Therapeutic Efficiency of Humic Acids in Intoxications

Humins, humic and fulvic acids represent molecules with complex structures. These compounds comprising humic substances (HS) exist naturally in soil, brown coal, peat, and water. They are formed during the decomposition and transformation of organic matter (animal and plant remains) and their formation explains several theories. Within their chemical structures, there are numerous phenolic and carboxyl groups and their derivatives that affect their different properties, such as their solubility in water or their absorption of cations or mycotoxins. The manifold chemical structure of HS alters their polyelectrolyte character and thus their chelating efficiency. For many years, HS have been studied due to their detoxification, anti-, and pro-inflammatory or anticancer and antiviral ability. This article summarizes the antioxidant and adsorption properties of humic acids, highlighting their usefulness in intoxications.

[1]  G. Téllez-Isaías,et al.  Humic Acids Preparation, Characterization, and Their Potential Adsorption Capacity for Aflatoxin B1 in an In Vitro Poultry Digestive Model , 2023, Toxins.

[2]  A. Marcin,et al.  The Effect of Humic Substances on the Content of Copper and Zinc in the Turkey Muscle , 2023, Asian Journal of Agriculture and Food Sciences.

[3]  E. Papadaki,et al.  Application of Humic and Fulvic Acids as an Alternative Method of Cleaning Water from Plant Protection Product Residues , 2022, Separations.

[4]  E. Tombácz,et al.  Screening of Humic Substances Extracted from Leonardite for Free Radical Scavenging Activity Using DPPH Method , 2022, Molecules.

[5]  K. Haghbeen,et al.  Structural and inhibitory effects of fulvic and humic acids against tyrosinase. , 2022, Journal of food biochemistry.

[6]  A. Piccolo,et al.  Antibacterial and antioxidant properties of humic substances from composted agricultural biomasses , 2022, Chemical and Biological Technologies in Agriculture.

[7]  G. Fabbrocini,et al.  Antiflammatory activity and potential dermatological applications of characterized humic acids from a lignite and a green compost , 2022, Scientific Reports.

[8]  G. Téllez-Isaías,et al.  Effects of humic acids on the recovery of different bacterial strains in an in vitro chicken digestive model. , 2022, Research in veterinary science.

[9]  Md Nashid Anjum,et al.  Antimicrobial, anti-inflammatory and antioxidant activities of natural organic matter extracted from cretaceous shales in district Nowshera-Pakistan , 2021, Arabian Journal of Chemistry.

[10]  I. Perminova,et al.  A Systematic Study of the Antioxidant Capacity of Humic Substances against Peroxyl Radicals: Relation to Structure , 2021, Polymers.

[11]  M. Asanuma,et al.  Neuron-Astrocyte Interactions in Parkinson’s Disease , 2020, Cells.

[12]  E. Nikolaev,et al.  Antiviral activity of natural humic substances and shilajit materials against HIV-1: Relation to structure , 2020, Environmental Research.

[13]  B. B. Johnson,et al.  Adsorption of humic and fulvic acids onto a range of adsorbents in aqueous systems, and their effect on the adsorption of other species: A review , 2020 .

[14]  R. Glávits,et al.  A toxicological evaluation of a fulvic and humic acids preparation , 2020, Toxicology reports.

[15]  A. Yari Khosroushahi,et al.  Health Beneficial Effects of Moomiaii in Traditional Medicine , 2020, Galen medical journal.

[16]  J. Vašková,et al.  The effect of humic acid in chronic deoxynivalenol intoxication , 2020, Environmental Science and Pollution Research.

[17]  P. Mudroň,et al.  Effect of humic acids on lead poisoning in bones and on a subcellular level in mitochondria , 2020, Environmental Science and Pollution Research.

[18]  J. Drobnik,et al.  Central European ethnomedical and officinal uses of peat, with special emphasis on the Tołpa peat preparation (TPP): An historical review. , 2020, Journal of ethnopharmacology.

[19]  O. Drozdova,et al.  Participation of cadmium (ll) and copper (ll) ions in intermolecular forces of humic acids in solutions , 2019, IOP Conference Series: Earth and Environmental Science.

[20]  D. Osolodkin,et al.  Examination of molecular space and feasible structures of bioactive components of humic substances by FTICR MS data mining in ChEMBL database , 2019, Scientific Reports.

