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Clinical trials of drugs for Alzheimer’s disease have called into question the role of amyloid in the disease. The reasons several drugs recently failed clinical trials for Alzheimer’s disease are presented. An alternative approach with a traditional plant medicine is discussed. The pharmacology of the phytochemicals found in the plant medicine is provided.

Inflammatory states are among the most common and most treated medical conditions. Inflammation comes along with swelling, pain and uneasiness in using the affected area. Inflammation is not always a simple symptom; more often is part of a defensive response of the body to an external threat or is a sign that the damaged tissue has not healed yet and needs to rest. The management of the pain associated with an inflammatory state could be a tricky task. In fact, most remedies simply quench the pain, leaving the inflammatory state unaltered. This review focuses on sesquiterpene lactones, a class of natural compounds, that represents a future promise in the treatment of inflammation. Sesquiterpene lactones are efficient inhibitors of multiple targets of the inflammatory process. Their natural sources are often ancient remedies with relevant traditional uses in folk medicines. This work also aims to elucidate how these compounds may represent the starting material for the development of new anti-inflammatory drugs.

Background: This study examined the chemistry and safety of Heteromeles arbutifolia, also called toyon or California holly, which is a traditional California Indian food and treatment for Alzheimer’s disease. Methods: Plant extracts were examined by HPLC/MS, NMR and other techniques to identify compounds. Volunteers were recruited to examine the acute safety of the plant medicine using a standard short-term memory test. Results: The plant was found to contain icariside E4, dihydroxyoleanenoic acid, maslinic acid, betulin, trihydroxyoxo-seco-ursdienoic acid, catechin, vicenin-2, farrerol, kaempferide and tetrahydroxyoleanenoic acid. These compounds are anti-inflammatory agents that may protect the blood-brain barrier and prevent inflammatory cell infiltration into the brain. The dried berries were ingested by six volunteers to demonstrate the safety of the medicine. Conclusion: The plant medicine was found to contain several compounds that may be of interest in the treatment of Alzheimer’s disease. The plant medicine was found to be safe.

Chinese and Chumash traditional medical approaches are similar in terms of disease causation, use of acupuncture or healing touch, plants, spiritual and philosophical approaches. This article provides a brief comparison and discussion of Chinese and Chumash traditional medical practices. A table of 66 plants is presented along with Chinese and Chumash uses of each plant. These uses are compared and contrasted.

Ribonucleotide reductase (RR) is an important therapeutic target for anticancer drugs. The structure of human RR features a 1:1 complex of two homodimeric subunits, hRRM1 and hRRM2. p53R2 is a newly identified homologue of hRRM2. We have devised a holoenzyme-based in vitro assay for the determination of the potency and subunit-selectivity of small-molecule inhibitors of RR. The assay was implemented using two forms of recombinant RR (hRRM2/hRRM1 and p53R2/hRRM1) and based on their [ 3 H]CDP reduction activity. Hydroxyurea was used to standardize the assay. We found that the activities of hRRM2/hRRM1 and p53R2/hRRM1 were decreased by hydroxyurea in a dose-dependent manner. The –NH–OH segment of hydroxyurea was shown to be essential for inhibition. In the presence of Fe(III) and reductants, less inhibition of enzymatic activity by hydroxyurea was observed, especially for p53R2/hRRM1. The potency of four hydroxyurea analogues (Schiff bases of hydroxysemicarbazide, SB-HSC) decreased in the order SB-HSC 21 > SB-HSC 24 > SB-HSC 2 > hydroxyurea (HU) > SB-HSC 29. SB-HSC 2 and SB-HSC 24 inhibited p53R2/hRRM1 significantly more than hRRM2/hRRM1, whereas SB-HSC 21 and SB-HSC 29 showed low subunit-selectivity. Electron paramagnetic resonance (EPR) measurements showed that inhibition of RR was accompanied by reduction of its tyrosyl radical. The method was validated by comparison with data obtained using cell-based assays. We suggest that this novel recombinant-holoenzyme-based in vitro assay is a useful tool for the discovery of more potent and subunit-selective inhibitors of RR.

