Studies on Lignin

2-Ethylthio-1-(4-hydroxy-3-methoxyphenyl)-propanone-(1) (I) which has been previously isolated from mercaptolysis oil of pine ethanol lignin was also obtained from mercaptolysis oil of spruce wood. 1-Ethylthio-1-(4-hydroxy-3-methoxyphenyl)-propanone-(2) (II), synthesis of which has been reported before, was found to be converted into (I) on mercaptolysis.     

Diarylheptanoids from the rhizomes of Zingiber officinale

Seven new diarylheptanoids, i.e., (3S,5S)-3,5-diacetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptane, (3R,5S)-3-acetoxy-5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptane, (3R,5S)-3,5-dihydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)heptane, (5S)-5-acetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptan-3-one, 5-hydroxy-1-(3,4-dihydroxy-5-methoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)heptan-3-one, 5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-7-(3,4-dihydroxy-5-methoxy-phenyl)heptan-3-one and 1,5-epoxy-3-hydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)heptane were isolated from the rhizomes of Chinese ginger (Zingiber officinale Roscoe), along with 25 known compounds, i.e., 8 diarylheptanoids, 14 gingerol analogs, a diterpene and 2 steroids. Their structures were elucidated by spectroscopic and chemical methods.     

Studies on Lignin

In comparison with the ethanolysis, the mercaptolysis of pine wood and pine ethanol lignin has been studied. The delignification was found to be almost complete when wood powder was cooked with the ethanolic hydrogen chloride containing 10% of ethyl mercaptan; while the same cooking without the mercaptan caused only 50% of delignification. Addition of 2% of mercaptan resulted more than 90% of delignification. As already reported briefly, from the mercaptolysis oil of pine ethanol lignin, 2-ethoxy-1-(4-hydroxy-3-methoxyphenyl)-propanone- (1), a thioether corresponding to Hibbert’s α-ethoxypropiovanillone, was isolated.     

Lignans from machilus thunbergii

Five new lignans, machilin A[(2S,3R)-2,3-dimethyl-1,4-dipiperonyl-butane], machilin B [(2S,3S)-2,3-dihydro-7-methoxy-3-methyl-2-piperon threo-2-(2-methoxy-4-trans-propenylphenoxy)-1-(4-hydroxy-3-methoxyphenyl)propan-1-ol], machilin E (erythro-1-acetoxy-2-(2-methoxy-4-trans-(3-hydroxy-1-propenyl)phenoxy]-l-piperonylpropane) were isolated from the bark of Machilus thunbergii and their structures were characterized.     

马尾伸筋草化学成分及抗骨质疏松活性研究

为研究马尾伸筋草(Lycopodium fargesii Hert.)的化学成分及其抗骨质疏松活性,采用硅胶、MCI、RP-18、Sephadex LH-20柱色谱及半制备高效液相色谱对马尾伸筋草的乙醇提取物进行系统分离,从乙酸乙酯部位中得到18个化合物,综合利用NMR、HR-ESI-MS等技术,分析鉴定化合物的结构,分别鉴定为α-芒柄蜡素(1)、26-去甲-8-氧化-α-芒柄蜡素(2)、serrat-14-en-3β,21α,24-triol(3)、serrat-14-en-3β,21β,24-triol(4)、1,20-eicosanediol(5)、二十三烷(6)、glycerolmonolinoleate(7)、glyceryl linolentate(8)、3-(4′-formylphenoxy)-4-methoxybenzaldehyde(9)、芹菜素(10)、对羟基苯甲醛(11)、香草酸(12)、3-羟基-4-甲氧基苯甲酸(13)、2-羟基-1-(4-羟基-3-甲氧基-苯基)-丙基-1-酮(14)、3-甲氧基-4-羟基桂皮醛(15)、8-acetoxy-5-hydroxyumbelliprenin(16)、trans-4-hydroxy-2-nonenoic acid(17)和正十烷硫醇(18)。化合物1~18均为首次从马尾伸筋草中分离得到,其中化合物16对破骨细胞活性具有显著的抑制作用,其IC₅₀为1.98μM。     

