IN VITRO ANTIFUNGAL ACTIVITY OF AQUEOUS AND ETHANOLIC EXTRACTS OF CARCIA PAPAYA ROOT AND BARK AGAINST CLINICAL CANDIDA ISOLATE

CHAPTER TWO LITERATURE REVIEW 2.1 Carica Papaya classification and vegetative growth Papaya (Carica papaya L.) is a fast-growing, short-lived, tropical tree, cultivated for its fruit, papain, pectin, and antibacterial substances (Niklas and Marler, 2007). Nowadays papaya is grown widely in tropical and subtropical lowland regions around the world, and the trade amounted nearly $200,000 million dollars by 2009 (Evans and Ballen, 2012). Carica papaya is a member of the Caricaceae family and is the most economically important species in the family (Carvalho and Renner, 2012). C papaya is the only member of the genus after its rehabilitation from the Vasconcella group which was considered part of the genus Carica, until the year 2000 (Badillo, 2000). The Caricaceae family, originated in Africa where two extant species occur. The dispersal to Central America from Africa occurred35 million years ago (MYA), possibly by floating vegetation carried by ocean currents. The Caricaceae members arrived to South America from Central America between 27 and 19 MYA, when the Central America land bridge already had begun to form, facilitating the range expansion from Mexico to South America. It is estimated that C. papaya diverged from its sister clade about 25 MYA, and belongs to a small clade restricted to Mexico, Guatamela and El Salvador that includes four species: three perennial herbs, Jarilla chocola, J. heterophylla, and J. nana that occur in seasonal tropical forests, and the tree let Horovitzia cnidoscoloides, endemic to Oaxaca in Mexico (Carvalho and Renner, 2014). Papayas possess a morphological structure and development according to Corner's model of architecture, a monopodial, single, orthotropic and non-branching trunk constructed by one vegetative meristem, with axillary inflorescences, hence with indeterminate growth. Carica papaya produces huge palmate-shaped leaves. Female flowers are produced at the axils of the leaf petiole, and later the fruits will occupy that position along the stem. Male individuals produce inflorescences. Three sex types of papaya are known: female, male, and hermaphrodite trees. In wild populations, most individuals are diclinous (dioecy), hereas cultivated papayas are dioecious or hermaphrodites (Carvalho and Renner, 2012; Chávez-Pesqueira et al., 2014). Cultivars can inbreed, resulting in stable characteristics across generations. For gynodioecious cultivated papaya, it has been reported that two-thirds of the plants correspond to hermaphrodites and one-third to female plants, though dioecious cultivars exist (VanBuren et al., 2015). Sex determination for the three types of