Toward crystalline molecular rotors with linearly conjugated diethynyl-phenylene rotators and pentiptycene stators.

A strategy for the construction of crystalline molecular rotors involves the assemblage of chemical structures that emulate the elements of macroscopic rotary devices, such as those found in macroscopic gyroscopes and compasses. In this report, we describe an efficient and short synthetic route for preparation of molecular rotors with two pentiptycene-units linked at their central benzene ring by triple bonds to a linearly conjugated phenylene rotator. Five analogous compounds with phenol, alkoxy, or alkoxycarbonyl substituents were synthesized and fully characterized in solution and in the solid-state through various methods, such as cross-polarization magic angle spinning (CPMAS) (13)C NMR and single crystal X-ray diffraction. Molecular and packing structures obtained from single crystal X-ray diffraction and crystallization properties were analyzed with the goal of identifying the key parameters that may hinder or facilitate the formation of dynamically functional, crystalline molecular rotors.

Batatins III-VI, glycolipid ester-type dimers from Ipomoea batatas.

Batatins III-VI (1-4), glycolipid ester-type dimers, were isolated from the tuberous roots of sweet potato (Ipomoea batatas) using recycle high performance liquid chromatography. Their structures were characterized by means of several high-resolution NMR and mass spectrometry techniques. These compounds are the first examples of ester-type dimers which consist of two units of the heterotetrasaccharide operculinic acid C. Each unit was esterified by a different amount and type of acid residues: (2S)-methylbutanoic, cinnamic, decanoic (capric) and dodecanoic (lauric) acids. Batatins III-VI (1-4) are an example of the presence of a large number of resin glycoside congeners in each morning glory species caused by partial acylation of their constitutive saccharide cores.

Batatinosides II-VI, acylated lipooligosaccharides from the resin glycosides of sweet potato.

Sweet potato ( Ipomoea batatas) belongs to the Convolvulaceae (morning glory family) and is native to Mexico and Central America. Its edible tuberous roots have been much appreciated since pre-Hispanic times in Mesoamerica and now play an important role as a basic diet staple and a medicinal plant worldwide. The hexane-soluble extract from roots, through preparative-scale recycling HPLC, yielded five new lipophilic oligosaccharides of jalapinolic acid, batatinosides II-VI ( 1- 5), as well as the known pescapreins I ( 6) and VII ( 7) and murucoidin I ( 8), which are part of the purgative resin glycoside mixture. NMR spectroscopy and FAB mass spectrometry were used to characterize their structures. Compounds 1 and 2 are tetraglycosidic lactones of operculinic acid C. The pentasaccharide structures for compounds 3 and 4 were confirmed to be macrolactones of simonic acid B, and that characterized for 5 was derived from operculinic acid A. The lactonization site of the aglycone was placed at C-3 of the second saccharide unit in all compounds except 4, where it was placed at C-2. All compounds contain an esterifying residue that is composed of a long-chain fatty acid, n-decanoic acid (capric) or n-dodecanoic acid (lauric). In compound 3, an additional short-chain fatty acid, (2 S)-methylbutyric acid, was also identified.

Batatins I and II, ester-type dimers of acylated pentasaccharides from the resin glycosides of sweet potato.

Batatins I (1) and II (2), two ester-type dimers of acylated pentasaccharides, have been isolated by recycling HPLC from the hexane-soluble extract of sweet potato (Ipomoea batatas var. batatas). The structures were elucidated by a combination of high-resolution NMR spectroscopy and mass spectrometry. Complete analysis and unambiguous assignments of the 1H and 13C NMR spectra of 1 and 2 were achieved by 2D shift correlation measurements. The glycosidic acid forming each branched pentasaccharide monomeric unit was confirmed as simonic acid B. Three different fatty acids esterify this core at the same positions in both batatins: C-2 on the second rhamnose unit and C-4 and C-2 (or C-3) on the third rhamnose moiety. The acylating residues were identified as (+)-(2S)-methylbutanoic, dodecanoic (lauric), and cinnamic acids. The site of lactonization by the aglycon in unit A was placed at C-3 of the second saccharide. The position for the ester linkage for monomeric unit B on the macrocylic unit A was identified as C-3 of the terminal rhamnose' ''. Through spectroscopic simulation of these complex oligosaccharides, the chemical shifts and coupling constants were deduced for the overlapped proton resonances with a non-first-order resolution. The experimental NMR spectroscopic values registered for batatinoside I (3), a new polyacylated macroyclic pentasaccharide also isolated from this plant, were used as the starting point for spectral simulation of 1 and 2. Both polymers 1 and 2 represent dimers of compound 3.

Profiling of the resin glycoside content of Mexican jalap roots with purgative activity.

Mexican Jalap roots, a prehispanic medicinal plant complex still considered to be a useful laxative, can be found as an ingredient in some over-the-counter products sold by herbalists in contemporary Mexico. The drug is prepared from the dried roots of several morning glories, all of which have been identified as members of the genus Ipomoea. Analysis of several commercial samples was assessed by generating HPLC and 13C NMR spectroscopic profiles of the glycosidic acids obtained through saponification of the resin glycoside contents. These profiles distinguish the three Mexican jalaps currently in frequent use and can serve as analytical tools for the authentication and quality control of these purgative herbal drugs. Ipomoea purga, the authentic "jalap root", yielded two new hexasaccharides of convolvulinic and jalapinolic acids, purgic acids A (1) and B (2), respectively. Scammonic acid A (3), a tetrasaccharide, was produced from Ipomoea orizabensis, the Mexican scammony or false jalap. Operculinic acid B (4), a pentasaccharide, was identified in Ipomoea stans. Semipreparative HPLC was performed to obtain pure samples of new compounds 1 and 2 in sufficient quantity to elucidate their structure by high-field NMR spectroscopy. Purgic acid A (1) was identified as (11S)-hydroxytetradecanoic acid 11-O-beta-D-quinovopyranosyl-(1-->2)-O-beta-D-glucopyranosyl-(1-->3)-O-[beta-D-fucopyranosyl-(1-->4)]-O-alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranosyl-(1-->2)-O-beta-D-quinovopyranoside, while purgic acid B (2) was characterized with (11S)-hydroxyhexadecanoic acid as its aglycon but having the same glycosidation sequence in the oligosaccharide core.

Characterization of lipophilic pentasaccharides from beach morning glory (Ipomoea pes-caprae).

The hexane-soluble extract from the aerial parts of the herbal drug Ipomoea pes-caprae (beach morning-glory), through preparative-scale recycling HPLC, yielded six lipophilic glycosides, namely, five new pentasaccharides of jalapinolic acid, pescaproside A (1) and pescapreins I-IV (2-5), as well as the known stoloniferin III (6). Saponification of the crude resin glycoside mixture yielded simonic acid B (7) as the glycosidic acid component, whereas the esterifying residues of the natural oligosaccharides comprised five fatty acids: 2-methylpropanoic, (2S)-methylbutyric, n-hexanoic, n-decanoic, and n-dodecanoic acids. Pescaproside A (1), an acylated glycosidic acid methyl ester, is related structurally to the product obtained from the macrolactone hydrolysis of pescapreins I-IV (2-5). All the isolated compounds (1-6), characterized through high-field NMR spectroscopy, were found to be weakly cytotoxic to a small panel of cancer cell lines.