EVALUATION OF THE ANTIMICROBIA; ANTIOXIDANT AND STAINING PROPERTIES OF SIX INDIGENOUNS PLANTS EXTRACTS COLLECTED FROM SOUTHERN NIGERIA

1.0Background of Study

The Nigeria climate favours a great array of plant species many of which have varied medicinal and antimicrobial potentials (Adewusi, 1997; Adeuse-Poku et al., 2003; Ajebesone and Aina, 2004, Agyili et al., 2006). It is estimated that there are over 65,000 species of flowering plants that have medicinal properties (Akpulu et al., 1994; Akoachere et al., 2002, Akinpelu and Kolawole 2004). The vast medicinal use of plants is attributed to the abundant quantity of phytochemicals they contain (Farombi et al., 2005). Again, staining of microorganisms has been an important aspect of Medical Microbiology as it assists in identification, isolation and characterization of these organisms. Dyes, from which stains are made, are either natural or synthetic products. Most of the dyes used for bacterial and fungal smears are synthetic (Ochei and Kolhatkar, 2008). However, synthetic dyes cause skin allergies and other harms to human body on exposure and produce toxic waste (Goodarzian and Ekrami, 2010). The use of non-allergic and non-toxic stains has become a matter of importance due to the increased environmental awareness in order to avoid some hazardous synthetic ones. Research has shown that extracts obtained from natural sources such as plants, animal, vegetable sources, insects and soil hold promise as a potential source of cheaper stains (Ihuma et al., 2012). The medicinal plants of interest are Garcinia kola, Vitex doniana, Lantana aculeate, Lawsonia inermis, Cnestis ferruginea and Pterocarpus soyauxii.

Garcinia kola Heckel (Clusiaceae), commonly known as bitter kola is a widespread tree of evergreen forest valued in Nigeria for its medicinal nuts which has led to its exploitation in the natural forests (Farombi et al., 2005). Garcinia kola stem bark has been shown to contain a complex mixture of phenolic compounds such as tannins, guttiferin

(Etkin, 1981), biflavonoids, xanthenes, benzophenone, kolaflavanone and Garcinia flavanone (Iwu and Igboko, 1982) all of which have antimicrobial activity. Its mesocarp (fruit part) also contains alkaloids, anthocyanins, quinines and anthraquinones (Morabandza et al., 2013). Garcinia kola exhibits purgative, antiparasitic, anti-inflammatory, antibacterial and antiviral activity (Akintonwa and Essien, 1990). Terpenoids (phytochemical present in G. kola) have exhibited antimicobial activity against Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, methillin-resistant Staphylococcus aureus, S. epidermidis, Listeria monocytogenes, Enterobacter cloacae, Candida albicans and Aspergillus flavus (Santo et al., 2008; Nero and Moreira, 2010; Piera et al., 2011; Leandro and Vargas, 2012). The ethanolic fruit extract of the plant also demonstrated a potent antioxidant action better than the aqueous extract in a concentration dependent manner (Ogunmoyole et al., 2012).

Vitex doniana (Verbanaceae) is a tropical fruit bearing tree widely distributed in West Africa and high rainfall areas. It is commonly known as Fon or Ewe oyi by traditional healers and plants sellers in Bénin (Atawodi et al., 2003). It is also widely distributed in eastern, western and northern parts of Nigeria as a perennial tree, the plant commonly called black plum or African olive (English). It is locally called Mbembe or Uchakoro (Igbo), Ori nla (Yoruba) and Dinyar (Hausa), (Adejumo, et al., 2013). It is an erect branched evergreen tree of 20-60m high with a pronounced trunk of grey-brown, fissured bark (Keay et al., 1964). Chemical constituents of the plant include glycosides, flavonoids, alkaloids, essential fatty acid (Arokiyaraj et al., 2009). The presence of flavonoids in this plant extract explains its antioxidant activity. Flavonoids are potent water-soluble antioxidants and free radical scavengers which prevent oxidative cell damage and have strong anticancer activity. Flavonoids also lower the risk of heart diseases (Salah et al., 1995; Del-Rio et al., 1997; Okwu and Okwu, 2004). Previous study has demonstrated that 70% ethanolic, methanolic and ethyl acetate extracts of stem bark of V. doniana have proved an activity against S.

aureus organism (Ouattara et al., 2013). Methanolic, ethanolic and acetone leaves extracts of

V. doniana inhibited E. coli, S. aureus, B. subtilis and S. typhi organisms at varying concentrations of the extracts. Leaf extracts of V. doniana also inhibited sporulation and mycelia development of Aspergillus flavus, A. parasiticus, A. terreus, A. ochraceus, A.nidulans and A. fumigatus (Lagnika et al., 2012).

