PHYTOCHEMICAL SCREENING AND ANTIMICROBIAL ACTIVITIES OF AQUEOUS AND METHANOLIC LEAF EXTRACT OF Ricinus communis (CASTOR PLANT) ON SOME SELECTED PATHOGENIC MICROORGANISMS

PHYTOCHEMICAL SCREENNG AND ANTIMICROBIAL ACTIVITIES OF AQUEOUS AND METHANOLIC LEAF EXTRACT OF Ricinus communis (CASTOR PLANT) ON SOME SELECTED PATHOGENIC MICROORGANISMS

ABSTRACT

The Phytochemical Screening of Aqueous and Methanolic leaf extract of Ricinus communis (Castor Plant) was carried out to determine the presence of secondary metabolites in the Aqueous and Methanolic extract of R. communis (Castor plant) leaf. The Phytochemical screening performed on both Aqueous and Methanolic leaf extract of R. communis revealed the presence of Tannins, Saponins, Alkaloids, Cardiac Glycoside and Flavonoid except for Flavonoid that was absent for Aqueous extract. The Antimicrobial activity of R. communis Aqueous and Methanolic leaf extract was determined by agar well diffusion method on some selected pathogenic microorganisms (Streptococcus spp, Klebsialla spp, Aspergillus niger and Candida albicans) at 200mg/ml, 100mg/ml, 50mg/ml and 25mg/ml concentrations. The highest zone of inhibition obtained was 19.63mm on Streptococcus spp by R. communis Methanolic extract at 200mg/ml concentration, while the lowest zone of inhibition was 6.99mm on A. niger by R. communis Aqueous leaf extract at 25mg/ml concentration. The Aqueous and Methanolic extract of R. communis leaf showed Minimum Inhibitory Concentration (MIC) by broth dilution method. The least MIC was 25mg/ml concentration for Methanolic leaf extract on A. niger and Aqueous leaf extract on C. albicans, while the highest MIC was 100mg/ml concentration for Aqueous leaf extract on S. spp, whereas the Minimum Microbicidal Concentration (MMC) was determined and the highest MMC was 200mg/ml concentration for Aqueous extract of R. communis on S. spp and the least MMC was 50mg/ml concentration for Methanolic extract on A. niger and Aqueous extract on C. albicans. From the results obtained, R. communis significantly inhibited the growth of the test microorganisms.

CHAPTER ONE

1.0                                                                                                                      INTRODUCTION

Medicinal plants are significant for the study of their conventional uses through the confirmation of their pharmacological effects and they might be natural composite sources that can act as new anti-infectious agents (Ushimaru. 2017). Numerous medicinal plants are gifted to mankind by nature, and a distinguished number of modern drugs have been manufactured from these naturally known medicinal plants, such as herbal medication and health care preparations, is also found in modern literature. In fact, plants have diversity of biological active compounds, and it is a sign which makes the plants a wealthy source of a variety of drugs (Farombi, 2013).

Plant extracts and their active phytochemcial compounds have been used for antimicrobial activities and have significant remedial properties. In the recent years, a wide range of investigations have been carried out throughout the world to confirm antimicrobial properties of different medicinally important plants. A number of plants showed efficient antimicrobial activities, which were comparable to that of synthetic standard drugs or antimicrobial agents. An increase in the incidence of impending transferable diseases is hazard. Isolation of different extracts and many other chemical compounds from plants efficient antimicrobial activities can be of immense impact in the healthcare. Medicinal action of the plants is defined to some important chemical compounds that pass on a definite physiological action on the human body (Satish et al., 2018).

The castor plant (Ricinus communis) is a specie of flowering plant in the spurge family, Euphorbiaceae. It belongs to a monotypic genus, Ricinus and subtribe, Ricininae. Castor is indigenous to India, Southeastern Mediterranean Basin and Eastern Africa but is widespread throughout the world. Ricinus communis is a herbal medicine with great medicinal importance. All the parts of the plant (viz, leaf, bark, flower, seed, oil etc.) have been reported to have medicinal value, and specially, the oil of this plant (called cathartic) has been extensively used in Ayurveda, Unani. Homeopathic and Allopathic system of medicines. Although oil of Ricinus communis which have been used as a medicine in traditional system for treatment of lumbago, rheumatism and sciantica and swelling etc. as well known very less focus has been given to other plants say the leaves, stem, and roots. (Mathur et al., 2011; Takhi et al., 2011, and Jain & Nafis, 2020)

The castor contains many compounds that are poisonous to human beings, animals, insects and microorganisms. The major toxic protein, ricin is used as a biological weapon as a single milligram can kill an adult human being. It is mainly present in seeds. Ricin inhibits protein synthesis by acting mainly on eukaryotic ribosomes. So, fungi are more susceptible to it than bacteria (Zartman et al., 2013). In addition, the plant contains steroids, saponins, alkaloids, flavonoids, tannins, phenols, phytates, oxalates and glycosides in different parts of the plant including roots, leaves and seeds. All these compounds are responsible for antimicrobial properties of castor. Since, these toxic compounds are present in all parts of the plant so antimicrobial properties are also shown by whole plant (Jena and Gupta. 2012).

