PHARMACOGNOSTIC AND ANTIULCER STUDIES ON THE LEAF OF LEUCAS MARTINICENSIS (JACQ) R.Br. (LAMIACEAE)

ABSTRACT

Leucas martinicensis is an annual herb which is used for repellant of mosquito. It has minty odor. It is an erect plant which is usually unbranched, with length of up to 1m, which is finely hairy. The plant are widely used in Northern part of Nigeria and it has been exploited for both its medicinal and economic properties with no scientific justification about its antiulcer activities. It is traditionally used for the management of a number of ailments including the treatment of diarrhea, skin rashes, epilepsy, gastroenteritis, cholera, relieving pain during pregnancy and as anti-malaria. The pharmacognostic studies and antiulcer activities of the leaves of Leucas martinicensis (Lamiaceae) was carried out to validate the ethno medicinal claimed of the leaves in treating ulcer. Evaluation of the fresh, powdered leaves and phytochemicals screening were carried out. The acute toxicity and antiulcer properties revealed the leaves potential as source of drug for further utilizations. The microscopical characters and physical constants of the leaf were determined, which revealed the presence of some prominent features like multicellular covering trichomes and diacytic stomata. The physical constants evaluated showed moisture content 8.9% of Leucas martinicensis, total ash value of 6.8 %, water soluble ash of 6.0 %, acid insoluble ash of 3.5 %, ethanol extractive value of 16.0 % and water extractive value of 20.3 %. Phytochemical analysis of the leaves extracts revealed the presence of alkaloids, tannins, flavonoids, carbohydrate, cardiac glycosides, saponins, triterpenes and steroids and anthracenes. The median lethal dose (LD50) of the extract was found to be greater than 3000 mg/kg when administered orally in rats and considered practically non-toxic. The extract demonstrated protective activity against ethanol induced gastric ulcer lesions in albino rats. This is evidenced in the significant and increased preventive index with doses (300, 600 and 900 mg/kg) of the extract. The methanol extract was observed to have the best activity compared to organic solvent fractions. The results provided some pharmacognostic standards for proper identification of the plant and scientific basis for the traditional use of the leaf in the treatment of ulcer.

CHAPTER ONE

1.0 INTRODUCTION

1.1 Background of the Study

Herbal medicine is recognized as the most common form of alternative medicine (Ogbonnia et al., 2011). The World Health Organization (WHO) estimates that 80 % of the world’s population relies on these “alternative” plant-based medicines as their primary medical intervention especially in the developing countries, Even in the developed countries where modern medicines are more popular, interest in the use of natural product is on the increase (Rickert et al., 1999; Kroll and Shaw, 2003; Ogbonnia et al., 2008). The use of herbs in the treatment of illnesses has been very successful over the years and its historic usage has been useful in drug discovery and development. Herbal prescriptions and natural remedies are commonly employed in developing countries for the treatment of various diseases, this practice being an alternative way to compensate for some perceived deficiencies in orthodox pharmacotherapy (Sofowora, 1989; Zhu et al., 2002). The popularity and availability of the traditional remedies have generated concerns regarding the safety, efficacy and responsibility of practitioners using traditional remedies (Chan, 1995). Herbal remedies are considered safer and less damaging to the human body than synthetic drugs (Alam et al., 2011). However, the lack of standardization has been a major concern regarding the use of herbal medicines (Angell and Kassierr, 1998). Therapeutic efficacy of medicinal plants depends upon the quality and quantity of chemical constituents. The misuse of herbal medicine or natural products starts with wrong identification. The most common error is when one common vernacular name is given to two or more entirely different species (Dineshkumar, 2007).

Generally herbal formulations involve the use of fresh or dried plant parts. Correct knowledge of such crude drugs is very important aspect in preparation, safety and efficacy of the herbal product. The process of standardization can be achieved by stepwise pharmacognostic studies (Nivedithadevi and Somasundaram, 2012). Standardization is a system to ensure that every packet of medicine that is sold has the correct amount and will induce its therapeutic effect (Nasreen and Radha, 2011). Determination of extractive values, ash residues and active components saponin, alkaloids and essential oil content where applicable splay a significant role for standardization of the indigenous crude drugs (Hina et al., 2011).

Standardization of herbal formulations is essential in order to assess the quality of drugs, based on the concentration of their active principles, The quality assessment of herbal formulations is of paramount importance in order to justify their acceptability in modern system of medicine (Satheesh, 2011).

Focus on plants research has increased Worldwide and several studies had showed immense potential of medicinal plants (Dahanurkar et al., 2000). Herbal medicines derived from plants extracts are increasingly being recognized in treating various clinical diseases, with relatively little knowledge of their modes of action (Begum et al., 2008).

