Ge-Regulated Ordered Phase in Pseudosphere-Structured LiNi0.5Mn1.5O4 Spinel Effectively Inhibits Mn Dissolution.

Due to the higher energy density, high thermal stability, and low cost, LiNi0.5Mn1.5O4 (LNMO) spinel, with a large voltage operating window, has been one of the most promising cathode materials for lithium-ion batteries (LIBs). However, the interfacial reaction between the cathode and electrolyte and the two-phase reaction within the bulk of LNMO would destroy the original structure and lead to capacity deterioration, posing a significant challenge. Therefore, the way to suppress the transition-metal (TM) dissolution in LNMO has attracted much attention. However, the ordered/disordered phase regulation by metal atom doping to prohibit TM dissolution has not been extensively explored. Herein, a Ge-doping strategy is proposed to adjust the ratio of disordered/ordered phases in LNMO, resulting in exceptional structural stability. For the modified spinel cathode, there is almost no voltage drop and the capacity retention is up to 92.2% over 1000 cycles at 1C. These results demonstrate that incorporating Ge into LNMO forms a robust structure that effectively increases the amount of Mn4+ while blocking the diffusion of TM ions. In addition, Ge-doping also protects the bulk from further reactions with electrolytes, significantly enhancing the interfacial stability and relieving voltage decay in cycling. This approach can also be applied to design other high-stability cathodes through ordered/disordered phase regulation.

Regulating effect of ß-ketoacyl synthase domain of fatty acid synthase on fatty acyl chain length in de novo fatty acid synthesis.

Fatty acid synthase (FAS) is a multifunctional homodimeric protein, and is the key enzyme required for the anabolic conversion of dietary carbohydrates to fatty acids. FAS synthesizes long-chain fatty acids from three substrates: acetyl-CoA as a primer, malonyl-CoA as a 2 carbon donor, and NADPH for reduction. The entire reaction is composed of numerous sequential steps, each catalyzed by a specific functional domain of the enzyme. FAS comprises seven different functional domains, among which the ß-ketoacyl synthase (KS) domain carries out the key condensation reaction to elongate the length of fatty acid chain. Acyl tail length controlled fatty acid synthesis in eukaryotes is a classic example of how a chain building multienzyme works. Different hypotheses have been put forward to explain how those sub-units of FAS are orchestrated to produce fatty acids with proper molecular weight. In the present study, molecular dynamic simulation based binding free energy calculation and access tunnels analysis showed that the C16 acyl tail fatty acid, the major product of FAS, fits to the active site on KS domain better than any other substrates. These simulations supported a new hypothesis about the mechanism of fatty acid production ratio: the geometric shape of active site on KS domain might play a determinate role.

Potent Inhibitory Effect of Chinese Dietary Spices on Fatty Acid Synthase.

Dietary spices have been adopted in cooking since ancient times to enhance flavor and also as food preservatives and disease remedies. In China, the use of spices and other aromatic plants as food flavoring is an integral part of dietary behavior, but relatively little is known about their functions. Fatty acid synthase (FAS) has been recognized as a remedy target, and its inhibitors might be applied in disease treatment. The present work was designed to assess the inhibitory activities on FAS of spices extracts in Chinese menu. The in vitro inhibitory activities on FAS of 22 extracts of spices were assessed by spectrophotometrically monitoring oxidation of NADPH at 340 nm. Results showed that 20 spices extracts (90.9 %) exhibited inhibitory activities on FAS, with half inhibition concentration (IC(50)) values ranging from 1.72 to 810.7 µg/ml. Among them, seven spices showed strong inhibitory effect with IC(50) values lower than 10 µg/ml. These findings suggest that a large proportion of the dietary spices studied possess promising inhibitory activities on FAS, and subsequently might be applied in the treatment of obesity and obesity-related human diseases.

Inhibitory effects of tannic acid on fatty acid synthase and 3T3-L1 preadipocyte.

Tannic acid is a hydrolyzable tannin that exists in many widespread edible plants with a variety of biological activities. In this study, we found that tannic acid potently inhibited the activity of fatty acid synthase (FAS) in a concentration-dependent manner with a half-inhibitory concentration value (IC50) of 0.14 microM. The inhibition kinetic results showed that the inhibition of FAS by tannic acid was mixed competitive and noncompetitive manner with respect to acetyl-CoA and malonyl-CoA, but uncompetitive to NADPH. Tannic acid prevented the differentiation of 3T3-L1 pre-adipocytes, and thus repressed intracellular lipid accumulation. In the meantime, tannic acid decreased the expression of FAS and down-regulated the mRNA level of FAS and PPARgamma during adipocyte differentiation. Further studies showed that the inhibitory effect of tannic acid did not relate to FAS non-specific sedimentation. Since FAS was believed to be a therapeutic target of obesity, these findings suggested that tannic acid was considered having potential in the prevention of obesity.