Summary Background: From the deductive point of view, neurotransmitter receptors can be divided into categories such as cholinergic (muscarinic, nicotinic), adrenergic (α- and β-), dopaminergic, serotoninergic (5-HT1∼5-HT5), and histaminergic (H1 and H2). Selective agonists and antagonists of each receptor subtype can have specific useful therapeutic applications. For understanding the molecular mechanisms of action, an inductive method of analysis is useful. Objective: The aim of the present study is to examine the structure–activity relationships of agents acting on G-protein coupled receptors. Method: Representative sets of G-PCR agonists and antagonists were identified from the literature and Medline [P.M. Walsh (2003) Physicians’ desk reference; M.J. O'Neil (2001) The Merck index]. The molecular weight (MW), calculated logarithm of octanol/water partition coefficient (C log P) and molar refraction (CMR), dipole moment (DM), Elumo (the energy of the lowest unoccupied molecular orbital, a measure of the electron affinity of a molecule and its reactivity as an electrophile), Ehomo (the energy of the highest occupied molecular orbital, related to the ionization potential of a molecule, and its reactivity as a nucleophile), and the total number of hydrogen bonds (Hb) (donors and receptors), were chosen as molecular descriptors for SAR analyses. Results: The data suggest that not only do neurotransmitters share common structural features but their receptors belong to the same ensemble of G-protein coupled receptor with seven to eight transmembrane domains with their resultant dipoles in an antiparallel configuration. Moreover, the analysis indicates that the receptor exists in a dynamic equilibrium between the closed state and the open state. The energy needed to open the closed state is provided by the hydrolysis of GTP. A composite 3-D parameter frame setting of all the neurotransmitter agonists and antagonists are presented using MW, Hb and μ as independent variables. Conclusion: It appears that all neurotransmitters examined in this study operate by a similar mechanism with the G-protein coupled receptors.

Summary Objective: A large number of structurally and functionally diverse compounds act as substrates or modulators of p-glycoprotein (p-gp). Some of them possess multiple drug resistance (MDR)-reversing activity, but only a small number of them have entered clinical study. In order to uncover the factors which exert a significant impact on the interaction between substrates/modulators and p-gp, we have performed structure–activity relationship (SAR) analyses, including molecular modelling, two-dimensional (2D) and three-dimensional (3D) parameter-frame-setting analysis, quantitative structure activity relationship (QSAR) analysis among substrates/modulators, as well as clinically promising MDR-reversing agents. Methods: The physicochemical parameters C log P, CMR and all regression equations were derived by using C log P version 4·0 and the latest CQSAR software, respectively. Molecular modelling and all other parameter calculations were performed by using HyperChem version 5·0 program, after geometry optimization and energy minimization using the AM1 semiempirical method. Results: SAR analyses indicate that MDR reversal activity is correlated with the lipophilicity (C log P), molecular weight (log Mw), longest chain (Nlc) of the molecule and the energy of the highest occupied orbital (Ehomo). In addition, the presence of a basic tertiary nitrogen atom in the structure is also an important contributor to p-gp inhibitory activity. Some separation in space is achieved for different subsets of p-gp substrates and inhibitors using Nlc, C log P and Ehomo as three independent parameters in the 3D-parameter-frame setting. Conclusion: A highly effective p-gp modulator candidate should possess a log P value of 2·92 or higher, 18-atom-long or longer molecular axis, and a high Ehomo value, as well as at least one tertiary basic nitrogen atom. The results obtained may be useful in explaining drug–p-gp interactions for different compounds, including drug interactions and the development of new MDR chemosensitizers.

A series of hydroxyguanidine derivatives, which are substituted salicylaldehyde Schiff-bases of 1-amino-3- hydroxyguanidine tosylate, were tested for the inhibition of RNA synthesis of mouse hepatitis virus (MHV). It was shown that these compounds could selectively inhibit virus-specific RNA synthesis. Every aspect of viral RNA synthesis, including synthesis of negative-stranded RNA, subgenomic mRNA transcription and genomic RNA replication, was inhibited to roughly the same extent. These compounds are the first known inhibitors of coronaviral RNA synthesis and should prove useful for understanding the mechanism of viral RNA synthesis.

Saw palmetto, Serenoa repens, produces berries that are the source of a popular medicine used in the treatment of benign prostatic hyperplasia, prostate infections, prostatitis, chronic pelvic pain syndrome, prostate cancer, hypotonic neurogenic bladder, sexual dysfunction and other conditions. Several clinical trials have been conducted with various extracts of the plant. The results have been mixed. Metaanalyses and systematic reviews of the trials have concluded that S. repens appears to be effective in the treatment of benign prostatic hyperplasia. The mechanism of action of the medicine is not clear. This review discusses the possibility that medium length fatty acids from S. repens decrease the inflammation of the prostate by altering adipokine secretion from visceral fat. This leads to less hyperplasia and perhaps less risk of promoting prostate cancer.