New antioxidative phenolic glycosides isolated from Kokuto non-centrifuged cane sugar

Nine compounds, 3-hydroxy-4,5-dimethoxyphenyl-beta-D-glucopyranoside (1), beta-D-fructfuranosyl-alpha-D-(6-vanilloyl)-glucopyranoside (2), beta-D-fructfuranosyl-alpha-D-(6-syringyl)-glucopyranoside (3), 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxy-1-(E)-propenyl)-2-methoxyphenoxy]propyl-beta-D-glucopyranoside (4), 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxy-1-(E)-propenyl)-2,6-dimethoxyphenoxy] propyl-beta-D-glucopyranoside (5), dehydrodiconiferyl alcohol-9'-beta-D-glucopyranoside (6), 4-[ethane-2-[3-(4-hydroxy-3-methoxyphenyl)-2-propen]oxy]-2,6-dimethoxyphenyl-beta-D-glucopyranoside (7), 4-[ethane-2-[3-(4-hydroxy-3-methoxyphenyl)-2-propen]oxy]-2-methoxyphenyl-beta-D-glucopyranoside (8), and 3-hydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-2-[4-(3-hydroxy-1-(E)-propenyl)-2,6-dimethoxyphenoxy]propyl-beta-D-glucopyranoside (9), were isolated from Kokuto non-centrifuged cane sugar. Their structures were elucidated by spectroscopic evidence, mainly based on the NMR technique. Among them, seven new glycosides were identified. The 2-deoxyribose oxidation method was used to measure their antioxidative activity. All of these compounds showed antioxidative activities.     

Synthesis and antioxidant, anti-inflammatory and gastroprotector activities of anethole and related compounds

Some derivatives of trans-anethole [1-methoxy-4-(1-propenyl)-benzene] (1) were synthesized, by introducing hydroxyl groups in the double bond of the propenyl moiety. Two types of reactions were performed: (i) oxymercuration/demercuration that formed two products, the mono-hydroxyl derivative, 1-hydroxy-1-(4-methoxyphenyl)-propane (2) and in lesser extent the dihydroxyl derivative, 1,2-dihydroxy-1-(4-methoxyphenyl)-propane (3) and (ii) epoxidation with m-chloroperbenzoic acid that also led to the formation of two products, the dihydroxyl derivative (3) and the correspondent m-chloro-benzoic acid mono-ester, 1-hydroxy-1(4-methoxyphenyl)-2-m-chlorobenzoyl-propane (4). The structures of these compounds were confirmed mainly by mass, IR, 1H and 13C NMR spectral data. The activity of anethole and hydroxylated derivatives was evaluated using antioxidant, anti-inflammatory and gastroprotector tests. Compounds (2) and (3) were more active antioxidant agents than (1) and (4). In the anti-inflammatory assay, anethole showed lower activity than hydroxylated derivatives. Anethole and in lesser extent its derivatives 2 and 4 showed significant gastroprotector activity. All tested compounds do not alter significantly the total number of white blood cells.     

Phenolic constituents from the core of kenaf (Hibiscus cannabinus)

Four lignans, boehmenan H [2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxy-3-methoxycinnamoyloxy)propyl]-3-hydroxymethyl-7-methoxybenzodihydrofuran], boehmenan K [2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxycinnamoyloxy)-1-propenyl]-3-(4-hydroxy-3-methoxycinnamoyloxymethyl)-7-methoxybenzodihydrofuran], threo-carolignan H [threo-1-(4-hydroxy-3-methoxyphenyl)-2-[4-[3-(4-hydroxy-3-methoxycinnamoyloxy)propyl]-2-methoxyphenoxy]-1,3-propanodiol], and threo-carolignan K [threo-1-(4-hydroxy-3-methoxyphenyl)-3-(4-hydroxy-3-methoxycinnamoyloxy)-2-[4-[3-(4-hydroxycinnamoyloxy)-1-propenyl]-2-methoxyphenoxy]-1-propanol] as well as several other lignans, aldehydes and a tyramine derivative were isolated from the acetone extract of core of kenaf (Hibiscus cannabinus). All the structures were established by spectroscopic methods. The hitherto unreported 13C NMR spectra of some compounds are also presented and discussed. 2D NMR techniques have allowed the revision of certain previously reported 13C NMR assignments of some scarce naturally occurring compounds.     

