A Comparative Phylogenetic Evaluation of Chloroplast ITS Sequences to Analyze the Bioactivity in Medicinal Plants: A Case Study of Clerodendrum Plant Genus (Lamiaceae)

Research Article

Austin J Comput Biol Bioinform. 2015;2(1): 1011.

A Comparative Phylogenetic Evaluation of Chloroplast ITS Sequences to Analyze the Bioactivity in Medicinal Plants: A Case Study of Clerodendrum Plant Genus (Lamiaceae)

Melapu VK1, Joginipelli S1, Naidu BVA2 and Darsey J3*

1Department of Bioinformatics, University of Arkansas at Little Rock, USA

2Department of Botany, Andhra University, India

3Department of Chemistry, University of Arkansas at Little Rock, USA

*Corresponding author: Darsey J, Department of Chemistry, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR

Received: March 17, 2015; Accepted: April 01, 2015; Published: April 08, 2015

Abstract

According to World Health Organization (WHO) approximately 47% of drugs used today to cure many diseases were derived from natural products such as plants. Although many approved and clinical-trial drugs have been derived from natural products, the last 20 years have shifted emphasis from natural products to less expensive synthetic products. Due to the paucity of traditional medicinal knowledge and lack of ethnobotanical information about most of the medicinal plants, the emphasis has shifted to synthetic products. Multidisciplinary research with phylogeny to incorporate ethnobotanical knowledge as well as traditional medicinal knowledge will facilitate researchers to identify new drug molecules. In this paper, we use phylogeny inferred from ITS sequence of chloroplast DNA of thirty eight different species of Clerodendrum plant to predict chemical diversity and potential medicinal activity of plants from Lamiaceae family. Phylogenetic signal in medicinal properties in plants is used to identify nodes on phylogeny with high bioscreeing potential. Phytosterol diversity and inhibition of angiotensin receptors by these compounds is significantly correlated with phylogeny. We produced a phylogenetic hypothesis for medicinally important plants of Laminaceae family based on the maximum likelihood, Neighborjoining, minimum evolution, UPGMA, and maximum parsimony methods. The genealogical trees generated with each method proved phylogenetic hypothesis by densely clustering plants with similar medicinal uses and plants belonging to same distribution. Different species of Clerodendrum plant genus were studied and their medicinal uses were evaluated in the light of phylogenetic relationships.

Keywords: WHO; Internal transcribed spacer; Phylogeny; Ethnobotanical; Clerodendrum; Lamiaceae; Bioscreeing, Phytosterol; Angiotensin receptors; Maximum likelihood; Neighbor-Joining; Minimum evolution; UPGMA; Maximum Parsimony

Abbreviations

ITS: Internal Transcribed Spacer; ME: Minimum Evolution; MEGA: Molecular Evolutionary Genetics Analysis; NCBI: National Center for Biotechnology Information; NJ: Neighbor-Joining; OLS: Ordinary Least Sqaures; OUT: Operational Taxonomy Units), UPGMA: Unweighted Pair Group Method with Arithmetic mean; WHO: World Health Organization

Introduction

Throughout the ages, humans have relied on nature for their basic needs such as food, shelter, clothing and medicines. Due to the natural ability of plants to synthesize wide variety of compounds; they are used as source of medicines to cure ailments and prevent diseases. Countries with ancient civilization such as India, China, Egypt, etc used plants as remedies for various conditions and ailments. According to World Health Organization (WHO) approximately 25% of drugs used today to cure many diseases were derived from plants and plant substances [1]. Researchers across the globe from different regions of the world have worked on medicinal plants to identify and discover new molecules and to make advances in production of drugs derived from plant products. Ethnobotanical knowledge about plants and their species is essential for further investigations to discover new molecules from plants. Compiling a comprehensive list of medicinal plants and their species across different regions of the world will preserve our knowledge about the medicinal plants and will facilitate researchers to identify new molecules [2, 3].The field of bio-prospecting and bioscreening guided by the ethnomedicinal knowledge from traditional medicine, led to the discovery of several plant derived pharmaceuticals such as Taxol, Chloroquine, Crystodigin, Galanthamine, and Nitisinone etc [4]. Chemotherapy drug Taxol used in current treatment for breast cancer, ovarian cancer and lung cancer is derived from chemical obtained from Taxus brevifolia plant [5]. Ancient Egyptians used cinchona bark or bark from willow tree to treat and cure malarial fevers, active chemical compound quinine was extracted and is still used in treatment of malarial fevers. Crystodigin and Lanoxin drugs used in treatment of heart conditions such atrial fibrillations and congestive heart failure, are derived from digitoxin obtained from Digitalis purpurea (Floxglove) plant [6]. Although many approved and clinical-trial drugs have been derived from natural products, the last 20 years have shifted emphasis from natural products to less expensive synthetic products. Therefore, improvements in bioprospecting on the basis of phylogenetic methods have very recently been given considerable attention by mostly Chinese medicinal plant chemists, British biologists, and some ethnobotanists. One approach to increasing drug discovery via natural products is to use phylogenetic methods (“genealogical focusing”) to locate lineages on the “tree of life” that are most likely to yield useful drug-like scaffolds [7].

Clerodendrum plant genus of about 400 to 500 species, belonging to Lamiaceae family is a subtropical and tropical plant mostly distributed in Africa, Asia and Pacific Oceania [8]. The genus comprising of about 400 to 500 species shows high degree morphological variation and has many medicinal uses. The medicinal properties are not randomly distributed in plants, some group of plants show high medicinal properties than the other group. This suggests that there is a phylogenetic pattern of medicinal properties across the world and is revealed with phyglogenetic analysis [9]. Here in this study we have performed phylogenetic analysis on thirty eight different species of Clerodendrum plant to understand and evaluate the cross cultural patterns, medicinal properties and chemical diversity. We have inferred the phylogeny using ITS (Internal Transcribed Spacer) regions of chloroplast DNA.

Materials and Method

Collection of medicinal plant species of clerodendrum

Some species of Clerodendrum plant such as Clerodendrum infortunatum, Clerodendrum serratum, Clerodendrum viscosum, etc. were collected from (Western Ghats of India, Coimbatore, Hyderabad, India) southern region of India, with the help of Dr. B.V.A Rama Rao Naidu, Botanists and Taxonomist. A voluntary survey about the medicinal plants was conducted to know the medicinal properties of the plants from medical practitioners of the study region. Some species of Clerodendrum were retrieved from extensive literature search including ethnobotanical databases, published research articles. We collected information on the medicinal applications of Clerodendrum throughout the range of the genus. Table 1 shows the thirty eight different species of Clerodendrum genus, its medicinal uses, and the geographical distribution of the species in the region (Table 1).