Accepted Manuscript

Chemical composition and antioxidant activities of some indigenous spices

consumed in Nigeria

Henrietta Ene-Obong, NneOla Onuoha, Lilian Aburime, Obioma Mbah

PII: S0308-8146(16)32094-5
DOI: http://dx.doi.org/10.1016/j.foodchem.2016.12.072
Reference: FOCH 20364

To appear in: Food Chemistry

Received Date: 30 June 2016

Revised Date: 6 December 2016
Accepted Date: 20 December 2016

Please cite this article as: Ene-Obong, H., Onuoha, N., Aburime, L., Mbah, O., Chemical composition and
antioxidant activities of some indigenous spices consumed in Nigeria, Food Chemistry (2016), doi: http://dx.doi.org/
10.1016/j.foodchem.2016.12.072

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1 Title Page

2 Title: Chemical composition and antioxidant activities of some indigenous spices consumed in
3 Nigeria
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5 Henrietta Ene-Obong1, NneOla Onuoha2, Lilian Aburime3, Obioma Mbah4

1, 3
6 Department of Biochemistry (Human Nutrition and Dietetics Unit), Faculty of Basic Medical
7 Sciences, University of Calabar, Calabar, Cross River State, Nigeria
2, 4
8 Department of Home Science, Nutrition and Dietetics, University of Nigeria, Nsukka
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16 Corresponding author: Prof. Henrietta N. Ene-Obong
17 Department of Biochemistry (Human Nutrition & Dietetics Unit), Faculty of Basic Medical
18 Sciences, University of Calabar, Calabar, Cross River State, Nigeria

19 E-mail: nkeneobong@yahoo.com; nkeneobong@gmail.com1 ;

20 Phone: +234-8036754151
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36 Chemical composition and antioxidant activities of some indigenous spices consumed in Nigeria
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39 Abstract
40 The chemical compositions and antioxidant capacities of seven spices consumed in Southern Nigeria

41 were determined. They were purchased from majors markets in the study area. Edible portions of the

42 spices were ground into fine powder and their nutrient and phytochemical compositions determined using

43 standard methods. Antioxidant activity were determined on aqueous extract using standard assays,

44 namely, 1,1-diphenyl-2picrylhydrazyl (DPPH) free radical ability and ferric reducing antioxidant

45 potential (FRAP). The spices were rich in macro-and micro-nutrients. Ricinodendron. heudelotii had the

46 highest protein (30.6%) and fat (24.6%) contents. Tetrapleura. tetaptera had the least fat content. The

47 total phenol, flavonoid and vitamin C contents differed significantly (p<0.001) from each other.

48 Aframomum citratum had the highest amount of total phenol, flavonoid and DPPH scavenging ability,

49 while Afrostyrax lepidophyllus had the best FRAP. The spices have good nutrient profile and antioxidant

50 potentials. Their increased consumption is recommended and use as functional foods needs to be

51 exploited.

52 Keywords: Nutrients; phytocKhemicals; antioxidant activity; indigenous spices.

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54 1. Introduction

55 The double burden of disease in both developed and developing countries of the world

56 has continued to pose serious health challenges. Apart from under nutrition, middle and low

57 income countries have begun to experience an increase in the prevalence of non-communicable

58 diseases (NCDs). These conditions impose a lot of healthcare cost on individuals, households

59 and nations; hence majority of the population are driven to look to food as cheaper alternatives.

60 Advances in food and nutritional sciences has shown that apart from nutrients, certain foods

61 contain some bioactive substances which provide some health benefits; including reduction in

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62 cancer risk and modification of tumor behavior (Kaefer & Milner, 2008). Spices are typical

63 examples of such foods.

64 Spices are said to be pungent or aromatic substances which are used as additives for the purpose

65 of flavouring, colouring and preserving foods (Abishek, Panchal, Poudyal & Brown, 2009). In

66 Africa, especially in Nigeria most traditional and indigenous delicacies are prepared with

67 traditional and indigenous spices. These spices are used as additives or cures for certain ailments

68 and diseases or just to add taste or flavor to food. They are also used as preservatives to kills

69 harmful bacteria or prevent their growth (Dalby, 2002). Spices could be obtained from any part

70 of plant as fresh or dried seeds, kernels, bulbs, stalk, roots, barks, leaves, pods or buds. They

71 have been used for thousands of centuries by many cultures to enhance the flavor and aroma of

