Termite soldiers

A group of novel diterpenoids has been isolated from the sticky secretions of the frontal glands of nasute termite soldiers. The structure of trinervi-2, 3a,9a-triol... 

The principal component of the defensive secretion of the termite soldiers Ancistrotermes cavithorax has been shown by spectroscopic methods and synthesis to be ancistrofuran (28). Further studies on the components of the defence secretion of the West African termite species Amitermes evuncifer have revealed the presence of the two bicyclic ethers (29) and (30) together with the... 

The synthesis of the title compound (73), which is the defense substance of the termite soldier, is outlined in Scheme 5. ... 

Termite soldiers produce a large number of different chemical defense agents. Several of these molecules are unusual bioactive terpenoids such as the secotrinervitanes that have been isolated and their structure elucidated. In the laboratory of T. Kato, the total synthesis of (+)-3a-acetoxy-7,16-secotrinervita-7,11-dien-15P-ol was accomplished. The Nagata hydrocyanation was used to introduce a carbon at the P-position of a macrocyclic enone intermediate. The substrate was treated with excess diethylaluminum cyanide in dry toluene and the addition resulted in the formation of a 1 1 mixture of diastereomers, which could be readily separated by column chromatography. The cyano group was later converted to the corresponding methyl ester. 

The isolation, structural elucidation, and total synthesis of insect pheromones continue to be a very active area of natural product research (c/. Vol. 8, pp. 66, 102). A recent paper in this area describes the identification of ancistrodial (36) and ancistrofuran (37) as components of the defence secretion of termite soldiers Ancistrotermes cavithorax). 

Cubitene (95), which was isolated from an East African termite soldier, Cubitermes umbratus, possesses an unusual twelve-membered ring. Its structure was determined by A-ray analysis. The irregular isoprenoid structure may be derived via a cembrene derivative or by coupling farnesyl pyrophosphate with dimethylallyl pyrophosphate to give an irregular diterpenoid directly. 

A further group of trinervitene (126) diterpenoids have been isolated from the frontal glands of a termite soldier, Nasutitermes rippertii. These include the 9/8-mono-ol, the 2/8,3a-diol and its acetates, the 2/3,3a,9o -triol and its triacetate, the 2j8,3a,13a-triol and its triacetate, and the 13-oxotrinervi-j8,3a-diol and its diacetate. Isotrinervi-2jS-ol has been obtained from the defensive secretions of T. gratiosus. Kempene-1 (127) and kempene-2 (128) are tetracyclic diterpenoids of a related type which were obtained from another Nasutitermes species. The structure (128) was established by A-ray analysis. 

A full paper on the isolation of cembrene-A (64) and (3Z)-cembrene A from a termite soldier, Cubitermes umbratus, has appeared. An 11,12-epoxycem-brene (65), which has been extracted from Greek tobacco, may act as a biogenetic precursor of some of the 8,11- and 8,12-epoxycembranoids which are also found in tobacco. 

A prenylated cadinene, biflora-4,10(19),15-triene (77), has been isolated from a termite soldier. Prenylated sesquiterpenoid structures have also been assigned to perrottetianal A (78) and B (79), which were isolated from Porella perrottetiana, and a further series of sacculatane diterpenoids including 18- and... 

Ants and termites have evolved the same three castes - reproductive, workers and soldiers. Workers and termites soldiers may be male or female, but among ants they are female only, while in the honeybee Apis sp.) and stingless bees (Melipona and Trigona) the larger queens and workers differ from each other but there is no special soldier class 418). For discussion concerning the involvement of pheromones in caste formation and evolution see Blum 419) and Jaffe 420). 

Quennedey 503) described three fundamental types of mechanisms by which termite soldiers defend their colonies (see Fig. 1). 

In termite soldiers the heads and bodies are so thoroughly modified into chemical and physical weapons that the soldiers can neither feed themselves nor reproduce. They are unique in exhibiting a diverse group of multipurpose allomones. Soldiers of the advanced genera have lost their mandibles through evolutionary processes, but have developed an ability to biosynthesize diterpenes which is unique in insects 528, 531). 

