1 ASSESSMENT OF THE PHYTOCHEMICAL, PROXIMATE,

2 VITAMIN AND MINERALCOMPOSITION OF SOLANUM GILO L.

3
4 Author details:
5 *SUNDAY ONYKWERE EZE AND CHIDINMA QUEENETH KANU
6 DEPARTMENT OF PURE AND INDUSTRIAL CHEMISTRY
7 ABIA STATE UNIVERSITY, UTURU, NIGERIA
8
9
10 E-MAIL: sundayoeze@yahoo.com
11 chidinmaqueeneth@gmail.com
12 sundayoeze@yahoo.com, sundayoeze@yahoo.com

13 ABSTRACT

14 Assessment of the phytochemical, proximate, vitamins and mineral composition of S.gilo

15 L was undertaken using standard methods. The phytochemical screening revealed that the
16 plant contained tannins, saponins, phenols, cyanogenic glycosides, alkaloids and
17 flavonoids, The results showed that S. gilo L had alkaloid content of 6±2.23%, flavonoid
18 19.5±0.02%, saponin 5±0.3%), tannin 1±0.24%, phenol 1.8±0.02%, and cyanogenic
19 glycosides 4.7±0.21%.The proximate analysis showed a moisture content of
20 (6±1.41%),ash (14.8±0.02%) crude fiber (29.33±0.02%), lipid (37.61±0.01%), protein
21 (0.18±0.02%) and carbohydrate (13.03±0.01%). S. gilo .L. also showed high level of
22 vitamins incuding vitamin B1 (1.2±0.16µg), vitamin B2 (10.71±0.16 µg) vitamin C
23 (264±2.15 mg/g), vitamin B3 (7.33±0.02 µg). It also showed trace amounts of vitamin E
24 (0.52±0.02 µg), high mineral contents of potassium (4150±2.14mg/g) and sodium
25 (270±1.41 mg/g), and trace amounts of other elements including lead (0.04±0.01 mg/g)
26 and cadmium (0.025±0.002 mg/g), The result show that S.gilo .L is endowed with
27 appreciable amounts of bioactive substances and nutritive components which justifies its
28 wide use in ethnomedicine and as stew condiment as well as being used food.

29 Key Words: Solanum gilo, phytochemical, spectrophotometric methods, nutritive

30 analysis

31

32 INTRODUCTION

1
33 Solanum gilo is a species of the African egg plant or garden egg as it is commonly

34 called in many parts of Nigeria where they are used for hospitality in place of kola nuts

35 and as stew condiments with other Solanum species in traditional medicine as

36 antioxidants and laxatives.[1,2,3] The species is solanacaea and the plant genus solanum

37 which have over 1000 species worldwide of which about 25 species are known in Nigeria

38 including those domesticated and wild ones with their leaves, fruits or both used as

39 vegetables or in traditional medicine [4]. Solanum gilo is cultivated in Africa including

40 Nigeria [5] as an annual crop and is usually called “afufa” in Igbo, where there are many

41 other Nigerian and other African species and varieties.[6].

42 The garden egg species are commonly consumed almost on daily basis by both

43 rural and urban families. The eggplants form part of the traditional Sub-Saharan African

44 culture. The fruits, said to represent blessings and fruits, are offered as a token of

45 goodwill during visits, marriages and other social events.

46 There are wide variations existing within and between the African eggplant

47 species including variation in characters like diameter of corolla, petiole length, leaf

48 blade width, plant branching, fruit shape, color[7].

49 Solanum gilo is grown in areas of high rainfall. The fruits are around with the top

50 and bottom flattened out and have grooved portions with a length of 5-6cm and a width

51 of 6-7cm. It possesses very tiny seeds and its stalk is curved or erect. [8].This species of

52 garden egg have bitter taste and is cultivated in the same way with other species. The

53 fruit turn red or orange in colour when ripened.

2
54 The use of the African egg plant in indigenous medicine range from weight reduction

55 to treatment of several ailments including constipation, weight loss, obesity, diabetes,

56 glaucoma, rheumatic disease and swollen joint pains [9]. These pharmacological

57 properties have been attributed to the presence of certain chemical substances in the

58 plants such as crude fiber, phenols, ascorbic acid, and alkaloids [10]

59 In this study, nutritive and phytochemical, vitamin and mineral analyses were

60 carried out on an indigenous egg plant S. gilo L. because of its nutritive and medicinal

61 benefits.

