Recent Articles – Oct, 12th 2018

From ACS Central Science

Imaging Mass Spectrometry Reveals Crosstalk between the Fallopian Tube and the Ovary that Drives Primary Metastasis of Ovarian Cancer


This is a great project and a great paper by Laura Sanchez group! A worthwhile reading.

From Chemical Reviews

Production and Synthetic Modifications of Shikimic Acid

From the Journal of Natural Products


Matrine-Type Alkaloids from the Roots of Sophora flavescens and Their Antiviral Activities against the Hepatitis B Virus


Spatial Distribution of Collections Yielding Marine Natural Products


Auranthine, a Benzodiazepinone from Penicillium aurantiogriseum: Refined Structure, Absolute Configuration, and Cytotoxicity


Irpeksins A–E, 1,10-seco-Eburicane-Type Triterpenoids from the Medicinal Fungus Irpex lacteus and Their Anti-NO Activity


From the Journal of the American Chemical Society

Oriented-External Electric Fields Create Absolute Enantioselectivity in Diels–Alder Reactions: Importance of the Molecular Dipole Moment


This seems to be an incredibly important breakthrough.

From Nature

First report of antimicrobial resistance pre-dates penicillin

This is a very interesting story.

How seventeenth-century sisters broke the mould on scientific illustration


How to write a thorough peer review


I highly reccomend the reading of this Nature paper. Well thought.

From Organic Letters

Stereodivergent Total Synthesis of Hapalindoles, Fischerindoles, Hapalonamide H, and Ambiguine H Alkaloids by Developing a Biomimetic, Redox-Neutral, Cascade Prins-Type Cyclization


Theionbrunonines A and B: Dimeric Vobasine Alkaloids Tethered by a Thioether Bridge from Mostuea brunonis


Synthesis and Characterization of Anguibactin To Reveal Its Competence To Function as a Thermally Stable Surrogate Siderophore for a Gram-Negative Pathogen, Acinetobacter baumannii


Plagiochianins A and B, Two ent-2,3-seco-Aromadendrane Derivatives from the Liverwort Plagiochila duthiana


From Angewandte Chemie International Edition

Chlorophyll Breakdown in a Fern—Discovery of Phyllobilin Isomers with a Rearranged Carbon Skeleton


Thinking Outside the Box—Novel Antibacterials To Tackle the Resistance Crisis


Computational Studies on Biosynthetic Carbocation Rearrangements Leading to Quiannulatene: Initial Conformation Regulates Biosynthetic Route, Stereochemistry, and Skeleton Type


Total Syntheses of Asperchalasines A–E


Genome Editing Reveals Novel Thiotemplated Assembly of Polythioamide Antibiotics in Anaerobic Bacteria


Structure, Total Synthesis, and Biosynthesis of Chloromyxamides: Myxobacterial Tetrapeptides Featuring an Uncommon 6‐Chloromethyl‐5‐methoxypipecolic Acid Building Block


From the European Journal of Organic Chemistry

Synthesis and biological evaluation of (modified) miuraenamides

From Chemistry World

Chemistry World is the dissemination journal edited by the Royal Society of Chemistry, UK. I consider some Chemistry World articles as of interest to the scientific community.

Wanted: chemistry’s next superstar – The drop in chemistry undergraduates highlights the need for more inspirational scientists

Time to rewrite the textbooks – How science corrects is an important lesson in the classroom

From folklore to pharmacy

Artificial intelligence seeks out new anticancer drugs – A combination of machine learning methods yields promising results for drug discovery

Novartis exit from antibiotics a setback for race against resistance

Derek Barton and shape-shifting molecules



Recent articles – Oct. 6th, 2018

From the Journal of Natural Products

Bromopyrrole Alkaloid Inhibitors of the Proteasome Isolated from a Dictyonella sp. Marine Sponge Collected at the Amazon River Mouth


From Nature

Major publishers sue ResearchGate over copyright infringement – Elsevier and the American Chemical Society say that the academic-networking website violates US copyright law.

University tenure decisions still gloss over scientists’ public outreach – Analysis of internal documents shows that promotions and tenure largely depend on metrics such as the number of publications and citations.

