New phenolic glycosides from Nigerian mistletoe (Loranthus micranthus Linn.) parasitizing on Hevea brasiliensis

OM Agbo; D Lai; BF Okoye; PO Osadebe; P Proksch

doi:10.1055/s-0033-1352205

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Planta Med 2013; 79 - PJ1
DOI: 10.1055/s-0033-1352205

New phenolic glycosides from Nigerian mistletoe (Loranthus micranthus Linn.) parasitizing on Hevea brasiliensis

OM Agbo ¹, D Lai ², BF Okoye ³, PO Osadebe ¹, P Proksch ²

¹University of Nigeria Nsukka – Department of Pharmaceutical and Medicinal Chemistry
²Heinerich-Heine University, Düsseldorf, Germany – Institute of Pharmaceutical Biology and Biotchnology
³Nnamdi Azikiwe University, Awka Nigeria – Department of Pharmaceutical and Medicinal Chemistry

Congress Abstract

Two (2) new phenolic glycosides, linamarin gallate (1) and walsuraside B (2), together, with twelve (12) known polyphenols (3 – 14) were isolated from the leafy twigs of Nigerian mistletoe Loranthus micranthus (Linn.) parasitic on Hevea brasiliensis. Compound 1 was characterized as an unusual cyanogenic glycoside. All the compounds were isolated for the first time from mistletoe. The structures of the new compounds were unambiguously elucidated by a combination of 1D (¹H, ¹³C), 2D (COSY, HSQC, HMBC) NMR and Mass Spectroscopy (HPLC/ESI-MS, HR/ESI-MS). All the isolated compounds exhibited strong antioxidant activity with IC₅₀ values in the range of 23.8 – 50.1µM and were found to be more active than the reference compound, chlorogenic acid (IC₅₀= 67.9µM) in the DPPH assay.