62 MATERIALS AND METHOD

63 Collection and Identification of Sample

64 Unripe fruits of S. gilo L. were collected from a local farm in Isiala-Ngwa North

65 L.G.A of Abia State Southeast Nigeria. The fruits were identified in the Department of

66 Plant Science and Biotechnology, Abia State University, Uturu.

67 Preparation of samples

68 Healthy fruits were selected and thoroughly washed with water to remove dirt and

69 unwanted particles. The stalks were removed and unwanted with particles. The edible

70 part was cut in pieces, dried at 105oC and ground into powder before being used for

71 analysis. The pulverized sample was stored in an air-tight container at room temperature.

72

73

3
74 PHYTOCHEMICAL SCREEENING

75 Aqueous extract of the sample was prepared by soaking 100g of the powdered

76 samples in 200ml of distilled water for 12 hours. The extracts were filtered using

77 whatman filter paper No. 42 (125mm). Chemical tests were carried out on the aqueous

78 extracts and on the powdered samples to identify the constituents using standard

79 procedures.

80 Colour intensity was used to categorize the presence of each photochemical into

81 present moderate or slightly present.

82 Test for Tannin

83 The determination of the presence of tannin in the test sample was carried out

84 using ferric chloride test described by Harbone [11] as reported by Osagie [12].

85 2g of the powdered sample was added into 10mls of distilled water. The mixture

86 was shaken for 30 minutes and the filterate used as aqueous extract. 2mls of the aqueous

87 extract was added into a test tube and 3mls of distilled water was added to it and shaken

88 very well for homogenate, two drops of dil. Ferric chloride (FeCl3) was added to the

89 mixture. The formation of a very dark precipitate indicated the presence of tannin.

90 Test for Saponin

91 The presence of saponins in the test sample was done using the Harbone [11], as

92 reported by Osagie [12]. The test for saponin is known as Froth test. In froth test, 2mls of

93 the aqueous extracts were mixed with 6mls of distilled water in a test tube. The mixture

94 was shaken well and the formation of froth indicated the presence of saponins.

4
 95 Test for Alkaloids

96 The presence of alkaloids in each sample was investigated using the method

97 described by Okwu [13]. 2g of sample is shaken with 5ml of 2% HCl on a steam bath and

98 filtered with Whatmann filter paper no. 42.

99 To 1ml of filtrate, 0.5ml of Wagner’s reagent (2g of iodine and 3g of potassium

100 iodine were dissolved in 20ml of distilled water and made up to 100ml with distilled

101 water). A reddish brown precipitate indicates the presence of alkaloids.

102 Test for Flavonoids

103 The determination of the presence of flavonoids in the sample was done using the

104 acid-alkaline test by Osagie [12]. 2mls of the aqueous extract was added into a test tube

105 and a few drops of concentrated ammonia were added. The formation of a yellow

106 colouration shows the presence of flavonoids.

107 Test for Phenols

108 This was investigated using Okwu [13] methods. The free fat sample was boiled

109 with 50ml flask and 10ml of distilled water was added to it. To the solution, 2ml of

110 ammonium hydroxide and 5mls of conc. Amyl alcohol was added. The mixture was

111 allowed to react for 30 minutes for colour development.

112 Test for Cyanogenic glycosides

113 The presence of cyanogenic glycosides was carried out by putting 20g of sample

114 in 50cm3 conical flask. A dry drip of alkaline picrate paper (prepared by soaking in equal

115 volumes of 10% Na2CO3 and 1% picric acid solution) is hung from the mouth of the

5
116 flask, without touching the sample. The mouth of the flask is plugged highly with cotton

117 wool or tissue paper. The set up is then heated up to one hour in a water bath. A change

118 of colour from yellow (of the picrate paper) to orange, then brick red colour indicates the

119 presence of cyanogenic glycosides Harbone [11] as modified by Okwu [13].

120 Proximate Analysis

121 Proximate (nutritive) composition of the fruits were determined, this include:

122 moisture, protein, lipid, crude fiber, ash, carbohydrate composition of the sample.

123 Moisture, lipid, protein, carbohydrate, crude fiber and Ash contents were

124 determined using the Official Method of the Association of Official Analytical Chemists

125 (A.O.A.C) [14] as reported by Asibey-Berko [15].

