Preparation and Application of Reversed Phase Chromatorotor^TM for the Isolation of Natural Products by Centrifugal Preparative Chromatography

Abstract

A method of preparation of rotors with a reversed phase (RP) solid silica gel sorbent layer has been developed for centrifugal preparative chromatography (CPC), also known as rotational planar chromatography (RPC). The rotors consist of binder free RP solid SiO 2 layers of different thicknesses packed between two supported circular glass discs and can be used in any appropriate device for centrifugal chromatography, like Chromatotron ® and CycloGraph ® . Polar and /or semi-polar compounds with close R f values, as well as extracts and column fractions were separated and /or purified in a preparative and / or semipreparative scale using the RP rotors, eluted with mixtures of aqueous-based solvents. We herein report three examples of its application, using RP Chromatorotors TM , for the isolation of the diastereoisomeric alkaloids banistenosides I and II from Banisteriopsis caapi, saponins III and IV from Fagonia cretica, and the sesquiterpenes artemisinin (V) and artemisinic acid (VI) from Artemisia annua.

In vitro opioid receptor affinity and in vivo behavioral studies of Nelumbo nucifera flower

“…Fractionation of the basic CHCl 3 partition of white flower, using CPTLC over customized alumina Chromatorotor™ (Muhammad et al, 2013), afforded compounds 2–7. Similarly, the acidic partition yielded compound 1 and additional quantities of 2.…”

“…The acidic aqueous layer was then basified with 30% NH 4 OH (pH 11) and partitioned with CHCl 3 (3 times) to yield the basic CHCl 3 partition (1.5 g). The basic fraction (1.4 g) was chromatographed over a CPTLC, using a 6 mm customized Chromatorotor™ (Muhammad et al, 2013) packed with neutral alumina, using a Chromatotron ® , and eluted with CH 2 Cl 2 -MeOH (99:1 to 90:10) to yield N-nor-nuciferine (2, 58 mg), asimilobine (3, 80 mg), armepavine (4, 31 mg), O-methylcoclaurine (5, 28 mg), N-methylcoclaurine (6, 46 mg), and coclaurine (7, 65 mg). The acidic fraction (236 mg) was subjected to CPTLC, using a 2 mm customized alumina Chromatorotor™ with CH 2 Cl 2 -MeOH (99:1) as solvent, to afford the nuciferine (1, 60 mg) and additional amounts of 2 (13 mg).…”

New Polyisoprenylated Polycyclic Phloroglucines from Clusia gundlachii

“…Compounds were visualized by observing under UV light, followed by and sprayed with 10% H 2 SO 4 -MeOH reagent followed by heating. Centrifugal preparative TLC (using a Chromatotron, Harrison Research Inc., model 8924, tagged with a fraction collector) was carried out on RP C 18 silica gel, using a custom-made rotor [10] or silica gel (coated with F 254 indicator, Analtech, Newark, DE, USA) rotor. The samples were dried using a Savant Speed Vac Plus SC210A.…”

“…The EtOH extract of C. gundlachii was subjected to centrifugal thin layer chromatography (CPTLC; using a Chromatotron ® ) over reversed-phase C 18 SiO 2 , packed in a custom-made ChromatoRotor TM [10], using a gradient solvent system (see Experimental Section). Fractions 19-22 were further purified using CPTLC with silica gel plates, which afforded five new polycyclic phloroglucines, namely gundlachiione A-E (1)- (5).…”