Biotransformation of bufadienolides by cell suspension cultures of Saussurea involucrata

The biotransformation of three bioactive bufadienolides, namely, bufotalin (1), telocinobufagin (2), and gamabufotalin (3) by cell suspension cultures of Saussurea involucrata yielded 11 products. Bufotalin yielded 3-epi-bufotalin (1a), 3-epi-desacetylbufotalin (1b), 3-epi-bufotalin 3-O-β-D-glucoside (1c), 1β-hydroxybufotalin (1d), and 5β-hydroxybufotalin (1e); telocinobufagin yielded 3-dehydroscillarenin (2a), 3-dehydrobufalin (2b), and 3-epi-telocinobufagin (2c); and gamabufotalin yielded 3-epi-gamabufotalin (3a), 3-dehydrogamabufotalin (3b), and 3-dehydro-Δ1-gamabufotalin (3c), respectively. Among these 11 products, 1a, 1b, 1c, 1d, 3a and 3c are previously unreported. The structures of these metabolites were elucidated based on NMR spectroscopic analyses and mass spectrometry. Most metabolites showed significant cytotoxic activities against human hepatoma (HepG2) and breast cancer (MCF-7) cell lines. In addition, the time course for the biotransformation of 3 was investigated.     

Study of the karyotype of the malaria mosquito]

A study of the karyotype composition of 22 geographycally removed natural populations of the malarial mosquito Anopheles messeae Fall revealed a chromosomal polymorphism characteristic of the whole species. 13 paracentric inversions were detected, no other gene arrangements being discovered. All the inversions can be divided into two classes: 1) wide spread inversions in hetero- and homozygous forms; 2) endemic ones discovered in individual populations in the form of heterozygotes. According to the presented photomap of salivary gland chromosomes, the inversion localization are as follows: IL1 (2a--4a), IL2 (1c--4a), IL3 (2a--3b), IL4 (1c--3b), IIR1 (7c--12c), IIR2 (10b--14b), IIL1 (15b--17a), IIIR1 (24a--26c), IIIR2 (23a--24c), IIIR3 (23b--25c), IIIR4 (27c--29c), IIIR5 (27d--30c), IIIL1 (34a--39d).     

Investigation of frequency of occurrence of core Y haplogroups in residents of Moscow and St. Petersburg

The collection of DNA from 239 Moscow residents and 62 St. Petersburg residents has been investigated by means of a biochip for genotyping haplogroup markers of the Y chromosome, including M130 (C), M145 (DE), P257 (G), M69 (II), U179 (I), M304 (J), M185 (L), M231 (N), M175 (O), P224 (R), L146 (R1a), and M343 (R1b). The distribution of haplogroup frequency in populations native to Moscow and St. Petersburg has been obtained. Three subsamples that vary in the duration of residence (one, two, or three generations) were compared. The increase in J, G, and R1b frequencies may be related to immigration from the Caucasus and other regions.     

Flora of planktonic microalgae of Amursky Bay, Sea of Japan

Long-term studies of the species composition of phytoplankton in Amursky Bay (Sea of Japan) carried out during the period from 1991 to 2006 revealed a total of 357 species of planktonic microalgae from eight divisions: Cyanophyta (8 species), Chrysophyta (8), Bacillariophyta (157), Cryptophyta (5), Dinophyta (143), Raphidophyta (3), Euglenophyta (11), and Chlorophyta (22 species). An annotated checklist of species is presented. In comparison with the late 1960s and early 1970s, the species richness of phytoplankton increased markedly; a greater number of bloom-forming species was recorded.     

延胡索的化学成分研究(英文)

采用现代分离技术和方法,从延胡索根茎中分离得到17个化合物,通过波谱分析鉴定其结构。包括11个生物碱类化合物,二氢白屈菜红碱(1)、去氢紫堇碱(2)、四氢非洲防己胺(3)、异紫堇球碱(4)、紫堇碱(5)、四氢黄连碱(6)、药根碱(7)、黄连碱(8)、小檗碱(12)、巴马汀(13)和延胡索乙素(14);2个蒽醌类化合物,大黄素(9)和大黄素甲醚(10);1个三萜类化合物,即3β-羟基-齐墩果烷-111,3(18)-二烯-28-酸(11)和3个甾醇类化合物,豆甾醇(15)、β-谷甾醇(16)和胡萝卜苷(17)。其中,化合物9～11首次从该属植物中分离得到,1首次从该种中分离得到。     

