MEMBERSHIPS IN PROFESSIONAL ORGANIZATIONS
American Chemical Society
American Society of Pharmacognosy
CURRENT RESEARCH INTERESTS:
For over a decade we have focused much of our research efforts into
secondary plant chemistry. The fundamental steps in carrying out this type of
research are usually the same from one project to another: 1) pick an
interesting plant, 2) isolate and identify pertinent substances from the plant,
and 3) develop means to quantify each of these substances.
The excellent resources at UAF have enabled us to repeatably accomplish the
chemistry behind these steps. For instance, most quantifications may be
accomplished by High Performance Liquid Chromatography (HPLC) or Gas
Chromatography (GC) and as recent as 1996, the department upgraded these two
essential pieces of equipment. Our new GC has a split/splitless injector with
autosampling capabilities and is interfaced with a state of the art mass
spectrometer. It is currently being upgraded to include a thermal desorbsion
unit for the analyses of volatiles from solid matrices such as soils or
fragrances trapped by absorbents such as Tenax or activated charcoal. Our new
HPLC is interfaced with a UV/Vis photodiode array detector enabling complex
analyses to be routinely performed. In addition, most secondary metabolites are
routinely isolated by a combination of extraction and chromatography
methodologies. Our lab has successfully used flash chromatography (Si Gel and
Reverse Phase) for most systems and this has enabled us to obtain gram
quantities of many of our more interesting compounds. These are sufficiently
pure to be structurally characterized via NMR, UV, FTIR and MS using facilities
currently present in our department. Occasionally, however, we are forced to
obtain 2-dimensional NMR, high resolution mass spectra, and even x-ray
crystallography data from other facilities that we collaborate with.
Hence, all we need is an interesting plant to justify our efforts to examine
its chemistry. Fortunately this has not been a problem- particularly with
Alaskan plants. Our initial efforts were devoted to proving Alaskan plants are
chemically defended against herbivory- a concept that wasn't popular until the
early to mid 1980s with many plant/animal ecologist. This was a collaborative
effort (primarily with the Institute of Arctic Biology) and quickly evolved to
other projects. We became interested in developing models for why some trees or
plant parts are more defended than others. This led to the discovery of several
dynamic systems involving tree responses to season, climate, herbivory, and
environment. From these dynamics we have developed models to explain certain
population dynamics (including the snowshoe hare and two important insect
systems), the role of learning in food selection, and, to a lesser extent,
plant succession. Recent work has examined the chemical basis of two famous
suspected poisonings in Interior Alaska. We have also contracted with a company
to search for Alaskan plants with potential pharmaceutical applications and
hence worthy of further study.
Not all of our work, however, focuses on ecological studies. For instance, we
found that enzymatic cleavage of the sugar unit from salicortin (a commonly
encountered plant metabolite) results in an unusual sequence of reactions that
leads to enzyme inactivation (see the following reaction
scheme). Hence salicortin belongs to a rare class of enzymatically active
compounds often referred to as "suicide inhibitors" which have many
potential applications in pharmaceuticals and probes for enzyme
structure/activity relationships. Ultimately, however, we feel that some of
these reactions may have consequences for ecological systems and we plan to
pursue this line of reasoning in the near future.
To summarize, our interest in plant chemistry is diverse and often involves a strong collaborative component. Our success can be measured in part by the following list of publications and presentations, many of which involve students as co-authors.
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T.P. Clausen. 1980. Ph.D. Thesis. Multinuclear NMR Study on the Highly Bridged Aryl Substituted Coates Cation and Similar Studies on the Classical Aryl Substituted 2-Adamantyl and 7-Norbornyl Cations.
D.G. Farnum, and T.P. Clausen. 1981. 13C NMR of Aryl Substituted Cations: The Sigma-Bridged Coates Cation and the 2-Adamantyl Cation. Tetrahedron Letters. 22:549-552.