Lantana aculeata is a well known medicinal plant in traditional medicinal system and recent scientific studies have emphasized the possible use of L. aculeata in modern medicine (Kalita et al., 2012). It is a flowering ornamental plant belonging to the family, Verbenaceae. Different parts of L.aculeata are reported to possess essential oils, phenolic compounds, flavonoids, carbohydrates, proteins, alkaloids, glycosides, iridoid glycosides, phenyl ethanoid, oligosaccharides, quinine, saponins, steroids, triterpens, sesquiterpenoides and tannin as major phytochemical groups (Bhakta and Ganjewala, 2009; Kensa, 2011). Several previous reports have described antifungal, anti-proliferative and antimicrobial activities of L. aculeata (Saxena et al., 1992; Kasali et al., 2002; Nagao etal., 2002; Rajakaruna et al., 2002; Tripathi and Shukla, 2002; Kumar et al., 2006). The extracts of L. aculeata exhibited antimicrobial activity against S. aureus, Proteus vulgaris, P.aeruginosa, Víbrio cholerea, E. coli and two multi resistant strains E. coli and S. aureus (Barreto et al., 2010).

Lawsonia inermis (Henna) is a medicinal plant that is widely distributed across the Northern and Southern parts of Nigeria (Emin and Mehmet, 2012). It is used as a kind of natural dye and is used as a raw material for natural hair dye (Kok et al., 2005). The use of L. inermis as counter stain has been reported (Chukwu et al., 2011). The naturally available L. inermis could be a potential alternative to antimicrobials that become less effective or ineffective against certain pathogenic microorganisms (Dinesh Babu and Subhasree, 2009). The plant contains substances such as lawsone (principal colouring matter), gallic acid, glucose, mannitol, fats, resin, mucilage and traces of an alkaloid. The leaves extract of L.

inermis also contain phytochemicals such as glycosides, phytosterol, tannins, steroidal compounds and flavonoids (Raja et al., 2013). The presence of flavonoids explains the antioxidant property of this plant extract. L. inermis leaves, flower, seeds, stem bark and roots have been found to exhibit antioxidant, antidiabetic, hepatoprotective, hypoglycemic, antimicrobial, anticancer and wound healing properties (Hema et al., 2010). The extract of L. inermis was shown to have promising antibacterial properties against S. aureus and P. aeruginosa (Santhamari et al., 2011). It was also reported that methanol, aqueous, chloroform and acetone leaves extracts of L. inermis inhibited the activity of S. aureus, B. subtilis, S. typhi, S. epidermidis, E. coli, Klebsiella species and Shigella species (Gull et al., 2013).

Cnestis ferruginea (Connaraceae) is a shrub or climber of deciduous forest and widely dispersed in West Africa and other tropical parts of Africa and bears orange-red fruits with velvety hairs on the follicle (Irvin, 1961; Margaret, 1965; Ronal, 1974, Burkill, 1995). Common names of the plant in Nigeria include “Fura amarya”, “otito” (Hausa); “Okpu nkita”, “amunkita” (Igbo); and “Akara oje”, “Bonyin bonyin” (Yoruba); “Ukpo-ibieka” (Edo) and “Usiere ebua” (Efik) (Burkill, 1995). The plant is about 3.0-3.6m high with densely, rusty brown, pubescent branches, indecidous leaves with more or less alternate or sometimes opposite, ovate to narrowly oblong leaflets. The ovoid follicles are 1-5 in fruit, often united at base (Garonn et al., 2007). The plant has an ornamental value and is used across Tropical Africa to treat diverse ailments (Ishola and Ashorobi, 2007). Different parts and preparations of C. ferruginea have been reported to be used in traditional African medicine for the treatment of various conditions (Burkill, 1985; Ishola and Ashorobi, 2007).

Pterocarpus soyauxii is a 30-55 feet high rain forest tree. It belongs to the Papilionaceae family, branch of spermaphytes (Burkill, 1995). The plant stem bark, greyish brown to brown-colour, scales off in fine irregular scales and contains a red sap. It is commonly known as African Padauk and has a high hygroscopic stability, and good natural

durability due to its extractives (Deon et al., 1980). Other common names are mukwa or narra. The scientific name is Latinized Ancient Greek and means “wing fruit”, referring to the unusual shape of the seed pods in this genus. It contains about 13% extractives, which were abundantly used as a dye-source in the 19th century (Rajalakshi et al., 2013). In previous report attempt has been made to investigate the feasibility of employing the natural dye extracted from P. soyauxii as a sensitizer for Titanium dioxide (TiO2) thin films. This is because natural dyes enable efficient sensitization without complex synthetic and purification process. Titanium dioxide is a non toxic and inexpensive material with appropriate photoelectrochemical properties for solar cells application (Rajalakshmi et al., 2013). Various parts of this plant are used in Africa for the treatment of different diseases and this is attributed to the presence of phytochemicals and minerals in the plant extract (Oteng-Gyang and Mbachu, 1987; Kimpouni, 1999; Okafor, 1999; Sarah, 1999).