A hypothesis concerning the efficacy of such secretions has been advanced by Prestwich (519). On comparing the resin of Scotch pine (Pinus sylvestris) which contains alpha and beta-pmcnQ with the secretion ejected by certain termite soldiers, he concluded that in both cases the diterpenes present in the mixture substantially retard the rates of evaporation of the monoterpenes, thus increasing the effect of the secretion as a sticky and irritant agent. 

Prestwich, G.D., S.P. Tanis, J.P. Springer, and J. Clardy Nasute Termite Soldier Frontal Gland Secretions. 1. Structure of Trinervi-2-p-3-a-9a-triol-9-0-acetate, a Novel Diterpene from Trinervitermes Soldiers. J. Amer. Chem. Soc. 98, 6061-6062... 

F.G. PiLKiEWicz, I. Miura, and K. Nakanishi Nasute Termite Soldier Frontal... 

B.A. SoLHEiM, J. Clardy, F.G. Pilkiewicz, I. Miura, S.P. Tanis, and K. Nakan-iSHi Kempene-1 and -2, Unusual Tetracyclic Diterpenes from Nasutitermes Termite Soldiers. J. Amer. Chem. Soc. 99, 8082-8083 (1977). 

Membered-Ring Diterpene from a Termite Soldier. J. Amer. Chem. Soc. 100, 2560-2561 (1978). 

Chemical Defense by Termite Soldiers. J. Chem. Ecol 5, 459-480 (1979). 

WiEMER, D.F., J. Meinwald, G.D. Prestwick, and I. Miura Cembrane A and (3Z)-Cembrane A Diterpenes from a Termite Soldier. (Isoptera Termitidae Termi-tinae). J. Org. Chem. 44, 3950-3952 (1979). 

M.S. Collins Chemotaxonomy of Subulitermes and Nasutitermes Termite Soldiers Defense Secretions. Evidence Against the Hypothesis of Diphyletic Evolution of the Nasutitermitinae. Biochem. Syst. Ecol. 9, 83-88 (1981). 

R.W. Jones, and M.S. Collins Terpene Biosynthesis by Nasute Termite Soldiers (Isoptera Nasutitermitinae). Insect Biochem. 11, 331-336 (1981). 

M.S. Collins Chemical Defense Secretions of the Termite Soldiers of Acorhino-termes and Rhinotermes (Isoptera, Rhinotermitinae) Ketones, Vinyl Ketones and P-Ketoaldehydes Derived from Fatty Acids. J. Chem. Ecol. 8,147-161 (1982). 

M. Tempesta, and C. Turner Longipenol. A Novel Tetracyclic Diterpene from the Termite Soldier Longipeditermes longipes. Tetrahedron Lett. 25, 1531-1532 (1984). 

Tempesta, M.S., J.K. Pawlak, T. Iwashita, Y. Naya, K. Nakanishi, and G.D. Prestwick Cubegene, A Diterpenoid with a Novel Carbon Skeleton from a Termite Soldier (Isoptera Termitidae Termitinae). J. Org. Chem. 49, 2077-2079 (1984). 

Isolation and Identification of Diterpenes from Termite Soldiers. Methods in Enyz-mol. 110, 417-425 (1985). 

The defence secretions of termite soldiers continue to prove to be a rich source of natural products, and knowledge of their chemistry has now far outstripped investigation of the precise functions of each compound. Some of the most complex structures come from species in the subfamily Nasutitermitinae, and structural relationships between the compounds have been used to suggest revisions to... 

Larger quantities of secretion are used in more aggressive interactions, for example with termite soldiers or small lizards. The poison gland, which contains the equivalent of about five droplets, may be almost completely voided in these circumstances, and then responding ants are frequently further alarmed... 

Braekman, J. C., Daloze, D., Dupont, A., Pasteels, J., Tursch, B., Declerq, J. P., Germain, G. and Van Meerssche, M. (1980) Secotrinervitane, a novel bicyclic diterpene skeleton from a termite soldier. Tetrahedron Letters, 21, 2761-2. 

Deligne, J. (1971) Mechanics of the fighting behaviour of the termite soldiers (Insecta Isoptera). Forma et Function, 4, 176-87. 

---