Co-production from proposal to paper – Three examples show how public participation in research can be extended at every step of the process to generate useful knowledge.

The best research is produced when researchers and communities work together – Knowledge generated in partnership with the public and policymakers is more likely to be useful to society and should be encouraged.

‘Test-tube’ evolution wins Chemistry Nobel Prize – Frances Arnold, Gregory Winter and George Smith controlled evolution in the lab to produce greener technologies and new medicines.

Better teachers are needed to improve science education – The latest training techniques emphasize classroom practice and design thinking.

Expanding the reach of science – Science education could bring new opportunities to developing countries.

Science and technology education – Science education is being modernized to give students the skills they will need for jobs in the future.

From Organic Letters

Plagiochianins A and B, Two ent-2,3-seco-Aromadendrane Derivatives from the Liverwort Plagiochila duthiana


One-Pot Total Synthesis of Evodiamine and Its Analogues through a Continuous Biscyclization Reaction


Total Synthesis of the Proposed Structure of Mycobactin J


Divergent Coupling of 2-Carbonyl-anilines and Diazo-cyclopentanones: Asymmetric Total Synthesis of (+)-Leucomidine A


From Organic & Biomolecular Chemistry

First enantioselective total synthesis of altersolanol A

Total synthesis, structural revision and biological evaluation of γ-elemene-type sesquiterpenes


Recent Articles – Sept 30, 2018

From ACS Chemical Biology

Molecular Basis for Autocatalytic Backbone N-Methylation in RiPP Natural Product Biosynthesis


From Science

Vaccines Against a Vanishing Virus?

From the Journal of Medicinal Chemistry

Two Decades under the Influence of the Rule of Five and the Changing Properties of Approved Oral Drugs


Structure-Based Drug Design and Identification of H2O-Soluble and Low Toxic Hexacyclic Camptothecin Derivatives with Improved Efficacy in Cancer and Lethal Inflammation Models in Vivo


Improved Total Synthesis and Biological Evaluation of Coibamide A Analogues


From The Journal of Organic Chemistry

A Copper-Mediated Conjugate Addition Approach to Analogues of Aconitine-Type Diterpenoid Alkaloids


Another remarkable syntheses by Richmond Sarpong’s group

Total Synthesis of (+)-Pyrenolide D


From the Journal of the American Chemical Society

Twelve-Step Asymmetric Synthesis of (−)-Nodulisporic Acid C


From Marine Drugs

Antibiotics from Deep-Sea Microorganisms: Current Discoveries and Perspectives

A review by Marcel Jaspars and Donatella de Pascalle research teams.

From Nature

Can we engineer ourselves to be lucky scientists?

Brexit is already damaging European science

The quest for postdoctoral independence

No more first authors, no more last authors

From Organic Letters

Tricholumin A, a Highly Transformed Ergosterol Derivative from the Alga-Endophytic Fungus Trichoderma asperellum


Premnafulvol A: A Diterpenoid with a 6/5/7/3-Fused Tetracyclic Core and Its Biosynthetically Related Analogues from Premna fulva


Total Synthesis of Anti-tuberculosis Natural Products Ilamycins E1 and F

From Natural Product Reports

Challenges in the configuration assignment of natural products. A case-selective perspective

From Phytochemistry

Armochaetoglasins A–I: Cytochalasan alkaloids from fermentation broth of Chaetomium globosum TW1-1 by feeding L-tyrosine


Recent articles – Sept 22nd, 2018

From Science magazine

A New Antibiotic? Yes, Please

From the Journal of Natural Products

Active Natural Product Scaffolds against Trypanosomatid Parasites: A Review


Dinghupeptins A–D, Chymotrypsin Inhibitory Cyclodepsipeptides Produced by a Soil-Derived Streptomyces


Nematicidal Cyclic Lipodepsipeptides and a Xanthocillin Derivative from a Phaeosphariaceous Fungus Parasitizing Eggs of the Plant Parasitic Nematode Heterodera filipjevi


Diversity-Oriented Synthesis of Steviol Glycosides

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Parasubindoles A–G, Seven Eremophilanyl Indoles from the Whole Plant of Parasenecio albus


