Sesquiterpenes from the red alga Laurencia tristicha

Phytochemical investigation on Laurencia tristicha afforded eleven cuparane-derived sesquiterpenes, including ten monomers and one dimer, and their structures were elucidated by a combination of spectroscopic analysis and comparison with those reported in literature. Four compounds, laurinterol acetate, debromolaurinterol acetate, aplysinal, and (−)-α-bromocuparene were obtained from L. tristicha for the first time. Additionally, the chemotaxonomic significance of these cuparane-derived sesquiterpenes, as well as their plausible biogenetic pathway, was also discussed.     

Growth and the content of laurinterol and debromolaurinterol in Laurencia okamurae (Ceramiales, Rhodophyta)

The growth of Laurencia okamurae and the content of laurinterol and debromolaurinterol were influenced by various factors. Temperature influenced growth raere te with a maximum at 25°C, regardless of daylength. Maturity depended on temperature rather than daylength; the plants grew without maturing at 15°C, while the plants matured within two weeks at 25°C. The plants were able to grow at salinities of 14–50‰ with maximum growth at 26‰. The salinities growth rash;50‰te reduced with decreasing concentration of nitrate below 1.2 × 10^-3 M, and of total phosphate below 7.5× 10^-8 M. Bromide concentration had no effect on growth, and the plants grew without bromide. Variation in temperature between 15–25°C and daylength produced no obvious change in laurinterol and debromolaurinterol contents. On the other hand, an increase in salinity led to an increase for both. The plants cultured in a completely artificial medium, modified ASP₁₂NTA, showed a marked drop in their content of these metabolites. An increase in concentrations of nitrate, total phosphate or bromide did not restore the content. This revised version was published online in June 2006 with corrections to the Cover Date.     

A c-15 non-terpenoid from the red alga Laurencia okamurai

The structure of a new C-15 bromoallene from the red alga Laurencia okamurai was deduced by spectral methods.     

A halogenated chamigrane epoxide and six related halogen-containing sesquiterpenes from the red alga Laurencia okamurai

From the red alga Laurencia okamurai a new chamigrane epoxide and six known halogenated chamigranes were isolated. The structure of the new epoxide     

Chemical composition of Laurencia spp. collected from the Seto Inland Sea of Japan

The chemical composition of three Laurencia spp., Laurencia sp., L. okamurae and L. saitoi, which were collected from the Seto Inland Sea of Japan, has been examined. Laurencia sp. collected from the coast of Matoba Park, Takehara, Hiroshima Prefecture, contained a brominated chamigrane-type sesquiterpene (1), named matobol, as the main metabolite. The structure of matobol was determined as (+)-(2R,3R,6R,10S)-2,10-dibromochamigr-7(14)-en-3-ol (1). This is the first time that the optically active 1 has been isolated from Laurencia. On the other hand, L. okamurae from the coast of Ikunoshima Island, Hiroshima Prefecture, produced laurinterol (2) that is a known cyclolaurane-type sesquiterpene characteristic to this species in Japan. L. saitoi from the coast of Matoba Park contained a known bromoallenic C₁₅-acetogenin, neolaurallene (3).     

Halogenated metabolites with antibacterial activity from the Okinawan Laurencia species

The chemical compositions of five species of the red algal genus Laurencia from coastal waters of Okinawa Prefecture, Japan, have been investigated. A halogenated C(15) acetogenin, (12E)-lembyne-A, was isolated from L. mariannensis, and a halogenated sesquiterpene, (6R,9R,10S)-10-bromo-9-hydroxy-chamigra-2,7(14)-diene, was first found from L. majuscula as a naturally occurring compound. Laurencia nidifica yielded previously known laurinterol and isolaurinterol. Samples of L. cartilaginea and L. concreta afforded no halogenated metabolites. The structures of these halogenated metabolites as well as their antibacterial activity against some marine bacteria are reported.     

Antibacterial activity of halogenated sesquiterpenes from Malaysian Laurencia spp

During our studies on Malaysian Laurencia species, brominated metabolites, tiomanene, acetylmajapolene B, and acetylmajapolene A were isolated from an unrecorded species collected at Pulau Tioman, Pahang along with known majapolene B and majapolene A. Acetylmajapolene A was a mixture of diastereomers as in the case of majapolene A. Tiomanene may be a plausible precursor for acetylmajapolenes B and A. In addition, three known halogenated sesquiterpenes and two known halogenated C₁₅ acetogenins were found from other two unrecorded species collected at Pulau Karah, Terengganu and Pulau Nyireh, Terengganu, respectively. Some of these halogenated metabolites showed moderate antibacterial activity against some marine bacteria.     

