Yun-Bao Liu

Rearranged Prenylated C6―C3 Compounds and a Highly Oxygenated seco-Prezizaane-Type Sesquiterpene from the Stem Bark of Illicium oligandrum

Three new rearranged prenylated C(6)-C(3) compounds, named illioliganones A, B, and C (1-3), and a new highly oxygenated seco-prezizaane-type sesquiterpene, oligandriortholactone (7), together with three known prenylated C(6)-C(3) compounds (4-6) and a known sesquiterpene lactone (8), have been isolated from the stem bark of Illicium oligandrum. The structures of 1-3 and 7 were elucidated by spectroscopic methods including 1D and 2D NMR, HRMS, and CD experiments. The absolute configuration of the 11,12-diol moiety in 2 and 3 was determined on the basis of observing the induced circular dichroism after addition of Mo(2)(OAc)(4) in DMSO solution. The anti-inflammatory and cytotoxic activities of 1-8 were evaluated.

New vernocuminosides from the stem barks of Vernonia cumingiana Benth.

Seven new stigmastane-type steroidal glycosides, vernocuminosides A-G (1-7), have been isolated from the stem barks of Vernonia cumingiana Benth. The structural elucidation and stereochemistry determination were achieved by spectroscopic and chemical methods including 1D and 2D NMR ((1)H-(1)H COSY, HSQC, HMBC, and NOE) experiments, especially the employment of Snatzkes method expressed by the induced circular dichroism spectra. Anti-inflammatory activities and cytotoxicities of compounds 1-7 were evaluated.

Prenylated C6–C3 compounds with molecular diversity from the roots of Illicium oligandrum

Eleven prenylated C(6)-C(3) compounds, illioliganpyranone A (1), illioliganfunone A-D (2-5), and illioliganone D-I (6-11), together with five known prenylated C(6)-C(3) compounds (12-16), were isolated from roots of Illicium oligandrum. The structures of 1-11 were elucidated by spectroscopic methods including 1D and 2D NMR, HRESIMS, and CD experiments. Possible biosynthetic pathways to compounds 1-16 derived from a common precursor of 5-allylbenzene-1,2,4-triol were postulated. All compounds were evaluated for cytotoxic activities against five human cancer cell lines (HCT-8, Bel-7402, BGC-823, A549 and A2780). Compound 15 exhibited significant cytotoxicity against HCT-8, BGC-823, A549, and A2780 cell lines with IC(50) values of 0.30-2.57 μM. Compound 16 showed moderate selective cytotoxicity against sensitive A2780 cells with IC(50) value of 1.38 μM.

Bisindole Alkaloids with Neural Anti-inflammatory Activity from Gelsemium elegans

Three new trace bisindole alkaloids geleganimines A and B (1, 2) and geleganamide (3) were isolated from the aerial parts of Gelsemium elegans. Their structures were elucidated by spectroscopy, particularly from their carbon-proton coupling constants, and electronic circular dichroism. Compounds 1-3 are the first bisindole alkaloids discovered from the genus Gelsemium. Geleganimine B exhibited anti-inflammatory activity indirectly by suppressing lipopolysaccharide-induced pro-inflammatory factors in BV2 microglial cells with an IC50 value of 10.2 μM. These findings confirm the importance of bioactive trace components in medicinal plant research.

Grayanoids from the Ericaceae family: structures, biological activities and mechanism of action

Grayanoids, occurring exclusively in Ericaceae plants, are well-known highly toxic components from the genera Rhododendron, Pieris, Leucothoe, Craibiodendron, Lyonia, Kalmia, etc. Grayanoids have been the topic of research in many phytochemical and pharmacological laboratories due to their complex structures and fascinating bioactivities. This review, citing 100 references, summarises their chemistry, including the total synthesis and bioactivity of grayanoids isolated from the Ericaceae family in the last five decades, to illustrate the chemo-diversity and biological significance of these diterpenoids.

Lycojaponicumins D and E: Two New Alkaloids from Lycopodium japonicum

Two new alkaloids, lycojaponicumins D (1) and E (2), were isolated from the club moss Lycopodium japonicum. Their structures were elucidated by spectroscopic methods, calculated ECD, CD experiments and X-ray diffraction analysis. Lycojaponicumin D (1) possesses an unprecedented 5/7/6/6 tetracyclic skeleton formed by an unusual C3-C13 linkage, which is first reported in Lycopodium alkaloids. The plausible biogenetic pathway of 1 is proposed.

Chiral Resolution and Absolute Configuration of a Pair of Rare Racemic Spirodienone Sesquineolignans from Xanthium sibiricum

A pair of racemic spirodienone neolignan enantiomers, (±)-sibiricumin A, were isolated from the extract of the fruits of Xanthium sibiricum. The resolution of (+)- and (-)-sibiricumin A was achieved by chiral HPLC. The absolute configurations of the racemes were assigned by X-ray and by electronic circular dichroism (ECD). This experiment is the first unambiguous determination of the absolute configuration of spirodienone neolignan.

Sesquiterpenes and Alkaloids from the Roots of Alangium chinense

Four new sesquiterpenes (1-4), four new alkaloids (5a, 6a, 6b, and 7), and nine known compounds (5b and 8-15) were isolated from an ethanolic extract of roots of Alangium chinense. The structure of 1 was confirmed by X-ray crystallography. The configurations of 5 and 6 were assigned by chiral HPLC analysis and CD spectra. Compounds 3, 4, 8-13, and 15 exhibited antiviral activity against Coxsackie virus B3 with IC50 values of 1.4-15.4 μM. Compounds 2-4, 7, and 9-13 showed antioxidant activities against Fe(2+)-cysteine-induced rat liver microsomal lipid peroxidation, with IC50 values of 3.8-45.7 μM. Compound 5b displayed neuritis inhibitory activity against microglial inflammation factor, with an IC50 value of 6.7 μM. None of the compounds exhibited detectable cytotoxic activity toward any of five tumor cell lines (A549, Be-17402, BGC-823, HCT-8, and A2780) in the MTT assay.

Mollolide A, a diterpenoid with a new 1,10:2,3-disecograyanane skeleton from the roots of Rhododendron molle.

Mollolide A (1), a diterpenoid featuring a new 1,10:2,3-disecograyanane skeleton, was isolated from the roots of Rhododendron molle. Its structure was elucidated through extensive MS, IR, and NMR spectroscopy analyses. The absolute configuration was determined by single-crystal X-ray diffraction of its p-bromobenzoate derivative (1b). Compound 1 exhibits a significant analgesic effect at a dose of 20 mg/kg and antiviral activity against the Coxsackie B3 virus with an IC50 value of 27.7 μM.

Antiviral spirooliganones A and B with unprecedented skeletons from the roots of Illicium oligandrum.

Two novel spirooliganones A (1) and (2), a pair of spiro carbon epimers, with a rare dioxaspiro skeleton were isolated from the roots of Illicium oligandrum. The structures were fully determined by spectroscopic analysis and chemical methods, especially modified Moshers method, and X-ray diffraction analysis. Spirooliganone B was found to exhibit more potent activities against coxsackie virus B3 and influenza virus A (H3N2) (IC50 3.70-5.05 μM) than spirooliganone A. The biosynthetic pathway involving a hetero-Diels-Alder reaction of the epimers was proposed.