[21]  H. von Briesen,et al.  The Differential Anti-HIV Effect of a New Humic Substance-Derived Preparation in Diverse Cells of the Immune System , 2019, Acta naturae.

[22]  Qixing Zhou,et al.  Integrating Biolayer Interferometry, Atomic Force Microscopy, and Density Functional Theory Calculation Studies on the Affinity between Humic Acid Fractions and Graphene Oxide. , 2019, Environmental science & technology.

[23]  Mahmud Tareq Hassan Khan,et al.  A comprehensive review on tyrosinase inhibitors , 2019, Journal of enzyme inhibition and medicinal chemistry.

[24]  J. Vašková,et al.  EFFECTS OF HUMIC ACIDS ON POULTRY UNDER STRESS CONDITIONS , 2018, SLOVENIAN VETERINARY RESEARCH.

[25]  M. Çalışır,et al.  Humic Acid Enhances Wound Healing in the Rat Palate , 2018, Evidence-based complementary and alternative medicine : eCAM.

[26]  P. Moore,et al.  Effect of humic acids on intestinal viscosity, leaky gut and ammonia excretion in a 24 hr feed restriction model to induce intestinal permeability in broiler chickens. , 2018, Animal science journal = Nihon chikusan Gakkaiho.

[27]  D. Hernández-Patlán,et al.  Effects of Humic Acids on Recovery of Salmonella Enterica Serovar Enteritidis , 2018 .

[28]  A. Ghio,et al.  Human lung injury following exposure to humic substances and humic-like substances , 2018, Environmental Geochemistry and Health.

[29]  O. Koroleva,et al.  Long-term kinetics study and quantitative characterization of the antioxidant capacities of humic and humic-like substances , 2018, Journal of Soils and Sediments.

[30]  E. Andrásofszky,et al.  Effect of fulvic and humic acids on copper and zinc homeostasis in rats. , 2018, Acta veterinaria Hungarica.

[31]  J. Bekier,et al.  Humic acid and biochar as specific sorbents of pesticides , 2018, Journal of Soils and Sediments.

[32]  M. Yusubov,et al.  Physicochemical Characterization and Antioxidant Activity of Humic Acids Isolated from Peat of Various Origins , 2018, Molecules.

[33]  M. Navrátilová,et al.  The effect of humic acid on zinc accumulation in chicken broiler tissues , 2018 .

[34]  Y. Zhernov Natural humic substances interfere with multiple stages of the replication cycle of human immunodeficiency virus , 2018 .

[35]  M. Soler‐Lopez,et al.  Structure and Function of Human Tyrosinase and Tyrosinase-Related Proteins. , 2018, Chemistry.

[36]  Jae-Hyuk Yu,et al.  Occurrence, Toxicity, and Analysis of Major Mycotoxins in Food , 2017, International journal of environmental research and public health.

[37]  Changyu Cao,et al.  Effects of selenium-lead interaction on the gene expression of inflammatory factors and selenoproteins in chicken neutrophils. , 2017, Ecotoxicology and environmental safety.

[38]  M. Klučáková,et al.  Lignitic Humic Acids as Environmentally-Friendly Adsorbent for Heavy Metals , 2017 .

[39]  E. Andrásofszky,et al.  Effect of fulvic and humic acids on iron and manganese homeostasis in rats. , 2017, Acta veterinaria Hungarica.

[40]  D. Sarkar,et al.  Assessing redox properties of standard humic substances , 2017, International Journal of Environmental Science and Technology.

[41]  F. Bernerd,et al.  Skin Hyperpigmentation in Indian Population: Insights and Best Practice , 2016, Indian journal of dermatology.

[42]  F. Göze,et al.  The histopathological and morphometric investigation of the effects of systemically administered humic acid on alveolar bone loss in ligature-induced periodontitis in rats. , 2016, Journal of periodontal research.

[43]  R. Apak,et al.  Determination of total antioxidant capacity of humic acids using CUPRAC, Folin-Ciocalteu, noble metal nanoparticle- and solid-liquid extraction-based methods. , 2016, Talanta.

[44]  Bruna Alice Gomes de Melo,et al.  Humic acids: Structural properties and multiple functionalities for novel technological developments. , 2016, Materials science & engineering. C, Materials for biological applications.