Structural diversity and geographical distribution of halogenated secondary metabolites in red algae,Laurencia nangii Masuda (Rhodomelaceae,Ceramiales), in the coastal waters of North Borneo Island

The red algae genus Laurencia (Rhodomelaceae, Ceramiales) is known as a prolific producer of halogenated secondary metabolites with a high level of species diversity and geographical distribution. In North Borneo Island, Malaysia, there are four main Laurencia species: Laurencia snackeyi, Laurencia majuscula, Laurencia similis and L. nangii. Although the chemistry of Laurencia is well studied, the diversity of compounds in L. nangii has not been thoroughly investigated. Therefore, we studied the chemical constituents of seven populations of L. nangii from Tunku Abdul Rahman Marine Park (two populations), Dinawan Island (one population), Tun Mustapha Marine Park (two populations) and Tun Sakaran Marine Park (two populations). Halogenated compounds were isolated and the structures determined via spectroscopic methods. A total of 20 metabolites belonging to the classes of sesquiterpenes, acetylenes, bromoallenes, diterpenes and triterpenes were identified. Populations from Tunku Abdul Rahman Marine Park and Dinawan Island contained non-chamigrane-type sesquiterpenes, acetylenes and diterpenes. Populations from Tun Mustapha Marine Park contained chamigrane-type sesquiterpenes, acetylenes and diterpenes. However, the chemical compositions of populations from Tun Sakaran Marine Park were found to differ significantly, containing chamigrane-type and non-chamigrane-type sesquiterpenes, bromoallenes and triterpenes. This investigation has revealed the presence of interesting chemotaxonomical markers in populations of L. nangii and the existence of chemical races in this species.     

Aplysiallene,a New Bromoallene as an Na,K-ATPase Inhibitor from the Sea Hare,Aplysia kurodai

A new bromoallene metabolite, named aplysiallene, was isolated from the Japanese sea hare, Aplysia kurodai, as an Na,K-ATPase inhibitor. Its structure was elucidated by spectroscopic methods. The known metabolites, laurinterol and debromolaurinterol, isolated from this animal were also evaluated for their Na,K-ATPase inhibitory activity.     

Aplysiallene, a new bromoallene as an Na, K-ATPase inhibitor from the sea hare, Aplysia kurodai

A new bromoallene metabolite, named aplysiallene, was isolated from the Japanese sea hare, Aplysia kurodai, as an Na, K-ATPase inhibitor. Its structure was elucidated by spectroscopic methods. The known metabolites, laurinterol and debromolaurinterol, isolated from this animal were also evaluated for their Na, K-ATPase inhibitory activity.     

Nonhalogenated organic molecules from Laurencia algae

The marine red algae of the genus Laurencia have produced more 700 secondary metabolites and exhibited high molecular diversity and intriguing bioactivity. Since the halogenated structures have been comprehensively reviewed previously, this review, covering up to the end of 2012, mainly focuses on the source, structure elucidation, and bioactivity of nonhalogenated organic molecules from Laurencia spp. as well as the relationship between nonhalogenated and halogenated products. Overall, 173 new or new naturally occurring compounds with 58 skeletons, mainly including sesquiterpenes, diterpenes, triterpenes, and C₁₅-acetogenins, are described.     

Chemical and phylogenetic relationships among Aristolochia L. (Aristolochiaceae) from southeastern Brazil

In this report, a molecular phylogeny based on the plastid gene matK and on the region between the genes trnL and trnF, and a chemical relationship based on the pattern of sesquiterpenes, is proposed for Aristolochia species from southeastern Brazil. We found that Aristolochia is a monophyletic genus and species considered to be derived contain labdanoic acids (LAs) in their leaves. The phenetic relationship recovered with sesquiterpenes did not agree with the phylogenetic relationships for Aristolochia, and three main clusters were recognized, namely, germacrene-D, germacrene-C and Z-caryophyllene groups. The presence of different sesquiterpene structures in species that are phylogenetically closely related may reflect adaptations to avoid predation of herbivores specialized in feeding on Aristolochiaceae plants.     

Allelopathic potential of two sesquiterpene lactones from Magnolia grandiflora L.

