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PubMed1993

Bioactive compounds from the buds of Platanus orientalis and isolation of a new kaempferol glycoside.

A new compound kaempferol 3-O-alpha-L-(2"-E-p-coumaroyl)-rhamnopyranoside, as well as the known flavonoids, kaempferol 3-O-beta-D-(6"-E-p-coumaroyl)-glucopyranoside, kaempferol 3-O-alpha-L-(2",3"-di-E-p-coumaroyl)-rhamnopyranoside, and caffeic acid were obtained from the methanolic extract of Platanus orientalis L. buds. All the compounds were isolated by column chromatography and identified using 1H-NMR, 2D-1H-NMR (COSY), 1H-13C-NMR, and CIDMS techniques. Cytotoxic and antimicrobial studies were carried out in vitro against human cell lines and against Gram-positive and Gram-negative organisms.

Anti-Infective Agents↗
PubMed1991

Uptake of N-(4'-pyridoxyl)amines and release of amines by renal cells: a model for transporter-enhanced delivery of bioactive compounds.

The importing of vitamin B6 by renal proximal tubular cells from the rat is facilitated and Na(+)-dependent and reflects specificity for the meta-phenolate pyridinium structure with a 5-hydroxymethyl function. This transporter can, however, accept competitively each of the natural nonphosphorylated vitamers (pyridoxine, pyridoxamine, and pyridoxal) and other B6 analogues differing only in the groups at position 4. A series of N-(4'-pyridoxyl)amines was synthesized by sodium borohydride or boro[3H]hydride reduction of aldimines formed by condensing the amines with pyridoxal. The unlabeled B6-secondary amine compounds were found to competitively inhibit the uptake of [4'-3H]pyridoxine by the renal cells. Moreover, the 3H-labeled N-(4'-pyridoxyl)amines were shown to enter the cells by the process facilitated by the B6 transporter. Upon entry the labeled compounds were converted to N-(5'-phospho-4'-pyridoxyl)amines in a reaction catalyzed by pyridoxal kinase, an enzyme that tolerates considerable functional variation in position 4 of the B6 structure. The 5'-phosphates were subsequently converted within the cell to pyridoxal 5'-phosphate with liberation of the original amine in a reaction catalyzed by pyridoxamine (pyridoxine) 5'-phosphate oxidase, an enzyme with broad specificity for 4'-substituted amines on the 5'-phospho-B6 structure. This system illustrates how knowledge of transporter specificity can permit design of a compound with potential biologic activity. A drug or other intracellular effector may be piggybacked onto a transported solute (e.g., vitamin or other nutrient) that gains facilitated entry to a cell and is, thereafter, metabolized to release the active compound.

Amines↗
PubMed2001

Bioactive compounds from Iostephane heterophylla (Asteraceae).

The novel bisabolene sesquiterpenes 3-6, were isolated from Iostephane heterophylla, using bioguided fractionation. The new compounds were determined to be (12R/12S)-12,13-epoxy-xanthorrhizols (3,4) and (12R/12S)-12,13-dihydro-12,13-dihydroxy-xanthorrizols (5,6) and their structures were characterized by analysis of spectroscopic data and by chemical correlation from xanthorrhizol (2). The stereochemistry at C-12 of 5 was deduced using the modified Mosher experiment. Some of the isolated compounds elicited activity against gram positive and gram negative bacteria, levadura and dermatophytes.

Anti-Bacterial Agents↗
PubMed2006

Natural products as templates for bioactive compound libraries: synthesis of biaryl derivatives of (+/-)-vasicine.

A reliable and high-yielding procedure for preparation of 7-aryl and 7-heteroaryl derivatives of (+/-)-vasicine in two steps from the naturally occurring material is described. This protocol broadens the chemical space for selective modifications of the vasicine tricyclic structure, thereby making it a valuable starting point for the development of novel compound libraries with potentially beneficial biological profiles.