Lignans of Larix leptolepis

Five lignans have been isolated from wood of Larix leptolepis. They are identified as 1-(4-hydroxy-3-methoxyphenyl)-2-4-[2-formyl-(E)-vinyl]-2-methoxyphenoxy-propane- 1,3-diol, 1-(4-hydroxy-3-methoxyphenyl)-2-2-methoxy-4-[1-(E)-propen-3-ol]-phenoxy- propane-1,3-diol, 1-(4-hydroxy-3-methoxyphenyl)-2-(4-formyl-2-methoxyphenoxy)-propane-1,3-diol, 1,2-bis-(4-hydroxy-3-methoxyphenyl)-propane-1,3-diol and a trilignol, leptolepisol C.     

柯拉斯那沉香中2-(2-苯乙基)色酮类化学成分研究

为研究柯拉斯那(Aquilaria crassna Pierre ex Lecomte)沉香的化学成分。实验采用多种柱色谱方法从该沉香中分离得到9个2-(2-苯乙基)色酮类化合物,通过现代波谱学技术分别鉴定为6-甲氧基-2-[2-(3′-羟基-4′-甲氧基苯基)乙基]色酮(1)、5-羟基-6-甲氧基-2-[2-(3′-羟基-4′-甲氧基苯基)乙基]色酮(2)、tetrahydrochromone F(3)、6-甲氧基-2-[2-(3′-甲氧基-4′-羟基苯基)乙基]色酮(4)、6-甲氧基-7-羟基-2-[2-(4′-甲氧基苯基)乙基]色酮(5)、6,7-二甲氧基-2-[2-(3′-羟基-4′-甲氧基苯基)乙基]色酮(6)、6,7-二甲氧基-2-[2-(4′-甲氧基苯基)乙基]色酮(7)、6-羟基-2-[2-(4′-羟基苯基)乙基]色酮(8)、5-羟基-2-[2-(2′-羟基苯基)乙基]色酮(9)。化合物2、3和5～9均为首次从柯拉斯那所得沉香中分离得到。采用MTT法对单体化合物的细胞毒活性进行测试,测试结果表明,化合物1,2和4具有微弱的细胞毒活性。     

Synthesis and biological evaluation of 4-hydroxy-4-(4-methoxyphenyl)-substituted proline and pyrrolidin-2-ylacetic acid derivatives as GABA uptake inhibitors

A series of enantiomerically pure 4-hydroxy-4-(4-methoxyphenyl)-substituted proline and pyrrolidin-2-ylacetic acid derivatives have been synthesized starting from the respective N-protected 4-hydroxy derivatives via oxidation to the corresponding 4-oxo compounds, subsequent addition of organometallic reagents, final hydrolysis and deprotection. The major diastereoisomers obtained by the addition of the Grignard reagents were found to have opposite stereoconfigurations depending on whether cerium trichloride was present or absent as an additive. The final compounds were evaluated for their capability to inhibit the GABA transport proteins GAT1 and GAT3. 4-Hydroxyproline derivatives substituted with a tris(4-methoxyphenyl)methyloxyethyl residue at the nitrogen and a 4-methoxyphenyl group in 4-position showed, with the exception of the (2R,4R)-diastereomer, an improved inhibition at GAT3 compared to the derivatives missing the 4-methoxyphenyl group in 4-position. This may imply that an appropriate lipophilic group at the C-4 position of the proline moiety is beneficial for potent inhibition at GAT3.     

