British Journal of Pharmaceutical Research 16(2): 1-22, 2017; Article no.BJPR.32973 ISSN: 2231-2919, NLM ID: 101631759 SCIENCEDOMAIN international www.sciencedomain.org Plants in Respiratory Disorders I- Anti-asthmatics, A Review Simeon K. Adesina 1*, Imoh Imeh Johnny 1 and Gbola Olayiwola 2 1Department of Pharmacognosy and Natural Medicine, Faculty of Pharmacy, University of Uyo, Uyo, Akwa Ibom State, Nigeria. 2Department of Clinical Pharmacy and Pharmacy Administration, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria. Authors’ contributions This work was carried out in collaboration between all authors. Author SKA designed the study. Authors SKA, IIJ and GO have contributed to the chemistry, ethnopharmacology and biological studies in this review and have also collaborated in literature search, data collection and referencing. Author SKA wrote the first draft of the manuscript. All the authors read through and approved the final manuscript for publication. Article Information DOI: 10.9734/BJPR/2017/32973 Editor(s): (1) Vasudevan Mani, Universiti Teknologi MARA (UiTM), Selangor, Malaysia. Reviewers: (1) Yahya Elshimali, UCLA School of Medicine, Charles R. Drew University of Medicine and Science, USA. (2) Vijayan Mini, Carmel College, India. (3) Renshan Sun, Third Military Medical Unversity, China. Complete Peer review History: http://www.sciencedomain.org/review-history/18911 Received 25 th March 2017 Accepted 29 th April 2017 Review Article Published 4th May 2017 ABSTRACT Aim of This Review : Respiratory disorders pose a big threat to life and constitute a major public health problem worldwide. This review is an attempt to bring together some of the common medicinal plants traditionally used to manage asthma. The review focuses on anti-asthmatic plants, their chemistry and pharmacology in an attempt to justify use and also provide a direction for future research. Study Approach: Information on the above was sourced from published articles and reviews on the subject available from various data bases and journals. Fifty-six medicinal plants that have been investigated for anti-asthmatic properties have been reviewed. Findings: Table 1 gives a list of plants reviewed and the mechanism of anti-asthmatic action. Herbal products are receiving increasing attention all over the world for the management of _____________________________________________________________________________________________________ *Corresponding author: E-mail: [email protected]; Adesina et al.; BJPR, 16(2): 1-22, 2017; Article no.BJPR.32973 respiratory disorders as these have shown anti-asthmatic, antihistaminic, anti-allergic, anti- anaphylactic and anti-inflammatory activities. The biochemistry and medicinal significance of polyphenols and flavonoids are now better appreciated in the management of respiratory disorders. Conclusion: Medicinal plants remain the main ingredients of indigenous medicines; this review justifies the need for polyherbal formulations for use in the management of respiratory disorders. Keywords: Respiratory disorders; anti-asthmatic plants; phytochemistry; ethnopharmacology, biological studies. 1. INTRODUCTION borne allergens, occupational sensitizers, smoke, air pollution etc. [2]. As noted by Singh et al. [5], Respiratory allergies are known to include stress and acute anxiety or an extreme emotional allergic rhinitis and allergic asthma which always arousal may also trigger asthmatic attacks. cause wheezing, coughing, shortness of breath, Asthma can be grouped as extrinsic when sneezing, running nose and sinus problems, and caused by allergic responses to such things as in some cases red, watery and itching eyes [1]. dust, certain foods, animal fur etc. causing 10 – Respiratory disorder considered in this review is 20% of adult asthma, or intrinsic when caused by asthma- bronchial asthma, occupational asthma, genetics, infections, pollutants and physiological allergic asthma, cough-variant asthma, exercise- and psychological stress, making about 30 – induced asthma, nocturnal asthma and childhood 50% of adult asthma [5]. asthma. Clinically, asthma has been described as airway Asthma has been described as a chronic obstruction that involves inflammation of the inflammatory disease of the airways usually pulmonary airway and bronchial hyper- characterized by variable and recurring responsiveness that is usually reversible [6]. symptoms which include coughing, wheezing and shortness of breath [2]. The National 2. HERBAL THERAPY FOR ASTHMA Institute of Health defines it as a chronic inflammatory disorder of the airways in which The pharmacological management of asthma many cells and cellular elements play a role, depends largely on (i) bronchodilators – β – in particular, mast cells, eosinophils, T- adrenergic