It basically deals with authentication, standardization, and study of natural drugs. Most of the researches in pharmacognosy have been done in identifying controversial species of plants, authentication of commonly used traditional medicinal plants through morphological, phytochemical and physicochemical analysis. The importance of pharmacognosy has been widely felt in recent times. Unlike taxonomic classification, pharmacognostic study includes parameters which help in identifying adulteration in dry powder form also.

This is again necessary because once the plant is dried and made into powder form, it loses its morphological identity and easily prone to adulteration. Pharmacognostic studies ensure plant identity, lays down standardization parameters which will help prevent adulterations. Such studies will help in authentication of the plants and ensures reproducible quality herbal products which will lead to safety and efficacy of natural products (Sumitra, 2014).

Pharmacognostic evaluation includes macroscopic, microscopic, physico-chemical, fluorescence and phytochemical studies of herbal parts or powdered drug Herbal raw material shows a number of problems when quality and authentication aspects are considered. This is because of nature of herbal parts, ingredients and different phytochemical present in plants (WHO, 2011). To ensure quality of herbal medicines, proper control of starting raw material is very important. The physico-chemical evaluation includes qualitative and quantitative tests, assays and instrumentation analysis. Qualitative and quantitative chemical tests include the presence or absence, quantity, values and identification of various phytochemical like flavonoids, glycosides, saponins, alkaloids etc. (Harborne, 1992; Evans, 2009). Macroscopic identity of medicinal plant materials is based on sensory evaluation parameters like shape, size, colour, texture, odour and taste while microscopy involves comparative microscopic inspection of powdered herbal drug. Further, advances in microscope technology have increased the accuracy and capabilities of microscopy as a mean of herbal crude material identification due to the implication of light and scanning electron microscopes (SEM) in herbal drug standardization (Bhutani, 2003).

Peptic ulcer is an excoriated area of the gastric or duodenal mucosa caused by action of the gastric juice. It is a chronic and recurrent disease, and is the most predominant of the gastrointestinal diseases.

Ulcer is basically an inflamed break in the mucus membrane lining the alimentary tract. Ulceration occurs when there is a disturbance of the normal equilibrium caused by either enhanced aggression or diminished mucosal resistance (Sravani et al., 2011). A peptic ulcer in the stomach is called a gastric ulcer. One that occurs in the duodenum is called a duodenal ulcer. People can have both gastric and duodenal ulcers at the same time (Ramakrishnan and Salinas, 2007). The anatomic sites where ulcer occurs commonly are stomach and duodenum, causing gastric and duodenal ulcer, respectively (Rang et al., 2003). Pathophysiology of ulcer is due to an imbalance between aggressive factors (acids, pepsin, Helicobacter pylori and non-steroidal anti-inflammatory agents) and local mucosal defensive factors (mucus bicarbonate, blood flow and prostaglandins). Integrity of gastroduodenal mucosa is maintained through a homeostatic balance between these aggressive and defensive factors (Raskin et al., 1995). About 19 out of 20 peptic ulcers are duodenal while gastric ulcers found in the stomach wall are less common (Gadekar, 2010). The gastric mucosa is continuously exposed to potentially injurious agents such as acids, pepsin, bile acids, food ingredients, bacterial products (Helicobacter pylori) and drugs (Grossman, 2009).These agents have been implicated in the pathogenesis of gastric ulcer, including enhanced gastric acid and pepsin secretion, inhibition of prostaglandin synthesis and cell proliferation growth, diminished gastric blood flow and gastric motility (Grossman, 2009). Symptoms of ulcer include epigastric pain of a burning nature (postprandial pain and pain relieved by food or antacids), nausea, vomiting, belching and bloating.

Complications of protracted untreated cases include anemia caused by gastro-intestinal blood loss, weight loss attributed to a reduced appetite caused by fear of pain and vomiting associated with a gastric ulcer or pyloric stenosis and mucosal perforation (Hunt et al., 2006). Current management of peptic ulcer disease involves the use of proton pump inhibitor (PPI), an antibiotic (triple therapy) (Malfertheiner, 2002).

However, reviewed literature showed that plant constituents like Flavonoids, Tannins, Terpenes, Steroids, Saponins, and Alkaloids is responsible for antiulcer activity (Khalid et al., 2010). Recently, there has been a rapid progress in the understanding of the pathogenesis of peptic, ulcer. Most of the studies focus on newer and better drug therapy. These have been made possible largely by the availability of the proton pump inhibitors, histamine receptor blockers, drugs affecting the mucosal barrier and prostaglandin analog. However, the clinical evaluation of these drugs showed development of popularly known, tolerance and incidence of relapses and side effects which make their efficacy arguable. This has been the rationale for development of new antiulcer drugs, which include herbal drugs (Manonmani et al., 1995).