G.A. Olah, G.K. Surya Prakash, D.G. Farnum and T.P. Clausen. 1983. Comments on the Application of the Gassman-Fentiman Tool of Increasing Electron Demand to the 13C Nuclear Magnetic Resonance Spectroscopic Study of Substituted 2-Aryl-2-Norbornyl Cations. Journal of Organic Chemistry 2146
J.P. Bryant, G.D. Wieland*, T.P. Clausen and P. Kuropat. 1985. Interactions of Snowshoe Hares and Feltleaf Willow (Salix alaxensis) in Alaska. Ecology.66:1564-1573.
P.B. Reichardt, J.P. Bryant, T.P. Clausen and G.D. Wieland*. 1984. Defense of Winter-Dormant Alaska Paper Birch Against Snowshoe Hare. Oecologia (Berlin.). 65:58-69.
J.P. Bryant, F.S. Chapin III, P.B. Reichardt and T.P. Clausen. 1985. Adaptation to Resource Availability as Determinant of Chemical Defense Strategies in Woody plants. Pages 219-237 In T. Swain and G. Cooper-Driver (eds.). Recent Advances in Phytochemistry, Vol. 19.
J.P. Bryant, F.S. Chapin III, T. Clausen and P. Reichardt. 1987. Effect of Resource Availability upon the Woody Plant-Mammal Interaction. In: “Proceedings-Symposium on Plant-Herbivore Interactions,” F.D. Provenza, J.T. Flinders, and E.D. McArthur, eds., Intermountain Forest Service, Ogden, UT., 37-42.
J.P. Bryant, F.S. Chapin, III, P.B. Reichardt and T.P. Clausen. 1987. Response of Winter Chemical Defense in Alaska Paper Birch and Green Alder to Manipulation of Plant Carbon/Nutrient Balance. Oecologia (Berlin).72:510-514.
J.P. Bryant, T.P. Clausen, P.B. Reichardt, M.C. McCarthy* and R.A. Werner. 1987. Effect of Nitrogen Fertilization upon the Secondary Chemistry and Nutritional Value of Quaking Aspen (Populus tremuloides Michx.) Leaves for the Large Aspen Tortrix (Choristoneura conflictana (Walker)). Oecologia (Berlin.). 73:513-517.
T.P. Clausen, P.B. Reichardt and J.P. Bryant. 1986. Pinosylvin and Pinosylvin Methyl Ether as Feeding Deterrents in Green Alder. Journal of Chemical Ecology 12:2117-2131.
B.R. Mattes, T.P. Clausen and P.B. Reichardt. 1987. Volatile Constituents of Balsam Poplar: The Phenol Glycoside Connection. Phytochemistry. 26:1361-1366.
P.B. Reichardt, T.P. Clausen and J.P. Bryant. 1987. Plant Secondary Metabolites as Feeding Deterrents to Vertebrate Herbivores: Palatability Assays and Structure/Activity. In: “Proceedings-Symposium on Plant-Herbivore Interactions,” F.D. Provenza, J.T. Flinders and E.D. McArthur, eds., Intermountain Forest Service, Ogden, UT., 3-8.
T.P. Clausen. 1988. A Simple Apparatus for Continuous Steam Distillation. Journal of Chemical Education 65: 92.
P.B. Reichardt, T.P. Clausen, and J.P. Bryant. 1988. Phenol Glycosides in Plant Defense Against Herbivores, In Biologically Active Natural Products. Potential Use in Agriculture, ACS Symposium Series, Vol. 380, H.G. Cutler, ed., American Chemical Society, Washington, D.C., 130-142.
P.B. Reichardt, T.P. Clausen and J.P. Bryant. 1988. A Critical Look at the Role of Phenol Glycosides in Plant Defense. In H.G. Cutler (ed.). Biologically active natural products. ACS Symposium Series. Natural Products for Potential Use in Agriculture. Pages 130-142.
T.P. Clausen, P.B. Reichardt, T. Evans*, and J.P. Bryant. 1989. A Simple Method for the Isolation of Salicortin, Tremulacin, and Tremuloiden from Quaking Aspen (Populus tremuloides). Journal of Natural Products, 52, 207-209.
T.P. Clausen, P.B. Reichardt, J.P. Bryant, R.A. Werner, K. Post*, and K. Frisby*. 1989. “A Chemical Model for Short-term Induction in Quaking Aspen (Populus tremuloides) Foliage Against Herbivores,” Journal of Chemical Ecology, 15:2335-2346.