Alpha-mangostin inhibits intracellular fatty acid synthase and induces apoptosis in breast cancer cells.

BACKGROUND: Fatty acid synthase (FAS) has been proven over-expressed in human breast cancer cells and consequently, has been recognized as a target for breast cancer treatment. Alpha-mangostin, a natural xanthone found in mangosteen pericarp, has a variety of biological activities, including anti-cancer effect. In our previous study, alpha-mangostin had been found both fast-binding and slow-binding inhibitions to FAS in vitro. This study was designed to investigate the activity of alpha-mangostin on intracellular FAS activity in FAS over-expressed human breast cancer cells, and to testify whether the anti-cancer activity of alpha-mangostin may be related to its inhibitory effect on FAS. METHODS: We evaluated the cytotoxicity of alpha-mangostin in human breast cancer MCF-7 and MDA-MB-231 cells. Intracellular FAS activity was measured by a spectrophotometer at 340 nm of NADPH absorption. Cell Counting Kit assay was used to test the cell viability. Immunoblot analysis was performed to detect FAS expression level, intracellular fatty acid accumulation and cell signaling (FAK, ERK1/2 and AKT). Apoptotic effects were detected by flow cytometry and immunoblot analysis of PARP, Bax and Bcl-2. Small interfering RNA was used to down-regulate FAS expression and/or activity. RESULTS: Alpha-mangostin could effectively suppress FAS expression and inhibit intracellular FAS activity, and result in decrease of intracellular fatty acid accumulation. It could also reduce cell viability, induce apoptosis in human breast cancer cells, increase in the levels of the PARP cleavage product, and attenuate the balance between anti-apoptotic and pro-apoptotic proteins of the Bcl-2 family. Moreover, alpha-mangostin inhibited the phosphorylation of FAK. However, the active forms of AKT, and ERK1/2 proteins were not involved in the changes of FAS expression induced by alpha-mangostin. CONCLUSIONS: Alpha-mangostin induced breast cancer cell apoptosis by inhibiting FAS, which provide a basis for the development of xanthone as an agent for breast cancer therapy.

Inhibitory effects of grape skin extract and resveratrol on fatty acid synthase.

BACKGROUND: Grape skin, a rich source of phytochemicals, has been reported to possess remarkable anti-obesity activity. Fatty acid synthase (FAS) is a key enzyme catalyzing the synthesis of fatty acid de novo, and has been considered as an anti-obesity target. To elucidate the anti-obesity mechanism of grape skin, we investigated the effects of grape skin extract (GSE) and resveratrol, one of the phytochemicals in GSE, on FAS and FAS over-expressed 3 T3-L1 preadipocyte. METHODS: Purified FAS was obtained from chicken liver. Dried grape skin was extracted by 50% ethanol and partitioned by ethyl acetate. Inhibitory effects of GSE and resveratrol on FAS including fast-binding inhibition, time-dependent inhibition, and enzyme kinetics were determined. Inhibitory effects of GSE and resveratrol on 3T3-L1 preadipocyte were also measured. RESULTS: GSE inhibited the overall reaction and ß-ketoacyl reductase (KR) reaction of FAS with IC50 values of 4.61 µg/ml and 20.3 µg/ml. For inhibition by resveratrol, the relevant IC50 values were 11.1 µg/ml and 21.9 µg/ml, respectively. And both GSE and resveratrol showed time-dependent inhibition for FAS, with the kobs values of 0.028 min-1, and 0.040 min-1 respectively. They inhibited the overall reaction of FAS competitively with acetyl-CoA, noncompetitively with malonyl-CoA and in a mixed manner with NADPH. Moreover, the inhibition on KR domain by resveratrol was time-dependent with kobs value of 0.106 min-1. In 3 T3-L1 preadipocytes, resveratrol reduced lipid accumulation remarkably. CONCLUSIONS: GSE and resveratrol are potent FAS inhibitors and they bound reversibly to the KR domain of FAS to inhibit the reduction of the saturated acyl groups in fatty acid synthesis. Based on the valid data and deliberate analysis, we proposed that GSE and resveratrol have great medical potential and officinal value in treating obesity and related diseases.