126 Mineral Analysis

127 Mineral composition of sample was determined using the official method of the

128 Association of official Analytical Chemists A.O.A.C [14].

129 Two grams (2g) of the sample was dry ashed with a porcelain crucible in a muffle

130 furnace at 500oC for 24 hours. The resulting ash was cooled in a desiccator and weighed.

131 The ash was treated with 10ml of 50% HCL.

132 The quantification was carried out using 5 series atomic absorption

133 spectrophotometer.

134

135

6
136 Vitamin Analysis

137 Determination of Vitamins B, (thiamine) and Vitamin B2 (riboflavin) was carried

138 out using spectrophotometric method as described by Okwu [13]. Determination of

139 vitamin B3, Vitamin C, and Vitamin E, content of the sample was investigated using

140 spectrophotometric methods as described by Rukowski [16].

141 Results and Discussion

142 Table 1 shows Qualitative Analysis of Phytochemicals present in S.gilo. The

143 result revealed that the fruit of S.gilo contain a significant amount of Alkaloids which is

144 known to give plant a bitter taste [17].The presence of this alkaloid makes this fruit

145 highly nutritional and medicinal.

146 Flavonoids were found to be present in both fruits, flavonoid have a wide range

147 of biological and pharmacological activities including anti-oxidant, anti-inflammatory

148 and anti-microbial activities[18]. Flavonoids are also responsible for the colour of most

149 fruits.

150 Saponins were found present in both species. Saponins are known by their froth

151 foaming which they produce when shaken in aqueous solutions [19]. They are being

152 promoted as adjuvants in vaccines [20].

153 Tannins were found to be slightly present in both species. The astringency from

154 tannin is known to cause the dry and pucker feeling in the mouth following the

155 consumption of unriped fruits food rich in tannin can be used in treatment of

156 hemochromotosis [21].

7
157 Phenol used as conversion to precursors to plastic but can be corrosive to the

158 eyes, skin and respiratory tract when prolonged exposure occurs. They are used in the

159 preparation of cosmetics like sunscreen [22].This species of eggplant S.gilo. contained a

160 significant amount of phenol making it useful when used as phenol source.

161 Cyanogenic glycosides found in some food cause increase in blood glucose and

162 lactic acid levels. They are toxic and often present in small quantities which may not be a

163 significant dosage for medicinal purposes. This species of eggplant showed significant

164 amount of this phytochemical making its consumption harmful to the body but the

165 toxicity can be reduced by boiling [23, 24].

166 Table 1: Qualitative Analysis of Phytochemicals Present in S.gilo

Phytochemical S.gilo
Alkaloid +
Flavonoid +
Saponin +
Tannin (+)
Phenol +
Cyanogenic glycoside +
167

168 + Present
169 (+) Slightly present
170

171 Table 2 shows quantitative analysis of the photochemicals present in S.gilo.

172 Alkaloid content of S.gilo was 6± 2.23% and compared very well with 4.5% value

173 reported by Jaegeer and Hepper [25]. Alkaloids are very important in medicine, they

174 uniformly invoke bitter taste in plants such alkaloids include codeine which is used in

175 cough medicine and as an analgesic. The alkaloid content of Solanum gilo L. is a

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176 moderate value for consumption of the fruit and this makes the plant very beneficial

177 medicinally.

178 Flavonoids generally possess anti-bacterial and antifungal activities [18]. They are

179 potential sources of natural preservatives, and also known to have anti-inflammatory and

180 anti-oxidants activities [26, 27]. Flavonoid than the 22% reported by many researchers

181 on different species of garden egg including The flavonoid content of S.gilo

182 (19.5±0.02%) was found to be lower than the value of 22% reported by many researchers

183 on different species of garden egg incuding solanum melongena, Osei et al [28] but

184 compared well with the 18.50% obtained by Irunyole and Akmyole [29].

185 Saponins are promoted as dietary supplements and nutriceuticals. They are also

186 adjuvants in vaccine production [20]. From the result S.gilo contained 5±0.37% saponin

187 content which was lower than the 10% reported by Xur et al[30] for another species of

188 garden egg and so S.gilo is a moderate source of saponins.

