Studies on the Chemotaxonomic Properties of Carica papaya L., a Member of the Family Caricaceae

Greener Journal of Biological Sciences

Vol. 10(1), pp. 27-32, 2020

ISSN: 2276-7762

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Studies on the Chemotaxonomic Properties of Carica papaya L., a Member of the Family Caricaceae

*¹Wahua, Chika; ²Adolga,Emmanuel

*¹Department of Plant Science and Biotechnology, Faculty of Science, University of Port Harcourt, Choba, P.M.B.5323, NIGERIA. Email: chika.wahua@ uniport.edu. com; Phone number: +2348064043448

² Department of Plant Science and Biotechnology, Faculty of Science, University of Port Harcourt, Choba, P.M.B. 5323, NIGERIA. Email: adolga@ gmail. com; Phone number: +2347068133667

ARTICLE INFO	ABSTRACT
*Article No.:* 022920042 *Type: Research*	The research investigated the chemotaxonomic characteristics of Carica papaya L., a perennial plant belonging to Caricaceae. The materials were fixed in FAA, sectioned and photomicrograph taken as described by Wahua. The morphological description revealed the cylindrical stem is greenish gray up to 10m high having leaf scars with hollow spongy-fibrous tissues. The leaf lamina is orbicular and 25 to75cm wide. The petiole is 30 to 100cm long, and spirally clustered near stem apex. The shoot system exudes white milky latex. The flowers are yellowish, funnel-shaped and often clustered in leaf axil. Three types of flowers are observed in Carica papaya: the female flowers are 3 to 5 cm long with large functional pistil and ovoid-shaped parietal ovary; male flowers have long panicles, 10 stamens in 2 rows while hermaphrodite flowers are larger with 5-carpellate ovaries. The hollow berry fruits are smooth and spherical up to 10 to 50cm long with fleshy orange or red pulp. Two varieties are known, the red and yellow fleshed fruit types. Seeds are numerous, oval and rounded gray or black in shape, embedded in gelatinous aril. Stomata are anomocytic. The petiole, midrib and stem anatomy showed the same cell arrangement pattern from the epidermal, hypodermis, general cortex to the pith with presence of laticiferous cells. The hypodermis is made of collenchyma while parenchyma occupied the cortex and pith. Node is unilacunar. Phytochemical analysis revealed the presence of: flavonoids, saponins, tannins, cardiac glycoside and steroids while terpenoids were absent. The study enhanced information on existing literature.
*Accepted:* 06/03/2020 *Published:* 07/05/2020
Corresponding Author Wahua, Chika* *E-mail:* chika.wahua@ uniport.edu.com *Phone:* +2348064043448
*Keywords:* *Morphology; palynology; phytochemistry; anatomy; Carica; papaya*.

INTRODUCTION

Origin and Geographical Distribution

Opinions differ on the origin of Carica papaya L. in tropical America (Garrett, 1995; Aradhya et al., 1999; OECD, 2005), it is likely that C. papaya originated from the lowlands of Eastern Central America, from Mexico to Panama (Nakasone & Paull, 1998). It’s seeds, which remain viable for several years if dried, were distributed to the Caribbean and South-East Asia (Philippines) during Spanish exploration in the 16^thCentury, from where it was further distributed to India, the Pacific and Africa (Villegas, 1997). Today, C. papaya is widely distributed throughout the tropical and warmer subtropical areas of the world (Villegas, 1997) and has become naturalized in many areas (Morton, 1987). It is now grown as a fruit crop in all tropical countries and many sub-tropical regions of the world. (Garrett, 1995).

Taxonomic Hierarchy and Botanic Description

Caricaceae Dumort. belongs to the Order Brassicales and was thought to comprise 31 species in three genera name Carica, Jacarantia and Janilla from tropical America but recent findings show that it comprises 6 genera and about 34 species mostly of dioecious trees, shrubs or herbs (APG IV 2016). The plant is a short lived, fast growing, woody, herb like tufted tree that can grow up to 10m in height (Morton, 1987). It generally branches only when injured; it is now grown as a fruit crop in all tropical countries and many sub-tropical regions of the world (OECD, 2005).

Carica L. has perfect, complete or hermaphrodite flowers and terminal flowers with rudimentary pistil and pistillate flowers with no vestiges of the androecium are present (Kubitzki, 2003).

Morphological Description of Carica papaya L.

The petiole is hollow and 25 to 100 cm long. The lamina is 25 to 74cm in diameter and palmately 7 to 11 lobed to varying degrees (Badillo, 1971).

Various parts of papaya are of utmost medicinal uses. Carica papaya leaves serve as antiseptic, while the brown, dried pawpaw leaves basically used as tonic and blood purifier.

The relevance of the study is to enhance information on the existing literature and taxonomic characteristics of Carica papaya.

The Objectives of the study is to provide extensive and more current description on Carica papaya using the morphological, anatomical, palynological and phytochemical properties.

MATERIALS AND METHODS

Geographic Location: The location of the parent plant studied was Port Harcourt, Rivers, Nigeria.

Morphological Studies: The meter rule was used to ascertain the plant height, leaf length and width etc.

Micro-morphological (Epidermal) Studies: Fresh leaves and young stem collected for this study were peeled and bleached using sodium hypochlorite for about 2 minutes following the method of Cutler (1978). The cleared epidermal layers obtained were stained with Alcian blue or safranin and temporarily mounted in aqueous glycerol solution. Photomicrographs were taken from good preparations. The stomatal index [S.I.] was obtained using the formula:

where S and E are mean numbers of stomata and epidermal cells respectively within the particular area under investigation.