Alkaloids↗
PubMed2006

Natural products as templates for bioactive compound libraries: part 2. Novel modifications of vasicine (peganine) core via efficient and regioselective generation of 3-lithiodeoxyvasicine and its stereoselective addition to aliphatic ketones section sign.

A general procedure for direct lithiation of deoxyvasicine was developed. 3-Lithiodeoxyvasicine intermediate was found to react with various aliphatic ketones providing derivatives of 3-(hydroxyalkyl)deoxyvasicine in good yields. Similar reaction with 4-alkylcyclohexanones yielded respective trans-adducts exclusively. This novel protocol was successfully scaled-up to result in multigram quantities of vasicine-containing core building blocks suitable for production of compound libraries. The described synthetic methodology offers access to a wide range of compounds with potentially beneficial biological profiles.

Alkaloids↗
PubMed2005

Suppression of colon carcinogenesis by bioactive compounds in grapefruit.

This study evaluated the hypothesis that untreated and irradiated grapefruit as well as the isolated citrus compounds naringin and limonin would protect against azoxymethane (AOM)-induced aberrant crypt foci (ACF) by suppressing proliferation and elevating apoptosis through anti-inflammatory activities. Male Sprague-Dawley rats (n = 100) were provided one of five diets: control (without added grapefruit components), untreated or irradiated (300 Gy, 137Cs) grapefruit pulp powder (13.7 g/kg), naringin (200 mg/kg) or limonin (200 mg/kg). Rats were injected with saline or AOM (15 mg/kg) during the third and fourth week and colons were resected (6 weeks post second injection) for evaluation of ACF, proliferation, apoptosis, and cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) protein levels. Experimental diets had no effect on the variables measured in saline-injected rats. However, in AOM-injected rats, the experimental diets suppressed (P < or = 0.02) aberrant crypt and high multiplicity ACF (HMACF; P < or = 0.01) formation and the proliferative index (P < or = 0.02) compared with the control diet. Only untreated grapefruit and limonin suppressed (P < or = 0.04) HMACF/cm and expansion (P < or = 0.008) of the proliferative zone that occurred in the AOM-injected rats consuming the control diet. All diets elevated (P < or = 0.05) the apoptotic index in AOM-injected rats, compared with the control diet; however, the greatest enhancement was seen with untreated grapefruit and limonin. Untreated grapefruit and limonin diets suppressed elevation of both iNOS (P < or = 0.003) and COX-2 (P < or = 0.032) levels observed in AOM-injected rats consuming the control diet. Although irradiated grapefruit and naringin suppressed iNOS levels in AOM-injected rats, no effect was observed with respect to COX-2 levels. Thus, lower levels of iNOS and COX-2 are associated with suppression of proliferation and upregulation of apoptosis, which may have contributed to a decrease in the number of HMACF in rats provided with untreated grapefruit and limonin. These results suggest that consumption of grapefruit or limonin may help to suppress colon cancer development.

Animals↗
PubMed2003

Study of the interaction of structurally similar bioactive compounds by thin-layer chromatography.

The interaction between steroids and cholesterol is studied by reversed-phase thin-layer chromatography (TLC) using TLC plates impregnated by cholesterol and methanol-water mixtures as the eluents. The R(M) values obtained are in linear correlation with the methanol concentration of the eluent. The slope obtained from the linear regression analysis, which is characteristic of the strength of interaction, is determined. Stepwise regression and principal component analysis are carried out to find a relationship between the physicochemical parameters of steroid drugs and the strength of the interaction, which is followed by nonlinear mapping and cluster analysis to visualize the obtained results. The results show that steric and electronic parameters of the steroid drugs have a significant effect on the strength of the interaction between these structurally similar molecules.

Cholesterol↗
PubMed1997

Screening for bioactive compounds targeting the cellular signal transduction pathway using an RT-PCR-based bioassay system.