Studies on Chemical Constituents of Essential Oil from Leaves of Jiang-Zhang

Jiang-Zhang is a Physiological type of Cinnamomum porrectum (Roxb.) Kosterm. The essential oil of leaves of Jiang-Zhang can be extracted by steam distillation, with yields of 0.5–0.8%. It contained dtral (α-,β-citral) 64.11% and can be used in aromatic and medicinal industries. We used the methods of GC, IR, GC/MS/DS and prepared derivative and 47 chemical constituents were identified, as follows: α-thujene (0.06 %), α-pinene (2.42%), camphene (1.26%), sabinene (0.21%),β- pinene (1.38%) myrcene(0.38%), α-phellandrene (0.32%),△3-carene (0.01%), p-cymene(0.21%),α-limonene (1.57%), 1 8-cineole (0.82 % ), β-phellandrene (0.10 %), cis-linalool oxide(0.07 % ), linalool (8.43 % ) epicamphor(0.26 % ), camphor(1.10 %), borneol( 1.07 % ), β-citral (neral) (28.28 % ), geraniol (0.25%), nerol (0.47%), α-citral (geranial) (35.83%), methyl citronellate (0.12%), n-undecane (0.18), safrole (0.02), methyl geranate (0.23%), geranyl formate (0.09%), α-copaene (0.12%), trans-methyl cinnamate (0.02%), n-dodecane (0.20), β-elemene (0.12%), caryophyllene (4.67%), α-guaiene (0.04), β-guaiene (0.06%), β-selinene (0.97%), azulene (0.38%), β-cubebene (0.30%), n-pentadecane (0.05%), β-gurjunene (0.04 %), epi-β-santalene (0.46 %), aremophliene (0.05 % ), alloaromadendrene (0.03 % ), α-elemene (0.26%), trans-β-farnesene (0.04%), (z)-β-farnesene (0.30%), r-elemene (0.03%), β-bisaboiol(0.41%), cedrol (0.16%), respectively.     

Constituents of Aristolochia cinnabarina

Nine compounds, aristolochic acid (1), aristolochic acid- Ⅱ (2), aristolochic acid- Ⅲ a (3), aristoloside (4), aristolactam-N-β-D-glucoside (5), aristolactam-β-D-glucoside (6), tuberosinone (7), tuberosinone N-β-D-glucoside (8) and 6-O-p-coumaroyl-D-glucopyranose (9), were isolated from methanol extracts of fresh roots of Aristolochia cinnabarina. Among them, compound 9 was reported in Aristolochiaceae for the first time.     

Analogs of leukotriene B4: effects of modification of the hydroxyl groups on leukocyte aggregation and binding to leukocyte leukotriene B4 receptors

The syntheses and agonist and binding activities of 5(S)-hydroxy- 6(Z), 8(E), 10(E), 14(Z)-eicosatetraenoic acid (12-deoxy LTB4), 5(S), 12(S)-dihydroxy-6(Z), 8(E), 10(E), 14(Z)-eicosatetraenoic acid (12-epi LTB4), 12(R)-hydroxy-6(Z), 8(E), 10(E), 14(Z)-eicosatetraenoic acid (5-deoxy LTB4), 5(R), 12(S)-dihydroxy-6(Z), 8(E), 10(E), 14(Z)-eicosatetraenoic acid (5-epi LTB4), 6(Z), 8(E), 10(E), 14(Z)-eicosatetraenoic acid (5, 12-deoxy LTB4) are described. These leukotriene B4 analogs were all able to aggregate rat leukocytes and compete with [3H]-leukotriene B4 for binding to rat and human leukocyte leukotriene B4 receptors with varying efficacy. The analog in which the 12-hydroxyl group was removed was severely reduced both in agonist action (aggregation) and binding. The epimeric 12-hydroxyl analog demonstrated better agonist and binding properties than the analog without a hydroxyl at this position. In contrast, in the case of the 5-hydroxyl the epimeric hydroxyl analog had greatly reduced agonist and binding activities while the 5-deoxy analog demonstrated potency only several fold less than leukotriene B4 itself. The dideoxy leukotriene B4 analog was more than a thousand fold less active than leukotriene B4 as an agonist and in binding to the leukotriene B4 receptor. These results show that binding to the leukocyte leukotriene B4 receptor requires a hydroxyl group at the 12 position in either stereochemical orientation but that the presence of a hydroxyl at the 5 position is less important. However, the epimeric C5 leukotriene B4 analog clearly interacts unfavourably with the binding site of the leukotriene B4 receptor.     