Seven ellagitannins isolated from Phyllanthus myrtifolius and P. urinaria (Euphorbiaceae) have been shown, for the first time, to be active against Epstein-Barr virus DNA polymerase (EBV-DP) at the microM level. All these compounds have the same moiety of a corilagin, and differ from each other by different substitutions at C-2 and C-4 of the glucose core. SAR analysis and molecular modeling reveal that the essential pharmacophore of these tannins resides in the corilagin moiety. The outer complex carboxylic acid moieties appear to act only as auxopharmacore.

Purpose. The main purpose of this study is to analyze the quantitative structure-activity relationship of two series of dihydroorotate dehydrogenase inhibitors (leflunomide and quinoline carboxylic acid analogues), and to determine the structural requirements for optimum activity of these analogues.

Twenty benzamide derivatives with and without EPS side effects have been compared in terms of their physicochemical properties and 3-D molecular modeling using the HyperChem program and the CQSAR program. While no single determining physicochemical property can be identified with the EPS side effects. Similarities and differences of the 3-D structures do exist among the ones with and without EPS side effects. These 3-D models of the ones without EPS side effects may be used tor further development of each subclass of therapeutic agents with improved pharmacological profile.

Purpose. This paper attempts to correlate the hydrophobic contribution constants (faa) of 21 amino acids in small peptides with commonly used physicochemical parameters. These faa constants can then be used to predict hydrophobicity change in peptides when any one of the amino acid residue is substituted with another.

Purpose. The main purpose of this study is to prepare and characterize polysaccharides from Panax notoginseng, investigate their effects on immune system in vitro in order to find new immunostimulants for the prevention and supporting treatment of infection and immunodeficiency related diseases. Methods. Polysaccharides were extracted with aqueous solution, separated with column chromatography. Their anticomplementary activities were investigated by using human serum and antibody-sensitized sheep red blood cells. Interferon-γ and tumor necrosis factor inductive activities were studied by using isolated mouse spleen lymphocytes and peritoneal macrophages, respectively. Results. Four polysaccharides, homogeneous in gel-filtration chromatography, were prepared and designated PF3111, PF3112, PBGA11, and PBGA12. Component sugar analysis revealed that they are heteroglycans with MWs ranging from 37 kD to 760 kD, composed of glucose, galactose, arabinose, mannose, and xylose in different molar ratios. Fraction PBGA12 has the most anticomplementary activity which is mediated through both alternative and classical pathways. All the polysaccharides except PBGA11 induced the production of interferon-γ in the presence of concanavalin A. They induced the production of significant amount of TNF-α in cell cultures. Conclusions. The polysaccharides from P. notoginseng have immunostimulating activities in vitro.

The species Homo sapiens has existed for 200 000 years or so. Medicinal plants have been important to humans as indicated by plants in prehistoric burial sites, mummy wrappings and ancient legends. It is likely that during the entire period of human existence, plants have been used as medicines. Thi...

In traditional Chinese medicine (TCM), usually several different plants are used in the treatment or prevention of illness, according to the condition and need of the individual patient. The outcome is observed subjectively by the physician so that the prescription can be adjusted according to the e...

A general mathematical model involving partition coefficient, molecular weight and hydrogen bonding has been formulated for correlating the structures and skin permeability of a wide range of compounds through human skin and through hairless mouse skin. The correlations obtained are dependent not only on the biological system but also on the vehicle used. Without the use of lipophilic vehicle, the ideal lipophilicity for maximum permeability through human skin as measured by log Po(oct/w)ranges from 2.5 to 6 (extrapolated value). When a lipophilic vehicle was used in hairless mouse skin study, the log Po(oct/w) was lowered to around 0.4 ~ 0.6. While increased M.W. always has a negative effect on the permeability, increased H-bond can have either a slight positive or a slight negative effect, depending on the experiments (absorption vs. permeability constant). Cross validations with previously unanalyzed data as well as other biological systems support the usefulness of the general model developed for passive diffusion.

Purpose. The main purpose of this study is to explore the additive-constitutive nature of common amino acids in their contribution to the partition coefficients of small peptides. Methods. The Log P values and other physico-chemical parameters of the peptides studied are taken from the literature. The frequency of appearance (ni) of each individual amino acid is calculated as the number of the amino acids in a given peptide. Results. The partition coefficients (Log P(oct./buff.) at PH 7) of 87 N-acetyl-peptide-amides have been correlated with the frequency of appearance of amino acids. From the correlation obtained, the de novo hydrophobic contribution constants of 19 amino acid residues are derived for the first time. The contribution constants are extended to 59 unmodified regular peptides with the inclusion of the pka values of both N-terminal and C-terminal amino acids. The models thus obtained have been validated with additional 27 peptides (both N-acetyl-peptide-amides and unmodified). Conclusions. The Log P of oligopeptides is very well correlated with the de novo hydrophobic contribution constants of amino acids. The models we have derived are reasonably accurate in predicting the hydrophobicities of new oligopeptides (≤tetrapeptides) at a fixed pH (e.g., 7).

