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Purification and collection of industrial products from oil-water mixtures are commonly implemented processes. However, the efficiencies of such processes can be severely influenced by the presence of emulsifiers that induce the formation of small oil droplets dispersed in the mixtures. Understanding of this emulsifying effect and its counteractions which occur at the oil/water interface is therefore necessary for the improvement of designs of these processes. In this paper, we investigated the interfacial mechanisms of protein-induced emulsification and the opposing surfactant-induced demulsification related to corn oil refinement. At corn oil/water interfaces, the pH-dependent emulsifying function of zein protein, which is the major storage protein of corn, was elucidated by the surface/interface-sensitive sum frequency generation (SFG) vibrational spectroscopy technique. The effective stabilization of corn oil droplets by zein protein was illustrated and correlated to its ordered amide I group at the oil/water interface. Substantial decrease of this ordering with the addition of three industrial surfactants to corn oil-zein solution mixtures was also observed using SFG, which explains the surfactant-induced destabilization and coalescence of small oil droplets. Surfactant-protein interaction was then demonstrated to be the driving force for the disordering of interfacial proteins, either by disrupting protein layers or partially excluding protein molecules from the interface. The ordered zein proteins at the interface were therefore revealed to be the critical factor for the formation of corn oil-water emulsion.

Polychlorinated biphenyls are wide pollutants readily detected in environmental and human specimens. DNA adduction occurs through the corresponding quinones. Polychlorinated biphenyls are first metabolized to arene oxides, which can be further oxidized to dihydroxy metabolites by microsomal cytochrome P450s. The catechol and hydroquinone products are further oxidized by peroxidases to quinones, which are electrophilic and capable of reacting with DNA to form adducts. DNA adduction is initiated by Michael addition preferentially to guanosine followed by stabilization through enolization. Another nucleophilic attack forms a five-membered ring, which aromatizes by dehydration to form the final adduct. This report describes the characterization and quantitative study of DNA adducts formed from lower chlorinated PCB-derived quinones. Quantitative study by HPLC/ESI-MS/MS and 3 2 P-postlabeling-HPLC gave the adduct levels in the range of 3-1200 adducts per 10 8 nucleotides. These results demonstrate that increasing chlorine substitution is associated with lower yields of DNA adduct. Although 3 2 P-postlabeling is more sensitive than HPLC/ESI-MS/MS for the quantitative analysis of DNA adducts, modification levels were severely underestimated by the 3 2 P-postlabeling assay as compared to the HPLC/ESI-MS/MS assay.

Three new oleanane-type triterpene glycosides (1-3), along with the sodium salt of alternoside II (4), were isolated from an ethanol extract of the leaves of Gymnema sylvestre. The structures of these new saponins were identified as 21 beta-O-benzoylsitakisogenin 3-O-beta-D-glucopyranosyl(1--3)-beta-D-glucuronopyranoside (1), the potassium salt of longispinogenin 3-O-beta-D-glucopyranosyl(1--3)-beta-D-glucuronopyranoside (2), and the potassium salt of 29-hydroxylongispinogenin 3-O-beta-D-glucopyranosyl(1--3)-beta-D-glucuronopyranoside (3). The aglycon of 3, gymnemagenol (3a), was characterized as 3 beta,16 beta,28, 29-tetrahydroxyolean-12-ene. Structure elucidation was accomplished by interpretation of NMR (DQF-COSY, HMQC, and HMBC) results, FABMS, and hydrolysis. Saponin 1 and the sodium salt of alternoside II (4) exhibited antisweet activity.

A new oleanane-type glycoside was isolated from the methanolic extract of the roots of Pulsatilla patens var. multifida (Ranunculaceae). Its structure was identified as 3- O -s-D-glucopyranosyl-(1 ? 2)-s-D-galactopyranosyl hederagenin 28- O -a-L-rhamnopyranosyl-(1 ? 4)-s-D-glucopyranosyl-(1 ? 6)-s-D-glucopyranosyl ester by interpretation of the spectroscopic data and partial hydrolysis. The saponin inhibited the growth of human melanoma A 375 cells.

The structural elucidation of glucuronide oleanane-type triterpene carboxylic acid 3,28-O-bisdesmosides (GOTCAB) is quite complicated compared to that of other saponins. In order to determine their structures, it is common to use chemical, enzymatic and spectral methods simultaneously. This review will discuss newer chemical, enzymatic and spectral means, compare structural study strategies in different periods, and summarize main characteristics of NMR spectral data, then propose a systematic method used in their structural elucidation. A compilation of glucuronide oleanane-type triterpene carboxylic acid 3,28-O-bisdesmosides isolated during 1962-1997 along with their occurrence, structural data and bioactivity is included. (C) 1999 Elsevier Science Ltd. All rights reserved.