W.J. Jacubas, G.W. Gullion and T.P. Clausen. 1989. Ruffed Grouse Feeding Behavior and its Relationship to Secondary Metabolites of Quaking Aspen Flower Buds. Journal of Chemical Ecology, 15:1899-1917.
T.P. Clausen, P.B. Reichardt, J.P.Bryant, R.A. Werner. 1989. Long-Term and Short-Term Induction in Quaking Aspen: Related Phenomena? In Phytochemical Induction by Herbivores, D.W. Tallamy and M. J. Raupp (Eds.) John Wley & Sons, Inc.
P.B. Reichardt, B.J. Anderson*, T.P. Clausen, and L.C. Hoskins. 1989. “Thermal Instability of Germacrone: Implications for Gas Chromatographic Analysis of Thermally Unstable Analytes,” Canadian Journal of Chemistry, 67:1174-1177.
S. Armbruster, S. Keller, M. Matsuki, and T. Clausen. 1989. Pollination of Dalechampia magnoliifolia by Male Euglosian Bees. American Journal of Botany, 76:1279-1285.
T.P. Clausen, J.W. Keller, and P.B. Reichardt. 1990. Aglycon Fragmentation Accompanies ß-Glucosidase Catalyzed Hydrolysis of Salicortin, A Naturally-Occurring Phenol Glycoside. Tetrahedron Letters, 31:4537-4538.
T.P. Clausen, F.D. Provenza, E.A. Burritt, P.B. Reichardt and J.P. Bryant. 1990. Ecological Implications of Condensed Tannin Structure: A Case Study,” Journal of Chemical Ecology, 16:2381-2392.
F.D. Provenza, E.A. Burritt, T.P. Clausen, J.P. Bryant, P.B Reichardt, and R.A. Distel. 1990. Food Aversion Learning in Goats: A Mechanism to Avoid Condensed Tannins in Blackbrush. American Naturalist, 136:810-828.
P.B. Reichardt, J.P. Bryant, B.R. Mattes, T.P. Clausen, F.S. Chapin III, and M. Meyer*. 1990. The Winter Chemical Defense of Alaskan Balsam Poplar Against Snowshoe Hares. Journal of Chemical Ecology, 16:1941-1960.
P.B. Reichardt, J.P. Bryant, B.J. Anderson*, D. Phillips*, T.P. Clausen, M. Meyer*, and K. Frisby*. 1990. Germacrone defends labrador tea from browsing by Snowshoe Hares. Journal of Chemical Ecology, 16:1961-1970.
J.P. Bryant, F.D. Provenza, J. Pastor, P.B. Reichardt, T.P. Clausen, and J.T. du Toit. 1991. Interactions Between Woody Plants and Browsing Mammals Mediated by Secondary Metabolites. Annual Reviews of Ecology and Systematics, 22:431-436.
J.P. Bryant, K. Danell, F.P. Provenza, P.B. Reichardt, T.P. Clausen, and R.A. Werner. 1991. Effects of Mammal Browsing upon the Chemistry of Deciduous Woody Plants. In D.W. Tallamy and M.J. Raup (eds.). Phytochemical Induction by Herbivores. John Wiley and Sons, New York. Pages 135-154.
P.B. Reichardt, F.S. Chapin, III, J.P. Bryant, B.R. Mattes, and T.P. Clausen. 1991. Carbon/Nutrient Balance Does Not Fully Explain Patterns of Plant Defense in Alaskan Balsam Poplar. Oecologia 88:401-406.
P.B. Reichardt, T.P. Clausen, and J.P. Bryant. 1991. The Role of Phenol Glycosides in Plant/Herbivore Interactions. In Handbook of Natural Toxins. Vol. 6. Plant and Fungal Toxins. R. Keeler and A. Wu (Eds.). Marcel Dekker. Pages 313-335.
T.P. Clausen, P.B. Reichardt, J.P. Bryant, and R.A. Werner. 1991 Short-Term and Long-Term Induction in Quaking Aspen: Related Phenomenon? In D.W. Tallamy and M.J. Raup (eds.). Phytochemical Induction by Herbivores. John Wiley and Sons, New York. Pages. 71-83.