The theoretical basis of stereoselectivity in drug targeting in terms of eudismic ratio and quantitative structure-activity relationship has been presented. Specific examples of the advantages of using the correct stereoisomers (eutomers) rather than the distomers or racemic mixtures have been discussed. With the recent development of new methods of chiral synthesis and chiral analysis, it is not longer justifiable to continue to use racemic mixtures as therapeutic agents, unless it can be proven to be safe to do so. In the area of using peptides, proteins, glycoproteins and polysaccharides as therapeutic agents, mother nature has been very selective in choosing the optically active starting materials (Bradley, 1994), it is a necessity to design and test the proper optical isomer when a mimetic or antagonist compound is contemplated as a therapeutic agent.

The 2-hydroxy-1H-isoindole-1,3-dione (HISD) derivatives are inhibitors of ribonucleotide reductase (RR). Among the seven new compounds of the PL series, three were found to be active in cell lines sensitive (CEM/0) or resistant to ara-C (CEM/ara-C/7A; CEM/dCk[-]). The compounds PL4, PL7 and PL8 exhibited IC50 values in micromolar range against the three CEM cell lines. The 3 compounds showed 100- to 1000-fold higher cytotoxicity compared to HU against all three CEM cell lines. Combination of each of the three active PL compounds with ara-C showed high degree of synergism in comparison to the combinations of HU with ara-C against both CEM/0 and CEM/ara-C/7A cell lines. The DNA synthetic capacity of CEM/0 cells treated with 10 μM PL4 for 24 or 48 h was inhibited ≥ 99.8% simultaneously the cellular NTP pools were severely depleted. Treatment of CEM/0 cells with 10 μM PL4 showed steady depletion in all the dNTP pools at 1 or 2 h and complete depletion by 4 h. The enzyme activity did not recover up to 48 h in ...

Hormones, neurotransmitters, cytokines and a number of extracellular ligands participate in extracellular signaling mechanisms that modify cellular biochemistry. Intracellular ligands are involved in an array of intracellular signaling processes that increase or decrease the effects of extracellular ligands. Both extracellular and intracellular mechanisms are important in drug effects, maintaining health and treating chronic disease. The management of chronic diseases is becoming a very common process for many people. Many questions remain to be answered about chronic diseases. What causes them? Is it possible to prevent them? How are they best treated?

Hormones, neurotransmitters, cytokines and a number of extracellular ligands participate in extracellular signaling mechanisms that modify cellular biochemistry. Intracellular ligands are involved in an array of intracellular signaling processes that increase or decrease the effects of extracellular ligands. Both extracellular and intracellular mechanisms are important in drug effects, maintaining health and treating chronic disease. The management of chronic diseases is becoming a very common process for many people. Many questions remain to be answered about chronic diseases. What causes them? Is it possible to prevent them? How are they best treated?