Surface Engineering and Trace Cobalt Doping Suppress Overall Li/Ni Mixing of Li-rich Mn-based Cathode Materials.

To supress Li/Ni mixing, the strategy of surface modification and Co doping is proposed. Doping trace Co can suppress Li/Ni mixing in the bulk phase of cathode particles, while the rock-salt shell of a cathode originally containing a large amount of Li/Ni mixed rows can be transformed into a cation-ordered spinel phase and a layered phase on the inside by means of surface engineering. Simultaneously, as a coating layer, the Li2MoO4 nanolayer forms on the surface. With the improved Li-ion diffusion, certain inhibitory effects on voltage attenuation and capacity loss are found. It shows that the surface modification with trace Co dopants greatly reduces the Li/Ni mixing level in the material, beneficial to improving the electrochemical performance. As expected, the Li-rich Mn-based cathode material with a low level of overall Li/Ni mixing shows an initial discharging capacity of 303 mAh g-1. This indicates that the joint application of doping and surface coating effectively enhances the performance of the cathode materials with an ultra-low dosage of Co. This idea is helpful to structure other layered cathode materials by surface engineering.

Compressive Mechanical Properties and Shock-Induced Reaction Behavior of Zr/PTFE and Ti/PTFE Reactive Materials.

Existing research on PTFE-based reactive materials (RMs) mostly focuses on Al/PTFE RMs. To explore further possibilities of formulation, the reactive metal components in the RMs can be replaced. In this paper, Zr/PTFE and Ti/PTFE RMs were prepared by cold isostatic pressing and vacuum sintering. The static and dynamic compressive mechanical properties of Zr/PTFE and Ti/PTFE RMs were investigated at different strain rates. The results show that the introduction of zirconium powder and titanium powder can increase the strength of the material under dynamic loading. Meanwhile, a modified J-C model considering strain and strain rate coupling was proposed. The parameters of the modified J-C model of Zr/PTFE and Ti/PTFE RMs were determined, which can describe and predict plastic flow stress. To characterize the impact-induced reaction behavior of Zr/PTFE and Ti/PTFE RMs, a quasi-sealed test chamber was used to measure the over-pressure induced by the exothermic reaction. The energy release characteristics of both materials were more intense under the higher impact.

Substrate-induced changes in protease active site conformation impact on subsequent reactions with substrates.

Enzymatic catalysis of biochemical reactions is essential to all living systems. The "lock and key" and "induced fit" models were early contributions to our understanding of the mechanisms involved in the reaction between an enzyme and its substrate. However, whether a given substrate-induced conformation is rigid or remains flexible has not yet been determined. By measuring the enzyme activity and intrinsic fluorescence of a nonspecific Eisenia fetida protease-I with different chromogenic substrates, we show that in subsequent reactions of protease with substrates, both the "lock and key" and "induced fit" mechanisms are used depending on the degree of conformational change required. Chromozym-Th- or chromosym-Ch-induced protease conformations were unable to bind chromozym-U. The chromosym-U-induced protease conformation remained flexible and could be further induced by chromozym-Th and chromozym-Ch. When low concentrations of guanidine HCl were used to disturb the conformation of the enzyme, only small changes in intrinsic fluorescence of the chromozym-Th-induced protease were detected, in contrast to the native enzyme whose intrinsic fluorescence markedly increased. This indicates that the substrate-induced enzyme was relatively rigid compared with the native protease. Utilizing a lock and key mechanism for secondary substrate reactions may have adaptive value in that it facilitates high efficiency in enzymatic reactions.

Suppression of fatty acid synthase, differentiation and lipid accumulation in adipocytes by curcumin.