The allelopathic effects of the two sesquiterpene lactones, costunolide and parthenolide, isolated from the leaves of Magnolia grandiflora L. were evaluated on the wheat (Triticum aestivum L.), lettuce (Lactuca sativa L.), radish (Raphanus sativus L.) and onion (Allium cepa L.). Seed germination of the test species was significantly reduced at 500 μg/ml by both compounds. Both sesquiterpenes showed pronounced inhibition of root length of the test species and the inhibitory effect was concentration-dependent. In addition, shoot growth of the four species was significantly inhibited at all the concentrations tested (10–500 μg/ml). Parthenolide reduced germination and inhibited seedling growth more than costunolide. Inhibition of root growth was generally greater than that of shoot growth. The results encourage the use of these sesquiterpenes as models for development of new herbicides.     

Sesquiterpenes from Porella species

The Porella liverworts contain abundant sesquiterpenes. ent-Biocyclogermacrene, three ent-aromadendrenes, a unique hydrocarbon, α-pinguisene and two drimane type sesquiterpenes were obtained together with the intensly pungent component, tadeonal, from P. vernicosa and P. gracillima. P. macroloba contained the same sesquiterpenes except for the absence of ent-bicyclogermacrene and the ent-aromadendrenes. The fragrant odor of P. perrottetiana was composed of α-pinene and camphor.     

Sesquiterpenes from Japanese liverworts

Five Japanese liverworts (Bazzania sp.) were examined for sesquiterpenes. B. japonica and B. pompeana contained two new drimane-type sesquiterpene esters, albicanyl 3,4-dihydroxycinnamate and albicanyl 2,4dihydroxycinnamate. Tridensenone, a new aromadendrane-type sesquiterpene ketone was isolated from B. tridens. The stereostructures of these new sesquiterpenes were elucidated mainly by spectrometry. Barbatane-, bazzanane- and cuparane-type sesquiterpenes were found in all of the five species investigated. These sesquiterpenes, along with the new drimane- and aromadendrane-type sesquiterpenes are useful chemosystematic markers.     

Within-plant distribution and emission of sesquiterpenes from Copaifera officinalis

Copaifera officinalis, the diesel tree, is known for massive production of oleoresin, mainly composed of sesquiterpene hydrocarbons. In this study, composition of these sesquiterpenes and their concentrations in leaves, stems and roots of C. officinalis at two developmental stages, including the three-week old (TW) seedlings and two-year old (TY) trees, were determined. The leaves of TW seedlings and TY trees contained similar number of sesquiterpenes, which also had comparable concentrations. The stems of TW seedlings had higher concentrations of sesquiterpenes than those of TY trees. In contrast, the number of sesquiterpene species and their concentrations in the roots of TW seedlings were much lower than those in the roots of TY trees. Cluster analysis of sesquiterpenes estimated that there are at least four terpene synthase genes involved in the production of sesquiterpenes in C. officinalis. Because sesquiterpenes are highly volatile, emissions of sesquiterpenes from healthy and wounded TW seedlings were examined using headspace analysis. Whereas very low emission of sesquiterpenes was detected from undamaged plants, the physically injured seedlings emitted a large number of sesquiterpenes, the quality and the relative quantity of which were similar to those in leaves determined using organic extraction. The implications of our findings to the biosynthetic pathways leading to the production of sesquiterpenes as well as their biological roles in C. officinalis are discussed.     

Sesquiterpenoids of Riccardia and Pallavicinia species

Riccardia species (Metzgeriales) contain various types of sesquiterpenes. R. jackii produces ent-selinane-, ent-aromadendrane-and ent-bicyclogermacrane-type sesquiterpenes together with (R)-cuparene and α-barbatene. Aneura pinguis (= Riccardia pinguis) is chemically quite different from R. multifida and R. jackii. The former produces a large amount of pinguisone. R. multifida contains 6-(3-methyl-2-butenyl)-indole and (+)-β-elemene as the major components. Pallavicinia longispina (Dilaenaceae; Metzgeriales) produces mainly spathulenol. The chiral properties of the sesquiterpenes isolated from R. jackii are quite similar to those of red algae, Laurencia species.     

Phytochemistry and chemotaxonomy of Sideritis species from the Mediterranean region

The phytochemical content of the Mediterranean species of the Sideritis genus has been reviewed. The components included in this review are monoterpenes, sesquiterpenes, diterpenes, triterpenes, sterols, flavones, coumarins and phenylpropanoids. From the chemotaxonomic point of view, we have divided the species from this region into four groups. The first of this is formed by taxa containing triterpenes, but not diterpenes. A second group is constituted by species having bicyclic diterpenes of the labdane type and not diterpenes. The third group is characterized by its content in tetracyclic diterpenes of the ent-kaurene type. A fourth group is composed of plants with tetracyclic diterpenes of the ent-beyer-15-ene and/or ent-atis-13-ene class. In addition, the relations of these Mediterranean species with those of the Macaronesian region have been examined.