Direct oxidative C-H alkynylation of N-carbamoyl tetrahydroisoquinolines and dihydroisoquinolines.

An efficient oxidative C-H alkynylation of N-carbamoyl tetrahydroisoquinolines mediated by a TEMPO oxoammonium salt has been established. A variety of electronically varied N-carbamoyl tetrahydroisoquinolines reacted with a range of alkynyl potassium trifluoroborates smoothly under mild metal-free conditions. Dihydroisoquinolines were also suitable components for the reaction. The synthetic applicability of the method for facile access to structurally diverse bioactive molecules was further demonstrated.

Pharmacokinetics and tissue distribution of pefloxacin mesylate in chickens.

A specific, sensitive and stable high-performance liquid chromatography (HPLC)-based analytical method was established to determine the level of pefloxacin mesylate (PM) in the plasma and various tissues of chickens. Chickens were randomly assigned to 12 equal experiment groups, including 11 treatment groups and one control group. The chickens in the treatment groups received oral administration of PM and were sacrificed at different pre-determined time points, with their blood and various organs harvested, extracted and analyzed by HPLC to quantify the level of the residual antibiotic. Method validation studies indicated that the HPLC measurement showed excellent precision, reproducibility, stability and robustness. The obtained pharmacokinetic parameters suggested that PM reached peak levels in various tissues within 1-2 h after its oral administration, and was mainly concentrated in liver and kidney. The antibiotic was also found to be cleared from chicken crureus, brain, testes, ovaries and pancreas at higher rates compared with other organs. Overall, the rapid accumulation of PM could at least be partially attributed to its relatively slow organ clearance. These results could serve as a useful guidance for the rational use of PM and other quinolone-derived antimicrobials in the treatment of infectious diseases in chickens and other animals.

Oxidative C-H functionalization of N-carbamoyl 1,2-dihydroquinolines.

A modular and efficient method for the synthesis of α-substituted 1,2-dihydroquinolines is described. Under mild metal-free conditions, readily available N-carbamoyl 1,2-dihydroquinolines undergo oxidative C-H alkynylation, alkenylation, and allylation with a range of potassium trifluoroborates using TEMPO oxoammonium salt as an oxidant.

3Cpro of foot-and-mouth disease virus antagonizes the interferon signaling pathway by blocking STAT1/STAT2 nuclear translocation.

UNLABELLED: Foot-and-mouth disease virus (FMDV) causes a highly contagious, debilitating disease in cloven-hoofed animals with devastating economic consequences. To survive in the host, FMDV has evolved to antagonize the host type I interferon (IFN) response. Previous studies have reported that the leader proteinase (L(pro)) and 3C(pro) of FMDV are involved in the inhibition of type I IFN production. However, whether the proteins of FMDV can inhibit type I IFN signaling is less well understood. In this study, we first found that 3C(pro) of FMDV functioned to interfere with the JAK-STAT signaling pathway. Expression of 3C(pro) significantly reduced the transcript levels of IFN-stimulated genes (ISGs) and IFN-stimulated response element (ISRE) promoter activity. The protein level, tyrosine phosphorylation of STAT1 and STAT2, and their heterodimerization were not affected. However, the nuclear translocation of STAT1/STAT2 was blocked by the 3C(pro) protein. Further mechanistic studies demonstrated that 3C(pro) induced proteasome- and caspase-independent protein degradation of karyopherin α1 (KPNA1), the nuclear localization signal receptor for tyrosine-phosphorylated STAT1, but not karyopherin α2, α3, or α4. Finally, we showed that the protease activity of 3C(pro) contributed to the degradation of KPNA1 and thus blocked STAT1/STAT2 nuclear translocation. Taken together, results of our experiments describe for the first time a novel mechanism by which FMDV evolves to inhibit IFN signaling and counteract host innate antiviral responses. IMPORTANCE: We show that 3C(pro) of FMDV antagonizes the JAK-STAT signaling pathway by blocking STAT1/STAT2 nuclear translocation. Furthermore, 3C(pro) induces KPNA1 degradation, which is independent of proteasome and caspase pathways. The protease activity of 3C(pro) contributes to the degradation of KPNA1 and governs the ability of 3C(pro) to inhibit the JAK-STAT signaling pathway. This study uncovers a novel mechanism evolved by FMDV to antagonize host innate immune responses.