From the Journal of the American Chemical Society

Streamlined Total Synthesis of Shishijimicin A and Its Application to the Design, Synthesis, and Biological Evaluation of Analogues thereof and Practical Syntheses of PhthNSSMe and Related Sulfenylating Reagents


Unveiling Biosynthesis of the Phytohormone Abscisic Acid in Fungi: Unprecedented Mechanism of Core Scaffold Formation Catalyzed by an Unusual Sesquiterpene Synthase


Cytochrome P450-Catalyzed Hydroxylation Initiating Ether Formation in Platensimycin Biosynthesis


From Nature Chemistry

A positive positive to negative

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From Nature magazine

Discovery of Galileo’s long-lost letter shows he edited his heretical ideas to fool the Inquisition


From Organic Letters

Structures and Synthesis of Hitoyopodins: Bioactive Aromatic Sesquiterpenoids Produced by the Mushroom Coprinopsis cinerea


Enantioselective and Divergent Syntheses of Alstoscholarisines A, E and Their Enantiomers


Asymmetric Cα-Alkylation of Proline via Chirality Transfers of Conformationally Restricted Proline Derivative: Application to the Total Synthesis of (−)-Amathaspiramide F


Total Synthesis of Asperphenins A and B


From Natural Product Reports

Total synthesis of sesterterpenoids

From Organic & Biomolecular Chemistry

Xylopsides A–D, four rare guaiane dimers with two unique bridged pentacyclic skeletons from Xylopia vielana

Dimericursones A and B: two unprecedented hexacyclic dimeric diterpenoids from the root barks of Jatropha curcas

From the European Journal of Organic Chemistry

Total synthesis of an anticancer natural product (±)‐peharmaline A and its analogues

From Angewandte Chemie International Edition

Enzymology of Anthraquinone‐γ‐Pyrone Ring Formation in Complex Aromatic Polyketide Biosynthesis


Brazilian News on Science – Sept 22th, 2018

Some posts will be dedicated to news from the Brazilian press on science and related subjects. I apologize to people who cannot read in Portuguese.

Novo acelerador de partículas do país terá R$ 70 mi para 1ª volta de elétrons – Sirius, em Campinas, ainda precisa de R$ 510 milhões para conclusão, mas teste deve ser em novembro.

Novo satélite caçador de planetas da Nasa faz suas duas primeiras descobertas

Hayabusa2 lança dois minirrovers à superfície do asteroide Ryugu

Sob ecstasy, polvos ficam mais sociáveis e abraçam colegas em estudo

Dos micróbios ao homem: a vida tem um objetivo? – Marcelo Gleiser

Morre aos 96 o agrônomo Warwick Kerr, brasileiro que ajudou a decifrar as abelhas

Para quem não sabe, Kerr foi também o primeiro Diretor Científico da FAPESP.

Ayahuasca impulsiona ciência psicodélica no Brasil

Ensino superior volta a crescer no país, mas só na modalidade a distância

Propostas dos candidatos na educação miram melhoria do ensino médio

Universidades do Brasil caem em ranking mundial de empregabilidade de egressos

Mais da metade dos brasileiros não tem diploma do ensino médio, aponta OCDE

No topo de ranking, ES alavanca ensino médio sem ‘reinventar a roda’

Cientistas propõem criação de Marco Legal para grandes colaborações internacionais


Recent articles – September 19th, 2018

From Organic Letters

Crystalline Sponge Method Enabled the Investigation of a Prenyltransferase-terpene Synthase Chimeric Enzyme, Whose Product Exhibits Broadened NMR Signals


Computationally Assisted Assignment of the Kadsuraols, a Class of Chemopreventive Agents for the Control of Liver Cancerol-2018-02207d_0008

Total Synthesis of Repraesentin F and Configuration Reassignment by a Gold(I)-Catalyzed Cyclization Cascade


Sophalines E–I, Five Quinolizidine-Based Alkaloids with Antiviral Activities against the Hepatitis B Virus from the Seeds of Sophora alopecuroides


Total Synthesis of Chaetoglobin A via Catalytic, Atroposelective Oxidative Phenol Coupling


Hyperdioxane A, a Conjugate of Dibenzo-1,4-dioxane and Sesquiterpene from Hypericum ascyron


Bioinspired Synthesis of Pygmaeocins and Related Rearranged Abietane Diterpenes: Synthesis of Viridoquinone


Total Biosynthesis of Brassicicenes: Identification of a Key Enzyme for Skeletal Diversification


From Nature magazine

Reboot undergraduate courses for reproducibility

Collaboration across institutes can train students in open, team science, which better prepares them for challenges to come, says Katherine Button.