[45]  C. Colak,et al.  The Acute Effect of Humic Acid on Iron Accumulation in Rats , 2016, Biological Trace Element Research.

[46]  S. Madec,et al.  Natural Co-Occurrence of Mycotoxins in Foods and Feeds and Their in vitro Combined Toxicological Effects , 2016, Toxins.

[47]  Kai-na Zhou,et al.  Sodium humate accelerates cutaneous wound healing by activating TGF-β/Smads signaling pathway in rats , 2016, Acta pharmaceutica Sinica. B.

[48]  Shungui Zhou,et al.  Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity , 2015, Scientific Reports.

[49]  W. Kloas,et al.  The effect of mycotoxin deoxynivalenol (DON) on the oxidative stress markers in rainbow trout (Oncorhynchus mykiss, Walbaum 1792) , 2015 .

[50]  Petr Petr,et al.  A CASUISTIC STUDY ABOUT BEHAVIOUR OF HUMIC SUBSTANCES IN A PATIENT’S EXPOSURE TO WHOLE BODY BATH , 2015 .

[51]  H. Sumida,et al.  Effects of humic acids on the sorption and bioavailability of pyrene and 1,2-dihydroxynaphthalene , 2015 .

[52]  A. S. Tarasova,et al.  Antioxidant activity of humic substances via bioluminescent monitoring in vitro , 2015, Environmental Monitoring and Assessment.

[53]  V. Dohnal,et al.  Oxidative stress-mediated cytotoxicity and metabolism of T-2 toxin and deoxynivalenol in animals and humans: an update , 2014, Archives of Toxicology.

[54]  J. Vašková,et al.  The Effect of Humic Acid on the Content of Trace Element in Mitochondria , 2014 .

[55]  Y. A. El-Shafea IN VIVO AND IN VITRO EVALUATION OF EFFICACY OF HUMIC ACID AGAINST AFLATOXINS , 2014 .

[56]  M. Kononova Soil Organic Matter: Its Nature, Its Role in Soil Formation and in Soil Fertility , 2013 .

[57]  G. Cano-Sancho,et al.  Mycotoxins: occurrence, toxicology, and exposure assessment. , 2013, Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association.

[58]  G. Ramage,et al.  Investigating the biological properties of carbohydrate derived fulvic acid (CHD-FA) as a potential novel therapy for the management of oral biofilm infections , 2013, BMC oral health.

[59]  X. Cui,et al.  Mycotoxin-Containing Diet Causes Oxidative Stress in the Mouse , 2013, PloS one.

[60]  A. Bruccoleri Positional adaptability in the design of mutation-resistant nonnucleoside HIV-1 reverse transcriptase inhibitors: a supramolecular perspective. , 2013, AIDS research and human retroviruses.

[61]  M. Mézes,et al.  DEPOSITION OF ORGANIC TRACE METAL COMPLEXES AS FEED ADDITIVES IN FARM ANIMALS , 2012 .

[62]  O. Smirnova,et al.  Antioxidant activity of humic acids in radical-chain oxidation processes , 2012, Russian Journal of Applied Chemistry.

[63]  W. Zawadzki,et al.  The effect of humic-fatty acid preparation on selected haematological and biochemical serum parameters of growing rabbits. , 2012, Polish journal of veterinary sciences.

[64]  R. Schwarzenbach,et al.  Antioxidant properties of humic substances. , 2012, Environmental science & technology.

[65]  O. Smirnova,et al.  Antioxidant and pro-oxidant activity of ascorbic and humic acids in radical-chain oxidation processes , 2012, Russian Journal of Applied Chemistry.

[66]  C. Velmurugan,et al.  Evaluation of safety profile of black shilajit after 91 days repeated administration in rats. , 2012, Asian Pacific journal of tropical biomedicine.

[67]  O. Smirnova,et al.  Antioxidant properties of humic acids from brown coal , 2011 .

[68]  J. Fink-Gremmels,et al.  Isotherm modeling of organic activated bentonite and humic acid polymer used as mycotoxin adsorbents , 2011, Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment.

[69]  V. R. Khairullina,et al.  Antioxidant properties of humic substances isolated from peloids , 2011, Pharmaceutical Chemistry Journal.

[70]  R. Schwarzenbach,et al.  Protein encapsulation by humic substances. , 2011, Environmental science & technology.