Hepatotoxic mechanism of diclofenac sodium on broiler chicken revealed by iTRAQ-based proteomics analysis.

BACKGROUND: At the therapeutic doses, diclofenac sodium (DFS) has few toxic side effects on mammals. On the other hand, DFS exhibits potent toxicity against birds and the mechanisms remain ambiguous. OBJECTIVES: This paper was designed to probe the toxicity of DFS exposure on the hepatic proteome of broiler chickens. METHODS: Twenty 30-day-old broiler chickens were randomized evenly into two groups (n = 10). DFS was administered orally at 10 mg/kg body weight in group A, while the chickens in group B were perfused with saline as a control. Histopathological observations, serum biochemical examinations, and quantitative real-time polymerase chain reaction were performed to assess the liver injury induced by DFS. Proteomics analysis of the liver samples was conducted using isobaric tags for relative and absolute quantification (iTRAQ) technology. RESULTS: Ultimately, 201 differentially expressed proteins (DEPs) were obtained, of which 47 were up regulated, and 154 were down regulated. The Gene Ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway analysis were conducted to screen target DEPs associated with DFS hepatotoxicity. The regulatory relationships between DEPs and signaling pathways were embodied via a protein-protein interaction network. The results showed that the DEPs enriched in multiple pathways, which might be related to the hepatotoxicity of DFS, were "protein processing in endoplasmic reticulum," "retinol metabolism," and "glycine, serine, and threonine metabolism." CONCLUSIONS: The hepatotoxicity of DFS on broiler chickens might be achieved by inducing the apoptosis of hepatocytes and affecting the metabolism of retinol and purine. The present study could provide molecular insights into the hepatotoxicity of DFS on broiler chickens.

iTRAQ-based quantitative proteomic analysis reveals the toxic mechanism of diclofenac sodium on the kidney of broiler chicken.

Diclofenac sodium (DS) is one of the nonsteroidal anti-inflammatory drugs (NSAIDs), which exhibits potent toxicity to birds. To search the molecular mechanism of DS induced nephrotoxicity in broiler chicken, 20 apparently healthy 30-day old broiler chickens were separated randomly into two groups (n = 10): Group A was kept as control while DS was administered at the dose rate of 10 mg/kg body weight in group B through oral gavage. Kidney samples were collected, and the proteins were identified and quantified by iTRAQ. 434 differentially expressed proteins (DEPs) were screened, including 277 up-regulated DEPs and 157 down-regulated DEPs. The functional annotation and classification results indicated that DEPs were significantly enriched in apoptosis and metabolism-related pathways via GO and KEGG analysis. Compared with the control group, the most significant enrichment pathways are "ribosome", "metabolic pathways" and "protein processing in endoplasmic reticulum". Based on the proteomic results and relevant literature, some DEPs that potentially related to the toxicity of DS were screened. The mRNA transcript levels of these DEPs were characterized by qRT-PCR, and the results showed that Slc22a7, Gatm, Glud1, Agxt2 and Gldc were significantly down-regulated, while Gsl, Gpt2 and Asns were significantly up-regulated. We speculate that the toxic mechanism of DS to chicken might be that it induces kidney cell apoptosis, interferes with purine metabolism and inhibits the expression of OAT2. The current study provides a reference for elucidating the nephrotoxic mechanism of diclofenac sodium to broiler chicken from the molecular perspective.

Tea Polyphenols Enhanced the Antioxidant Capacity and Induced Hsps to Relieve Heat Stress Injury.