Biotransformation of terpenoids by mammals, microorganisms, and plant-cultured cells

This review article summarizes our knowledge of the metabolism of mono- and sesquiterpenoids in mammals, microorganisms, cloned-insect enzymes, and plant-cultured cells. A number of unusual enzymatic reactions and products are reported such as the stereoselective formation of primary alcohols from sterically congested Me2C groups. Such enzymatic processes, including unknown chemical transformations under abiotic conditions, could lead to the discovery of new chemical reactions and might be helpful in the design of new drugs. The transformations of the following mono- and sesquiterpenoids (in alphabetical order) are discussed: (+)-(1R)-aromadendrene (61), (-)-allo-aromadendrene (62), (+/-)-camphene (21), (-)-cis-carane (20), (+)-3-carene (17), (+/-)-carvone (27), (-)-beta-caryophyllene (43), (+)-cedrol (35), cuminaldehyde (25), (+)-curdione (69), (-)-cyclocolorenone (60), (-)-elemol (51), (2E,6E)-farnesol (31), germacrone (67), ginsenol (40), (-)-globulol (63), isoprobotryan-9alpha-ol (82a), juvenile hormone III (33), (+)-ledol (65), (+)-longifolene (46), myrcene (3), (-)-myrtenal (23), (+)-nootkatone (48), patchouli alcohol (37), (-)-perillaldehyde (24), (-)-alpha- and beta-pinene (8 and 9), alpha-santalol (28), (-)-6beta-santonin (83a), 6beta-tetrahydrosantonin (83b), beta-selinene (57), alpha-thujone (26a), beta-thujone (26b), T-2 toxin (87), and valerianol (53).     

竹节参化学成分研究

从竹节参的乙醇提取物分离得到了12个化合物,通过MS和NMR等方法鉴定为:竹节参皂苷Ⅳa(1),楤木皂苷A(2),竹节参皂苷Ⅰb(3),竹节参皂苷Ⅴ(4),尿嘧啶(5),胸嘧啶(6),尿苷(7),鸟苷(8),胸苷(9),腺苷(10),肌苷(11),胞苷(12),其中5 ～ 12为首次从该植物中分离.     

Pattern of compensatory expression of voltage-dependent Ca2+ channel alpha1 and beta subunits in brain of N-type Ca2+ channel alpha1B subunit gene-deficient mice with a CBA/JN genetic background.

The Ca(2+) channel alpha(1B) subunit is a pore-forming component capable of generating N-type Ca(2+) channel activity. Although the N-type Ca(2+) channel plays a role in a variety of neuronal functions, alpha(1B)-deficient mice with a CBA/JN genetic background show no apparent behavioral or anatomical-histological abnormality, presumably owing to compensation by other Ca(2+) channels. In this study, we examined the mRNA expression of the alpha(1A), alpha(1C), alpha(1D), alpha(1E), beta(1), beta(2), beta(3) and beta(4) subunits in the olfactory bulb, cerebral cortex, hippocampus and cerebellum of alpha(1B)-deficient mice. We found that the mRNA expression levels of the alpha(1A), alpha(1C), alpha(1D), alpha(1E), beta(1), beta(2), beta(3) and beta(4) subunits were the same in the olfactory bulbs of wild, heterozygous and homozygous alpha(1B)-deficient mice. In the cerebral cortex, alpha(1A) mRNA in homozygous alpha(1B)-deficient mice was expressed at a higher level than in wild or heterozygous mice, but no difference in the expression levels of the alpha(1C), alpha(1D), alpha(1E), beta(1), beta(2), beta(3) and beta(4) subunits was found among wild, heterozygous and homozygous mice. In hippocampus and cerebellum, beta(4) mRNA in homozygous alpha(1B)-deficient mice was expressed at a higher level than in wild or heterozygous mice, but no difference in the expression levels of the alpha(1A), alpha(1C), alpha(1D), alpha(1E), beta(1), beta(2) and beta(3) subunits was found among wild, heterozygous and homozygous mice. These results suggest that the compensatory mechanisms differ in different brain regions of alpha(1B)-deficient mice with a CBA/JN genetic background.     