[71]  S. Nortcliff Principles of Soil Chemistry . 4th edition. Edited by K. H. Tan. Boca Raton, FL, USA: CRC Press (2011), pp. 362, £63.99. ISBN 978-1-4398-1392-8. , 2011, Experimental Agriculture.

[72]  M. Pilátová,et al.  Effects of humic acids in vitro , 2011, In Vitro Cellular & Developmental Biology - Animal.

[73]  M. Sakai,et al.  Strong adsorption of DNA molecules on humic acids , 2011 .

[74]  D. Ciccarone Stimulant abuse: pharmacology, cocaine, methamphetamine, treatment, attempts at pharmacotherapy. , 2011, Primary care.

[75]  L. Verotta,et al.  Uncovering the structure of human red hair pheomelanin: benzothiazolylthiazinodihydroisoquinolines as key building blocks. , 2011, Journal of natural products.

[76]  R. Habibian,et al.  Evaluation of the efficacy of esterified glucomannan, sodium bentonite, and humic acid to ameliorate the toxic effects of aflatoxin in broilers , 2010 .

[77]  U. Farooq,et al.  Pattern of joints involvement in Kashin-Beck disease: a local osteochondropathy in China. , 2010, Journal of Ayub Medical College, Abbottabad : JAMC.

[78]  P. Janoš,et al.  Reduction and immobilization of hexavalent chromium with coal- and humate-based sorbents. , 2009, Chemosphere.

[79]  R. Schubert,et al.  Bimodal effect of humic acids on the LPS-induced TNF-alpha release from differentiated U937 cells. , 2009, Phytomedicine : international journal of phytotherapy and phytopharmacology.

[80]  Katrin Marcus,et al.  Identification of L-ferritin in Neuromelanin Granules of the Human Substantia Nigra , 2009, Molecular & Cellular Proteomics.

[81]  Michael P. Murphy,et al.  How mitochondria produce reactive oxygen species , 2008, The Biochemical journal.

[82]  D. Coultas,et al.  Exposures and Idiopathic Lung Disease , 2008, Seminars in respiratory and critical care medicine.

[83]  V. Hearing,et al.  The Protective Role of Melanin Against UV Damage in Human Skin † , 2008, Photochemistry and photobiology.

[84]  J. Richard,et al.  Some major mycotoxins and their mycotoxicoses--an overview. , 2007, International journal of food microbiology.

[85]  J. C. Rocha,et al.  Interaction between humic substances and metallic ions: a selectivity study of humic substances and their possible therapeutic application , 2007 .

[86]  Csaba Szabó,et al.  Peroxynitrite: biochemistry, pathophysiology and development of therapeutics , 2007, Nature Reviews Drug Discovery.

[87]  J. Fink-Gremmels,et al.  In vitro assessment of adsorbents aiming to prevent deoxynivalenol and zearalenone mycotoxicoses , 2007, Mycopathologia.

[88]  A. Dobson,et al.  Strategies to Prevent Mycotoxin Contamination of Food and Animal Feed: A Review , 2006, Critical reviews in food science and nutrition.

[89]  J. van Ryssen,et al.  In vitro and in vivo assessment of humic acid as an aflatoxin binder in broiler chickens. , 2006, Poultry science.

[90]  M. Kļaviņš,et al.  Immobilized humic substances as sorbents. , 2006, Chemosphere.

[91]  R. Marcos,et al.  Humic acids reduce the genotoxicity of mitomycin C in the human lymphoblastoid cell line TK6. , 2006, Mutation research.

[92]  Vesna B. Medakovic,et al.  Adsorption of mycotoxins by organozeolites. , 2005, Colloids and surfaces. B, Biointerfaces.

[93]  A. Folda,et al.  The modulation of thiol redox state affects the production and metabolism of hydrogen peroxide by heart mitochondria. , 2005, Archives of biochemistry and biophysics.

[94]  D. Lackland,et al.  Relationship of environmental exposures to the clinical phenotype of sarcoidosis. , 2005, Chest.

[95]  J. Havel,et al.  Humic substances - compounds of still unknown structure: applications in agriculture, industry, environment, and biomedicine , 2005 .

[96]  J. ',et al.  Humic Acid Substances in Animal Agriculture , 2005 .