Three years ago, as I prepared to start as a lecturer in the University of Bath’s psychology department, I reflected on my own undergraduate training. What should I emulate? What would I like to improve? The ‘reproducibility crisis’ was in full swing. Many of the standard research practices I had been taught were now shown to be flawed, from P-value hacking to ‘HARKing’ — hypothesizing after the results are known — and an over-reliance on underpowered studies (that is, drawing oversized conclusions from undersized samples).

It struck me that the research dissertation students do in their final year is almost a bootcamp for instilling these bad habits. Vast numbers of projects, limited time and resources, small sample sizes, the potential for undisclosed analytic flexibility (P-hacking) and a premium on novelty: together, a recipe for irreproducible results.

(read more…)

The fast track

Scientists are under increasing pressure to perform a variety of tasks earlier in their careers.

If ideas are the flames burning from the torches of discovery, scientists are the hands that hold them. Creative minds uphold the scientific enterprise.

In recognition of their leading role, Nature Index 2018 Rising Stars profiles 11 up-and-coming researchers in the natural sciences. These scientists are highlighted based on their recent contributions to the 82 journals tracked by the Nature Index, and their standing in the League of Scholars Whole-of-Web ranking, which assesses individuals on their research quality and impact, industry links and co-authorship networks. Their work ranges from analysing peatland and permafrost, to developing wearable electronics.

(read more…)

This is a short article that highlights the research of eleven young investigators, in the link in the middle of the text above. Among the young scientists, the chemist  Silvia Marchesan and the engineering Sahar Sharifzadeh.

Judge dismisses criminal charges against US university chemist over lab death

A judge in Los Angeles county has dismissed a criminal case against chemist Patrick Harran, who faced charges of violating health and safety standards after an accidental death in his laboratory nine years ago.

The charges stemmed from a 2009 incident in which Sheharbano Sangji, a research assistant in Harran’s lab at the University of California, Los Angeles (UCLA), died from third-degree burns incurred during a chemical fire. Sangji was handling t-butyl lithium with a syringe when the compound exploded into flames.

(read more…)

Turn off your e-mail and social media to get more done

Distractions are a fundamental aspect of the modern world, but we don’t have to become hermits to avoid them.

(read more…)

This is an article about the obvious.

Help graduate students to become good peer reviewers

Pedagogy helps to prepare undergraduates for the research lab

Optimized arylomycins are a new class of Gram-negative antibiotics

Multidrug-resistant bacteria are spreading at alarming rates, and despite extensive efforts no new class of antibiotic with activity against Gram-negative bacteria has been approved in over fifty years. Natural products and their derivatives have a key role in combating Gram-negative pathogens. Here we report chemical optimization of the arylomycins—a class of natural products with weak activity and limited spectrum—to obtain G0775, a molecule with potent, broad-spectrum activity against Gram-negative bacteria. G0775 inhibits the essential bacterial type I signal peptidase, a new antibiotic target, through an unprecedented molecular mechanism. It circumvents existing antibiotic resistance mechanisms and retains activity against contemporary multidrug-resistant Gram-negative clinical isolates in vitro and in several in vivo infection models. These findings demonstrate that optimized arylomycin analogues such as G0775 could translate into new therapies to address the growing threat of multidrug-resistant Gram-negative infections.

(it needs to have a subscription to read more)

Peer reviewers unmasked: largest global survey reveals trends

Scientists in emerging economies respond fastest to peer review invitations, but are invited least.

Scientists in developed countries provide nearly three times as many peer reviews per paper submitted as researchers in emerging nations, according to the largest ever survey of the practice.

The report — which surveyed more than 11,000 researchers worldwide — also finds a growing “reviewer fatigue”, with editors having to invite more reviewers to get each review done. The number rose from 1.9 invitations in 2013 to 2.4 in 2017.

(read more…)

This article is truly interesting. Some facts included in the article.