Activity of lupane triterpenoids from Maytenus species as inhibitors of nitric oxide and prostaglandin E2

In the present study, we report that three new lupane triterpenes (1-3), in addition to 16 known ones (4-19), were isolated from the root bark of Maytenus cuzcoina and the leaves of Maytenus chiapensis. Their structures were elucidated by spectral analysis, including homonuclear and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC, and HMBC). The natural compounds and derivatives 6a, 6b, 9a, and 9b have been tested for potential anti-inflammatory activity, and several compounds including 3-epicalenduladiol (2), 11alpha-hydroxy-glochidone (3), rigidenol (6), acetoxy-rigidenol (6a), 11alpha-acetoxy-30-chloro-3-oxo-lup-20(29)-ene (6b), betulin (9), 28-acetoxy-betulin (9a), epibetulin (12), epibetulinic acid (13), and betulonic acid (16) exhibited potent inhibitory effects on NO and prostaglandin E(2) production in mouse macrophages (RAW 264.7) stimulated with bacterial endotoxin. The structure-activity relationship is discussed in detail.     

Molecular Genetic Characterization of Six Recessive Viable Alleles of the Mouse Agouti Locus

The agouti locus on mouse chromosome 2 encodes a secreted cysteine-rich protein of 131 amino acids that acts as a molecular switch to instruct the melanocyte to make either yellow pigment (phaeomelanin) or black pigment (eumelanin). Mutations that up-regulate agouti expression are dominant to those causing decreased expression and result in yellow coat color. Other associated effects are obesity, diabetes, and increased susceptibility to tumors. To try to define important functional domains of the agouti protein, we have analyzed the molecular defects present in a series of recessive viable agouti mutations. In total, six alleles (a(mJ), a(u), a(da), a(16H), a(18H), a(e)) were examined at both the RNA and DNA level. Two of the alleles, a(16H) and a(e), result from mutations in the agouti coding region. Four alleles (a(mJ), a(u), a(18H), and a(da)) appear to represent regulatory mutations that down-regulate agouti expression. Interestingly, one of these mutations, a(18H), also appears to cause an immunological defect in the homozygous condition. This immunological defect is somewhat analogous to that observed in motheaten (me) mutant mice. Short and long-range restriction enzyme analyses of homozygous a(18H) DNA are consistent with the hypothesis that a(18H) results from a paracentric inversion where one end of the inversion maps in the 5' regulatory region of agouti and the other end in or near a gene that is required for normal immunological function. Cloning the breakpoints of this putative inversion should allow us to identify the gene that confers this interesting immunological disorder.     

Interaction of anions with rat liver arginase: specific inhibitory effects of fluoride

The inhibitory effects of anions, such as N(3)(-), NO(2)(-), BO(4)(3-), SCN(-), CH(3)COO(-), SO(4)(2-), ClO(4)(-), H(2)PO(4)(-), CN(-), I(-), Br(-), Cl(-) and F(-), on the hydrolysis of L-arginine (L-Arg) by rat liver arginase (RLA) have been studied. From all these anions, only F(-) exhibited a clear inhibitory effect at the mM level. Inhibition of RLA by F(-) is reversible and uncompetitive towards L-Arg binding with a K(i) value of 1.3+/-0.5 mM at pH 7.4. This effect is dependent on pH as the IC(50) value of F(-) towards RLA increases from 1.2 to 19 mM when increasing the pH from 7 to 10. Another specific inhibitor of RLA, N(omega)-hydroxy-L-nor-arginine (nor-NOHA), that has been recently shown to bind to RLA as a bridging ligand of its (Mn(II))(2) cluster, exhibits some similarities with F(-) in its inhibitory effects (identical pH dependence). It is thus tempting to propose that the inhibitory effects of F(-) could be due to its binding as a bridging ligand of the RLA (Mn(II))(2) cluster. However, further studies are required to determine the modes of interaction of F(-) with RLA.     