[97]  P. Riederer,et al.  Neuromelanin in human dopamine neurons: Comparison with peripheral melanins and relevance to Parkinson's disease , 2005, Progress in Neurobiology.

[98]  A. A. Starkov,et al.  Mitochondrial metabolism of reactive oxygen species , 2005, Biochemistry (Moscow).

[99]  N. Roney,et al.  Interaction profile for lead, manganese, zinc, and copper. , 2004, Environmental toxicology and pharmacology.

[100]  A. H. Rosa,et al.  Competition between humic substances and alpha-amino acids by metal species , 2004 .

[101]  G. Hill,et al.  Effect of dietary trace mineral concentration and source (inorganic vs. chelated) on performance, mineral status, and fecal mineral excretion in pigs from weaning through finishing. , 2004, Journal of animal science.

[102]  F. Zoccarato,et al.  Respiration-dependent Removal of Exogenous H2O2 in Brain Mitochondria , 2004, Journal of Biological Chemistry.

[103]  H. Martyniuk,et al.  Adsorption of metal ions on humic acids extracted from brown coals , 2003 .

[104]  B. Kwon,et al.  Characterization and biological activities of humic substances from mumie. , 2003, Journal of agricultural and food chemistry.

[105]  J. Dekker,et al.  Investigation of the Immunostimulatory Properties of Oxihumate , 2003, Zeitschrift fur Naturforschung. C, Journal of biosciences.

[106]  F. Lu,et al.  Humic acid mediates iron release from ferritin and promotes lipid peroxidation in vitro: a possible mechanism for humic acid-induced cytotoxicity , 2003, Archives of Toxicology.

[107]  M. Brand,et al.  Topology of Superoxide Production from Different Sites in the Mitochondrial Electron Transport Chain* , 2002, The Journal of Biological Chemistry.

[108]  B. Kwon,et al.  Medical drugs from humus matter: Focus on mumie , 2002 .

[109]  P. Wutzler,et al.  Anti-HSV-1 Activity of Synthetic Humic Acid-Like Polymers Derived from p -Diphenolic Starting Compounds , 2002, Antiviral chemistry & chemotherapy.

[110]  K. Wilkinson,et al.  Determination of electrophoretic mobilities and hydrodynamic radii of three humic substances as a function of pH and ionic strength. , 2001, Environmental science & technology.

[111]  A. Piccolo THE SUPRAMOLECULAR STRUCTURE OF HUMIC SUBSTANCES , 2001 .

[112]  E. A. Ghabbour,et al.  The effect of temperature on tight metal binding by peat and soil derived solid humic acids , 2001 .

[113]  R. Kretzschmar,et al.  Relating ion binding by fulvic and humic acids to chemical composition and molecular size. 1. Proton binding. , 2001, Environmental science & technology.

[114]  I. Arana,et al.  Humic materials offer photoprotective effect toEscherichia coli exposed to damaging luminous radiation , 2000, Microbial Ecology.

[115]  F. Zhao,et al.  Bioremediation of Contaminated Soils. , 2000 .

[116]  G. Barja Mitochondrial Oxygen Radical Generation and Leak: Sites of Production in States 4 and 3, Organ Specificity, and Relation to Aging and Longevity , 1999, Journal of bioenergetics and biomembranes.

[117]  M. Náray,et al.  [The favorable effect of humic acid based complex micro-element preparations in cadmium exposure]. , 1997, Orvosi Hetilap.

[118]  R. Goel,et al.  Antiulcerogenic and antiinflammatory studies with shilajit. , 1990, Journal of ethnopharmacology.

[119]  F. J. Sowden TRANSFORMATIONS OF NITROGEN ADDED AS AMMONIUM AND MANURE TO SOIL WITH A HIGH AMMONIUM-FIXING CAPACITY UNDER LABORATORY CONDITIONS , 1976 .

[120]  C. Saiz-Jimenez,et al.  Anthraquinones and phenols as intermediates in the formation of dark-colored humic acid-like pigments by Eurotium echinulatum , 1975 .

[121]  R. Klöcking,et al.  Antiviral properties of humic acids , 1972, Experientia.

[122]  P. Mudroň,et al.  Effects of Humic Acids in Chronic Lead Poisoning , 2018, Biological Trace Element Research.