PEER REVIEW IN NUMBERS – Data from the Global State of Peer Review report for 2013–17

68.5 million hours spent reviewing globally each year

16.4 days is the median review time

5 hours is the median time spent writing each review

477 words is the average length of review reports

10% of reviewers are responsible for 50% of peer reviews

41% of survey respondents see peer review as part of their job

75% of journal editors say the hardest part of their job is finding willing reviewers

71% of researchers decline review requests because the article is outside their area of expertise

42% of researchers decline review requests because they are too busy

39% of reviewers never received any peer-review training

Some of our colleagues think that peer-review should not be considered an important academic activity. OK, then. These fellows should read this another Nature article.

From the European Journal of Organic Chemistry

The Hydroxylated, Tetracyclic Bisquinolizidine Alkaloids Baptifoline and Epibaptifoline: Enantioselective Synthesis and Unambiguous Assignment of their Configuration at C‐13

From Angewandte Chemie International Edition

Total Synthesis of Asperchalasines A, D, E, and H


Outstanding syntheses by Dr. Jun Deng’s group. In the case of the synthesis of asperchalasine A, it involved three cycloadditions, one of which is a [5+2] cycloaddition.

Recent Articles

From Angewandte Chemie International Edition

Total Synthesis of C30 Botryococcene and epi‐Botryococcene by a Diastereoselective Ring Opening of Alkenylcyclopropanes


Synthesis, Structural Reassignment, and Antibacterial Evaluation of 2,18‐Seco‐Lankacidinol B


Editorial – Empowering Students to Innovate: Engagement in Organic Chemistry Teaching

I recently had the pleasure of competing for the Robert Foster Cherry Award for Great Teaching given biennially by Baylor University. In preparing for the competition, I spent considerable time reflecting on my own past experiences as a student, as well as the key philosophies that have helped to transform organic chemistry—often dreaded by students—into one of the most popular classes on the UCLA campus. In this Guest Editorial, I focus on just one key aspect, which involves capturing the extraordinary potential of our students to innovate.

As a “pre‐med” student at NYU, I took chemistry courses out of necessity. “OChem” in particular was reputed to be an intense weed‐out class that required exhaustive memorization and regurgitation of information. On our first day of class in 1997, Professor Yorke Rhodes convinced us otherwise. He told tales of the great contemporary organic chemists who were educated at NYU, such as Professors Eric Jacobsen and Al Myers, along with recent graduate Phil Baran, who was already a rising star in graduate school at the time.

(read more…)

Enantioselective Total Synthesis of (+)‐Plumisclerin A


Total Synthesis of Epicolactone


From Natural Product Reports

Hot off the Press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as huperphlegmine A from Huperzia phlegmaria.

Graphical abstract: Hot off the Press

From the Journal of Natural Products

Medermycin-Type Naphthoquinones from the Marine-Derived Streptomyces sp. XMA39


From ACS Medicinal Chemistry Letters

Marine Natural Products in Medicinal Chemistry


Recent Articles

Toward Understanding the Chemistry and Biology of 1-Deoxy-d-xylulose 5-Phosphate (DXP) Synthase: A Unique Antimicrobial Target at the Heart of Bacterial Metabolism



Synthetic Lava Brings Eruption into the Lab


Molecular Basis for Olefin Rearrangement in the Gephyronic Acid Polyketide Synthase



Biochemical and Structural Characterization of TtnD, a Prenylated FMN-Dependent Decarboxylase from the Tautomycetin Biosynthetic Pathway


Unexpected Bacterial Origin of the Antibiotic Icosalide: Two-Tailed Depsipeptide Assembly in Multifarious Burkholderia Symbionts


Chemistry and Properties of Indolocarbazoles


Open Access With A Vengeance

Derek Lowe – Here’s something to keep an eye on: eleven of the largest national research funding agencies in Europe have announced a plan to require open-access publication of papers arising from their grants. The plan is that by 2020, all such work must be published in compliant open-access journals or on compliant open-access platforms. (read more…)

Sulfonic Acid-Containing Flavonoids from the Roots of Phyllanthus acidus

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Calothrixamides A and B from the Cultured Cyanobacterium Calothrix sp. UIC 10520

The first author of this paper is Camila M. Crnkovic, a Brazilian student who obtained a PhD degree at the School of Pharmacy, University of Illinois, Chicago, under the supervision of Jimmy Orjala.


