Lasianosides A-E: New Iridoid Glucosides from the Leaves of Lasianthus verticillatus (Lour.) Merr. and Their Antioxidant Activity.

Gadah Abdulaziz Al-Hamoud,Kazuma Masuda,Sachiko Sugimoto,Shagufta Perveen,Hideaki Otsuka,Raha Saud Orfali,Tatsuo Nehira,Yoshi Yamano,Yoshio Takeda,Kenta Mizuno,Katsuyoshi Matsunami

doi:10.3390/molecules24213995

Abstract

The genus Lasianthus (Rubiaceae) consists of approximately 180 species, of which the greatest species diversity is found in tropical Asia. Some of the Lasianthus species have been used in folk medicine to treat tinnitus, arthritis, fever, and bleeding. Lasianthus verticillatus (Lour.) Merr. (Syn. Lasianthus trichophlebus auct. non Hemsl.) is a shrub, branchlets terete about 1.5–3 m in height. This paper studies the chemical composition of the leaves of L. verticillatus for the first time, which resulted in the isolation of five undescribed iridoid glucosides, lasianosides A–E (1–5), together with three known compounds (6–8). The undescribed structures of isolated compounds (1–5) were characterized by physical and spectroscopic data analyses, including one-dimensional (1D) and two-dimensional (2D) NMR, IR, UV, and high-resolution electrospray ionization mass spectra (HR-ESI-MS). Furthermore, the electronic circular dichroism data determined the absolute configurations of the new compounds. The free radical scavenging properties of isolated compounds was assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and their cytotoxicity was assessed toward human lung cancer cell line A549 by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Among the isolated compounds, 3 and 4 displayed potent radical scavenging activities with IC50 values of 30.2 ± 1.8 and 32.0 ± 1.2 µM, which were comparable to that of Trolox (29.2 ± 0.39 µM), respectively, while 5 possessed moderate activity with an IC50 value of 46.4 ± 2.3 µM. None of the isolated compounds exerted cytotoxicity against human cell line A549. As a result, lasianosides C, D, and E have the potential to be non-toxic safe antioxidant agents.

Highlights

Reactive oxygen species (ROS) are derived from exogenous and intracellular sources
Merr. leaves were separated by solvent fractionation, column chromatographies to afford separated by solvent fractionation, variousvarious column chromatographies (CC),(CC), and and to afford compounds
The chemical composition of L. verticillatus leaves was studied for the first time and resulted in the isolation of five undescribed iridoid glucosides, lasianosides A–E (1–5), together with three known compounds (6–8)

Summary

Introduction

Reactive oxygen species (ROS) are derived from exogenous (environmental pollution, cigarette smoke, UV irradiation, and toxic chemicals) and intracellular (mitochondrial energy generation) sources. The excessive ROS accumulation leads to oxidative stress through the reaction of ROS with biomolecules such as cell membrane lipids, proteins, and DNA, which causes a variety of chronic and degenerative disorders including cataract, rheumatoid arthritis, cancer, cardiovascular diseases, neurodegenerative disorders, and aging. A supplementation of exogenous antioxidants as free radical scavengers is thought to be an effective measure for preventing and repairing the damages caused by ROS [1]. Lung cancer is one of the leading causes of cancerous death for both the male and female in the world. Treatment options for lung cancer include surgery, chemotherapy, and radiation therapy. There is an increased and continued demand for new agents to treat and prevent this life-threatening disease [2]

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Conclusion