Brominated metabolites from an Okinawan Laurencia intricata

Two halogenated C₁₅ acetogenins, itomanallenes A and B, with a terminal bromoallene moiety along with a halogenated sesquiterpene, itomanol, have been isolated from the red alga Laurencia intricata collected in Okinawan waters. Their structures were deduced from 1D and 2D NMR experiments including ¹H–¹H COSY, HSQC, HMBC, and NOESY methods. The alcohol corresponding to itomanallene B seems to be a plausible precursor of itomanallene A, which has an unusual 2,10-dioxabicyclo[7.3.0]dodecene skeleton. Itomanol was found to be a selinane-type bromosesquiterpenoid, and is the first example of a selinane to be isolated from Japanese Laurencia species.     

番荔枝内酯抑制线粒体复合物Ⅰ的作用机理

番荔枝内酯是对线粒体复合物Ⅰ具有强烈抑制作用的天然产物,它是一条以含末端γ-内酯环及四氢呋喃环为主要结构特征的长烷基链化合物。本文简述了番荔枝内酯抑制线粒体复合物Ⅰ的动力学特征和构效关系以及作为抗癌药物与杀虫剂的应用情况。     

Terrestrial Plant-Derived Anticancer Agents and Plant Species Used in Anticancer Research

Cancer is a major cause of death and the number of new cases, as well as the number of individuals living with cancer, is expanding continuously. Due to the enormous propensity of plants that synthesize mixtures of structurally diverse bioactive compounds, the plant kingdom is potentially a very diverse source of chemical constituents with tumor cytotoxic activity. Despite the successful utilization of few phytochemicals, such as vincristine and taxol, into mainstream cancer chemotherapy, commercial plant-derived anticancer formulations represent only one-fourth of the total repertoire of the available treatment options. Though significant progress has been made towards the characterization of isolated compounds and their structure-related activities, the complex composition of plant extracts, along with the lack of reproducibility of activity and the synergy between different, even unidentified, components of an extract, prohibits the full utilization of plants in pharmaceutical research. In this review, the results of an extensive literature survey on the anticancer properties of terrestrial plants, covering a thirty-five-year-long span (1970–2005) are presented. A total of 187 plant species, belonging to 102 genera and 61 families have been identified as an active or promising source of phytochemicals with antitumor properties, corresponding to a 41 percent increase during the last five years. Among them, only 15 species (belonging to ten genera and nine families) have been utilized in cancer chemotherapy at a clinical level, whereas the rest of the identified species are either active against cancer cell lines or exhibit chemotherapeutic properties on tumor-bearing animals under experimental conditions. Phenylpropanoids are the most widely distributed compounds (18 families), followed by terpenoids (14 families), and alkaloids (13 families). Analytical, species-specific information on bioactive constituents and target cancers is provided. The outlook of phytochemistry-based cancer therapy is discussed, particularly in the perspective of identifying immunomodulatory anticancer agents with minimal toxicity on healthy tissues.

     

乐山蜘蛛抱蛋的甾体皂甙

乐山蜘蛛抱蛋;;蜘蛛抱蛋皂甙;;铃兰皂甙元Ｂ－５－Ｏ－β－Ｄ－吡喃葡萄糖甙     

Two New Halogenated Compounds from the Marine Red Alga Laurencia nipponica Yamada from the Kunashiri and Etorofu Islands

The red alga Laurencia nipponica comprises various chemical races distributed relative to the ocean current in Japanese coastal areas. We investigated the chemical compositions and chemical races of L. nipponica distributed from the Kunashiri and Etorofu Islands, the confluence of the Soya warm current and Oya-shio cold current. Two new halogenated secondary metabolites, deacetylneonipponallene ( 1 ) and neopacifenol ( 2 ), along with four known compounds, deoxyprepacifenol ( 3 ), pacifenol ( 4 ), halo-chamigrene diether ( 5 ), and isolaurallene ( 6 ) were isolated from L. nipponica collected at Chikappunai, Kunashiri Island, while Zaimokuiwa (Kunashiri Island) and Sana (Etorofu Island) populations contained 3 , 7-hydroxylaurene ( 7 ), 2,10-dibromo-3-chloro-9-hydroxy-α-chamigrene ( 8 ), and (3Z)-laurefucin ( 9 ). The structures of 1 and 2 were established using spectroscopic methods. The chemical races of L. nipponica distributed in this area were divided into 6 - and 9 -producing races. Interestingly, both races contained 4 as an additional race-index, as well as its derivatives, 2 and 5 . To the best of our knowledge, this is the first example of a race comprising a mixture of two race-index compounds, suggesting that the convergence of two currents causes the production of new and diverse chemical races in this species.     

Antifouling Brominated Diterpenoids from Japanese Marine Red Alga Laurencia venusta Yamada

The marine red algal genus Laurencia has abundant halogenated secondary metabolites, which exhibit novel structural types and possess various unique biological potentials, including antifouling activity. In this study, we report the isolation, structure elucidation, and antifouling activities of two novel brominated diterpenoids, aplysin-20 aldehyde ( 1 ), 13-dehydroxyisoaplysin-20 ( 2 ), and its congeners. We screened marine red alga Laurencia venusta Yamada for their antifouling activity against the mussel Mytilus galloprovincialis. Ethyl acetate extracts of L. venusta from Hiroshima and Chiba, Japan, were isolated and purified, and the compound structures were identified using 1D and 2D NMR, HR-APCI-MS, IR, and chemical synthesis. Seven secondary metabolites were identified, and their antifouling activities were evaluated. Compounds 1 , 2 , and aplysin-20 ( 3 ) exhibited strong activities against M. galloprovincialis. Therefore, these compounds can be explored as natural antifouling drugs.