Commercially processed dry ginger (Zingiber officinale): composition and effects on LPS-stimulated PGE2 production

Using techniques previously employed to identify ginger constituents in fresh organically grown Hawaiian white and yellow ginger varieties, partially purified fractions derived from the silica gel column chromatography and HPLC of a methylene chloride extract of commercially processed dry ginger, Zingiber officinale Roscoe, Zingiberaceae, which demonstrated remarkable anti-inflammatory activity, were investigated by gas chromatography-mass spectrometry. In all, 115 compounds were identified, 88 with retention times (R(t)) >21 min and 27 with <21 min. Of those 88 compounds, 45 were previously reported by us from fresh ginger, 12 are cited elsewhere in the literature and the rest (31) are new: methyl [8]-paradol, methyl [6]-isogingerol, methyl [4]-shogaol, [6]-isoshogaol, two 6-hydroxy-[n]-shogaols (n=8 and 10), 6-dehydro-[6]-gingerol, three 5-methoxy-[n]-gingerols (n=4, 8 and 10), 3-acetoxy-[4]-gingerdiol, 5-acetoxy-[6]-gingerdiol (stereoisomer), diacetoxy-[8]-gingerdiol, methyl diacetoxy-[8]-gingerdiol, 6-(4'-hydroxy-3'-methoxyphenyl)-2-nonyl-2-hydroxytetrahydropyran, 3-acetoxydihydro-[6]-paradol methyl ether, 1-(4'-hydroxy-3'-methoxyphenyl)-2-nonadecen-1-one and its methyl ether derivative, 1,7-bis-(4'-hydroxy-3'-methoxyphenyl)-5-methoxyheptan-3-one, 1,7-bis-(4'-hydroxy-3'-methoxyphenyl)-3-hydroxy-5-acetoxyheptane, acetoxy-3-dihydrodemethoxy-[6]-shogaol, 5-acetoxy-3-deoxy-[6]-gingerol, 1-hydroxy-[6]-paradol, (2E)-geranial acetals of [4]- and [6]-gingerdiols, (2Z)-neral acetal of [6]-gingerdiol, acetaldehyde acetal of [6]-gingerdiol, 1-(4-hydroxy-3-methoxyphenyl)-2,4-dehydro-6-decanone and the cyclic methyl orthoesters of [6]- and [10]-gingerdiols. Of the 27 R(t)<21 min compounds, we had found 5 from fresh ginger, 20 others were found elsewhere in the literature, and two are new: 5-(4'-hydroxy-3'-methoxyphenyl)-pent-2-en-1-al and 5-(4'-hydroxy-3'-methoxyphenyl)-3-hydroxy-1-pentanal. Most of the short R(t) compounds are probably formed by thermal degradation during GC (which mimics cooking) and/or commercial drying. The concentrations of gingerols, the major constituents of fresh ginger, were reduced slightly in dry ginger, while the concentrations of shogaols, the major gingerol dehydration products, increased.     

观光木酚性成分研究

从观光木(Tsoongiodendron odorum Chun)茎枝的80％乙醇提取物中分离得到11个酚性化合物,经波谱鉴定为:对羟基苯甲醛(1)、香草醛(2)、1,3,5-三甲氧基苯(3),丁香醛(4)、香草酸(5)、苏式-2,3-二-(4-羟基-3-甲氧基苯)-3-甲氧基丙醇(6)、赤式-2,3-二-(4-羟基-3-甲氧基苯)-3-甲氧基丙醇(7)、丁香酸(8)、3-羟基-1-(4-羟基-3,5-二甲氧基苯)-1-丙酮(9)、对羟基苯乙醇(10)和C-veratroylglycol( 11).其中,化合物1～4和6～ 11为首次从该植物中分离得到.     