189 Tannins have shown anti-viral, anti-bacterial and antiparasitic effects.The tannin

190 content of S.gilo (1±0.24) is slightly lower than the 2.5% value reported by Lambent and

191 Yang [31].

192 Phenols are beneficial as they are versatile precursor to large collection of drugs

193 e.g. Aspirin and many pharmaceutical drugs known to be corrosive to the eyes, skin and

194 respiratory tract on prolonged exposure. [32] S.gilo contained (1.8±0.02) which compare

195 well with 2% as reported by Vinson et al [33].

196 Cyanogenic glycosides are phyto-toxins, that causes a decrease in the utilization of

197 oxygen in the tissues. Cyanogenic-glycoside content of S.gilo (4.7±0.29) compared very

9
198 well with 6% as reported by Clark [34]. This signifies that raw consumption of these

199 species of egg plant can cause some element of toxicity to the body but this can be

200 prevented by boiling before consumption.

201 Table 2: Qualitative Analysis of the Phytochemicals Present in Solanum gilo L.

Phytochemical S.gilo
Alkaloid 6.00±2.23
Flavonoid 19.50±0.02
Saponin 5.00±0.37
Tannin 1.00±0.24
Phenol 1.80±0.02
Cyanogenic glycoside 4.70±0.21
202

203 Table 3 shows the proximate (nutritive) composition of S.gilo. The moisture

204 content of fruits is related to its dry matter content. It can be used as an index of stability

205 and susceptibility to fungal infection. It determines quality and freshness of fruits [5].

206 From the result this species is not a good source of moisture. The moisture content of

207 S.gilo is 6±1.41% and this result is far lower than the report of several researchers of 80-

208 85% moisture content for most fruits [35] but this is an advantage for longer storage than

209 many other fruits.

210 The ash is important fruit content because it determines the mineral composition

211 of the fruit [36]. S.gilo contains (14.8±0.02) ash which showed that of this species have

212 and appreciable amount of minerals which compare well with other species [37].

213 Crude fiber found in fruits such as pectins reduces rate of sugar uptake and plays

214 vital role in gastric emptying. S.gilo has a high crude fiber content (29.33±0.02) and this

215 makes it beneficial in reducing constipation and hence a lower possibility of incidence of

10
216 colon cancer as it will help in easy emptying of the bowels . The value for the fibre

217 content is also higher than reported by Norman [38].

218 The lipids in fruit serve both structural and metabolic functions like: energy

219 production and also promoting healthy cell function. S.gilo contained a reasonable

220 amount of lipids (37.61±0.01) which compared well with that reported by Ekpeyong in

221 [39] but a bit higher than 35% reported by Edijala et al in [40] but far greater than that

222 reported for the fruit of Nauclear latifolia [41].

223 Proteins are not general known to e higher in fruits, but they are of primary

224 importance because they are enzymes that catalyze chemical reactions and accelerate

225 some chemical reactions [42]. S.gilo showed a low protein content (0.18±0.22) which is

226 lower than the value of 3.5% reported by Grubben and Denton [34] as well as 1%

227 reported by Gbile and Adesina[43] and that reported for the fruits and leaves of Nauclear

228 latifolia [41]

229 Carbohydrates are important due to their nutritional and metabolic functions.

230 They serve as natural sweeteners as well as raw materials for various products [21].

231 S.gilo contained 13.03±0.01% carbohydrates and this makes it a good source of

232 carbohydrate and this compared well with the value of 14.5% as reported by Leung et al

233 [35] but lower than that reported by Eze and Ogbuefi in [41].

234

235

236

11
237 Table 3: Proximate Composition of S.gilo

Parameters S.gilo (mg/g)

Moisture 6.00±1.41
Ash 14.80±0.02
Crude fiber 29.33±0.02
Lipid 37.61±0.01
Protein 0.18±0.02
Cyanogenic glycoside 13.03±0.01
238

239 Table 4 showed the vitamin content of S.gilo. Vitamins B1, B2, B3, C and E were found

240 to be contained in it. Vitamins are associated with energy production in the body, as well

241 as essential for breakdown of fat and protein and keeping the mucus membrane healthy,

242 Vitamin B1 content of S.gilo (1.2±0.16) was higher than 0.18mg reported by Duel and

243 Sturtz [10] but compared well with 1.5mg reported by Rice et al [44] which showed that

244 it is not really good as a source of Vitamin B1 (Riboflavin).

