Worldwide, there are plants known as psychoactive plants that naturally contain psychedelic active components. They have a high concentration of neuroprotective substances that can interact with the nervous system to produce psychedelic effects. Despite these plants' hazardous potential, recreational use of them is on the rise because of their psychoactive properties. Early neuroscience studies relied heavily on psychoactive plants and plant natural products (NPs), and both recreational and hazardous NPs have contributed significantly to the understanding of almost all neurotransmitter systems. Worldwide, there are many plants that contain psychoactive properties, and people have been using them for ages. Psychoactive plant compounds may significantly alter how people perceive the world.
1. BMC Plant Biol. 2012 Nov 20;12:219. doi: 10.1186/1471-2229-12-219. The plant short-chain dehydrogenase (SDR) superfamily: genome-wide inventory and diversification patterns. Moummou H(1), Kallberg Y, Tonfack LB, Persson B, van der Rest B. Author information: (1)Université de Toulouse, INPT-ENSAT, UMR990 Génomique et Biotechnologie des Fruits, Avenue de l'Agrobiopole, BP 32607, Castanet-Tolosan F-31326, France. BACKGROUND: Short-chain dehydrogenases/reductases (SDRs) form one of the largest and oldest NAD(P)(H) dependent oxidoreductase families. Despite a conserved 'Rossmann-fold' structure, members of the SDR superfamily exhibit low sequence similarities, which constituted a bottleneck in terms of identification. Recent classification methods, relying on hidden-Markov models (HMMs), improved identification and enabled the construction of a nomenclature. However, functional annotations of plant SDRs remain scarce. RESULTS: Wide-scale analyses were performed on ten plant genomes. The combination of hidden Markov model (HMM) based analyses and similarity searches led to the construction of an exhaustive inventory of plant SDR. With 68 to 315 members found in each analysed genome, the inventory confirmed the over-representation of SDRs in plants compared to animals, fungi and prokaryotes. The plant SDRs were first classified into three major types - 'classical', 'extended' and 'divergent' - but a minority (10% of the predicted SDRs) could not be classified into these general types ('unknown' or 'atypical' types). In a second step, we could categorize the vast majority of land plant SDRs into a set of 49 families. Out of these 49 families, 35 appeared early during evolution since they are commonly found through all the Green Lineage. Yet, some SDR families - tropinone reductase-like proteins (SDR65C), 'ABA2-like'-NAD dehydrogenase (SDR110C), 'salutaridine/menthone-reductase-like' proteins (SDR114C), 'dihydroflavonol 4-reductase'-like proteins (SDR108E) and 'isoflavone-reductase-like' (SDR460A) proteins - have undergone significant functional diversification within vascular plants since they diverged from Bryophytes. Interestingly, these diversified families are either involved in the secondary metabolism routes (terpenoids, alkaloids, phenolics) or participate in developmental processes (hormone biosynthesis or catabolism, flower development), in opposition to SDR families involved in primary metabolism which are poorly diversified. CONCLUSION: The application of HMMs to plant genomes enabled us to identify 49 families that encompass all Angiosperms ('higher plants') SDRs, each family being sufficiently conserved to enable simpler analyses based only on overall sequence similarity. The multiplicity of SDRs in plant kingdom is mainly explained by the diversification of large families involved in different secondary metabolism pathways, suggesting that the chemical diversification that accompanied the emergence of vascular plants acted as a driving force for SDR evolution. DOI: 10.1186/1471-2229-12-219 PMCID: PMC3541173 PMID: 23167570 [Indexed for MEDLINE] 2. Plant J. 2012 Mar;69(6):1052-63. doi: 10.1111/j.1365-313X.2011.04855.x. Epub 2011 Dec 28. Systematic knockdown of morphine pathway enzymes in opium poppy using virus-induced gene silencing. Wijekoon CP(1), Facchini PJ. Author information: (1)Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada. Opium poppy (Papaver somniferum) remains the sole commercial source for several pharmaceutical alkaloids including the narcotic analgesics codeine and morphine, and the semi-synthetic drugs oxycodone, buprenorphine and naltrexone. Although most of the biosynthetic genes have been identified, the post-transcriptional regulation of the morphinan alkaloid pathway has not been determined. We have used virus-induced gene silencing (VIGS) as a functional genomics tool to investigate the regulation of morphine biosynthesis via a systematic reduction in enzyme levels responsible for the final six steps in the pathway. Specific gene silencing was confirmed at the transcript level by real-time quantitative PCR (polymerase chain reaction), and at the protein level by immunoblot analysis using antibodies raised against salutaridine synthase (SalSyn), salutaridine reductase (SalR), salutaridine 7-O-acetyltransferase (SalAT), thebaine 6-O-demethylase (T6ODM), codeinone reductase (COR), and codeine O-demethylase (CODM). In some cases, silencing a specific biosynthetic gene resulted in a predictable accumulation of the substrate for the corresponding enzyme. Reduced SalSyn, SalR, T6ODM and CODM protein levels correlated with lower morphine levels and a substantial increase in the accumulation of reticuline, salutaridine, thebaine and codeine, respectively. In contrast, the silencing of genes encoding SalAT and COR resulted in the accumulation of salutaridine and reticuline, respectively, which are not the corresponding enzymatic substrates. The silencing of alkaloid biosynthetic genes using VIGS confirms the physiological function of enzymes previously characterized in vitro, provides insight into the biochemical regulation of morphine biosynthesis, and demonstrates the immense potential for metabolic engineering in opium poppy. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd. DOI: 10.1111/j.1365-313X.2011.04855.x PMID: 22098111 [Indexed for MEDLINE] 3. J Biol Chem. 2011 Feb 25;286(8):6532-41. doi: 10.1074/jbc.M110.168633. Epub 2010 Dec 17. Atomic structure of salutaridine reductase from the opium poppy (Papaver somniferum). Higashi Y(1), Kutchan TM, Smith TJ. Author information: (1)Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA. The opium poppy (Papaver somniferum L.) is one of the oldest known medicinal plants. In the biosynthetic pathway for morphine and codeine, salutaridine is reduced to salutaridinol by salutaridine reductase (SalR; EC 1.1.1.248) using NADPH as coenzyme. Here, we report the atomic structure of SalR to a resolution of ∼1.9 Å in the presence of NADPH. The core structure is highly homologous to other members of the short chain dehydrogenase/reductase family. The major difference is that the nicotinamide moiety and the substrate-binding pocket are covered by a loop (residues 265-279), on top of which lies a large "flap"-like domain (residues 105-140). This configuration appears to be a combination of the two common structural themes found in other members of the short chain dehydrogenase/reductase family. Previous modeling studies suggested that substrate inhibition is due to mutually exclusive productive and nonproductive modes of substrate binding in the active site. This model was tested via site-directed mutagenesis, and a number of these mutations abrogated substrate inhibition. However, the atomic structure of SalR shows that these mutated residues are instead distributed over a wide area of the enzyme, and many are not in the active site. To explain how residues distal to the active site might affect catalysis, a model is presented whereby SalR may undergo significant conformational changes during catalytic turnover. DOI: 10.1074/jbc.M110.168633 PMCID: PMC3057844 PMID: 21169353 [Indexed for MEDLINE] 4. J Biol Chem. 2009 Sep 25;284(39):26758-67. doi: 10.1074/jbc.M109.030957. Epub 2009 Jul 30. Removal of substrate inhibition and increase in maximal velocity in the short chain dehydrogenase/reductase salutaridine reductase involved in morphine biosynthesis. Ziegler J(1), Brandt W, Geissler R, Facchini PJ. Author information: (1)Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada. Salutaridine reductase (SalR, EC 1.1.1.248) catalyzes the stereospecific reduction of salutaridine to 7(S)-salutaridinol in the biosynthesis of morphine. It belongs to a new, plant-specific class of short-chain dehydrogenases, which are characterized by their monomeric nature and increased length compared with related enzymes. Homology modeling and substrate docking suggested that additional amino acids form a novel alpha-helical element, which is involved in substrate binding. Site-directed mutagenesis and subsequent studies on enzyme kinetics revealed the importance of three residues in this element for substrate binding. Further replacement of eight additional residues led to the characterization of the entire substrate binding pocket. In addition, a specific role in salutaridine binding by either hydrogen bond formation or hydrophobic interactions was assigned to each amino acid. Substrate docking also revealed an alternative mode for salutaridine binding, which could explain the strong substrate inhibition of SalR. An alternate arrangement of salutaridine in the enzyme was corroborated by the effect of various amino acid substitutions on substrate inhibition. In most cases, the complete removal of substrate inhibition was accompanied by a substantial loss in enzyme activity. However, some mutations greatly reduced substrate inhibition while maintaining or even increasing the maximal velocity. Based on these results, a double mutant of SalR was created that exhibited the complete absence of substrate inhibition and higher activity compared with wild-type SalR. DOI: 10.1074/jbc.M109.030957 PMCID: PMC2785364 PMID: 19648114 [Indexed for MEDLINE] 5. J Biol Chem. 2009 Sep 4;284(36):24425-31. doi: 10.1074/jbc.M109.011320. Epub 2009 Jun 26. Mammalian cytochrome P450 enzymes catalyze the phenol-coupling step in endogenous morphine biosynthesis. Grobe N(1), Zhang B, Fisinger U, Kutchan TM, Zenk MH, Guengerich FP. Author information: (1)Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA. A cytochrome P450 (P450) enzyme in porcine liver that catalyzed the phenol-coupling reaction of the substrate (R)-reticuline to salutaridine was previously purified to homogeneity (Amann, T., Roos, P. H., Huh, H., and Zenk, M. H. (1995) Heterocycles 40, 425-440). This reaction was found to be catalyzed by human P450s 2D6 and 3A4 in the presence of (R)-reticuline and NADPH to yield not a single product, but rather (-)-isoboldine, (-)-corytuberine, (+)-pallidine, and salutaridine, the para-ortho coupled established precursor of morphine in the poppy plant and most likely also in mammals. (S)-Reticuline, a substrate of both P450 enzymes, yielded the phenol-coupled alkaloids (+)-isoboldine, (+)-corytuberine, (-)-pallidine, and sinoacutine; none of these serve as a morphine precursor. Catalytic efficiencies were similar for P450 2D6 and P450 3A4 in the presence of cytochrome b(5) with (R)-reticuline as substrate. The mechanism of phenol coupling is not yet established; however, we favor a single cycle of iron oxidation to yield salutaridine and the three other alkaloids from (R)-reticuline. The total yield of salutaridine formed can supply the 10 nm concentration of morphine found in human neuroblastoma cell cultures and in brain tissues of mice. DOI: 10.1074/jbc.M109.011320 PMCID: PMC2782035 PMID: 19561069 [Indexed for MEDLINE]