the basis of extensive spectroscopic analyses. Antibacterial and antioxidant studies on isolated compounds were also carried out.

Phenolic content and radical scavenging capacity of 31 species of ferns.

The total phenolic content of 31 species of fern plants was determined, and their antioxidant activities were assessed by DPPH radical scavenging analysis.