72 foods. Indigenous cultures recognized the value of spices mainly in preserving foods and for

73 their medicinal value. Such knowledge has been handed down from one generation to another;

74 thus not much attention is given to their nutritional value. Spices also improve appetite and

75 increase the flow of gastric juice. They are said to be useful in the management of convulsion,

76 leprosy, stomach ache, inflammation and rheumatoid pains, cough and loss of appetite (Valko,

77 Leibfritz, Moncol, Cronin, Mazur, Telser, 2007)).

78 Spices abound in Nigeria; some are specific to certain locations and usage is based on

79 cultural food habits and preferences. Despite their wide use in traditional cuisine, most of these

80 spices are missing in national and regional food composition databases/tables. This may be

81 attributed to the fact that spices were regarded as non- nutritive components of food (Kaefer &

82 Milner, 2008). Considerable amount of work has been done in Nigeria on spices, particularly

83 Monodora myristica and Piper guineense (Faleyimu & Oluwalana, 2008; Dike, 2010;

84 Ekeanyanwu, Oge & Nwachukwu, 2010; Uhegbu, Iweala & Kanu, 2011; Bassey, Johnny &
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85 Okoro, 2011; Akinwumi & Oyedepo, 2013; Okonkwo & Ogu, 2014), however there are issues

86 of proper identification, varying values and units of expression. There is need for more studies to

87 validate existing work and to examine less researched spices for the purpose of including them in

88 the national Food Composition Table (FCT) and exploiting them for other uses in human

89 nutrition.

90 This study was aimed at determining the nutrient and phytochemical compositions as well as the

91 antioxidant capacities of the following spices commonly consumed in Southern Nigerian. The image of

92 these samples is shown in Fig. 1.

93 Monodora myristica is a tropical tree of the family Annonaceae and popularly known as

94 African/Calabash nutmeg. The local names include: “Inwun” in efik; “ehuru” (Igbo), “ariwo”

95 Yoruba, “gujiya-dan-miya” in Hausa; while other names include”ehiri”,”airama” (Okafor, 1987).

96 The fruits are collected from the wild and the seeds dried and sold as whole or shelled seed,

97 which are then ground for use in soups and other foods. The odour and taste mimic that of

98 nutmeg and it is used as a popular spice in West African cuisine in stews, soups, and sauces. It is

99 also used to flavor peanut butter used in eating kola nuts or garden eggs (common items of

100 entertainment in parts of Southern Nigeria). Aqueous extract of the seed has been shown to

101 contain pharmacological compounds such as, alkaloids, flavonoid, vitamin A and E (Eze-Steven,

102 Ishiwu, Udedi, & Ogeneh, 2013), essential oils (Susheela, 2000), while ethanolic extract showed

103 presence of tannins and saponnins (Erukainure, Oke, Owolabi, Kayode, Umanhonlen & Aliyu,

104 2012) . Onyenibe, Fowokemi & Emmanuel (2015) also found that it contains cholesterol

105 lowering ability. A close relation of Monodora myristica is “ehu” in Igbo. Its local name is used

106 interchangeable with Monodora myristica (“ehuru”). It is used in flavouring soups and sauces

107 but has not been sufficiently characterized.

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108 Aframomum citratum is commonly known as “mfong” (efik), “olima” (Delta Ibo) and “erighoje”

109 (Urobo). Its English name is grain of paradise. It belongs to the family Zingiberaceae (Ginger

110 family) and a close relation of Afromomum melegueta (Alligator pepper). It is an aromatic plant

111 cultivated for its spicy fruits (Iwu, 1993). It is popularly used to prepare “banga” (palm fruit

112 pulp) soup and “nsala” (white soup) soup in Delta State. It has also been found to serve as

113 alternative strategy in managing risk factors and associated co-morbidities of diabetes mellitus

114 (Etoundi, Kuate, Ngondi & Oben, 2010). It extracts have been found to have antifungal,

115 cytotoxic, antibacterial, antihypercholesterolemic, antiviral and anti plasmodial activities (Tane,

116 Tatsimo, Ayimele & Connolly, 2011).

117 Afrostyrax lepidophyllus is also called Bush onion or Country onion in English: This spice

118 belongs to the family Huaceae. It is locally known as “oyim Efik”, meaning Efik onion, probably

119 because of its distinct strong odour similar to onion and garlic. It is best blended into bean

120 dishes, meat, stews, roasted fish and other spices (Iwu, 1993). The seed oil of A. lepidophyllus

121 has been shown to exhibit a strong inhibitory effect on growth of human cancer cells, and a

122 scavenging activity but with negligible antimicrobial effects (Fogang et al. 2014).