Keap1-Nrf2-ARE and heat shock proteins (Hsps) are important endogenous protection mechanisms initiated by heat stress to play a double protective role for cell adaptation and survival. H9C2 cells and 80 300-day-old specific pathogen-free chickens were randomly divided into the control and tea polyphenol groups and used to establish a heat stress model in vitro and in vivo. This task was conducted to explore the protection and mechanism of tea polyphenols in relieving thermal injury. A supplement with 10 µg/mL tea polyphenols could effectively relieve the heat damage of H9C2 cells at 42°C. Accordingly, weaker granular degeneration, vacuolar degeneration, and nucleus deep staining were shown. A strong antioxidant capacity was manifested in the upregulation of the total antioxidant capacity (T-AOC) (at 5 h, P < 0.05), Hemeoxygenase-1 mRNA (at 2 h, P < 0.01), superoxide dismutase (SOD) (at 2, 3, and 5 h, P < 0.05), and Nrf2 (at 0 and 5 h, P < 0.01). A high expression of Hsps was reflected in CRYAB at 3 h; Hsp27 at 0, 2, and 3 h (P < 0.01); and Hsp70 at 3 and 5 h (P < 0.01). The supplement with 0.2 g/L tea polyphenols in the drinking water also had a good effect in alleviating the heat stress damage of the myocardial cells of hens at 38°C. Accordingly, light pathological lesions and downregulation of the myocardial injury-related indicators (LDH, CK, CK-MB, and TNF-α) were shown. The mechanism was related to the upregulation of T-AOC (at 0 h, P < 0.05), GSH-PX (at 0.5 d, P < 0.01), SOD (at 0.5 d), and Nrf2 (at 0 d with P < 0.01 and 2 d with P < 0.05) and the induced expression of CRYAB (at 0.5 and 2 d), Hsp27 (at 0, 0.5, and 5 d), and Hsp70 (at 0 and 0.5 d). In conclusion, the tea polyphenols enhanced the antioxidant capacity and induced Hsps to relieve heat stress injury.

The effects of salvianolic acid B from radix salvia miltiorrhizae on the oral pharmacokinetics of metoprolol and metoprolol acid in rats.

The present study aimed to investigate the effects of salvianolic acid B (SalB) isolated from Radix Salvia miltiorrhizae on the oral pharmacokinetics of metoprolol (MET) and metoprolol acid (META) in rats. The pharmacokinetic parameters of MET and META were measured after oral (15 mg/kg) administration of MET in rats in the presence and absence of SalB. Compared to the control given MET alone, with the concurrent administration of SalB (50 mg/kg), the AUC and C(max) of MET increased by 51.7% and 27.7%, and the AUC and C(max) of META decreased by 26.5% and 19.6%, respectively. With the presence of SalB, the metabolic ratio was markedly decreased by 50.8%. However, no significant changes were observed in the pharmacokinetic parameters of SalB when it was combined with MET.

Pharmacokinetics of vertilmicin, a novel aminoglycoside antibiotic, in rats and dogs.

The pharmacokinetics of vertilmicin was investigated in rats and dogs following intramuscular or intravenous administration of vertilmicin. Following a single administration of an intramuscular dose, serum concentrations of vertilmicin peaked at 0.63 h in rats and 0.58 h in dogs. In rats, after intravenous administration of vertilmicin at dosages of 10, 20, and 40 mg/kg, the t1/2 values for vertilmicin were 0.81, 0.76, and 0.86 h, respectively, while after intramuscular administration of vertilmicin at dose of 20 mg/kg, the t1/2 value for vertiImicin was 0.79 h. In dogs, after intravenous or intramuscular administration of vertilmicin at a dose of 10 mg/kg, the t1/2 values for vertilmicin were 0.83 and 0.85 h, respectively. After intravenous dosing to rats vertilmicin was distributed to most organs and tissues, and kidney tissue exhibited the highest exposure, while the tissue with the lowest exposure was the brain. Following single intravenous administration of vertilmicin at a dose of 20 mg/kg to rats, about 81.1% of the vertilmicin was excreted in urine, while only 3.12 and 1.44% of the administered dose was excreted in feces and bile within 48 h. The mean values for the plasma protein binding of vertilmicin were 22.7 and 20.4% in rats and dogs, respectively. These results indicate that vertilmicin was rapidly absorbed and widely distributed into various tissues in rats. The pharmacokinetic behavior of vertilmicin was dose-dependent when increasing doses of vertilmicin were administered intravenously to rats. Renal excretion was the primary elimination route of vertilmicin following intravenous administration to rats.

Plasma and urinary tanshinol from Salvia miltiorrhiza (Danshen) can be used as pharmacokinetic markers for cardiotonic pills, a cardiovascular herbal medicine.