[123]  Saima,et al.  Evaluation of Humic Acid as an Aflatoxin Binder in Broiler Chickens , 2017 .

[124]  C. V. van Rensburg The Antiinflammatory Properties of Humic Substances: A Mini Review. , 2015, Phytotherapy research : PTR.

[125]  P. Marsalek,et al.  The effects of mycotoxin deoxynivalenol (DON) on haematological and biochemical parameters and selected parameters of oxidative stress in piglets. , 2013, Neuro endocrinology letters.

[126]  Ivana T. Kostić,et al.  Comparative study of binding strengths of heavy metals with humic acid , 2013 .

[127]  Nagendra Thakur,et al.  Shilajit : A Humic Matter Panacea for Cancer , 2012 .

[128]  J. Pedraza,et al.  Antioxidant activity of fulvic acid: A living matter-derived bioactive compound , 2011 .

[129]  H. K. Pandey,et al.  Shilajit: A panacea for high-altitude problems , 2010, International journal of Ayurveda research.

[130]  X. Lv,et al.  In Vitro Evaluation of the Efficacy of Sodium Humate as an Aflatoxin B1 Adsorbent , 2009 .

[131]  W. Prellwitz,et al.  The organ distribution of selenium in German adults , 2008, Biological Trace Element Research.

[132]  M. Navrátilová,et al.  Effect of Humic Acids on Lead Accumulation in Chicken Organs and Muscles , 2008 .

[133]  H. Ipek,et al.  Effects of humic acid on some hematological parameters, total antioxidant capacity and laying performance in Japanese quails , 2007 .

[134]  C. Steinberg,et al.  Humic substances , 2008, Environmental science and pollution research international.

[135]  J. Bailly,et al.  Étude De Quelques Acides Humiques Sur Gel De Dextrane , 2005, Plant and Soil.

[136]  K. Hatfield,et al.  Use of humic substances to remediate polluted environments : from theory to practice , 2005 .

[137]  H. Schulten,et al.  A state of the art structural concept for humic substances , 2005, Naturwissenschaften.

[138]  P. Corbi,et al.  Competition Between Humic Substances and α-Amino Acids by Metal Species , 2004 .

[139]  S. Pflugmacher,et al.  PURE HUMIC SUBSTANCES HAVE THE POTENTIAL TO ACT AS XENOBIOTIC CHEMICALS - A REVIEW , 2003 .

[140]  A. Piccolo The supramolecular structure of humic substances: A novel understanding of humus chemistry and implications in soil science , 2002 .

[141]  F. Lu,et al.  In vitro anti-influenza virus activity of synthetic humate analogues derived from protocatechuic acid , 2002, Archives of Virology.

[142]  D. Kinniburgh,et al.  Relating ion binding by fulvic and humic acids to chemical composition and molecular size. 2. Metal binding. , 2001, Environmental science & technology.

[143]  K. H. Tan Humic Matter in Soil and the Environment: Principles and Controversies , 1997 .

[144]  W. Dick Environmental Soil Science , 1996 .

[145]  K. H. Tan Principles of soil chemistry , 1993 .

[146]  J. A. Rice,et al.  Statistical evaluation of the elemental composition of humic substances , 1991 .

[147]  F. Livens Chemical reactions of metals with humic material. , 1991, Environmental pollution.

[148]  G. G. Choudhry Humic Substances. Structural Aspects, and Photophysical, Photochemical and Free Radical Characteristics , 1984 .

[149]  F. J. Stevenson HUmus Chemistry Genesis, Composition, Reactions , 1982 .

[150]  P. Wutzler,et al.  [Comparison of the in vitro activities of ammonium humate and of enzymically oxidized chlorogenic and caffeic acids against type 1 and type 2 human herpes virus (author's transl)]. , 1981, Die Pharmazie.

[151]  P. Liss,et al.  The Natural Environment and the Biogeochemical Cycles , 1980 .

[152]  M. Schnitzer Chapter 1 Humic Substances: Chemistry and Reactions , 1978 .

[153]  S. U. Khan Adsorption of pesticide by humic substances. A review. , 1972, Environmental letters.

[154]  N. J. King Lignin Biochemistry , 1966, Nature.

[155]  S. Waksman Humus: origin, chemical composition, and importance in nature , 1936 .