Curcumin is a well-known component of the cook seasoning and traditional herb turmeric (Curcuma longa), which has been reported to prevent obesity. However, the mechanism still remains to be determined. In this study, curcumin is found to be an effective inhibitor of fatty acid synthase (FAS), and its effects on adipocytes are further evaluated. Curcumin shows both fast-binding and slow-binding inhibitions to FAS. Curcumin inhibits FAS with an IC50 value of 26.8 µM, noncompetitively with respect to NADPH, and partially competitively against both substrates acetyl-CoA and malonyl-CoA. This suggests that the malonyl/acetyl transferase domain of FAS possibly is the main target of curcumin. The time-dependent inactivation shows that curcumin inactivates FAS with two-step irreversible inhibition, a specific reversible binding followed by an irreversible modification by curcumin. Like other classic FAS inhibitors, curcumin prevents the differentiation of 3T3-L1 cells, and thus represses lipid accumulation. In the meantime, curcumin decreases the expression of FAS, down-regulates the mRNA level of PPARγ and CD36 during adipocyte differentiation. Curcumin is reported here as a novel FAS inhibitor, and it suppresses adipocyte differentiation and lipid accumulation, which is associated with its inhibition of FAS. Hence, curcumin is considered to be having potential application in the prevention of obesity.

Evaluation of inhibition of fatty acid synthase by ursolic acid: positive cooperation mechanism.

The inhibitory effect of ursolic acid (UA) on fatty acid synthase (FAS, EC 2.3.1.85) was investigated. We found that UA potently inhibited the activity of FAS with a half-inhibitory concentration value (IC(50)) of 6.0 microg/ml. The inhibition kinetic results showed that the inhibition of FAS by UA was competitive against acetyl-CoA and malonyl-CoA, but uncompetitive to NADPH. UA at low concentration slowly inactivated FAS, but FAS was fast inactivated by high concentration of UA in a positive cooperative manner. Moreover, NADPH significantly enhanced the inactivation of FAS by low concentration of UA, but NADPH slightly decreased the inactivation of FAS by high concentration of UA. Taken together, the results suggest that ursolic acid decreases the FAS activity through inactivation of acetyl/malonyl transferase. The combination of NADPH and KR domain promotes the inhibitory effect of UA on FAS.

Inhibitory effects of thioethers on fatty acid synthase and 3T3-L1 cells.

Thioethers are the main flavor compounds found in Liliaceae Allium vegetables and have been shown to have beneficial effects against several diseases correlated with metabolic syndrome. The inhibitory effects of six thioethers on fatty acid synthase (FAS) were investigated. Dose-dependent and time-dependent inhibitions of FAS by one trisulfide and two disulfides were revealed. Diallyl trisulfide (DATS, IC(50) = 8.37 microM) was the most active of these thioethers. Inhibition kinetics, substrate protection analysis, and stoichiometric assay revealed that DATS interacted with both essential sulfhydryl groups on the acyl-carrier protein and beta-ketoacyl synthase domain of FAS to inactivate the enzyme. The inactivation by DATS represented affinity-labeling kinetics. The active thioethers also inhibited the differentiation and lipid accumulation of 3T3-L1 preadipocytes, and the effect was related to their inhibition of FAS. It is suggested that the inhibition on FAS by thioethers and Allium vegetables is an important factor for their effects against metabolic syndrome.

Inhibitory effects on bacterial growth and beta-ketoacyl-ACP reductase by different species of maple leaf extracts and tannic acid.

It is important to develop new antibiotics aimed at novel targets. The investigation found that the leaf extracts from five maples (Acer platanoides, Acer campestre, Acer rubrum, Acer saccharum and Acer truncatum Bunge collected in Denmark, Canada and China) and their component tannic acid displayed antibacterial ability against 24 standard bacteria strains with the minimum inhibitory concentration of 0.3-8.0 mg/mL. Unlike the standard antibiotic levofloxacin (LFX), these samples inhibited Gram-positive bacteria more effectively than they inhibited Gram-negative bacteria. These samples effectively inhibited two antidrug bacterial strains. The results show that these samples inhibit bacteria by a different mechanism from LFX. These samples potently inhibited b-ketoacyl-ACP reductase (FabG), which is an important enzyme in bacterial fatty acid synthesis. Tannic acid showed the strongest inhibition on FabG with a half inhibition concentration of 0.78 microM (0.81 microg/mL). Furthermore, tannic acid and two maple leaf extracts showed time-dependent irreversible inhibition of FabG. These three samples also exhibited better inhibition on bacteria. It is suggested that FabG is the antibacteria target of maple leaf extracts and tannic acid, and both reversible and irreversible inhibitions of FabG are important for the antibacterial effect.

Novel and potent inhibitors of fatty acid synthase derived from catechins and their inhibition on MCF-7 cells.