J.P. Bryant, F. Provenza, P.B. Reichardt, and T.P. Clausen. 1991. Mammal-Woody Plant Interactions. In “Herbivores: Their Interactions with Plant Secondary Metabolites, Vol 2. G.A. Rosenthall and M. Berenbaum (eds.), Academic Press, NY. Pages. 344-371.
J.P. Bryant, P.B. Reichardt, and T.P. Clausen. 1991. Effects of Global Warming on Woody Plant Secondary Metabolism in High Latitude Ecosystems. In “Physiological Ecology of Arctic Plants: Implications for Climate Change”, F.S. Chapin, III, R. Jefferies, G. Schaver, J. Reynolds, and J. Sovboda (eds.), Academic Press, NY. In Press.
J.P. Bryant, P.J. Kuropat, P.B. Reichardt, and T.P. Clausen. 1991. Controls Over the Allocation of Resources by Woody Plants to Antiherbivore Defense. In “Plant Chemical Defenses Against Mammalian Herbivory”, R.T. Palo and C.T. Robbins (eds.), CRC Press. In Press.
J.P. Bryant, P.B. Reichardt, and T.P. Clausen. 1992. Chemically-Mediated Interactions Between Woody Plants and Mammals: Management Implications. Journal of Range Management, 45:18-24.
T.P. Clausen, P.B. Reichardt, J.P. Bryant, and T. Sinclair. 1992.The Chemical Defense of Winter-Dormant Balsam Poplar: A Clarification. Journal of Chemical Ecology, 18:1505-1510.
W.S. Armbruster, A.L. Herzig and T.P. Clausen. 1992. Pollination of 2 sympatric Species of Dalechampia (Euphorbiaceae) in Surinam by Male Euglossine Bees. Am. J. Botany. 79:1374-1381.
C. Nichols-Orians, T.P. Clausen. 1992. 2’-Cinnamoylsalicortin, A New Phenol Glycoside Isolated From Salix Sericea. Phytochemistry. 31:2180-2181.
P.B. Reichardt, H.M. Merkin, T.P. Clausen, and J. Wu. 1992. Phenolic Glycosides from Salix lasiandra. Journal of Natural Products, 55:970-973.
J.P. Bryant, P.B. Reichardt, T.P. Clausen, and R.A. Werner.1993 Effects of Mineral Nutrition on Delayed-Inducible-Resistance in Alaska Paper Birch. Ecology. 74:2072-2084.
T.P. Clausen, P.B. Reichardt, J.P. Bryant, and F. Provenza. 1992. Condensed Tannins in Plant Defense: A Perspective on Classical Theories. In: Plant Polyphenols. Synthesis, Properties, Significance (R.W. Hemingway and P.E. Laks, Eds.) New York: Plenum Press, pp. 639-652.
C.M. Nichols-Orians, R.S. Fritz, and T.P. Clausen. 1993. The Genetic Basis for Variation in the Concentrations of Phenolic Glycosides in Salix sericea. Biochemical Systematics and Ecology. 21:535-542.
T. Evans, P.B. Reichardt, T.P. Clausen and S.M. Chang. 1995. Structurally Intriguing Glucosides from Alaskan Littletree Willow (Salix arbusculoides). Journal of Natural Products 58:1897-1900.
B. Johnson*, T. Clausen and J. Wood*. 1996. A Mixed Aldol Condensation-Michael Addition Experiment for the Organic Laboratory. Journal of Chemical Education 73:266.
J.P Schimel., K. van Cleve., R.G. Cates, T.P. Clausen, and P.B. Reichardt. 1996. Effects of Balsam Poplar (Populus balsamifera) Low Molecular Weight Phenolics on Microbial Activity in Taiga Floodplain Soil: Implications for Changes in N Cycling During Succession. Canadian Journal of Botany 74:84-90.
M. Ayers, T.P. Clausen, S.F. MacLean, A.M. Redman, and P.B. Reichardt. 1997. Diversity of structure and antiherbivore activity in condensed tannins. Ecology. 78:1696-1712.