123 Ricinodendron heudelotii belongs to the family Euphorbiaceae. It is called “njangsang” (Efik),

124 “okwe” (Igbo), “erinmado” (Yoruba), and “wawangula kurmi” (Hausa). It is a perennial native

125 tree in the tropic and sub-tropics. It is a very important plant because all parts of the tree are

126 used for one purpose or the other. It is seen on compound farms in Nigeria. The colours range

127 from red brown to black, while the kernels are white and yellowish. Substantial work has been

128 done on its oil content which ranged from 44.7-54.7% and containing mainly the polyunsaturated

129 fatty acids α-elaeostearic acid (Kapseu & Tchiegang, 1995) and eicosapentaenoic acid (Ezekwe,

130 Besong & Johnson, 2014).

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131 Piper guineense Schumach (“Ashanti pepper”, “Benin pepper”): popularly known as “uziza”

132 (Igbo), “odusa” (efik/Ibibio). It belongs to the family Piperaceae. The leaves and seeds are used

133 in preparing soups. The medicinal uses of this spice have been well documented by Echo,

134 Osuagwu, Agbor, Okpako, Ekanem (2012). Traditionally, the seeds are used as postpartum tonic

135 for women to stimulate uterine contraction which is assumed to clear the womb of remains of the

136 placenta and other remains after the birth of the child. A recent review by Morufu, Besong,

137 Serge, Djobissie, Mbamalu & Obimma (2016) revealed the many nutritional and non-nutritional

138 benefits of various parts of the plant. Aqueous extracts of the seed have also been shown to have

139 cholesterol lowering effects (Manta, Saxena, Nema, Singh & Gupta, 2013) and significant

140 increase in hemoglobin level, white blood cell and red blood cell counts of albino Wistar rats

141 (Uhegbu, Chinedu & Amadike (2015).

142 Tetrapleura tetraptera: is known as “uyayaka” (Efik), “ushakirisha/oshosho” (Igbo), “aridan”

143 (Yoruba), “ighimiaka” (Edo) and “oghokiriaho” (“Urogbo”), ‘ikoho” (Nupe). It belongs to the

144 family leguminosae. It is one of the most valued forest spices in Nigeria but is threatened by

145 extinction as a result of deforestation (Akachukwu, 1997). It adds good aroma and flavor to food

146 and therefore increases the pleasure of eating. It is a major spice ingredient for “white soup” and

147 “banga soup” (palm fruit palm) among the Efiks and Ibibios of Southern Nigeria.

148

149 . 2. Materials and Methods

150 2.1 Sample collection

151 Seven (7) spices were purchased from five vendors each in Mariam market in Calabar, Cross

152 River State and Ogboete market, Enugu, Enugu State, Nigeria. The samples were pooled and

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153 taken for identified by Taxonomists in two Nigerian Universities, namely the University of

154 Calabar, Calabar and the University of Nigeria, Nsukka,

155 2.2 Sample preparation

156 The selected samples were thoroughly screened to remove spoilt ones, stones and other

157 unwanted materials. The samples were prepared according to their usage pattern.

158 Monodora myristica (inwum): The seeds were toasted in a pan over fire for 2 minutes. The hard

159 shell was removed and the inner kernel thoroughly grounded into powder with electric kitchen

160 grinder.

161 Aframomum citratum (mfong): The purchased seeds were sorted to remove all unwanted

162 materials, washed and air-dried. They were then grounded into fine powder using an electric

163 kitchen grinder.

164 Afrostyrax lepidophyllus (oyim Efik): The dried shell was peeled off and the hard seeds were

165 broken into pieces with hammer, ground into fine powder and stored in an air tight container.

166 Ricinodendron heudelotii (Njangsang): the kernels were purchased as dried from the market.

167 They were washed, sundried, ground into fine flour and stored in an air tight container.

168 Piper guineense Schumach: The dried seeds as purchased from the market were picked and

169 sorted to remove all unwanted materials. The seeds were then rinsed in cold water, drained, sun

170 dried and ground into fine powder.