Chemical structures of a galactose-rich glycoprotein of Leishmania tarentolae

1. Aqueous phenol treatment of water extracted disrupted cells of Leishmania tarentolae (LV-414) provided a glycoprotein mixture which was purified by gel filtration chromatography, and Concanavalin A-Sepharose column. 2. The bound fraction on Concanavalin A-Sepharose column (protein 74%, and carbohydrate, 26%) had [alpha]D + 9 degrees and contained mannose (18%), galactose (60%), and glucose (22%), and some of the galactose residues were resistant to periodate oxidation. 3. Treatment of the phenol extract with hot aqueous NaBH4 containing NaOH gave a preparation having mannose (12%), galactose (82%), and glucose (6%). 4. Methylation analysis showed the presence of a mainly linear structure with non-reducing end-units of mannopyranose (6%), 3-O-substituted galactopyranosyl (64%), 2-O- (11%), and 6-O- (5%) substituted mannopyranosyl, and 4-O- (9%), and 4,6-di-O- (3%) substituted glycopyranosyl units. 5. The specific rotation of the preparation, +20 degrees, indicated beta-linked galactopyranosyl units.     

17-Epimerization of 17 alpha-methyl anabolic steroids in humans: metabolism and synthesis of 17 alpha-hydroxy-17 beta-methyl steroids.

The 17-epimers of the anabolic steroids bolasterone (I), 4-chlorodehydromethyltestosterone (II), fluoxymesterone (III), furazabol (IV), metandienone (V), mestanolone (VI), methyltestosterone (VII), methandriol (VIII), oxandrolone (IX), oxymesterone (X), oxymetholone (XI), stanozolol (XII), and the human metabolites 7 alpha,17 alpha-dimethyl-5 beta-androstane-3 alpha,17 beta-diol (XIII) (metabolite of I), 6 beta-hydroxymetandienone (XIV) (metabolite of V), 17 alpha-methyl-5 beta-androst-1-ene-3 alpha,17 beta-diol (XV) (metabolite of V), 3'-hydroxystanozolol (XVI) (metabolite of XII), as well as the reference substances 17 beta-hydroxy-17 alpha-methyl-5 beta-androstan-3-one (XVII), 17 beta-hydroxy-17 alpha-methyl-5 beta-androst-1-en-3-one (XVIII) (also a metabolite of V), the four isomers 17 alpha-methyl-5 alpha-androstane-3 alpha,17 beta-diol (XIX) (also a metabolite of VI, VII, and XI), 17 alpha-methyl-5 alpha-androstane-3 beta,17 beta-diol (XX), 17 alpha-methyl-5 beta-androstane-3 alpha,17 beta-diol (XXI) (also a metabolite of V, VII, and VIII), 17 alpha-methyl-5 beta-androstane-3 beta,17 beta-diol (XXII), and 17 beta-hydroxy-7 alpha,17 alpha-dimethyl-5 beta-androstan-3-one (XXIII) were synthesized via a 17 beta-sulfate that spontaneously hydrolyzed in water to several dehydration products, and to the 17 alpha-hydroxy-17 beta-methyl epimer. The 17 beta-sulfate was prepared by reaction of the 17 beta-hydroxy-17 alpha-methyl steroid with sulfur trioxide pyridine complex. The 17 beta-methyl epimers are eluted in gas chromatography as trimethylsilyl derivatives from a capillary SE-54 or OV-1 column 70-170 methylen units before the corresponding 17 alpha-methyl epimer. The electron impact mass spectra of the underivatized and trimethylsilylated epimers are in most cases identical and only for I, II, and V was a differentiation between the 17-epimers possible. 1H nuclear magnetic resonance (NMR) spectra show for the 17 beta-methyl epimer a chemical shift for the C-18 protons (singlet) of about 0.175 ppm (in deuterochloroform) to a lower field. 13C NMR spectra display differences for the 17-epimeric steroids in shielding effects for carbons 12-18 and 20. Excretion studies with I-XII with identification and quantification of 17-epimeric metabolites indicate that the extent of 17-epimerization depends on the A-ring structure and shows a great variation for the different 17 alpha-methyl anabolic steroids.     