Five new oleanane-type glycosides (1-5), along with two known triterpene saponins, were isolated from the roots of Pulsatilla patens var. multifida (Ranunculaceae). The structures of the new triterpene saponins were elucidated as 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester (1), hederagenin 3-O-[beta-D-glucopyranosyl(1-->2)][beta-D-glucopyranosyl(1-->6)]-beta -D-galactopyranoside (2), 3-O-beta-D-glucopyranosyl bayogenin 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (3), 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (4), and 3-O-[beta-D-glucopyranosyl(1-->2)][beta-D-glucopyranosyl(1-->6)]-beta -D-galactopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (5). Structure elucidation was accomplished by 1D and 2D NMR (HMQC, HMBC, and ROESY) methods, FABMS, and hydrolysis.

The structural elucidation of glucuronide oleanane-type triterpene carboxylic acid 3,28-O-bisdesmosides (GOTCAB) is quite complicated compared to that of other saponins. In order to determine their structures, it is common to use chemical, enzymatic and spectral methods simultaneously. This review will discuss newer chemical, enzymatic and spectral means, compare structural study strategies in different periods, and summarize main characteristics of NMR spectral data, then propose a systematic method used in their structural elucidation. A compilation of glucuronide oleanane-type triterpene carboxylic acid 3,28-O-bisdesmosides isolated during 1962-1997 along with their occurrence, structural data and bioactivity is included. (C) 1999 Elsevier Science Ltd. All rights reserved.

Two new C 20 –diterpenoid alkaloids, kirinines B and C, were isolated from the roots of Aconitum kirinense . Their structures were elucidated by spectroscopic methods as 1,19–epoxydenudatine and 1–acetyllepenine azomethine, respectively.

To study the chemical constituents of Corydalis humosa Migo.Some chromatography methods were used to separate the chemical constituents of this plant. Their structures were determined by NMR and MS spectral data.Six compounds were isolated from the 95% ethanolic extract of the tubers of C. humosa. The structures of these compounds were identified as tetrahydropalmatine (1), jatrorrhizine (2), berberine (3), tetrahydroberberine (4), palmaline (5) and (-)-tetrahydrocoptisine (6) respectively.Compounds 1-3 were isolated from this plant for the first time.

Five new ocotillone-type saponins, gynosides A-E (1-5), along with 10 known dammarane-type saponins, were isolated from the aerial parts of Gynostemma pentaphyllum. The structures of these new compounds were determined by NMR analysis and acid hydrolysis. The structure and stereochemistry of gynoside A (1) were confirmed by X-ray crystallography.

Patensin, a new triterpenoid glycoside, was isolated from the ethanolic extraction of the roots of Pulsatilla patens var. multifida. Its structure was established as hederagenin 3-O-beta-D-galactopyranosyl-(1-->2)-beta-D- glucopyranoside on the basis of hydrolysis and spectral evidence including 1D and 2D NMR techniques.

The significance of DNA adduction in ortho-phenylphenol-induced carcinogenesis remains unclear. Establishing adduct structures may contribute to resolving this issue. The chemical structures of the DNA adduction products resulting from the in vitro reaction of phenylbenzoquinone, the putative ultimate carcinogenic metabolite of the fungicide/disinfectant ortho-phenylphenol, are reported here. Three isomeric adducts that resulted from reaction of deoxyguanosine were characterized by UV, LC-ESI-MS, and MS/MS, and 1D and 2D COSY-NMR spectroscopy. The proposed mechanism of product formation is nucleophilic attack by the deoxyguanosine exocyclic amine nitrogen on an electrophilic quinone carbon, followed by stabilization through enolization. Another nucleophilic attack forms a five-membered ring, which aromatizes by dehydration to form the final product. Adducts were also characterized from deoxyadenosine and deoxycytidine, although conversions were at least 10 times lower. Structures are also proposed for these products. Cell culture studies confirmed that HepG2 cells incubated with phenylbenzoquinone at concentrations associated with cytotoxicity form the same DNA adducts.

A new lupane-type triterpene saponin, pulsatilloside C (1), was isolated from the roots of Pulsatilla chinensis. Its structure was established to be 3beta,23-dihydroxylup-20(29)-en-28-oic acid 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)- beta-D-glucopyranoside.

Comparison of the UV, MS, 1H NMR (nOe) and 13C NMR spectra of oxofangchirine with those of known oxidized and unoxidized bisbenzyltetrahydroisoquinoline (BBI) alkaloids revealed several spectral characteristics of the oxidized BBI alkaloids which are useful in structure elucidations.