GEX1A, a Polyketide from Streptomyces chromofuscus, Corrects the Cellular Defects Associated with Niemann-Pick Type C1 in Human Fibroblasts


Peloruside E (22-Norpeloruside A), a Pelorusane Macrolide from the New Zealand Marine Sponge Mycale hentscheli, Retains Microtubule-Stabilizing Properties


Colocynthenins A–D, Ring-A seco-Cucurbitane Triterpenoids from the Fruits of Citrullus colocynthis


Hexaricins, Pradimicin-like Polyketides from a Marine Sediment-Derived Streptosporangium sp. and Their Antioxidant Effects


Investigation of the Biosynthesis of the Lasso Peptide Chaxapeptin Using an E. coli-Based Production System


Diaporindenes A–D: Four Unusual 2,3-Dihydro-1H-indene Analogues with Anti-inflammatory Activities from the Mangrove Endophytic Fungus Diaporthe sp. SYSU-HQ3


Divergent Diels–Alder Reactions in the Biosynthesis and Synthesis of Endiandric-Type Tetracycles: A Computational Study


Target Identification of Yaku’amide B and Its Two Distinct Activities against Mitochondrial FoF1-ATP Synthase


C–H Hydroxylation in Paralytic Shellfish Toxin Biosynthesis

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Divergent Entry to Gelsedine-Type Alkaloids: Total Syntheses of (−)-Gelsedilam, (−)-Gelsenicine, (−)-Gelsedine, and (−)-Gelsemoxonine


Sodorifen Biosynthesis in the Rhizobacterium Serratia plymuthica Involves Methylation and Cyclization of MEP-Derived Farnesyl Pyrophosphate by a SAM-Dependent C-Methyltransferase


Metabolic and Biosynthetic Diversity in Marine Myxobacteria

Substrate-assisted enzymatic formation of lysinoalanine in duramycin


Biosynthesis and chemical diversity of β-lactone natural products

Graphical abstract: Biosynthesis and chemical diversity of β-lactone natural products

The architectures of iterative type I PKS and FAS

Graphical abstract: The architectures of iterative type I PKS and FAS

Pyridoxal phosphate-dependent reactions in the biosynthesis of natural products

Graphical abstract: Pyridoxal phosphate-dependent reactions in the biosynthesis of natural products

Unusual subunits are directly involved in binding substrates for natural rubber biosynthesis in multiple plant species


Recent Articles

Reconstitution of Enzymatic Carbon–Sulfur Bond Formation Reveals Detoxification-Like Strategy in Fungal Toxin Biosynthesis


Mycobacterial MenJ: An Oxidoreductase Involved in Menaquinone Biosynthesis


Estudo traz novas pistas sobre sofisticada sociedade que ergueu enigmáticas estátuas gigantes da Ilha de Páscoa – A maior parte dos quase 900 moais mede de 4 a 6 metros de altura

Céticos do clima devem pedido de desculpas a quem acreditou neles

Abyssomicin Monomers and Dimers from the Marine-Derived Streptomyces koyangensis SCSIO 5802


Review of Natural Product Biosynthesis: Chemical Logic and Enzymatic Machinery


Staurosporine Derivatives Generated by Pathway Engineering in a Heterologous Host and Their Cytotoxic Selectivity


Complete Genome of Micromonospora sp. Strain B006 Reveals Biosynthetic Potential of a Lake Michigan Actinomycete


Catenulobactins A and B, Heterocyclic Peptides from Culturing Catenuloplanes sp. with a Mycolic Acid-Containing Bacterium


Ansamycins with Antiproliferative and Antineuroinflammatory Activity from Moss-Soil-Derived Streptomyces cacaoi subsp. asoensis H2S5


Terpeno produzido por actinobactéria entra na composição de perfumes

Reportagem publicada no jornal Folha de São Paulo comenta sobre o “odor da chuva” e alguns de seus principais componentes, que já estão sendo utilizados na composição de perfumes, como a geosmina, produzida por uma actinobactéria.