171 Tetrapleura tetraptera (Uyayak): The dried fruits as purchased were cut into pieces and ground

172 into powder.

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173 All ground samples were stored in air-tight containers and kept in the refrigerator until ready for

174 analyses.

175 2.3 Chemical composition

176 2.3.1 Proximate analysis

177 The proximate composition (moisture, crude protein, crude fibre, lipid, and ash) were

178 determined using the standard A.O.A.C (2006) methods. The nitrogen conversion factor used

179 was 6.25. Total carbohydrate was obtained by difference as follows: 100 – (moisture + protein

180 +lipid + ash).

181

182 2.3.2 Mineral analyses

183 Mineral elements were determined using the Atomic Absorption Spectrophotometer

184 (Perkin–Elmer Model 3110, USA). Phosphorus was determined using the vanadomolybdate

185 method, while potassium and sodium were determined by flame photometric method.

186 2.3.3 Phytochemical determination and antioxidant activity

187 2.3.3.1 Preparation of extract

188 To 1g of each ground sample, 20 ml of distilled water was added and left overnight. The

189 mixtures were then sieved and centrifuged at 2000g for 3 minutes. The residues were discarded

190 and the supernatant labelled as the stock solutions; 1ml of the stock solution was diluted with 9

191 ml of distilled water to give a 10 ml working solution which was subsequently used for the

192 antioxidant assay. The stock solution and the working solution were preserved in a refrigerator

193 after each assay.

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194 2.3.3.2 Chemicals and Reagents

195 Chemicals and reagents used such as 1,10-phenanthroline, deoxyribose, gallic acid, Folin–

196 Ciocalteau’s reagent were procured from Sigma-Aldrich, Inc., (St Louis, MO), trichloroacetic

197 acid (TCA) was sourced from Sigma-Aldrich, Chemie GmbH (Steinheim, Germany), hydrogen

198 peroxide, methanol, sodium nitroprusside, gress reagent, acetic acid, hydrochloric acid, sodium

199 carbonate, aluminum chloride, potassium acetate, sodium dodecyl sulphate, iron (II) sulfate,

200 potassium ferricyanide and ferric chloride were sourced from BDH Chemicals Ltd., (Poole,

201 England). Except stated otherwise, all other chemicals and reagents were of analytical grades and

202 the water was glass distilled.

203

204 2.3.3.3 Determination of total phenol content

205 The total phenol content was determined according to the method of Singleton, Orthofer, &

206 Lamuela-raventos (1999). Briefly, appropriate dilutions of the extracts were oxidized with 2.5 ml

207 10% Folin-Ciocalteau’s reagent (v/v) and neutralized by 2.0 ml of 7.5% sodium carbonate. The

208 reaction mixture was incubated for 40 min at 45 oC and the absorbance was measured at 765 nm

209 in the spectrophotometer. The total phenol content was subsequently calculated as gallic acid

210 equivalent (GAE).

211 2.3.3.4 Determination of total flavonoid content

212 The total flavonoid content of the extracts was determined using a slightly modified method

213 reported by Meda, Lamien, Romito, Millogo & Nacoulma (2005). Briefly, 0.5 ml of

214 appropriately diluted sample extract was mixed with 0.5 ml methanol, 50 µl 10% AlCl3, 50 µl 1

215 M potassium acetate and 1.4 ml water and allowed to incubate at room temperature for 30 min.

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216 The absorbance of the reaction mixture was subsequently measured at 415 nm and the total

217 flavonoid content calculated as quercetin equivalent (QE).

218 2.3.3.5 Determination of vitamin C content

219 Vitamin C content of the polar extracts was determined using the method of Benderitter et al.

220 (1998). Briefly, 75 µL DNPH (2 g dinitrophenyl hydrazine, 230mg thiourea and 270mg

221 CuSO4.5H2O in 100mL of 5mol L−1 H2SO4) were added to 500 µL reaction mixture (300 µL of

222 an appropriate dilution of the polar extract with 100 µL 13.3% (TCA) and water).The reaction

223 mixtures were subsequently incubated for 3 h at 37 ◦C, then 0.5mL of 65% H2SO4 (v/v) was

224 added to the medium; their absorbance was measured at 520nm and the vitamin C content of the

225 samples was subsequently calculated.