Analysis of saturation isotherms of the novel α2-adrenoceptor antagonist radioligand [3H]-MK 912 revealed that the ligand labelled a homogenous population of α2B-adrenoceptors in the neonatal rat lung with a Kd of 0.77 nM and a Bmax of 231 fmol/mg protein. In rat kidney, combined saturation and competition experiments, using [3H]-MK 912 and the α2A-adrenoceptor selective drug guanfacine, revealed that ~ 81% of the sites labelled by [3H]-MK 912 were α2B-adrenoceptors and ~ 19% α2A-adrenoceptors; the Kds of [3H]-MK 912 being. 1.1 and 2.0 nM and the Bmax 134 and 33 fmol/mg protein, respectively. The kidney α2B-adrenoceptors were studied separately by using ~ 1.5 nM [3H]-MK 912 in the presence of 0.32 μM guanfacine, the latter which blocked ligand binding to α2A-adrenoceptors completely. Analysis of drug competition curves obtained during these conditions revealed that 18 out of 20 different agonists and antagonists yielded steep and uniphasic competion curves which modelled best into one site fits. However, both guanoxabenz and LT 11 appeared to inhibit [3H]-MK 912 binding at two sites; the Kds of guanoxabenz differing ~ 120-fold and that of LT 11 differing ~ 35-fold for the two sites. Moreover, the addition of mutual fixed concentrations of either 20 μM guanoxabenz or 20 μM LT 11 completely prevented the binding of the other compound to its high affinity site, indicating that both compounds labelled the same site with the high affinity. The analysis indicated that 29% of the sites were of high and 71% of low affinity. However, in the neonatal rat lung guanoxabenz and LT 11 (as well as 15 other compounds) yielded competition curves which modelled only into one site fits. The Kds obtained in the lung correlated well with the Kds obtained in the kidney for α2B-adrenoceptors; for guanoxabenz and LT 11 the values from the lung were close to those determined in the kidney for the low affinity site for guanoxabenz and LT 11. Moreover, when the rat RNG α2B-adrenoceptor was expressed in COS-7 cells and its binding properties tested using [3H]-MK 912 binding, guanoxabenz, LT 11 as well as a number of other drugs inhibited the ligand binding at a single α2-adrenoceptor site; the drug Kds being practically the same as those found for the neonatal rat lung. It is suggested that rat α2B-adrenoceptors may exist in two forms: α2B1 and α2B2. The α2B1-form, which shows high affinity for guanoxabenz and LT 11, is present in the adult rat kidney. The α2B2-form, which shows low affinity for guanoxabenz and LT 11, is present in the neonatal rat lung as well as in the adult rat kidney and it is encoded by the RNG gene.

The hydrophobicity of any peptide is a physicochemical property not only of the amino acid sequence, but also of the secondary and tertiary structure. It is also an essential factor to consider in peptide drug delivery, which has become increasingly important in recent years with the discovery of many peptides with potential pharmaceutical uses. The hydrophobicities (log P) of dito pentapeptides reported by Akamatsu and Fujita have been correlated with 12 parameters including 7 indicator variables. We have tried to simply this equation by using more common and simple parameters. Good correlations have been obtained for log P with a five-parameter equation using the sum of the hydrophobicity of component amino acids (log Paa), molecular weight (log MW), the frequency of beta-turn formation (F beta) of peptides, which is an important tertiary structural parameter, the dipole moment (mu) calculated with a computer-assisted program, and the number of amino acids in a peptide (N). This equation should be useful in drug delivery in predicting the relative hydrophobicity of new peptides with no ionizable side chains.

The parameters sometimes used to describe relative polarity of the solvents are dielectric constant (e) and partition coefficient (log P). Both of them have their limitations in terms of assessing relative solubilities of various organic/inorganic compounds in solvents commonly used. In an attempt to rectify this problem, we propose to use a new term “relative dipolarity (Dr)” which is defined as Dr = μ · M/L, and a two-dimensional Log P-Dr plot to classify all solvents from nonpolar to polar. We have found that among the single parameters examined Dr is the best single parameter to assess the relative polarity of the commonly used solvents. Dr also correlates better (than μ or e) with Log P. We have analyzed the relationship between Log P values of 25 solvents and their physicochemical parameters including molecular weight (MW), maximum hydrogen-bond ability (HBm), and either Dr, μ or e. The Log Poct/w values of 110 disubstituted benzenes are also very well correlated with parameters including MW, μ (or μ1 and μ2 of the substituent group dipole moments), HBm (or HBa as hydrogen-bond acceptor and HBd as hydrogen-bond donor).

