Morus is one of the main genera of the Moraceae family and widely cultivated in Southeast Asia for silkworm feeding. This genus also produces valuable bioactive phenolic compounds such as flavonoids, stilbenes, 2-arylbenzofurans, and Diels-Alder adducts. Previous phytochemical investigation of Morus shalun reported the Diels-Alder adducts as the mayor phenolic compounds isolated from root cultures. The Diels-Alder adduct is considered formed by the intermolecular [4+2]-cycloaddition between a diene of dehydroprenyl phenol with a dienophile of the α, β-unsaturated carbonyl group of a chalcone. This reaction in plant tissues is naturally catalyzed by the enzyme Diels-Alderase. The experiment was designed to determine the existence of Diels-Alderase isolated from a root culture of M. shalun by evaluating its activity in the biotransformation process of morachalcone A to produce kuwanon J. Biotransformation was detected using HPLC and LCMS. Kuwanon J showed significantly higher cytotoxic activities against the three human cancer cell lines HeLa, A459, and MCF7 compared with morachalcone A.


  • Ashraf MA, Iqbal M, Rasheed R, Hussain I, Riaz M, Arif MS (2018) Environmental Stress and Secondary Metabolites in Plants: An Overview. Plant Metabolites and Regulation under Environmental Stress. Elsevier Inc.
  • Auld DS (1988) Use of Chelating Agents to Inhibit Enzymes. Methods in Enzymology 158 (C): 110–114.
  • Bourgaud F, Gravot A, Milesi S, Gontier E (2001) bourgaud 2001- Production of plant secondary metabolites a historical perspective, Plant Science 161: 839–851.
  • Byrne MJ, Lees NR, Han L-C, van der Kamp MW, Mulholland AJ, Stach JEM, Race PR (2016) The Catalytic Mechanism of a Natural Diels–Alderase Revealed in Molecular Detail. Journal of the American Chemical Society 138: 6095-6098.
  • Dewick PM (2002) A Biosynthetic Approach. John Wiley and Sons, 2nd: 165-278.
  • Ferlinahayati Syah YM, Juliawaty LD, Achmad SA (2008) Phenolic Constituents from the Wood of Morus australis with Cytotoxic Activity. Z Naturforsch C 63(1-2): 35-9.
  • Fitriani R, Hakim EH (2017) New cytotoxic Diels-Alder type adducts from root culture of Morus alba var. shalun, Proceeding of 3rd World Congress on Natural Products Chemistry and Research & 12th world Pharma Congress, American Journal of Ethomedicines 4(2): 25.
  • Gao L, Han J, Lei X (2015) Enantioselective Total Syntheses of Kuwanon X, Kuwanon Y, and Kuwanol A. Org. Lett 183: 360-363.
  • Globocan (2019) Graph production: Global Cancer., Observatory (http://gco.iarc.fr), WHO, May 27.
  • Gogoi G, Borua PK, Al-Khayri JM (2017) Improved micropropagation and in vitro fruiting of Morus indica L. (K-2 cultivar). Journal of Genetic Engineering and Biotechnology 15 (1): 249–256.
  • Han J, Li X, Guan Y, Zhao W, Wulff WD, Lei X (2014) Enantioselective Biomimetic Total Syntheses of Kuwanons I and J and Brosimones A and B, Angew. Chem 53: 1 – 6.
  • Hashimoto T, Kuzuyama T (2016) Mechanistic insights into Diels-Alder reactions in natural product biosynthesis. Current Opinion in Chemical Biology 35: 117–123.
  • Hermawati E (2012) Research Report. Sandwich prog. Tokyo Univ. Jan-Feb.
  • Holli EEB, Nour AA, Ahmed AI (2017) Effect of Soaking on the Nutritional Values of Kordala (Maerua Pseudopetalosa) Seeds Grown in Kordofan Region, Sudan. Journal of Food Technology Research, 4(2): 40-45.
  • Iovine V, Benni I, Sabia R, D’Acquarica I, Fabrizi G, Botta B, Calcaterra A (2016) Total synthesis of (±)-kuwanol e. Journal of Natural Products 79(10): 2495–2503.
  • Kim HJ, Ruszczycky MW, Liu H (2012) Current developments and challenges in the search for a naturally selected Diels-Alderase. Current Opinion in Chemical Biology 16 (1–2): 124–131.
  • Klas K, Tsukamoto S, Sherman DH, Williams RM (2015) Natural Diels-Alderases: Elusive and Irresistable. Journal of Organic Chemistry 80(23): 11672–11685.
  • Lacoske MH, Theodorakis EA (2015) Spirotetronate polyketides as leads in drug discovery. Journal of Natural Products 78(3): 562–575.
  • Lee SB (1995) Effect of water activity on enzyme hydration & reaxtion rate in organic solvents. Journal of Fermentation and Bioengineering 79(5): 473–478.
  • Lu MC (2002) Micropropagation of Morus latifolia Poilet using axillary buds from mature trees. Scientia Horticulturae 96(1–4): 329–341.
  • Murashige T, Skoog F (1962) A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol. Plant 15: 473-497.
  • Nomura T, Hano YH, Ueda S (1995) Chemistry and Biosynthesis of natural Diels-Alder Type adduct from Moraceous plants, Studies in Natural products Chemistry 17.
  • Oikawa H (2005) Involvement of the Diels-Alderases in the biosynthesis of natural products. Bulletin of the Chemical Society of Japan 78(4): 537–554.
  • Reymond JL, Fluxà VS, Maillard N (2009) Enzyme assays. Chemical Communications 1(1): 34–46.
  • Thakur M, Bhattacharya S, Khosla PK, Puri S (2019) Improving production of plant secondary metabolites through biotic and abiotic elicitation. Journal of Applied Research on Medicinal and Aromatic Plants 12 (November 2018): 1–12.
  • Vijayan K, Saratchandra B, Teixeira da Silva JA (2011) Germplasm conservation in mulberry (Morus spp.). Scientia Horticulturae 128(4): 371–379.
  • Wei H, Zhu J-J, Liu X-Q, Feng W-H, Wang Z-M, Yan L-H (2016) Review of bioactive compounds from root barks of Morus plants (Sang-Bai-Pi) and their pharmacological effects. Cogent Chemistry 2(1): 1–16.
  • Woodward RB, Katz TJ (1959) The mechanism of the Diels-Alder reaction. Tetrahedron 5(1): 70–89.
  • Yang Y, Tan YX, Chen RY, Kang J (2014) The latest review on the polyphenols and their bioactivities of Chinese Morus plants. Journal of Asian Natural Products Research 16 (March): 690–702.


This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.