Ricinus communis possess good antimicrobial activities against pathogenic bacterial strains such as Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis as well as Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus vulgaris, Salmonella typhimurium, Escherichia coli and many others. Castor also shows antimicrobial activity against some fungal pathogens i.e. Candida albicans, Aspergillus niger etc (Islam et al., 2010; Mathur et al., 2011). However, in addition to human pathogens castor inhibitors also have negative effect on soil microbial community. Soil health and productivity is directly related to soil microflora as it is an intimate part of soil organic matter and supports growth and development of different crops in many ways.
Castor leaves are used in the treatment of rheumatism, headache, dropsy (edema), abscesses, ringworms, and warts. Also, they are used externally by nursing mothers to increase the flow of milk (Rana  et al., 2012).Castor oil is a natural emollient and can be applied to the skin and hair as a softener. Castor oil is used to cure temporary constipation, colic and acute diarrhea. Applied externally to treat ringworm and itch. Castor oil can support labor and delivery (Azhari et al., 2006).

There are various studies on the antimicrobial potential of leaf extracts of Ricinus communis. A study evaluating the antibacterial, antifungal and the percentage inhibition of various extracts of leaf of Ricinus communis plant showed that the methanolic leaf extracts of the Ricinus communis has significant potential to inhibit both bacterial and antifungal pathogens (Naz et al., 2012). Another study on the antimicrobial activity of various extracts of roots (200mg/mI) of Ricinus communis established the potential of Ricinus communis as an effective antimicrobial agent against pathogenic microorganisms such as Escherichia coli Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimuriurn, Proteus vulgaris, Bacillus subtillis, Candida abicans and Aspergillus niger (Mathur et al., 2011). A comparative study on the antibacterial effects of Ricinus communis leaf extract showed that leaf extracts have a better antibacterial activity in comparison with the standard drug named gentamycin (Kota et al., 2011).

1.1       Statement of the Problem

Dependence of human population on the available antibiotics or anti-fungi has led to an increment in the resistance in the microorganism towards them (Naz et al., 2012). However, a large portion of the world is still working in the search of better drugs. But the problem is still the same after some time the new drugs become ineffective or have a large number of side effects associated with them. Herbal antibiotics can be a good answer to this challenges by the microorganism, a large of the available plants have been used since time immemorial for the treatment of various diseases (Mathur, et al., 2011). As per a report of WHO in 1993 nearly 80% of the world population is dependent on the traditional system of medication that is the use of plants and their parts as medicine (Mathur, et al., 2011). It is against this problem that this study seeks to investigate the antimicrobial activities of aqueous and methanolic leave extract of castor plant on some selected microorganisms.

1.2       Justification to the problems

Medicinal plants can be a good alternative to conventional medicines in combating diseases caused by infectious microorganisms. These plants contain a number of natural products which can be used to manufacture synthetic drugs. Numerous plants with medicinal properties have been gifted to mankind by nature. The interest in scientific research of R. communis (Castor plant) is due to its efficacy in the alleviation of a number of diseases worldwide because of presence of phytochemical compounds in different parts of the plant. In the recent years, a number of researchers studied the antimicrobial properties of R. communis throughout the world. Results of such studies have shown that Ricinus communis possess good antimicrobial activities against pathogenic bacterial strains such as Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis as well as Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus vulgaris, Salmonella typhimurium, Escherichia coli and many others. It is in the light of these numerous advantages of castor plants that this study is justified to investigate the antimicrobial activities of aqueous and methanolic leave extract of castor plant on some selected microorganisms.

1.3       Aim of the study

The aim of this study is to investigate the antimicrobial activities of aqueous and methanolic leave extract of Ricinus communis (castor plant) on some selected microorganisms.

1.4       Objectives of the study

1.      To determine phytochemical constituents of R. communis plant aqueous and methanolic leave extract.

2.      To examine the antimicrobial activity of methanol and aqueous leave extract of R. communis.

3.      To determine the Minimum Inhibitory Concentration (MIC) and Minimum Microbicidal Concentration (MMC) of the leaf extract.