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Open AccessArticle

Nimbolide B and Nimbic Acid B, Phytotoxic Substances in Neem Leaves with Allelopathic Activity

1
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan
2
Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522, Japan
*
Author to whom correspondence should be addressed.
Molecules 2014, 19(6), 6929-6940; https://doi.org/10.3390/molecules19066929
Received: 24 April 2014 / Revised: 14 May 2014 / Accepted: 14 May 2014 / Published: 26 May 2014
Neem (Azadirachta indica) has been widely used as a traditional medicine and several bioactive compounds have been isolated from this species, but to date no potent allelopathic active substance has been reported. Therefore, we investigated possible allelopathic property and phytotoxic substances with allelopathic activity in neem. An aqueous methanol extract of neem leaves inhibited the growth of roots and shoots of cress, lettuce, alfalfa, timothy, crabgrass, ryegrass, barnyard grass and jungle rice. The extracts were then purified by several chromatographic runs while monitoring the inhibitory activity and two phytotoxic substances were isolated. The chemical structures of the two substances were determined by spectral data to correspond to novel compounds, nimbolide B (1) and nimbic acid B (2). Nimbolide B inhibited the growth of cress and barnyard grass at concentrations greater than 0.1‒3.0 μM. Nimbic acid B inhibited the growth of cress and barnyard grass at concentrations greater than 0.3–1.0 μM. These results suggest that nimbolide B and nimbic acid B may contribute to the allelopathic effects caused by neem leaves. View Full-Text
Keywords: allelopathy; Azadirachta indica; bioactive compound; growth inhibitor; medicinal plant; phytotoxicity allelopathy; Azadirachta indica; bioactive compound; growth inhibitor; medicinal plant; phytotoxicity
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Kato-Noguchi, H.; Salam, M.A.; Ohno, O.; Suenaga, K. Nimbolide B and Nimbic Acid B, Phytotoxic Substances in Neem Leaves with Allelopathic Activity. Molecules 2014, 19, 6929-6940.

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