Cardiotonic pills are a type of cardiovascular herbal medicine. To identify suitable pharmacokinetic (PK) marker(s) for indicating systemic exposure to cardiotonic pills, we examined the in vivo PK properties of putatively active phenolic acids from the component herb Danshen (Radix Salviae miltiorrhizae). We also performed in vitro and in silico assessments of permeability and solubility. Several phenolic acids were investigated, including tanshinol (TSL); protocatechuic aldehyde (PCA); salvianolic acids A, B, and D; rosmarinic acid; and lithospermic acid. Plasma TSL exhibited the appropriate PK properties in dogs, including dose-dependent systemic exposure in area under concentration-time curve (AUC) and a 0.5-h elimination half-life. In rats, more than 60% of i.v. TSL was excreted intact into the urine. In humans, we found a significant correlation between the urinary recovery of TSL and its plasma AUC. The absorption rate and bioavailability of TSL were not significantly different whether cardiotonic pills were given p.o. or sublingually. The gender specificity in plasma AUC disappeared after body-weight normalization, but the renal excretion of TSL was significantly greater in women than in men. PCA was predicted to be highly permeable according to in vitro and in silico studies; however, extensive presystemic hepatic elimination and degradation in the erythrocytes led to extremely low plasma levels and poor dose proportionality. Integrated in vivo, in vitro, and in silico studies on the other phenolic acids showed poor gut permeability and nearly undetectable levels in plasma and urine. In conclusion, plasma and urinary TSL are promising PK markers for cardiotonic pills at the tested dose levels.

Evaluation of WO2017098421: GSK's benzothiazine compounds as CD73 inhibitor filings.

INTRODUCTION: There are considerable interests in the development of novel small-molecule CD73 inhibitors for the treatment of cancers, autoimmune diseases, precancerous syndromes, and other diseases associated with CD73 activity. Areas covered: The application claims novel substituted benzothiadiazine derivatives as CD73 inhibitors for the treatment of cancer, precancerous syndromes, AIDS, autoimmune diseases, infections, atherosclerosis, and ischemia-reperfusion injury. Many of the exemplified compounds have pIC50 values between 5 to 8.4 against CD73. Expert Opinion: These benzothiadiazine derivatives provide good leads for the discovery of potent CD73 inhibitors for the treatment of cancer and other diseases mediated by adenosine and its action on adenosine receptors.

Recent advances in the discovery of potent and selective HDAC6 inhibitors.

Histone deacetylase HDAC6, a member of the class IIb HDAC family, is unique among HDAC enzymes in having two active catalytic domains, and has unique physiological function. In addition to the modification of histone, HDAC6 targets specific substrates including α-tubulin and HSP90, and are involved in protein trafficking and degradation, cell shape and migration. Selective HDAC6 inhibitors are an emerging class of pharmaceuticals due to the involvement of HDAC6 in different pathways related to neurodegenerative diseases, cancer, and immunology. Therefore, extensive investigations have been made in the discovery of selective HDAC6 inhibitors. Based on their different zinc binding groups (ZBGs), in this review, HDAC6 inhibitors are grouped as hydroxamic acids, a sulfur containing ZBG based derivatives and other ZBG-derived compounds, and their enzymatic inhibitory activity, selectivity and other biological activities are introduced and summarized.

Recent Research Advances in Selective Matrix Metalloproteinase-13 Inhibitors as Anti-Osteoarthritis Agents.

Matrix metalloproteinase-13 (MMP-13) plays a key role in the degradation of type II collagen in cartilage and bone in osteoarthritis (OA). The subtle differences between the S1' loop of MMP-13 and that of other MMPs offer a structural base for the design of selective MMP-13 inhibitors to mitigate the unperceived risk associated with inhibiting other MMP isoforms. In this review, we summarize zinc-binding and non-zinc-binding selective MMP-13 inhibitors. The zinc-binding MMP-13 inhibitors contain a small set of zinc-binding groups (ZBGs), including hydroxamic acid, pyrimidinetrione, reversed hydroxamic acid and hydantoin, carboxylic acid, 1,2,4,-triazole, and 1,2,4,-triazolone. The non-zinc-binding MMP-13 inhibitors have different structural scaffolds, including diphenyl ethers, biaryls (aryltetrazoliums, arylfurans, pyrazole-indoles), pyrimidines, and aryl/cycloalkyl-fused pyrimidines. This review provides a systematic overview of recent developments in MMP-13 inhibitors for the treatment of OA, with emphasis on their enzyme inhibitory potency, selectivity, and biological activities, and highlights the various binding modes of typical inhibitors with MMP-13.