A series of eight new N-hydroxy-N′-aminoguanidine (HAG) Schiff bases [ArCH = NNHC( = NH)NHOH · tosylate] was synthesized as potential antitumor agents through the inhibition of the enzyme ribonucleotide reductase (EC 1.17.4.1). Five of the HAG derivatives (LK02 through LK06) were designed to contain an orthohydroxy group on the phenyl ring of ArCH = to increase the stability of the Schiff base formed. In addition, two compounds with a substituted quinoline [LK10; ArCH = (4-hydroxy-7-trifluoromethylquinolin-3-yl)methylene] or isoquinoline (LK11; ArCH = (5-nitroisoquinolin-l-yl)methylene] moiety were synthesized through multiple-step reactions involving reduction and/or oxidation. The IC50 values of the newly synthesized HAG Schiff bases were determined against human leukemic CCRF-CEM/0 cells in culture. The IC50 values of two previously reported HAG derivatives [ATL25; ArCH = (5-nitro-isoquinolin-l-yl)methylene] and [LW02; ArCH = 2-hydroxy-3-allyl-benzylidene)] were also determined for the first time against CCRF-CEM/0 cells. Among the compounds tested, LK11 was found to be the most potent (IC50, 2.95 ± 0.1 µM) and the 4-methoxy-2-hydroxy-phenyl derivative (LK02) to be the least potent (IC50, 121 ± 16 µM). LK11 was about 15-fold more potent against CCRF-CEM/0 cells compared to the parent compound hydroxyguanidine sulfate (IC50, 46 ± 7.1 µM) and was about 32 times more potent than LK10 (IC50, 97.6 ± 0.9 µM). LK11 in combination was incubated in sequence with cytarabine (ara-C) at various molar ratios against CCRF-CEM/0 cells for 48 hr. The results were analyzed using both the isobologram and the median-effect methods. This combination at a 1:1 molar ratio was about 6-fold more potent (IC50, 0.16 µM) compared to ara-C alone (IC50, 1.05 µM) and about 18-fold more potent compared to LK11 alone (IC50, 2.95 ± 0.1 µM). In summary, the antileukemic potency of certain HAG derivatives can be improved by the presence of orthohydroxy groups of the phenyl ring, and a 1:1 molar combination of an isoquinoline HAG compound and ara-C leads to significant synergistic antileukemic activity against CCRF-CEM/0 cells in vitro.

In view of the increasing number of patients undergoing kidney dialysis or transplant every year, a survey of the literature on renal protective medicinal plants was undertaken. Most of them are from traditional Chinese medicine (TCM). Although many of the medicinal herbs reported have not been investigated in terms of active chemical ingredients, some do have compounds well characterized. They fall into a wide range of structures. Several groups of compounds with well established activities are discussed. These include: antioxidant phenolic compounds like tannins, flavonoids, isoflavonoids, unsaturated organic acids and lignans; circulation enhancing compounds like saponins, and basic alkaloids with multiple targets (G-protein coupled receptors). Also presented are proinflammatory and antiinflammatory fatty acids like linoleic (n-6) and α-linolenic (n-3) acids, respectively. Attention is also drawn to the plants containing nephrotoxic aristolochic acid. Different directions of future research are also presented. We hope that this review may provide some leads for new drug discovery and development, and more rational application of TCM.

Twenty benzamide derivatives with and without EPS side effects have been compared in terms of their physiological properties and 3-D molecular modeling using the HyperChem program and the CQSAR program. While no single determining physicochemical property can be identified with the EPS side effects. Similarities and differences of the 3-D structures do exist among the ones with and without EPS side effects. These 3-D models of the ones without EPS side effects may be used for further development of each subclass of therapeutic agents with improved pharmacological profile

During the course of our investigation of longevity promoting natural products and Chinese herbs in the last 15 years, we come to the conclusion that in order to have healthy, productive and graceful maturing, it is necessary to maintain a dynamic balance between proinflammatory and anti-inflammatory loads. This may also help to prevent cancer as well as premature degeneration of various organ systems. Modern life style and food intake tend to overload proinflammatory factors. To overcome this it is desirable to regularly consume fresh fruits, vegetables and multiple grains, various beans including soybeans and/or minimally processed, unbleached products. When this is not sufficient or possible, taking proper dietary supplements under the guidance of knowledgeable health professional can be helpful.

Acquired immunodeficiency syndrome (AIDS) is an immunosuppressive disease characterized by an immune impairment and a high susceptibility to unusual forms of certain neoplasms. Since the brain is an important site of the infection, it is necessary to explore new classes of drugs that have the ability to penetrate across the blood–brain barrier, and the potency to suppress viral replication within the central nervous system (CNS). Therefore, the ability to predicate the lipophilicity of the potent anti-AIDS drugs may provide useful information about the potential of the drugs to enter CNS. In this paper, the correlations of log P (octanol-buffer partition coefficient) and log f R (retention time in HPLC; R , was used by Balzarini et al.) with some physical constants like log MW (molecular weight), hydrogen bond forming ability (HB) of the substitu- ents, and the substituent group dipole moments (s) are analyzed. Good correlations of log P and log f R with log MW, HB, and s have been obtained.