Likewise trichome Index (T.I.) =

Where T and E are trichomes and epidermal cells respectively within the study area.

Anatomical Study: Seeds of the plant were plated in petri dishes containing wetted 110mm Whatman filter paper. After three to five days, harvest was made for primary anatomical study and two weeks to one month, for the secondary anatomy. The harvested stems, leaves, petioles, flowers, fruits and roots were fixed in FAA in the ratio of 1:1:18 of 40% formaldehyde, acetic acid and 70% alcohol for at least 48 hours following the method of Johansen, (1940). The free hand sectioning using a systematic arrangement of 5 razor blades as described by Wahua et al. (2013) was also adopted. Microphotographs were taken from good preparations using Sony camera of 7.2 Mega pixels having 2.4¹¹ LCD monitor and High sensitivity ISO 1250.

Phytochemical Study: Leaves of Carica papaya L. studied were sun dried for 72 hours (3 days) and weighed. Fifty grams (50g) of the dried leaves were macerated in 96% ethanol using a pestle and a mortar. The extract was thereafter filtered and evaporated to dryness (constant weight) using a rotary evaporator set at 45⁰C. Residue yields were noted and a portion was used for the phytochemical screening.

Phytochemical screening for saponin: Frothing tests was done following the method described by Wall et al. (1952)). The ability of saponins to produce frothing in aqueous solution and to haemolyse red blood cells was used as screening test for these compounds. 0.5g of the plant extract was shaken with water in a test tube. Frothing which persisted on warming was taken as preliminary evidence for the presence of saponins. The disc was then washed in ether, dried and placed on a 7 percent blood nutrient agar. Complete haemolysis of red blood cells around the disc after 6 hours was taken as further evidence of presence of saponins.

Test for alkaloids: This was carried out using 0.5g of the plant extract which was stirred with 5ml of 1 percent aqueous hydrochloric acid on a steam bath; 1ml of the filtrate was treated with a few drops of Mayer’s reagent and a second 1ml portion was treated similarly with Dragendorff’s reagent. Turbidity or precipitation with either of these reagents was taken as preliminary evidence for the presence of alkaloids in the extract being evaluated (Harborne, 1973 and Trease et al., 1989). A modified form of the tin-layer chromatography (TLC) method as described by Farnsworth et al. (1962) was used. One gram (1g) of the extract was treated with 40 percent calcium hydroxide solution until the extract was distinctly alkaline to litmus paper, and then extracted twice with 10ml portions of chloroform. The extracts were combined and concentrated to 5ml. The chloroform extract was then spotted on thin-layer plates. Four different solvent systems were used to develop each plant extract. The presence of alkaloids in the developed chromatograms was detected by spraying the chromatograms with freshly prepared Dragendorff’s spray reagent. A positive reaction on the chromatograms (indicated by an orange or darker colored spot against a pale yellow background) was confirmatory evidence that the plant extract contained alkaloid.

Test for tannins: Five grams (5g) of each portion of plant extract was stirred with 10ml of distilled water, filtered, and 5% ferric chloride reagent added to the filtrate. A blue-black, green, or blue-green precipitate was taken as evidence for the presence of tannins (Shoppee, 1964).

Test for anthraquinones: Borntrager’s test was used. Five grams (5g) of each plant extract was shaken with 10ml benzene, filtered and 5ml of 10 per cent ammonia solution added to the filtrate. The mixture was shaken and the presence of a pink, red, or violet color in the ammonia (lower) phase indicated the presence of free hydroxyanthraquinones.

Test for combined anthraquinones: Five (5g) of each plant extract was boiled with 10ml aqueous sulphuric acid and filtered while hot. The filtrate was shaken with 5ml of benzene, the benzene layer separated and half its own volume of 10 per cent ammonia solution added. A pink, red or violet coloration in the ammonia phase (lower layer) indicated the presence of anthraquinone derivatives in the extract (Trease and Evans, 1989).

Test for phlobatannins: The deposition of a red precipitate when an aqueous extract of the plant part was boiled with 1 percent aqueous hydrochloric acid was taken as evidence for the presence of phlobatannins (Trease and Evans, 1989).

Test for cardiac glycosides: Lieberman’s test was used in which 0.5g of the extract was dissolved in 2ml of acetic anhydride and cooled in ice. One milliliter (1ml) of Sulphuric acid was carefully added in drops until a color change from violet to blue to green indicated the presence of a steroidal aglycone portion of the cardiac glycoside (Shoppee, 1964).

RESULTS AND DISCUSSION

Investigation on the anatomical features of Carica papaya shows that the stem, petiole, midrib have the same cell arrangement from the epidermal layer through the hypodermis which is in line with the research work documented by (Wahua et al., 2013)

Phytochemical analysis of the extracted dried seeds using qualitative method showed the presence of Cardiac Glycosides, flavonoids, tannins, steroid, saponins, but terpenoids was absent in both the red and yellow fleshed fruit Carica papaya seeds. Steroid was present in the yellow fleshed fruit seed but was absent in the red fleshed fruit seed. These phytochemicals extracted exhibit some diverse pharmacological and biochemical actions or activities when ingested by animals.The pollen morphology of Carica papaya was studied critically, the pollen grains were observed to be tri-colporate with lalongate endoapertures, and spheroidal to prolate in shape; the exine is reticulate or bireticulate, and lumina and colpus membrane are granulate. This is confirmed in the works of Badillo (1971).