agonists, anticholinergics and lymphocytes, neutrophils and epithelial cells methylxanthines and (ii) steroidal anti- [3,4]. Asthmatic attacks may be mild, resulting inflammatory agents – corticosteroids and anti- from diffuse wheezes, adequate air exchange leucotrienes [7]. Many medicinal plants have and mild dyspnoea; moderate, with respiratory been identified as capable of treating respiratory distress at rest, marked wheezes but involving disorders. These herbs in asthma therapy are the use of accessory muscles or severe, when used to relieve convulsive bronchitis and marked respiratory distress is expressed and bronchial asthma. These disorders are thought to characterized by marked wheezes and be caused by a continuous contraction of respiratory failure. When severe, respiratory bronchial smooth muscles usually accompanied distress, confusion and lethargy are experienced. by mucosal oedema and increased secretions. Incidence of death may arise from very severe Asthma as an inflammatory rather than a asthmatic attacks and respiratory failures. bronchospatic disorder needs the medicinal plants with constituents that can control Asthma is said to be caused by a combination of underlying airway inflammation as well. genetic and environmental factors. A major risk factor for developing asthma is the genetic Most anti-asthmatic herbs act by stimulating β- disposition of the individual; asthma symptoms adrenergic receptors causing relaxation of the are known to be due to liberation of endogenous bronchial smooth muscles, thus acting as and intrinsic mediators-histamine, leukotrienes, bronchodilators. Some act as mast cell nitric oxide, chemokines and endothelin from stabilizers, anti-allergics, anti-anaphylactic, anti- mast cells, inflammation of the airway in the inflammatory agents, anti-spasmodic agents, lungs etc. Asthma has been triggered by various inhibition mediators – leukotrienes, lipoxygenase, other factors; viral respiratory infections, cyclooxygenase, cytokine etc. and even as chemicals including certain medications, air- immunomodulatory agents in the treatment of 2 Adesina et al.; BJPR, 16(2): 1-22, 2017; Article no.BJPR.32973 asthma. The implications of these are that inflammatory activity. The bronchospasmolytic medicinal plants that must be used for constituent caused 82% inhibition of maximum the treatment of asthma should have anti- contraction produced by histamine (400 µg/ml). inflammatory, immunomodulatory, antihistaminic, On histamine (8 µg/ml) precoated trachea, smooth-muscle relaxant and allergic activity cumulative doses of the fractions evoked a dose- [7,8]. Where a remedy of four or more plants’ dependent relaxation [13], parts is prescribed for a treatment, the multifaceted roles these herbs will play, 2.1.3 Aloe vera Linn, Aloaceae (Aloe, aloe suggesting different modes of action within the vera) body will assist greatly in the management of the disease effectively. Ancient Egyptian papyrus and Mesopotamia clay tablets described Aloe as useful in curing 2.1 Plants Used in the Management of infections, treating skin problems and as a Asthma laxative. There are reports about anti- tuberculosis activity of A. vera [14]. 2.1.1 Acanthus ilicifolius Linn, Acanthaceae (Holy leaved acanthus) A. vera contains anthraquinones/anthrones, carbohydrates, chromones, enzymes and Plant is well known in traditional medicine for the proteins – lectins and lectin-like substances management of asthma, hepatitis, rheumatoid [14]. arthritis and as a diuretic [9]. Plant is allergenic and anti-asthmatic. Gupta The plant contains the alkaloids – acanthicifoline, et al. [15] evaluated the in vitro antitubercular trigonelline, 2 – benzoxazolinone, benzoxazin-3- activity of 5 medicinal plants one of which is one etc., aliphatic glycosides, flavonoids, and A. vera . Extracts of A. vera exhibited anti- lignan glycosides [9]. tuberculosis activity, the proportion of inhibition for A. vera was 32% for MDR (multi-drug A. ilicifolius aerial parts and root extract resistant) isolate (DKU-156) and 85% for another showed strong antimicrobial and antifungal MDR isolate (JAL- 1236) while for sensitive activities. 6-Hydroxy benzoxazolinone, (Z) – 4- M. tuberculosis H37 RV strain, inhibition was 41%, coumaric acid 4-0-β-D-glucopyranoside and 3,5- at 4% v/v concentration in Lowenstein Jensen Dimethoxy – 4-hydroxymethyl benzoate isolated (L-J) medium. from the plant were identified as the antibacterial constituents of A. ilicifolius . The alkaloids 2- 2.1.4 Achyranthes aspera Linn., Benzoxazolinone and benzoxazinoids were Amaranthaceae (Rough Chaf tree, identified as anti-inflammatory agents. The Prickly chaff flower, Devil’s horse whip) ethanol root extract partially prevented anaphylactic shock induced