Fatty acid synthase (FAS) is a potential target for cancer, but potent inhibitors against FAS are scarce. In this study, we found that activities of catechins on inhibiting FAS increased greatly by heating them in acid. The enhancement was positively correlated to H(+) concentration. The inhibitory activities of the final products from different catechins were similar, all of which were less than 1 microg/mL. The product from (-)-epigallocatechin gallate (EGCG) was stable at room temperature, and its inhibitory kinetics and reacting sites on FAS were obviously different from the known FAS inhibitors. It also affected the viability of MCF-7 cells more obviously than EGCG. A putative route of the reaction progress was proposed and the effective inhibitors were deduced to be oligomers of 2-hydroxy-3-(3', 4', 5'-trihydroxyphenyl) propenoic acid by analysis of their spectra. The work affords new and potent FAS inhibitors that would be promising candidates for the treatment of cancer.

Low concentration of condensed tannins from catechu significantly inhibits fatty acid synthase and growth of MCF-7 cells.

Tannins exist widely in plants, but because they precipitate proteins, scientists frequently ignore them in search of bioactive components. Catechu, a traditional astringent, is rich in tannins. In this study, we found that condensed tannins from catechu potently inhibited animal fatty acid synthase (FAS). Among them, trimeric condensed tannin showed the most potent inhibition with IC(50) of 0.47 microg/ml and it also exhibited strong time-dependent inhibition. Its inhibitory kinetics and reacting sites on FAS were obviously different from the known inhibitors of FAS. Furthermore, condensed tannins were found to suppress the growth of MCF-7 breast cancer cells, and the effect was related to their activity of FAS inhibition. The inhibition of both FAS activity and MCF-7 growth was exhibited by low concentrations of condensed tannins without FAS being precipitated. These results suggest tannins would be a valuable resource of bioactive substances.

Inhibitory effect of green tea extract and (-)-epigallocatechin-3-gallate on mammalian thioredoxin reductase and HeLa cell viability.

Mammalian cytosolic thioredoxin reductase (TrxR1) is an attractive target for developing cancer chemopreventive agents since its inhibition is associated with a reduced growth of cancer cells. However, the known inhibitors of this enzyme mostly have a toxic effect on human health. We report on a non-toxic inhibitor, green tea. TrxR1 was found to be inhibited by green tea extracts (Gte) with an IC50 value of 256 microg/ml. Catechins, the major components of Gte, showed various inhibitory effects, in which (-)-epigallocatechin-3-gallate (EGCG) exhibited a stronger inhibition than any other catechins tested. The inhibition of TrxR1 by EGCG was close to competitive (Ki = 64 microM) with substrate DTNB and was non-competitive (Ki = 92 microM) with co-enzyme NADPH. The preincubation of TrxR1 with EGCG led to irreversible enzyme inactivation in a time-dependent manner, which was highly effective in the presence of NADPH. The inactivation included an equilibrium step used to form a reversible TrxR1-EGCG complex (EI) (dissociation constant Ki* = 43 microM), and an isomerization step used to form an irreversible complex (E*I) (rate constant k3 = 4.8 x 10(-3) s(-1)). We have identified thiol/selenol groups in the active site as reactive sites that mediated TrxR1 inhibition by EGCG. When cultured HeLa cells were treated with Gte or EGCG for 22-24 h, TrxR1 activity in cell extracts was significantly inhibited, accompanied by a reduction of cell viability in a concentration-dependent manner (IC50 = 40 microg/ml for Gte and 107 microM for EGCG). The inactivation of TrxR1 by Gte/EGCG is most likely linked to a reduction of HeLa cell viability.

The antibacterial efficacy of an aceraceous plant [Shantung maple (Acer truncatum Bunge)] may be related to inhibition of bacterial beta-oxoacyl-acyl carrier protein reductase (FabG).

Polyphenols, including flavonoids, are the major components of the extracts from aceraceous plants. They possess remarkable antibacterial and antitumour activity. Our study focused on whether the inhibition of the bacterial type II fatty acid synthesis system is the mechanism for the antibacterial effect of the related plant polyphenols. Extracts obtained from the fallen leaves of the Shantung maple (Acer truncatum Bunge) using different solvents, and the related pure compound PGG (1,2,3,4,6-penta-O-galloyl-beta-D-glucose), potently inhibited the FabG (beta-oxoacyl-ACP reductase) steps in the fatty-acid-elongation cycle with the IC(50) values between 0.9 and 7.2 microg/ml. An ethyl acetate extract appeared to inhibit FabG reductase in a mixed manner with NADPH, as did PGG with NADPH, demonstrating that they interfered with the binding of the cofactor to the enzyme. Gram-positive and Gram-negative bacteria and some fungi were used to evaluate the antibacterial abilities of different extract samples. The experiments showed that a higher polyphenol content of the extracts led to a more potent inhibitory capacity against FabG, thus enhancing the antibacterial efficacy.

