Phytoprostanes are prostaglandin/jasmonate-like products of nonenzymatic lipid peroxidation that not only occur ubiquitously in healthy plants but also increase in response to oxidative stress. In this work, we show that the two naturally occurring B 1 -phytoprostanes (PPB 1 ) regioisomers I and II (each comprising two enantiomers) are short-lived stress metabolites that display a broad spectrum of biological activities. Gene expression analysis of Arabidopsis (Arabidopsis thaliana) cell cultures treated with PPB 1 -I or -II revealed that both regioisomers triggered a massive detoxification and defense response. Interestingly, expression of several glutathione S-transferases, glycosyl transferases, and putative ATP-binding cassette transporters was found to be increased by one or both PPB 1 regioisomers, and hence, may enhance the plant's capacity to inactivate and sequester reactive products of lipid peroxidation. Moreover, pretreatment of tobacco (Nicotiana tabacum) suspension cells with PPB 1 considerably prevented cell death caused by severe CuSO 4 poisoning. Several Arabidopsis genes induced by PPB 1 , such as those coding for adenylylsulfate reductase, tryptophan synthase b-chain, and PAD3 pointed to an activation of the camalexin biosynthesis pathway that indeed led to the accumulation of camalexin in PPB 1 treated leaves of Arabidopsis. Stimulation of secondary metabolism appears to be a common plant reaction in response to PPB 1 . In three different plant species, PPB 1 -II induced a concentration dependent accumulation of phytoalexins that was comparable to that induced by methyl jasmonate. PPB 1 -I was much weaker active or almost inactive. No differences were found between the enantiomers of each regioisomer. Thus, results suggest that PPB 1 represent stress signals that improve plants capacity to cope better with a variety of stresses.Phytoprostanes belong to a novel family of plant effectors that are formed nonenzymatically by a free radical catalyzed biochemical mechanism from a-linolenic acid. Via an identical nonenzymatic mechanism, isoprostanes (isomers of prostaglandins) are formed in animals from arachidonic acid. Nomenclature used to name different phytoprostane classes conforms with the general isoprostane/prostaglandin terminology . Due to the nonenzymatic formation of phytoprostanes, two racemic regioisomers (type I and II) of each class can be generated. One pathway leads to the formation of B 1 -phytoprostanes (PPB 1 ; Fig. 1) that are chemically stable end products of lipid peroxidation. In animals, isoprostanes are not only extremely reliable markers of oxidative stress but also display potent (prostaglandin-) receptor-mediated biological activities in the nanomolar concentration range (Cracowski et al., 2002). Therefore, it is postulated that isoprostanes represent mediators of oxidant injury in animals.In plants, several classes of phytoprostanes are constitutively present, and, notably, their levels increase in a variety of conditions associated with enhanced free radical generatio...

Three new naphthylisoquinoline alkaloids, the 7,3'-coupled ancistrotanzanine C (6), the 5,1'-coupled O-methylancistrocladinine (7), and the likewise 5,1'-coupled O,N-dimethylancistrocladine (8, previously known only as a partial-synthetic compound), have been isolated from the highland liana Ancistrocladus tanzaniensis, along with the two known 7,3'-coupled naphthylisoquinoline alkaloids ancistrocladidine (4) and ancistrotectorine (5). All of the compounds are S-configured at C-3 and bear an oxygen at C-6, and thus belong to the so-called Ancistrocladaceae type, similar to 1-3 previously isolated from this newly discovered plant species. The structural elucidation was achieved by chemical, spectroscopic, and chiroptical methods. The biological activities of the alkaloids against the pathogens causing malaria tropica, leishmaniasis, Chagas' disease, and African sleeping sickness were evaluated.

The first phytochemical investigation of the recently discovered East African liana Ancistrocladus tanzaniensis is described, resulting in the isolation and structural elucidation of two new naphthylisoquinoline alkaloids, ancistrotanzanines A (5) and B (6), and the known compound ancistrotectoriline A (7). Ancistrotazanine A (5) represents a hitherto unprecedented 5,3'-coupling type between the naphthalene and isoquinoline portions, while 6 and 7 are 5,8'-coupled. The structures of the compounds were determined by spectroscopic, chemical, and chiroptical methods. Compounds 5 and 6 showed good activities against the pathogens of leishmaniasis and Chagas' disease, Leishmania donovani and Trypanosoma cruzi, while 5-7 displayed moderately potent antiplasmodial activities against Plasmodium falciparum parasites.