Abstract
The methanol root extract of Clerodendrum myricoides (Hochst.) Vatke afforded two new (1, 2) and two known (3, 4) iridoid glycosides. The structures of the isolated compounds were established based on NMR, IR, UV and MS data analyses. The crude extract and the isolated constituents were assayed for antiviral activity against the human respiratory syncytial virus (RSV) in human laryngeal epidermoid carcinoma (HEp-2) cells. The crude extract inhibited RSV infectivity at EC50 = 0.21 μg/ml, while it showed cytotoxicity against HEp-2 cells with CC50 = 9 μg/ml. Compound 2 showed 43.2% virus inhibition at 100 μM, while compounds 1 as well as 3 and 4 had only weak antiviral and cytotoxic activities.
Highlights
Clerodendrum (Lamiaceae) is a large and diverse genus which is composed of 580 species [1,2]
In addition to appli cation for treating cancer and inflammatory diseases, such as asthma, the leaves, roots, and stems of Clerodendrum species have been utilized as anti-infectious compounds against malaria, pneumonia/ pneumonitis and HIV [7,8,9]
The methanol extract of the root bark of C. myricoides was subjected to column chromatography on silica gel, and selected fractions were subsequently isolated by preparative reversed-phase HPLC to give the two new iridoid glycosides myricoidoside A (1), and B (2), as well as euphroside (3) [24], and 7-O-cinnamoyl-5-hydroxygardaloside (4) (Fig. 1) [25]
Summary
Clerodendrum (Lamiaceae) is a large and diverse genus which is composed of 580 species [1,2]. It is distributed in tropical and sub tropical regions and comprises small trees, shrubs and herbs. The genus Clerodendrum has been used in traditional medicine to treat various ailments in different regions of the World [3,4,5,6]. Due to its importance in Rwandese traditional medicine and the necessity to identify its active constituents, we have carried out a phytochemical investigation of its root extract. We report the isolation and the characterization of two new (1, 2) and two known (3, 4) iridoid glycosides from the methanol root extract. Since respiratory syncytial virus (RSV) is one of the most important causes of bronchitis and pneumonia in humans [23], antiviral activity against this virus, and the cytotoxicity of the crude extract and isolated iridoids, have been evaluated
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