226

227 2.3.3.6 Determination of reducing property (FRAP)

228 The reducing properties of the spice samples were determined by assessing the ability of the

229 extracts to reduce FeCl3 solution as described by Oyaizu (1986). A 2.5ml aliquot was mixed with

230 2.5 ml 200 mM sodium phosphate buffer (pH 6.6) and 2.5 ml 1% potassium ferricyanide. The

231 mixture was incubated at 50oC for 20 min. and then 2.5 ml 10 % trichloroacetic acid was added.

232 This mixture was centrifuged at 650 rpm for 10 min. 5 ml of the supernatant was mixed with an

233 equal volume of water and 1 ml 0.1% ferric chloride. The absorbance was measured at 700 nm.

234 The ferric reducing antioxidant property was subsequently calculated.

235 2.3.3.7 Determination of 1,1-diphenyl–2 picrylhydrazyl free radical scavenging ability

236 (DPPH*)

237 The free radical scavenging ability of extracts of the spices against DPPH (1,1-diphenyl–2

238 picrylhydrazyl) free radical were evaluated as described by Gyamfi, Yonamine & Aniya (1999).

239 Appropriate dilutions of the extracts (1 ml) were mixed with 1 ml, 0.4 mM methanolic solution

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240 containing DPPH radicals, the mixture was left in the dark for 30 min and the absorbance was

241 taken at 516 nm. The DPPH free radical scavenging ability was subsequently calculated as

242 percentage of the control.

243 2.4 Analysis of Data

244 The proximate and mineral compositions were performed in duplicates, while the total

245 phenol, flavonoid, vitamin C and the antioxidant activities were carried out in triplicates. Means

246 of duplicate and triplicate determinations were calculated. One way analysis of variance

247 (ANOVA) and Duncan Multiple range test was used to compare the means. The EC50 was

248 calculated using non-linear regression.

249 3 Results and discussion

250 The proximate composition of the spices is shown in Table 1. The moisture content of the

251 spices were all <10% except for Tetrapleura tetraptera (“uyayak”) which was 13.5%. The high

252 moisture could be an indication of its freshness. The relatively low moisture content of these

253 spices guarantees longer shelf life and makes them safe for consumption as they are sold under

254 normal room temperature, without any form of refrigeration. High moisture level will encourage

255 the growth of microorganism.

256 The protein content ranged from 5.0% in Piper guineense to 30.6% in Ricinodendron heudelotii

257 (“ngangsang”). The 10.5% protein reported for T. tetraptera in this study was above the range of

258 values (5.48 – 7.84%) reported by Uyoh, Ita & Nwofia (2014) who worked on twenty accessions

259 collected from different parts of Cross River State, Nigeria. This may probably be due to

260 seasonal variation/time of harvest. The protein content of Ricinodendron heudelotii (30.0%)

261 was higher than all the other spices (ranging from 5-13.3%) and compares very well with that of

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262 soybean, while the protein contents of the other spices compared favourably with those of cereals

263 grains. Ash values did not vary much except for Monodora myristica with 2.0% and Piper

264 guineense with a value of 4.9%; other spices had values ranging from 3.0 – 3.6%. The relatively

265 high ash content indicates presence of mineral constituents in the spices. Crude fibre values

266 varied from 4.4% - 10.3%; Monodora spp. (“ehu”) had the highest value followed by

267 Ricinidendron heudelotii. These nutrient values are high relative to several food groups.

268 Unfortunately, most of these spices are not consumed in large quantities and so their contribution

269 to nutrient intake may not be very significant; however, the protein content of Ricinodendron

270 heudelotii cannot be overlooked. The high protein value obtained from this study is comparable

271 with the value reported by Ezekwe et al. (2014). It is therefore not surprising to note that R.

272 heudelotii is used as a thickening agent for

273 soups and incorporated into baby cereals and cakes or used as substitute for peanuts in the

274 Cameroon (Leakey, 1999). The fat content ranged from 8.5% in Tetrapleura tetraptera to 24.5%

275 in Ricinodendron heudelotii, and so all the spices could be classified as oily seeds and this can

276 account for their relatively high energy values. Energy value was lowest for Tetrapleura

277 tetraptera (1583KJ/379Kcal) and highest in Ricinodendron heudelotii (2000KJ/480Kcal).

278 The fat content reported in this study was lower than the values reported by some authors

279 (Manga, Fondoun, Kengue, & Thiengang, 2000; Faleyimu & Oluwalana, 2008; Ezekwe et al.