W.S. Armbruster, J.J. Howard, T.P. Clausen, E. Debevec, J. Loquvam, M. Matsuki, B. Cerendolo*, and F. Andel*. 1997. Do Biochemical Exaptations Link Evolution of Defense and Pollination Systems? Historical Hypotheses and Experimental Tests with Dalechampia Vines. American Naturalist 149:461-484.
Z. Jianjun, S.G. Withers, P.B. Reichardt, E. Treadwell*, and T.P. Clausen. 1998. Salicortin: A Repeat-Attack New-Mechanism-Based Agrobacterium faecalis b-Glucosidase Inhibitor. Biochemical Journal. 332:367-371.
C.L. Whittle, R.T. Bowyer, T.P. Clausen, and L.K. Duffy. 2000 Putative Pheromones in Urine of Rutting Male Moose (Alces alces): Evolution of Honest Advertisement. Journal of Chemical Ecology 26:2747-2762.
J. Lokvam, J. Braddock, P.B. Reichardt and TP.. Clausen. 2000. Two New Polyprenylated Benzophenones from the Trunk Latex of Clusia grandiflora. Phytochemistry 55:29-34.
G. Vourc’h, JL Martin, P. Duncan, J. Escarre and T.P. Clausen. 2001. Defensive Adaptations of Thuja plicata to Ungulate Browsing: A Comparative Study Between Mainland and Island Populations. Oecologia (Berl.) 126:84-93.
T.J. Volz and T.P. Clausen. 2001. Tannins in Puccinellia Arctica: Possible Deterrents to Herbivory by Canada Geese. Journal of Chemical Ecology 27:725-732.
G. Vourc’h, B. Vila, D. Gillon, J. Escarre’, F. Guibal., H. Fritz, T. Clausen, and J. Martin. 2002. Disentangling the causes of damage variation by deer browsing on young Thuja plicata. Oikos. 98:271-283.
C. Riggins and T.P. Clausen. 2003. Root Acetylenes from Artemisia arctica. J. Biochemical Systematics. 31:211-214.
E. Reiter, E. Treadwell, E. Cederstrom*, P.B. Reichardt, and T.P. Clausen. 2003. Diterpenes from Colophospermum mopane: Missing Links in the Biogenesis of 9,13-Epoxylabdanes. Journal of Natural Products. 66:30-33.
B. K. Hale, D. A. Herms, R. T. P. Clausen, and D. Arnold. 2005. Effects of drought stress and nutrient availability on dry matter allocation, phenolic glycosides and rapid induced resistance of poplar to two Lymantriid defoliators. Journal of Chemical Ecology. 31:2601-2620.
T.P. Clausen, T.K Green, and B. Steiner*. Use of the chemical Literature as a Template to Probe Stereoselective Reactions by NMR. Currently under review by the J. Chem. Ed.
B.M. Englund, L. Griffeth*, and T. Clausen. A 9,13-Epoxylabdane from Colophospermum Mopane. Manuscript being revised for submission to Photochemistry
J.P. Bryant, T. P. Clausen, et al. (33 authors***). Fire is a template for a birch-hare selection mosaic. Manuscript being revised for submission to PNAS.
J. Lokvam, T.P. Clausen, D. Grapov, and T.A. Kursar. 2007. Golloyl Depsides of Tyrosine from Young Leaves of Inga Laurina. Journal of Natural Products. 70:134-136.
J.P. Bryant, Z. Feng, R.K. Swihart, J. Villalba, F. Provenza, L. Dziba, T. Clausen, and P. Reichardt. Toxin-regulated functional responses in browsing systems Submitted to Oikos.
Z. Feng, J. Bryant, R.K. Swihart, Ya Li, T. Clausen, P. Reichardt, J. Villalba, F. Provenza, L. Dziba. Modeling Vertebrate Herbivory When Toxins Affect Functional Responses. Submitted to Am. Naturalist.
P. Tomco and T. Clausen. A Novel Triterpenoid from Mountain Birch. The data collection for this paper has been completed and the paper will be submitted to J. Nat. Prod. over the Summer of 2007.
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February 28, 2007