Substituted Schiff bases of l-amino-3-hydroxyguanidine (SB-HAG) were tested for the first time against noninfected T4 lymphocytes (CEM-6 cells) and the same cell line infected by HIV-1 in vitro. Twenty-one of 23 compounds at micromolar levels did not inhibit the growth of the noninfected T4 cells, suggesting minimal cytotoxicity. The antiviral effects of these compounds in a micromolar concentration range have been shown to be nonsignificant (

Combretastatins and their synthetic analogues, having structural features resembling that of colchicine, also have similar modes of action. In this report we have correlated the cytotoxicity of combretastatins against the murine leukemic cell line L1210 with physicochemical parameters such as the summation of the Hansch-Fujita pi constant, which was used as an index of lipophilicity of the substituent groups on ring A (sigma pi a) and ring B (sigma pi b), the vector summation of the group dipole moments of ring A (sigma mu a) and ring B (sigma mu b), the nature of the linker chain between ring A and ring B (Bt-L), indicator parameters (NOH)a and (NOH)b, which represent the number of hydroxyl groups on ring A and ring B, respectively, and the summation of pi values of the substituents on the linker (sigma pi L). Cytotoxicity correlated well with (sigma pi b), (NOH)a, (Bt-L), and (sigma mu b), and the dependency on (sigma pi b) was found to be parabolic.

A series of N-hydroxy-N'-aminoguanidine (HAG) derivatives were studied and compared for their effects on ribonucleotide reductase activity in cell-free extracts; on nucleic acid synthesis and the growth of human colon carcinoma HT-29 cells; and on mouse leukemia L1210 cells in culture. The HAG derivatives [RCH=NNHC(=NH)NHOH-tosylate] studied could be grouped as: (1) hydroxybenzylidines; (2) methoxybenzylidines; and (3) nitrobenzylidines substituted at the R position. 2'-Hydroxybenzylidine-HAG, the lead compound, was relatively active in both HT-29 cells and L1210 cells (20 +/- 5 and 13 +/- 4 microM for 50% inhibition of HT-29 and L1210 cell growth respectively). The monohydroxybenzylidene compounds were generally more active than the dihydroxy- and trihydroxybenzylidene-HAG derivatives. The methoxybenzylidene-HAGs were as active as the monohydroxybenzylidene-HAGs. 2'-Hydroxy-4'-methoxybenzylidene-HAG was much more active than 2',4'-dihydroxybenzylidene-HAG. The mononitrobenzylidene-HAGs were more active than the dinitrobenzylidene-HAG compound. In general, L1210 cells were more sensitive to the effects of the HAG compounds than were HT-29 cells. There was good agreement between the concentration of drug required to inhibit the growth of HT-29 cells and that required to inhibit the growth of L1210 cells. There was also good correlation between the ability of HAG derivatives to inhibit ribonucleotide reductase activity and to inhibit tumor cell growth. Some derivatives, such as 2',3',4'- and 3',4',5'-trihydroxybenzylidene-HAG inhibited L1210 cell growth by 50% at lower concentrations (7.8 and 11.9 microM respectively) than the concentrations needed for 50% inhibition of HT-29 cell growth (196 and 234 microM respectively) and ribonucleotide reductase activity (122 and 188 microM respectively). The studies of nucleic acid synthesis in L1210 cells using [3H]cytidine as a precursor showed that 2',3',4'-trihydroxybenzylidine-HAG inhibited DNA synthesis at a lower concentration (29 microM for 50% inhibition) than was needed for the inhibition of RNA synthesis and formation of [3H]deoxycytidine nucleotides in the acid-soluble fraction (320 and 820 microM for 50% inhibition respectively). These results indicate that 2',3',4'-trihydroxybenzylidine-HAG inhibits DNA synthesis in L1210 cells through other mechanisms rather than exclusively through the inhibition of ribonucleotide reductase activity.

Further modifications of the structural features of Schiff bases of hydroxyaminoguanidines (SB-HAG) led to nine substituted salicylaldehyde Schiff bases of HAG (SSB-HAG) derivatives and three other SB-HAG derivatives. These new compounds were tested for the first time against infection by a coronavirus, mouse hepatitis virus (MHV). The most active compound, 2 [1-[(3'-allyl-2'-hydroxybenzylidene)amino]- 3-hydroxyguanidine], against the growth of MHV is about 376 times more active than hydroxyguanidine and about 564 times more active than HAG itself when the TCID50 values are compared. Plaque assays of MHV released from cells treated with these compounds suggest that SSB-HAG tosylate may inhibit the transcription of viral RNAs in virus-infected cells. Quantitative structure-activity relationship (QSAR) analyses of two subsets show that the inhibitory activities correlate well with the electronic and the lipophilic parameters. The structural requirements for the antiviral activity of substituted SSB-HAG tosylate against coronaviral infection are stringent according to the inhibitory activities and QSAR analysis of these new compounds.

