DETERMINATION OF EFFECT OF AVOCADO SEED EXTRACT ON GROWTH OF CANDIDA ALBICANS YEAST

CHAPTER ONE Introduction 1.0. Background There is growing awareness worldwide, for using medicinal plants, over the conventional antibiotics, as an alternative for the treatment, management and prevention of infectious diseases. Indeed, conventional antibiotics are rapidly becoming less effective due to the emergence of multi-drug resistance among microbial strains (Ali et al., 2015). This renewed interest in alternative therapies may also have been prompted by an increased incidence of the disease as well as opportunistic infections, especially in immunocompromised people who have become difficult to manage with orthodox antibiotics (Badria and Zidan, 2004). One approach to circumvent this challenge is to use bioactive plant phytochemicals (Singh et al., 2009). The use of plants as phytotherapeutic agents is also relatively less expensive than conventional medicines. When given in higher concentrations, they rarely have such drastic side effects on the host (Saraf, 2010).Plants are known to have a broad spectrum of antimicrobial activity and are a source of many of these compounds (Ayodele and Banuso, 2004).Most plants have been shown to possess antibacterial, antifungal and antiviral properties (Ali et al., 2004).These plants include Thymus vulgaris, Cassia fistula, Xylopia aethiopica, Allium cepa, A. sativa and Anarcardium occidentalis (Amadi et al., 2007; Akpomie and Olorungbon, 2011). The most important bioactive constituents of plants are flavonoids, tannins, phenolics, alkaloids and their antimicrobial activity may reside in a variety of these phytochemicals (Gonclaves et al., 2005).These phytochemicals are secondary metabolites present in plants that allow them to fight against many disease-causing pathogens, so they have pharmacological potential (Husaine et al., 2011).Persea americana (avocado) is one of the most important fruits used as food in most tropical and subtropical countries. Different parts of the plant are used in herbal preparations. The peel, leaves and fruits are used in the treatment of haemorrhagia, hypertension. The leaf extract effectively inhibited herpes simplex virus type I and II (Sturluson, 2017). The seeds of P.americana have been applied to treat various diseases such as dysentery, skin infections, toothache (Pamplora and Roger, 1999). The seeds are also rich in tannin and carotenoids (Lu et al., 2005) and have high antioxidant activity and a phenol content greater than 70% (Soong and Barlow, 2004). Rodríguez Caperna et al. 2011 reported that the seed extracts of P.Americana have been shown to be more effective against gram-positive bacteria than gram-negative bacteria and are active against organisms such as Cryptococcus neoformans (Leite et al., 2009); Enterococcus faecalis, Salmonella enteritidis, Citrobacter freundii, Pseudomonas aeruginosa, S. typhimurium (Chia and Dykes, 2010).The seed oil and the leaves have different applications in ethnomedicine