Studies on pharmacokinetics and bioavailability of aminophylline in partridge chickens.

Veterinary medicine plays a significant role in the development of animal husbandry. Drugs residual in food would follow the food-chain coming into human body, which might bring hidden dangers to people. Chicken is the prime source of meat food, whose quality is important for our life and health. Therefore, it is necessary to realize the withdrawal period and establish an efficient, sensitive and accurate method for monitoring the metabolic process of drugs in chicken body. In this paper, the pharmacokinetics of aminophylline in partridge chicken after intravenous and oral administration was investigated using a sensitive high-performance liquid chromatography method. Plasma concentration-time profiles of aminophylline were analyzed by a non-compartmental model using Topfit 2.0. Following intravenous and oral administration, the peak concentrations (C max) were found to be (16.5 ± 3.0) µg/mL at (0.08 ± 0) h and (7.4 ± 1.5) µg/mL at (1.83 ± 1.11) h, respectively. The elimination half-time (t 1/2) after intravenous and oral administration were, respectively, (13.1 ± 4.17) h and (11.65 ± 1.14) h. Areas under the plasma concentration-time curve (AUC) were (209.6 ± 22.8) µg h mL(-1)(AUC0-t ) and (219.5 ± 28.3) µg h mL(-1) (AUC0→∞ ) after intravenous, and (165.1 ± 37.0) µg h mL(-1)(AUC0-t ) and (179.3 ± 35.6) µg h mL(-1) (AUC0→∞ ) after oral administration. Mean retention time (MRT) after intravenous and oral administration were, respectively, (14.06 ± 0.86) and (15.27 ± 0.62) h. The total clearance rates (CLtol) were (0.77 ± 0.10) mL min(-1) kg(-1) of intravenous and (0.97 ± 0.20) mL min(-1) kg(-1) of oral administration. The apparent distribution volume (V d) was (0.87 ± 0.27) and (0.97 ± 0.20) L kg(-1), respectively, for intravenous and oral administration. The absolute bioavailability (F) after oral administration was (83.1 ± 11.7) %. The results showed that aminophylline in partridge chickens had a longer elimination half-time, a smaller clearance rate, as well as a higher absolute bioavailability for oral administration. Therefore, aminophylline in partridge chickens produced a long healing efficacy and oral administration can achieve a good absorption which could meet the requirement.

Developments of DNA-dependent Protein Kinase Inhibitors as Anticancer Agents.

Repair of DNA double-strand breaks (DSBs) is critical for the maintenance of genome integrity, cell survival, and prevention tumorigenesis. Three pathways are responsible for the repair of DNA DSBs: homologous recombination (HR), single strand annealing (SSA) and non-homologous end joining (NHEJ). DNA-dependent Protein Kinase (DNA-PK), the key component of the NHEJ pathway, becomes an important target for cancer therapy. A large number of small molecules exhibit inhibitory activities against DNA-PK in an ATP-competitive manner. This paper reviews the recent developments of a diversity of small molecule DNA-PK inhibitors, with emphasis on their structural features, biological activities, and structure-activity relationships (SARs).

Developments of kinesin spindle protein inhibitors as antitumor agents based on the five-membered heterocycle scaffolds.

Kinesin spindle protein (KSP) plays an essential role in centrosome separation and formation of the bipolar mitotic spindle. Its exclusive involvement in the mitotic spindle of proliferating cells presents an opportunity for developing new anticancer agents with reduced side effects relative to antimitotics that target tubulin. Small molecule KSP inhibitors have demonstrated their potential as novel antimitotic agents. Several KSP inhibitors have progressed into clinical trials and many others are in preclinical developments. Recently, KSP inhibitors of wide structural diversity have appeared in literatures. This review will summarize the developments of KSP inhibitors based on the five-membered heterocycle scaffolds in recent 10 years. These small molecule KSP inhibitors were classified as dihydropyrazoles, dihydropyrroles, thiophenes, dihydrothiadiazoles, thiazoles and fused pyrroles, their structure-activity relationships were discussed.

Highly efficient expression of interleukin-2 under the control of rabbit ß-globin intron II gene enhances protective immune responses of porcine reproductive and respiratory syndrome (PRRS) DNA vaccine in pigs.

Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) had caused catastrophic losses in swine industry in China. The current inactivated vaccine provided only limited protection, and the attenuated live vaccine could protect piglets against the HP-PRRSV but there was a possibility that the attenuated virus returned to high virulence. In this study, the eukaryotic expression vector pVAX1© was modified under the control of rabbit ß-globin intron II gene and the modified vector pMVAX1© was constructed. Porcine interleukin-2 (IL-2) and GP3-GP5 fusion protein of HP-PRRSV strain SD-JN were highly expressed by pMVAX1©. Mice inoculated with pMVAX1©-GP35 developed significantly higher PRRSV-specific antibody responses and T cell proliferation than those vaccinated with pVAX1©-GP35. pMVAX1©-GP35 was selected as PRRS DNA vaccine candidate and co-administrated with pVAX1©-IL-2 or pMVAX1©-IL-2 in pigs. pMVAX1©-IL-2+pMVAX1©-GP35 could provide enhanced PRRSV-specific antibody responses, T cell proliferation, Th1-type and Th2-type cytokine responses and CTL responses than pMVAX1©-GP35 and pVAX1©-IL-2+pMVAX1©-GP35. Following homologous challenge with HP-PRRSV strain SD-JN, similar with attenuated PRRS vaccine group, pigs inoculated with pMVAX1©-IL-2+pMVAX1©-GP35 showed no clinical signs, almost no lung lesions and no viremia, as compared to those in pMVAX1©-GP35 and pVAX1©-IL-2+pMVAX1©-GP35 groups. It indicated that pMVAX1©-IL-2 effectively increases humoral and cell mediated immune responses of pMVAX1©-GP35. Co-administration of pMVAX1©-IL-2 and pMVAX1©-GP35 might be attractive candidate vaccines for preventing HP-PRRSV infections.

Recent developments of 19-nor-1,25-dihydroxyvitamin D3 analogues.

The vitamin D hormone, 1α,25-dihydroxyvitamin D3 [1,25-(OH)2 D3 ], exerts its hormonal effects predominantly on intestine, bone, and kidney, where it plays a crucial role in calcium and phosphorus homeostasis and bone mineralization. In addition to its classical actions, 1,25(OH)2 D3 exerts pleiotropic effects in a wide variety of target tissues and cell types, often in an autocrine/paracrine fashion. These biological activities of 1,25(OH)2 D3 have suggested a multitude of potential therapeutic applications for the vitamin D hormone in the treatment of hyperproliferative disorders (e.g. cancer and psoriasis), immune dysfunction (autoimmune diseases), and endocrine disorders (e.g. hyperparathyroidism). However, the calcemic effects induced by 1,25(OH)2 D3--hypercalcemia, increased bone resorption, and soft tissue calcification--limit the use of the natural ligand in these clinical applications. Therefore, numerous 1,25(OH)2 D3 analogues have been synthesized with the intent of producing therapeutic agents devoid of hypercalcemic and hyperphosphatemic side effects. To this aim, much attention has been focused on the development of 19-nor-vitamin D3 derivatives that lack the ring-A exocyclic methylene group (C19). In this review, the 19-nor-1,25(OH)2 D3 analogues are classified according to modifications made at the A-ring, the side chain, or both the A-ring and side chain, as well as other positions. The biological activities of these 19-nor-1,25(OH)2 D3 analogues are summarized and their structure-activity relationships and binding features with the vitamin D receptor (VDR) are discussed.

Recent developments of small molecule PI3K/mTOR dual inhibitors.

The phosphoinositide 3-kinases (PI3Ks) are lipid kinases that play a central role in control of cell growth, proliferation, migration, survival and angiogenesis, and drive the progression of tumors by activating phosphoinositidedependent kinase, protein kinase B (Akt) and the mammalian target of rapamycin (mTOR). The PI3K/Akt/mTOR pathway has been shown to play an important role in cancer and has become an important target for anticancer drug development. An interest in targeting two important points along this critical signaling pathway has spurred the development of dual PI3K/mTOR inhibitors that could both prevent cancer cell proliferation and induce programmed cell death (apoptosis) by fully suppressing Akt activation. This review summarizes the developments of a diversity of small molecule dual PI3K/mTOR inhibitors in recent 10 years, with an emphasis on their structural features, the relevant biological activities, and the structure-activity relationships (SARs).