Phytochemical and bioactivities of Knema glauca and Knema furfuracea

Abstract

Chemical investigation of the stems, leaves and fruits of Knema glauca (family Myristicaceae) led to the isolation of a new linear diterpene named glaucaic acid, a phenylacylresorcinol, 2,6-dihydroxyphenyl-tetradecan-1-one. In addition to an acylresorcinol, malabaricone A, a phenylacylphloroglucinol, 1-(2,4,6-trihydroxyphenyl)-9-phenylnonan-1-one, an acylphloroglucinol, 1-(2,4,6-trihydroxyphenyl)-undecan-1-one, a flavan-acylphloroglucinol, myristinin A, a flavan-phenylacylphloroglucinol, myristinin D, two furofuran lignans, asarinin and sesamin, and a flavan, (±)-7,4΄-dihydroxy-3΄-methoxyflavan. From the stems and leaves of Knema furfuracea, another myristicaceous plant, a new arylnaphthalene lignan named furfuracin, together with two known lignans, (+)-trans-1,2-dihydrodehydroguaiaretic acid and fragransin A2, two acylbenzoic acids as a 1:1 mixture of gingkoic acid and anarcardic acid, two phenylacylbenzoic acids as a 1:2 mixture of 2-hydroxy-6-(12-phenyldodecyl)benzoic acid and 2-hydroxy-6-(12-phenyldodecen-8΄Z-yl)benzoic acid, and an isoflavone, biochanin A, were isolated. The chemical structures of these compounds were determined by spectroscopic analyses, including UV, IR, MS and NMR, and comparison with previously reported data. 1-(2,4,6-Trihydroxy-phenyl)-undecan-1-one was moderately cytotoxic against NCI-H187 cell line with an IC50 value of 5.60 µg/ml, whereas 2,6-dihydroxyphenyl-tetradecan-1-one was moderately cytotoxic against KB cell line with an IC50 value of 9.15 µg/ml. 1-(2,4,6-Trihydroxy-phenyl)-9-phenylnonan-1-one exhibited moderate cytotoxicity against BC cell line with an IC50 value of 8.23 µg/ml. Malabaricone A, 1-(2,4,6-trihydroxy-phenyl)-undecan-1-one and 1-(2,4,6-trihydroxy-phenyl)-9-phenylnonan-1-one were active against Mycobacterium tuberculosis, herpes simplex virus type 1 and were able to inhibit the formation of Advanced Glycation End-Products. Moreover, malabaricone A was able to display higher anti-malarial activity than the standard compound, dihydroartemisinin, with an IC50 value of 2.78 nM