A substitutive substrate for measurements of beta-ketoacyl reductases in two fatty acid synthase systems.

Bacterial beta-ketoacyl-ACP reductase (FabG) and the beta-ketoacyl reductase domain in mammalian fatty acid synthase (FAS) have the same function and both are rendered as the novel targets for drugs. Herein we developed a convenient method, using an available compound ethyl acetoacetate (EAA) as the substitutive substrate, to measure their activities by monitoring decrease of NADPH absorbance at 340 nm. In addition to the result, ethyl 3-hydroxybutyrate (EHB) was detected by HPLC analysis in the reaction system, indicating that EAA worked effectively as the substrate of FabG and FAS since its beta-keto group was reduced. Then, the detailed kinetic characteristics, such as optimal ionic strength, pH value and temperature, and kinetic parameters, for FabG and FAS with this substitutive substrate were determined. The Km and kcat values of FabG obtained for EAA were 127 mM and 0.30 s(-1), while those of this enzyme for NADPH were 10.0 microM and 0.59 s(-1), respectively. The corresponding Km and kcat values of FAS were 126 mM and 4.63 s(-1) for EAA; 8.7 microM and 4.09 s(-1) for NADPH. Additionally, the inhibitory kinetics of FabG and FAS, by a known inhibitor EGCG, was also studied.

Antimicrobial effect by extracts of rhizome of Alpinia officinarum Hance may relate to its inhibition of beta-ketoacyl-ACP reductase.

Inhibitory effects on bacterial growth showed that 40% ethanol extract of galangal (rhizome of Alpinia officinarum Hance) can inhibit Staphylococcus aureus, alpha-Hemolytic streptococcus, beta-Hemolytic streptococcus and Streptococcus pneumoniae. beta-ketoacyl-ACP reductase (FabG, EC.1.1.1.100) is a key enzyme in type II fatty acid synthase system in bacteria and catalyzes beta-ketoacyl-ACP reduction. The galangal extracts inhibited FabG with an IC(50) value of only 4.47 +/- 0.10 microg/mL and is more potent than other previously published inhibitors. Kinetics studies showed that the inhibition consisted of both reversible and irreversible inhibition. The extracts of galangal inhibit FabG in a competitive pattern against NADPH. So far, no inhibitor has been reported to exhibit irreversible inhibition of FabG, whereas the galangal ethanol extract can inhibit FabG irreversibly. The irreversible inhibition presented two phases. It is probable that the galangal extract inhibit FabG, thereby displaying antibacterial ability.

Parasitic loranthus from Loranthaceae rather than Viscaceae potently inhibits fatty acid synthase and reduces body weight in mice.

AIM OF THE STUDY: Our previous results have shown one species of parasitic loranthus (Taxillus chinensis (DC.) Dancer) exhibits potent inhibition on fatty acid synthase (FAS) that is proposed to be a potential therapeutic target for treatment of obesity. However, the medicinal parasitic loranthus come from tens of plants of two families, the Loranthaceae and the Viscaceae. This study was carried out to figure out whether these parasitic loranthus from the two families have similar inhibitory ability on FAS, and whether the parasitic loranthus with potent inhibitory ability on FAS significantly reduce body weight of animal. MATERIALS AND METHODS: CD-1 mice were used to test the effects of samples on their body weight and food intake in 20 days. The reversible and irreversible inhibition on FAS was assayed to study the inhibitory ability of sixteen different medicinal plants from these two families, which were collected in nature. RESULTS: The reversible inhibitory ability of the extracts from the Loranthaceae was nearly 400-fold stronger than that from the Viscaceae. The species from the genus Taxillus Tieghem showed the best effect on FAS in both reversible and irreversible inhibition. Moreover, the difference in host plants did not affect markedly on the inhibitory ability of parasitic loranthus. The medicinal herb with high inhibitory ability on FAS significantly reduced the body weight and food intake of mice by oral administration. CONCLUSIONS: The medicinal herbs from the family Loranthaceae, rather than those from the family Viscaceae, should be suitable to apply as botanical sources of parasitic loranthus for weight control. The herbs from genus Taxillus Tieghem are the best.