Three new phenylpropanoids from the roots of Piper taiwanense and their inhibitory activities on platelet aggregation and Mycobacterium tuberculosis.

Bioassay-guided fractionation of the active AcOEt-soluble fraction from the roots of Piper taiwanense has led to the isolation of two new phenylpropanoids, taiwanensols A and B (1 and 2, resp.), a new natural product, taiwanensol C (3), and 3-acetoxy-4-hydroxy-1-allylbenzene (4). The compounds were obtained as two isomer mixtures (1/2 and 3/4, resp.). Their structures were elucidated by spectroscopic analyses, including 1D- and 2D-NMR spectroscopy and mass spectrometry, and by the comparison of their NMR data with those of related compounds. Compounds 1-4 were evaluated for their antiplatelet and antitubercular activities. The mixtures 1/2 and 3/4 showed potent inhibitory activities against platelet aggregation induced by collagen, with IC50 values of 35.2 and 8.8 µM, respectively. In addition, 1/2 and 3/4 showed antitubercular activities against Mycobacterium tuberculosis H37Rv, with MIC values of 30.0 and 48.0 µg/ml, respectively.

Neolignans and phenylpropanoids from the roots of Piper taiwanense and their antiplatelet and antitubercular activities.

Bioassay-guided fractionation of roots from Piper taiwanense led to isolation of three neolignans, diallylcatechol (1) and neotaiwanensols A, B (2, 3), two diphenylpropanoid ethers, taiwandimerols A, B (4, 5), with one phenylpropanoid, 2,3-diacetoxy-1-methoxy-5-allylbenzene (6), previously unknown in nature, together with 18 known compounds (7-24). Their structures were elucidated by spectroscopic evidence. Among the isolates, hydroxychavicol acetate (7), and 4-allylcatechol (8) showed potent inhibitory activities against platelet aggregation induced by collagen, with IC50 values of 2.1, and 5.3 µM, respectively. Hydroxychavicol acetate (7), 4-allylcatechol (8), and trans-caffeicaldehyde (9) showed antitubercular activities against Mycobacterium tuberculosis H37Rv, with MIC values of 30.3, 27.6, and 25.5 µg/mL, respectively.

Secondary metabolites from the stems of Engelhardia roxburghiana and their antitubercular activities.

Bioassay-guided fractionation of stems of Engelhardia roxburghiana led to isolation of: four diarylheptanoids, engelheptanoxides A-D (1-4); two cyclic diarylheptanoids, engelhardiols A (5) and B (6); one naphthoquinone dimer, engelharquinonol (7); and one 1-tetralone, (4S)-4,6-dihydroxy-1-tetralone (8), along with 24 known compounds (9-32). The structures of 1-8 were by spectroscopic analysis. Compounds 5, 6, 13, 22, and 23 showed antitubercular activity against Mycobacterium tuberculosis H(37)Rv with MIC values of 72.7, 62.1, 9.1, 15.3, and 70.1µM, respectively.

A new 3,4-dihydronaphthalen-1(2H)-one from the leaves of Cinnamomum philippinense.

Investigation of the leaves extract of Cinnamomum philippinense (Merr.) Chang (Lauraceae) led to the isolation of one novel compound, cinnamophilin D. Its structure was determined through in-depth spectroscopic and mass-spectrometric analyses.

Isolation of a nitrobenzoate from the leaves of Cinnamomum tenuifolium.

Investigation of leaf extract of Cinnamomum tenuifolium (Lauraceae) led to the isolation of one new nitrobenzoate, ethyl 3,5-dihydroxy-4-nitrobenzoate (1), along with four known compounds. This is the first report of Cinnamomum metabolites with a nitro benzenoid derivative. Their structures were determined through in-depth spectroscopic and mass spectrometric analyses.

Isolation of a 2-oxetanone from the fruits of Synsepalum dulcificum.

Ficumone, a 2-oxetanone isolated from the fruits of Synsepalum dulcificum, has been characterised as (R*)-4-hydroxy-2-oxetanone by means of spectroscopic methods.

Prenyl Coumarins from Fatoua pilosa.

Six new prenylcoumarins, (+)-fatouain A (1), (-)-fatouain B (2), (+)-fatouain C (3), (-)-fatouain D (4), (+)-fatouain E (5), and (-)-fatouain F (6), along with two new bis-prenylcoumarins, (+)-fatouain G (7) and (+)-fatouain H (8), have been isolated from whole plants of Fatoua pilosa. The relative configurations of 1, 3, and 4 were confirmed by their acetonides on the basis of NOEDIF experiments, the results providing additional support for the relative configurations of 2, 5, 6, 7, and 8.

Dihydrobenzo[c]phenanthridine alkaloids from stem bark of Zanthoxylum nitidum.

Five novel alkaloids, zanthomuurolanine ( 1), epi-zanthomuurolanine ( 2), zanthocadinanines A ( 3) and B ( 4), and epi-zanthocadinanine B ( 5), composed of dihydrochelerythrine and a cadinane-type sesquiterpene linked by a methylene bridge, have been isolated from stem bark of Zanthoxylum nitidum. These structures were elucidated by spectroscopic techniques (UV, IR, MS, CD, 1H NMR, 13C NMR, DEPT, COSY, NOESY, HSQC, and HMBC analyses). Single-crystal X-ray diffraction studies confirmed the relative configurations of 1 and 4 and provided additional support for the structures of 2, 3, and 5.