Comparative biological study of roots, stems, leaves, and seeds of Angelica shikokiana Makino

Abstract

Ethnopharmacological relevance

Angelica shikokiana has been used as a health food for its anticancer, anti-inflammatory, antibacterial, antiallergic, and blood vessel dilating effects in Japan. It can also be used to prevent and treat hepatitis, diabetes, hyperlipidemia, and arteriosclerosis.

Aim of the study

The present study was designed to compare the biological activities such as melanin synthesis inhibitory, anti-allergy, anti-lipase, anti-bacterial, anti-oxidant, and neuroprotective activities of different parts of the plant that may justify the use of this plant in folk medicine.

Material and methods

The roots, stems, leaves and, seeds of Angelica shikokiana were separately extracted with water and ethanol. Each extract was examined for melanin synthesis inhibitory and anti-allergy activity on B16-melanoma and RBL-2H3 cells using IgE and A23187 as a stimulant for β-hexosaminidase release, respectively. We also evaluated the inhibition of two enzymes, lipase and acetylcholine esterase, and of the bacterial growth of two species, Escherichia coli and Staphylococcus aureaus. The anti-oxidant activity was determined using oxygen radical anti-oxidant capacity, ORAC assay and its relation to the phenolic content was estimated using the Folin–Ciocalteu method. Besides, the protective effect of the extracts against H₂O₂-induced oxidative stress in mouse neuroblastoma, Neuro-2A cells was investigated.

Results

The most active extract exhibiting melanin synthesis inhibition (63%) and at the same time with low cytotoxicity (15%) was the ethanol extract of roots at 20 µg/ml, followed by the ethanol extract of stems (57% inhibition, 5% cytotoxicity). On the other hand, the highest inhibitions of β-hexosaminidase release were recorded for the ethanol extract of leaves with IC₅₀ value of 6.89 µg/ml followed by the water extract of the seeds and leaves with IC₅₀ value of 78.32 and 88.44 µg/ml, respectively. For anti-lipase assay, ethanol extracts of the stems and roots showed the strongest inhibition with IC₅₀ values of 204.06 and 216.24 µg/ml, respectively. None of the examined extracts showed any activity against Escherichia coli. while the ethanol extract of the roots and stems showed moderate inhibition for Staphylococcus aureus with minimum inhibitory concentration of 400 µg/ml. Ethanol extract of the roots showed only 30% inhibition of acetylcholine esterase enzyme. The results of anti-oxidant, phenolic content and protective effect against H₂O₂-induced cytotoxicity assays showed highly correlated data. Ethanol extract of the stems (ORAC value of 1.08 µmol Trolox/ mg and phenolic content 44.25 μg GAE/mg) increased the cell viability of H₂O₂-treated Neuro-2A cells by 28%.

Introduction

The Umbelliferae plant Angelica shikokiana (Japanese name Inutouki), commonly called “Yamaninjin,” is an endemic species and perennial herb that is cultivated in the Oita Prefecture of Japan and used as a substitute drug for ginseng roots (Kimura and Okuda, 1989). The stems and roots are used as a health tea preparation for treating diseases of the circulatory system and digestive system, liver dysfunctions, and hyperlipidemia (Okuda, 1985) and for the prevention of anemia, hypertension, diabetes, neuralgia, dermatitis, and symptoms of aging (Kurumaya and Kurumaya, 2006). The extract of the whole plant is used as an ingredient in antitumor preparations (Mizuno and Okubo, 1999) and as a hair growth promoter (Izume et al., 2007). In our study, ethanol and water extracts of the roots (RE and RW), stems (STE and STW), leaves (LE and LW), and seeds (SE and SW) of Angelica shikokiana were prepared and screened for different biological activities such as melanin synthesis inhibition, anti-inflammatory, anti-lipase and anti-acetylcholine esterase, antibacterial and anti-oxidant especially that the literature survey did not show any reference to a previous work for comparing the biological activities of roots, stems, leaves and seeds of Angelica shikokiana.