A novel bioassay system based on RT-PCR has been established to search for biologically active compounds which can modulate the expression of genes encoding important regulatory proteins. Changes in target mRNA level in the treated cell cultures were quantitatively determined by competitive PCR using internal standard DNA. The compounds discovered using this bioassay will be useful tools to elucidate the mechanisms of cellular signaling guiding the expression of the target genes. As the first application of the new bioassay strategy, the expression of the interleukin-2 gene in Jurkat cells, a human T cell line, was investigated. Screening of several crude drugs used in traditional Chinese medicines demonstrated that the aqueous acetone extract of Coptidis Rhizoma enhanced the expression of the interleukin-2 gene by about 5-fold as compared to the control.

Cell Line↗
PubMed2006

Spectroscopic studies and life time measurements of binding of a bioactive compound to bovine serum albumin and the effects of common ions and other drugs on binding.

The mechanism of binding of anti-inflammatory drug, nimesulide (NIM) with bovine serum albumin (BSA) was investigated by fluorescence, absorption, circular dichroism (CD) and lifetime measurements under simulative physiological conditions. The analysis of fluorescence data indicated the presence of both dynamic and static quenching mechanism in the binding. Various binding parameters have been evaluated. The CD spectral data revealed the decrease in alpha-helical content of BSA from 70.9% (in free BSA) to 42.03% (in bound form) thereby indicating the conformational change in BSA upon binding. The binding of NIM to BSA was also confirmed by absorption spectra. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r between the donor (BSA) and acceptor (NIM) was found to be 2.17 nm. The association constants of NIM-BSA decreased in presence of the common ions and other drugs thereby indicating the availability of higher concentration of free drug (NIM) in plasma.

Animals↗
PubMed2006

[Synthesis and structure-activity relationships of bioactive compounds using sterols].

Sterols are widely and abundantly distributed in nature. It is convenient to utilize them for the preparation of useful compounds such as pharmaceuticals with steroid and secosteroid skeletons. This paper describes the synthesis and structure-activity relationships of naturally occurring active forms of vitamin D analogues, sterols having neurite outgrowth activity, and liver X receptor agonist. The active form of vitamin D(4) showed similar biological activities but had higher affinity to the vitamin D-binding protein compared with the corresponding vitamins D(2) and D(3). This shows that the active form of vitamin D(4) is a good candidate for an agent to replace the active forms of vitamins D(2) and D(3). In the course of screening for low molecular-weight compounds that exhibit neurite outgrowth activity in the culture broth, we found that the natural product dictyosterol showed strong activity. From screening of the analogues, it was found that the double bond between C22 and C23 in the side chain of the sterol is essential for its activity. Ergost-22-ene-1alpha,3beta-diol was found to serve as a stronger liver X receptor agonist than 24(S), 25-epoxycholesterol, which regulates the expression of genes involved in lipid metabolism. Structure-function study showed that the 1alpha-hydroxyl group, the saturated steroid structure, and the double bond between C22 and C23 are needed to function as a liver X receptor agonist.

Animals↗
PubMed2001

New biflavanones and bioactive compounds from Stellera chamaejasme L.

AIM: To study the chemical constituents of the root of Stellera chamaejasme L. METHODS: Various column chromatographies on silica gel and RP-18 were employed for isolation and purification. Structures of compounds were elucidated by spectral analysis. RESULTS: Eight lignans and three biflavonoids possessing a C-3/C-3" linkage were isolated. They are ruixianglangdusu A (1) and B (2), 4',4'",5,5",7,7"-hexahydroxy-3,3"-biflavone (3), (+)-kusunokinin (4), lirioresinol-B (5), magnolenin C (6), (-)-pinoresinol monomethyl ether (7), (-)-pinoresinol (8), (+)-matairesinol (9), isohinokinin (10) and (-)-eudesmin (11). CONCLUSION: Compounds 1 and 2 are new biflavanones, 1 is enantiomeric to known chamaejasmenin C, 4, 6, 8, 9, 10 and 11 were isolated from this plant for the first time, and 7 was isolated from natural resources for the first time. In vitro bioassays showed that 3 and 8 exhibited antibacterial activity, and 1, 2, 9 and 11 exhibited immunomodulatory activity.

Adjuvants, Immunologic↗