245 Vitamin B2 plays a supportive role in the treatment of sickle-cell anaemia. It is

246 also the precursors for enzyme w-factors that help in their work as catalysts in

247 metabolism [8]. Vitamin B2 content of S.gilo ( 10.71±0.4) compared with the value of

248 12.20mg reported by Rice et al [44] and so a good source of vitamin B2.

249 Vitamin B3 (Nicotinamide) is also a precursor for enzyme co-factors that help in

250 their work as catalyst in body metabolism. Its deficiency causes pellagra[10]. Vitamin B3

251 content of S.gilo (7.33±0.02) is less than 10.58mg obtained by Dobson,[ 23] with that of

252 also compared very well with 8.50mg reported by Osei, et al[28]

253 Vitamin C (Ascorbic acid) are always found in fruits in high amounts. It is a very

254 import anti-oxidant [8]. Ascorbic acid content of S.gilo ( 264±2.5) correlated with the

12
255 results reported by Szeto et al [45], which reported 400mg and 258mg respectively for

256 the eggplants.

257 Vitamin E (Tocopherol)

258 This is an important anti-oxidant used for the preparation of various kinds

259 cosmetic products ranging from soaps, creams, etc. This species contained very low

260 amount of Vitamin E of S.gilo were low ( 0.52±0.02), but compared very well with the

261 0.5mg reported by Rice et al[44].

262 Table 4: Vitamin Content of S.gilo

Parameter S.gilo (µg/g)

Thiamine (B1) 1.20±0.16
Riboflavin (B2) 10.71±0.16
Nicotinamide (B3) 7.33±0.02
Ascorbic Acid(c) (mg) 264±2.15
∞-tocopherol (E) 0.52±0.02
263

264 Table 5 shows the amount of trace minerals found in S.gilo. This species of garden

265 egg showed the presence of trace minerals. They are needed by the body in very little

266 amount though they are also useful. These trace minerals include Pd, Zn, Cu, Cd, Fe and

267 Se, they are important for immune system function, energy metabolism and anti-oxidant

268 function [21]. From the result, S.gilo contained appreciable amount of these minerals and

269 so a rich source of these minerals. The amount of minerals found in these species

270 compared well with the NAFDAC[46] standard of trace minerals found in food including

271 Pd and Zn which should not be above 5mg/g. therefore consumption of these species of

272 garden egg will not be toxic since these minerals are found in trace amounts.

13
273

274 Table 5: Trace Mineral Content of S.aetheopicum and S.gilo

Parameters (mg/g) S.gilo (mg/g) NAFDAC STANDARD

(mg/g)
Pd 0.04±0.01 0.30
Zn 0.13±0.02 5.00
Fe 0.65±0.02 5.00
Cu 0.04±0.01 5.00
Cd 0.025±0.002 0.01
Se 0.01±0.007 0.01
275

276 Table 6 shows the macro-mineral composition of S.aethiopicum and S.gilo. These

277 minerals are minerals needed by the body in large moderate amounts. They are important

278 in daily function and processes which include formation of bone and teeth and health19

279 e.g. Ca, Mg, P [36] also energy production, nerve and muscle function [20] e.g. k, Na.

280 both species contained very high amounts of potassium (4250± 3.91 and 4150±2.14)

281 respectively. S.gilo contained high amount of sodium (270±1.41) as compared

282 S.aethiopicum containing (0.63±0.03). the macro-minerals content of S.aethiopicum and

283 S.gilo were comparatively lower than the amount required except for potassium contents

284 of 20 (4250±3.91 and 4150±2.14) respectively by NAFDAC40 which requires that food

285 should contain up to 20-30 mg/g of this minerals. Therefore these two species of

286 eggplants are not good sources of Ca, P, Mg and Na.

287

288

289

14
290 Table 6: Macro-Mineral Content of S.aethiopicum and S.gilo

Parameters (mg/g) S.gilo (mg/g) NAFDAC STANDARD

(mg/g)
Ca 0.135±0.02 30.00
K 4150±2.14 25.00
P 1.16±0.02 25.00
Mg 0.55±0.02 20.00
Na 270±1.41 30.00
291

292 Conclusion

293 S. aethiopicum is enriched with important phytochemical and nutritional

294 constituents in significant amounts including vitamins and minerals in appreciable high

295 levels. The results of the nutritional and phytochemical analyses justify the therapeutic

296 use and consumption of this species of eggplant and recommends it as a good fruit.

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