隔山消化学成分的研究

从隔山消的石油醚部分分离得到6个芳香类化合物,分别鉴定为2,4-二羟基苯乙酮（1-（2,4-dihy—droxph—enyl）ethanone,1）、奎乙酰苯（acetylquinol,2）、对羟基苯乙酮（1-（4-hydroxyphenyl）ethanone,3）、4-羟基-3-甲氧基苯乙酮（1-（4-hydroxy-3-methoxyphenyl）ethanone,4）、2,4-二羟基-5-甲氧基苯乙酮（1-（2,4-dihydroxy-5-methoxyphenyl）ethanone,5）、3-羟基4-甲氧基苯甲酸（3-hydroxy-4-methoxy—benzoicacid,6）。除化合物2外,其余5个化合物均首次从该植物中分离得到。     

柬埔寨柯拉斯那沉香的化学成分研究

该文采用ODS、硅胶、Sephadex LH-20等柱色谱技术,对柬埔寨野生柯拉斯那沉香(Aquilaria crassna)进行了研究。结果表明:从柬埔寨柯拉斯那所产沉香的乙醇提取物中进行分离共得到了10个化合物,包括一对对映异构体(9a/9b)。经波谱解析分别鉴定为6-甲氧基-2-[2-(3-羟基-4-甲氧基苯)乙基]色酮(1)、6-甲氧基-2-[2-(3-甲氧基-4-羟基苯)乙基]色酮(2)、6,7-二甲氧基-2-(2-苯乙基)色酮(3)、6-羟基-2-(2-苯乙基)色酮(4)、6-羟基-2-[2-(4-甲氧基苯)乙基]色酮(5)、8-氯-6-羟基-2-[2-(3-羟基-4-甲氧基苯)乙基]色酮(6)、8-氯-6-羟基-2-[2-(4-甲氧基苯)乙基]色酮(7)、oxidoagarochromone B(8)、4'-demethoxyaqusisnenone D(9)。其中,化合物6、7和9均为首次从柯拉斯那沉香中分离得到。活性测试结果显示,化合物1和2对乙酰胆碱脂酶具有一定的抑制活性,化合物2对人慢性髓原白血病细胞K562具有较弱的抑制作用。     

Synthesis and preliminary evaluation of pharmacological properties of some piperazine derivatives of xanthone

A series of 9 piperazine derivatives of xanthone were synthesized and evaluated for cardiovascular activity. The following pharmacological experiments were conducted: the binding affinity for adrenoceptors, the influence on the normal electrocardiogram, the effect on the arterial blood pressure and prophylactic antiarrhythmic activity in adrenaline induced model of arrhythmia (rats, iv). Three compounds revealed nanomolar affinity for α₁-adrenoceptor which was correlated with the strongest cardiovascular (antiarrhythmic and hypotensive) activity in animals’ models. The most promising compound was 4-(3-(4-(2-methoxyphenyl)piperazine-1-yl)propoxy)-9H-xanthen-9-one hydrochloride (12) which revealed antiarrhythmic activity with ED₅₀ value of 0.69 mg/kg in adrenaline induced arrhythmia (rats, iv). Other synthesized xanthone derivatives, that is, (R,S)-4-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazine-1-yl)propoxy)-9H-xanthen-9-one hydrochloride (10) and (R,S)-4-(2-acetoxy-3-(4-(2-methoxyphenyl)piperazine-1-yl)propoxy)-9H-xanthen-9-one hydrochloride (11) also acted as potential antiarrhythmics in adrenaline induced model of arrhythmia in rats after intravenous injection (ED₅₀ = 0.88 mg/kg and 0.89 mg/kg, respectively). These values were lower than values obtained for reference drugs such as propranolol and urapidil, but not carvedilol.Results were quite promising and suggested that in the group of xanthone derivatives new potential antiarrhythmics and hypotensives might be found.     