Chemistry and immunomodulatory activity of frankincense oil

The yield of steam distillation of frankincense essential oil (3%); and its physicochemical constants were determined. Capillary GC/MS technique was used for the analysis of the oil. Several oil components were identified based upon comparison of their mass spectral data with those of reference compounds published in literature or stored in a computer library. The oil was found to contain monoterpenes (13.1%), sesquiterpenes (1%), and diterpenes (42.5%). The major components of the oil were duva-3,9,13-trien-1,5alpha-diol-1-acetate (21.4%), octyl acetate (13.4%), o-methyl anisole (7.6%), naphthalene decahydro-1,1,4a-trimethyl-6-methylene-5-(3-methyl-2-pentenyl) (5.7%), thunbergol (4.1%), phenanthrene-7-ethenyl-1,2,3,4,4a,5,6,7,8,9,10,10a-dodecahydro-1,1,4a,7-tetramethyl (4.1%), alpha-pinene (3.1%), sclarene (2.9%), 9-cis-retinal (2.8%), octyl formate (1.4%), verticiol (1.2%) decyl acetate (1.2%), n-octanol (1.1%). The chemical profile of the oil is considered as a chemotaxonomical marker that confirmed the botanical and geographical source of the resin. Biologically, the oil exhibited a strong immunostimulant activity (90% lymphocyte transformation) when assessed by a lymphocyte proliferation assay.     

Diterpenoids from the pericarp of Platycladus orientalis

Eight labdane-type diterpenes, 7beta,13S-dihydroxylabda-8(17),14-dien-19-oic acid (1), 12R,15-dihydroxylabda-8(17),13E-dien-19-oic acid (3c), 12R,15-dihydroxylabda-8(17),13Z-dien-19-oic acid (3d), 12R,13R,14S-trihydroxylabda-12,15-epoxy-8(17)-en-19-oic acid (4a), 12S,13S,14R-trihydroxylabda-12,15-epoxy-8(17)-en-19-oic acid (4b), 15-hydroxy-12-oxolabda-8(17),13E-dien-19-oic acid (5), 14R,15-dihydroxylabda-8(17),12Z-dien-19-oic acid (7a) and 14S,15-dihydroxylabda-8(17),12Z-dien-19-oic acid (7b), along with 20 known diterpenoids, were isolated from the pericarp of Platycladus orientalis. Their structures were unambiguously elucidated by NMR spectroscopic and single crystal X-ray diffraction analyses, as well as via chemical correlation conversion. NMR spectroscopic data of known isomers 8c and 8d were reported as a supplement to existing data.     

Synthesis, characterization, and antitumor properties of some metal complexes of 2,6-diacetylpyridine bis(N4-azacyclic thiosemicarbazones)

Complexes of Mn(II), Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Pt(II) with 2,6-diacetylpyridine bis(N4-azacyclic thiosemicarbazones), abbreviated as H2L, have been prepared and characterized by elemental analysis, molar conductance, magnetic moments (300-78 K) and spectral studies. On the basis of these studies, a distorted six-coordinate structure for Fe(L)Cl and a distorted five-coordinate structure for M(L) (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), or Pt(II] are suggested. The ligands undergo deprotonation and appear to coordinate through the thione sulphur, the imine nitrogen and pyridyl nitrogen. All the ligands and metal complexes were screened for their antitumor activity against P 388 lymphocytic leukemia test system in mice, and it was found that a few of them possess significant activity at the dosages used.     

Chemical Constituents from Roots of Jatropha curcas

Thirteen compounds were isolated from the roots of datropha curcas L. Combining the determination of physico-chemical constants and spectral analyses (IR, 1H-NMR, 13C-NMR, EIMS, FABMS), the structures of the compounds were identified as 5α-stigmastane-3, 6-dione (1), nobiletin (2), β-sitosterol (3), taraxerol (4), 2S-tetracosanoic acid glyceride-1(5),5-hydroxy-6,7-dimethoxycoumarin (6), jatropholone A (7), jatropholone B (8), 6-methoxy-7-hydroxycoumarin (9), caniojane (10), 3-hydroxy-4-methoxybenzaldehyde (11), 3-methoxy-4-hydroxybenzoic acid (12) and daucosterol (13). Among them, compound 5 is a new compound which has never been reported in China and abroad, compound 1, 2, 9, 10, 11, 12 were first time isolated from the plant, 7 and 8 are a pair of stereoisomers which can be inverted in dilute basic solution. 10 is a diterpenoid containing peroxide bridge.