The pA 2 (or log K) values at the muscarinic cholinergic receptor of the guinea pig ileum for a series of 1,3-dioxolanes have been correlated with the hydrophobic constant π and π2. A correlation coefficient of 0.97 and standard deviation of 0.30 were obtained with 16 of the 18 compounds (P < 0.05). A series of 17 analogues of amino esters of α-methyl tropic acid and α-substituted phenyl acetic acids, which were tested in the isolated rat ileal muscle, was analyzed, with a correlation coefficient of 0.92 and a standard deviation of 0.25 (P < 0.05). Based on these results, the role of hydrophobic forces in the drug receptor interactions of muscarinic cholinergic receptors was analyzed. Optimum values for the physicochemical parameters were determined and their use in enhancing potency was suggested.

A literature survey was conducted on herbs, their preparations and ingredients with reported liver protection activities, in which a total of 274 different species and hundreds of active ingredients have been examined. These ingredients can be roughly classified into two categories according to their activities: (1) the main ingredients, such as silybin, osthole, coumarin, glycyrrhizin, saikosaponin A, schisandrin A, flavonoids; and (2) supporting substances, such as sugars, amino acids, resins, tannins and volatile oil. Among them, some active ingredients have hepatoprotective activities (e.g. anti-inflammatory, anticancer, antioxidant, immunomodulating and liver cirrhosis-regulating effects). Calculation of physicochemical parameters indicates that the main ingredients with negative and positive Elumo values possibly display their hepatoprotective effects through different mechanisms, such as antioxidative, anti-inflammatory and immunomodulating effects. As the combination of herbs may achieve some treatment effects synergistically and/or additively, it is common in Chinese medicine to use mixtures of various medicinal herbs with pharmacologically active compounds to have synergistic and/or additive effects, or to reduce harmful effects of some pharmacologically active compounds. In particular, the active compounds with Clog P around 2 are suitable for passive transport across membranes and accessible to the target sites. Thus, Elumo and Clog P values are good indicators among the calculated parameters. Seven different physicochemical parameters (MW, Clog P, CMR, μ, Ehomo, Elumo and Hf) and four major biological activities (antioxidant, anti-inflammatory, antiviral/antitumor and immunomodulating) are discussed in this review. It is hoped that the discussion may provide some leads in the development of new hepatoprotective drugs.

The tumor cell growth inhibitory activities (log 1/GI 50 ) of 166 anticancer agents studied at the National Cancer Institute (NCI) in vitro anticancer screening program have allowed us to analyze the relative importance of physicochemical parameters in influencing the inhibitory activities. Increased molecular weight, as measured by the logarithm of molecular weight (log MW), is found to be an important contributor to the tumor cell growth inhibitory activities. The tumor cell growth inhibitory activities in different subpanels of the tumor cells are highly inter-correlated with each other. A simple binary quantitative structure-activity relationship (QSAR) model was derived from the 166 anticancer drugs, based on the tumor cell growth inhibitory activities transformed into a binary (active or inactive) data format. The model obtained can be tested with additional new data, and may be useful to identify active compounds from a large compound library to be included in high throughput screening.

More than 130 different compounds have been identified from over 16 species of the Epimedium genus of the Berberidaceae family. Eight of these species have been used in the Traditional Chinese Medicines (TCM) over centuries to treate a wide range of diseases. From in vitro and in vivo experimental data, and preliminary structure-activity relationship (SAR) analysis of the androgenic/anti-estrogenic and anti-oxidant activities of the icariin series of flavonoids and glycosides, the results appear to be consistent with those of known anti-estrogenic flavonoids, such as luteolin. Further QSAR analysis of the different active ingredients is now in progress and will be reported elsewhere. Our survey suggests the possibility of multiple targets and multiple mechanisms of action by Epimedium preparations and their purified compounds. These may serve as leads for further new drug development.

More than 130 different compounds have been identified from over 16 species of the Epimedium genus of the Berberidaceae family. Eight of these species have been used in the Traditional Chinese Medicines (TCM) over centuries to treate a wide range of diseases. From in vitro and in vivo experimental data, and preliminary structure-activity relationship (SAR) analysis of the androgenic/anti-estrogenic and anti-oxidant activities of the icariin series of flavonoids and glycosides, the results appear to be consistent with those of known anti-estrogenic flavonoids, such as luteolin. Further QSAR analysis of the different active ingredients is now in progress and will be reported elsewhere. Our survey suggests the possibility of multiple targets and multiple mechanisms of action by Epimedium preparations and their purified compounds. These may serve as leads for further new drug development.