Preparative isolation and purification of two amides fromMallotus lianusCroiz by high-speed counter-current chromatography

Mallotumides A-C: Potent Cytotoxic Cycloheptapeptides from the Roots of Mallotus spodocarpus

The structures of potent cytotoxic cycloheptapeptides, mallotumides A-C (1-3, respectively) isolated from the roots of Mallotus spodocarpus Airy Shaw, were elucidated by extensive spectroscopic analysis. The absolute configuration of 1 was determined by single-crystal X-ray crystallographic data. All three cycloheptapeptides exhibited potent cytotoxicity against various cancer cell lines with IC50 values ranging from 0.60 to 4.02 nM.

Megastigmane glycoside and phenol glycosides from the bark of Mallotus barbatus

A new megastigmane glycoside, barbatcoside A (1), and two new phenol glycosides, barbatcosides B (2) and C (3), together with eight known compounds (4-11) were isolated from the bark of Mallotus barbatus Müll. Arg. Their structures were elucidated using extensive 1D and 2D NMR as well as HRESIMS spectroscopic data. The stereochemistry of compounds 1 and 2 were established based on the experimental CD curves. The anti-inflammatory activities of compounds 1-11 from M. barbatus were evaluated using LPS-stimulated RAW 264.7 cell models. Compounds 2 and 3 substantially inhibited the release of NO with IC50 values of 34.78 μM and 20.73 μM, respectively.

Three new triterpenoids from Mallotus macrostachyus

Three new triterpenoids, mallomacrostins A-C (1-3), and 11 known ones (4-14) were obtained from the twigs and leaves of Mallotus macrostachyus. Mallomacrostin A possessed a new trinor-D:B-friedobaccharane skeleton. The structures of the new compounds were elucidated on the basis of extensive spectroscopic techniques including HR-ESIMS and NMR and the structure of 1 was confirmed by single crystal X-ray diffraction analysis. Spectroscopic data of the known compound 4 were provided for the first time. Compounds 2 and 10 exhibited significant anti-inflammatory activity by inhibiting LPS-induced release of nitric oxide with IC₅₀ of 70.0 μM and 14.0 μM, respectively.

Separation of alkaloids from herbs using high-speed counter-current chromatography

Alkaloids represent a most widespread group of bioactive natural products. Because of their alkalinity and structural diversity, the fractionation and purification of the alkaloids from herbs can often present a number of practical difficulties using the conventional chromatographic techniques. High-speed counter-current chromatography (HSCCC) is a liquid-liquid partition chromatography with a support-free liquid stationary phase, and is gaining more and more popularity as a viable separation technique for bioactive compounds from natural resources. In the present review, focus is placed on the separation of alkaloids by both conventional HSCCC and pH-zone-refining counter-current chromatography (CCC) techniques from herbs. The review presents the separation of over 120 different alkaloid compounds from more than 30 plant species by the conventional HSCCC and pH-zone-refining CCC. Based on the data from the literature, the proper solvent systems for the separation of alkaloids by the conventional HSCCC and pH-zone-refining CCC are also summarized.