Inhibition of lipid peroxidation and protein oxidation in rat liver mitochondria by curcumin and its analogues

Curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, 1) is a yellow ingredient isolated from turmeric (curcumin longa). It has been shown to exhibit a variety of biological activities including antioxidative activity. In order to find more active antioxidants with 1 as the lead compound we synthesized curcumin analogues, i.e., 1-(3,4-dihydroxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (2), 1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)-1,6-heptadiene-3,5-dione (3), 1,7-bis-(4-hydroxyphenyl)-1,6-heptadiene-3,5-dione (4), 1-(3,4-dimethoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (5), 1,7-bis(3,4-dimethoxyphenyl)-1,6-heptadiene-3,5-dione (6), and 1,7-diphenyl-1,6-heptadiene-3,5-dione (7), and evaluated their antioxidative activity. The in vitro oxidative damage to both lipids and proteins in rat liver mitochondria was used as a model to study the free radical-induced oxidative damage of biological lipids as well as proteins and the protective effects of these curcumin analogues. It was found that these compounds, except 6 and 7, could effectively inhibit the free radical induced lipid peroxidation and protein oxidative damage of rat liver mitochondria by H-atom abstraction from the phenolic groups. Compound 2 which bear ortho-diphenoxyl functionality exhibited remarkably higher antioxidative activity for lipids and proteins than curcumin and other analogues, and the 4-hydroxy-3-methoxyphenyl group also play an important role in the antioxidative activity.     

Determination of diarylheptanoids from Alpinia officinarum (Lesser Galangal) by HPLC with photodiode array and electrochemical detection

Normal-phase column chromatography followed by semi-preparative reversed-phase HPLC has been used to isolate, from the rhizomes of Alpinia officinarum, five diarylheptanoids identified as 5-hydroxy-7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-3-heptanone, 5-methoxy-7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-3-heptanone, 7-(4"-hydroxyphenyl)-1-phenylhept-4-en-3-one, 7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-hept-4-en-3-one, 1,7-diphenylhept-4-en-3-one. The levels of these five diarylheptanoids in root material were determined quantitatively by HPLC with UV detection and the assay methods so developed were simple, rapid and accurate. Four of the diarylheptanoids could also be detected by HPLC with electrochemical detection (ECD) in the oxidative mode, and ECD was found to have a higher sensitivity than photodiode array detection.     

Dilignol glycosides from needles of Picea abies

(2R,3R)-2 3-Dihydro-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-5-benzofuranpropanol 4′-O-β-d-glucopyranoside [dihydrodehydrodiconiferyl alcohol glucoside], (2R,3R)-2 3-dihydro-7-hydroxy-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-5-benzofuranpropanol 4′-O-β-d-glucopyranoside and 4′-O-α-l-rhamnopyranoside, 1-(4′-hydroxy-3′-methoxyphenyl)-2- [2″-hydroxy-4″-(3-hydroxypropyl)phenoxy]-1, 3-propanediol 1-O-β-d-glucopyranoside and 4′-O-β-d-xylopyranoside, 2,3-bis[(4′-hydroxy-3′-methoxyphenyl)-methyl]-1,4-butanediol 1-O-β-d-glucopyranoside [(?)-seco-isolariciresinol glucoside] and (1R,2S,3S)-1,2,3,4-tetrahydro-7-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl)-6-methoxy-2 3-naphthalenedimethanol α²-O-β-d-xylopyranoside [(?)-isolariciresinol xyloside] have been isolated from needles of Picea abies and identified.     

Trichotomoside: a new antioxidative phenylpropanoid glycoside from Clerodendron trichotomum

The structure and antioxidant properties of a new natural glycoside, trichotomoside (1), isolated from Clerodendron trichotomum, were investigated. Trichotomoside was identified as 2-(3-hydroxy-4-methoxyphenyl)ethyl 3-O-(2,3-di-O-acetyl-alpha-L-rhamnopyranosyl)-4-O-[(2E)-3-(3-hydroxy-4-methoxyphenyl)prop-2-enoyl]-beta-D-glucopyranoside. The compound was active towards intracellular reactive oxygen species (ROS) and exhibited DPPH-radical-scavenging effects. The radical-scavenging activity of 1 was found to protect the viability of Chinese hamster lung fibroblasts (V79-4 cells) exposed to H2O2 and gamma-irradiation.