Por que o cheiro da chuva é tão bom? – Bactérias, plantas e até trovoadas têm influência no aroma de ar limpo

Não é só alívio, após um longo período de seca, que faz com que o cheiro da chuva seja tão bom. Há também a química envolvida.

Bactérias, plantas e até trovoadas têm influência no aroma de ar limpo e terra molhada que a gente sente após uma tempestade. Conhecido como “petrichor”, esse odor tem sido estudado por cientistas e até por fabricantes de perfume.


O nome “petrichor” foi cunhado por dois pesquisadores australianos em 1960. A palavra vem do grego “petros”, que significa “pedra”, e do termo “ichor”, que quer dizer “o fluido que passa pelas veias dos deuses”.

Essa fragrância que a gente sente quanto a chuva bate no solo é produzida por uma bactéria. “Micróbios são abundantes no solo”, explica o professor Mark Buttner, diretor do departamento de microbiologia do John Innes Centre, na Inglaterra.

“Quando você diz que sente cheiro de terra molhada, na verdade está sentindo o cheiro de uma molécula sendo criada por um certo tipo de bactéria”, disse ele à BBC News.

Essa molécula é o “geosmin” (1), produzido pela bactéria Streptomyces. Presente na maioria dos solos saudáveis, essa bactéria também é usada para produzir alguns tipos de antibióticos.

Quando as gotas de água caem na terra, fazem com que o geosmin (1) seja lançado no ar, tornando-o bem mais abundante do que antes da chuva. “Vários animais são sensíveis a esse cheiro, mas os seres humanos são extremamente sensíveis a ele”, diz Buttner.


Os pesquisadores Isabem Bear e RG Thomas, que deram o nome de “petrichor” ao cheiro da chuva, descobriram que na década de 1960 ele já era “capturado” para ser vendido como uma essência chamada “matti ka attar”, em Uttar Pradesh, na Índia.

Agora, o geosmin está se tornando mais comum como ingrediente de perfume. “É uma substância potente. Há algo de bem primitivo nesse cheiro”, afirma a perfumista Marina Barcenilla. “Mesmo quando você o dilui, ainda é possível identificá-lo”, acrescenta.

Mas nós temos uma relação contraditória com o geosmin –ao mesmo tempo em que somos atraídos pelo aroma dele, muitos de nós tem aversão pelo gosto.

Embora não seja tóxico para seres humanos, pequenas quantidades podem fazer com que rejeitemos um copo de água ou de vinho que tenha sido “contaminado” pela substância. “Não sabemos por que não gostamos de geosmin. Por algum motivo, associamos a algo ruim”, diz o professor Jeppe Lund Nielson, da Universidade de Aalborg, na Dinamarca.


De acordo com Nielson, pesquisas sugerem que o geosmin pode estar relacionado ao “terpeno” –fonte do perfume de várias plantas. E a chuva pode acentuar essas fragrâncias, diz o professor Philip Stevenson, pesquisador-chefe do Royal Botanic Gardens, em Londres.

“Normalmente, as químicas das plantas que têm cheiro bom são produzidas pelos ‘cabelos’ das folhas. As chuvas podem danificar as folhas e, com isso, soltar os componentes dela”, explica.

“A chuva também pode romper materiais secos das plantas, liberando substâncias químicas de forma similar a quando quebramos e esmagamos ervas. Com isso, o cheiro fica mais forte.”

Períodos de seca também podem reduzir o metabolismo das plantas. O retorno das chuvas pode desencadear uma aceleração, fazendo com que as plantas exalem um cheiro agradável.

As trovoadas também desempenham um papel relevante, ao criar um aroma de ozônio acentuado e limpo, em decorrência das descargas elétricas na atmosfera.

“Além dos raios, as trovoadas e chuvas ajudam a melhorar a qualidade do ar. A poeira, o aerossol e outras partículas são varridas pela chuva e pelos raios, limpando o ar”, explica a professora Maribeth Stolzenburg da Universidade do Mississippi, nos EUA.

Conheçam mais sobre a biossíntese da geosmina, e outros terpenos de bactérias, em artigo de David E. Cane e Haruo Ikeda, publicado em 2012 na revista Accounts of Chemical Research.