280 2014). The fat value reported for Monodora myristica was lower than values obtained by

281 Ekeanyanwu et al. (2010) and Bassey et al. (2011), while value for Piper guineense was similar

282 to the one reported by Okonkwo & Ogu (2014). The observed differences may be attributed to

283 location, maturity, time of harvest, soil type/pH and other conditions. Most of the spices have

284 been shown to contain essential oils (Kiin-Kabari, Barimalaa, Achinewhu & Adeniji, 2011;

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285 Susheela, 2000); for example, Ezekwe et al. (2014) showed that the fat of Ricinodendron

286 heudelotii contains high levels of polyunsaturated fatty acids (PUFA) and rich with substantial

287 amounts of omega-3 fatty acids, especially eicosapentaenoic acid (EPA), making it a potential

288 alterative to fish oil. A review by Swanson, Block & Mousa (2012) showed that EPA and

289 docohexaenoic acid (DHA) are important for proper fetal development, including neuronal,

290 retinal and immune function and may affect many aspects of cardiovascular functions.

291 For minerals, calcium values ranged from 415 - 660 mg/100g; 220 -715 mg/100g for

292 potassium, 130 - 690 mg/100g for phosphorus, 230 – 690 mg/100g for magnesium, 210 – 323

293 mg/100g for sodium and 5.85 – 19.5 mg/100g for manganese. The iron content ranged from 11.8

294 -24.3 mg/100g, being highest in Afrostyrax lepidophyllus, followed by Monodora spp (20.2

295 mg/100g). Similar high value (21.7 mg/100g) has been reported for Monodora myristica

296 (Ekeanyanwu et al. 2010). Copper values ranged from 0.93 – 3.22 mg/100g, while selenium and

297 iodine ranged from 0.01 – 0.09 mg/100g and 1.74 – 3.68 mg/100g, respectively. Generally,

298 Tetrapleura tetraptera showed the least values for most of the minerals except for zinc (Table 2)

299 where it had similar value of 6.78 mg/100g with Aframomum citratum (“mfong”). Apart from

300 Tetrapleura tetraptera all the spices proved to be potential sources of macro- and micro

301 minerals. Calcium deficiency is likely in Nigeria especially with the low intake of rich calcium

302 containing foods, e.g. milk and milk products, and vegetables. Even though spices are not

303 consumed in large quantities, some of the spices, e. g., Ricinodendron heudelotii could serve as a

304 potential source of calcium which could make substantial contribution to the intakes of

305 population groups if consumed on a more regular basis. Their high calcium and potassium

306 contents need to be exploited in view of their importance in heart and bone health (Weaver,

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307 2013). They could also be exploited in tackling micronutrient deficiencies, e.g., iron, zinc and

308 copper and iodine.

309 The total phenol and flavonoid and vitamin C content of the spices are shown in Fig 2.

310 Total phenol of Aframomum citratum (13.47 mg/GAE/g) was significantly (p<0.001) higher than

311 the other three spices. The total phenol content of Ricinodendron heudelotii (“njangsang”) was

312 the least (3.64 mg/GAE/g). Similarly, flavonoid content of R. citratum (1.47 mgQE/g) was

313 significantly (p<0.001) the highest, while Afrostyrax lepidophyllus (0.12 mgQE/g) had the least.

314 The vitamin C content varied from each other (Table 2); from 2.03 mgAAE/g in Ricinodendron

315 heudelotii to 7.14 mgAAE/g in Monodora myristica. The lower phenolic content of Monodora

316 myristica compared to Aframomum citratum and Afrostyrax lepidophyllus has been reported by

317 other researchers (Etoundi et al. 2010; Duthie, Gardiner & Kyle (2003).

318 The ferric reducing antioxidant power (FRAP) of the selected spices is shown in Figs 3.

319 Afrostyrax lepidophyllus (“Oyim Efik”/country onion) showed a significantly (p<0.001) higher

320 FRAP value (7.88 mgAAE/L). This was followed by Monodora myristica (5.80 mgAAE/L). R.

321 heudelotii (1.77mgAAE/L) had the least FRAP. The free radical scavenging abilities of the

322 selected spices are shown in Fig. 4. DPPH was significantly (p<0.001) highest for Aframomum

323 citratum (73.3%). EC50 which is the effective concentration at which 50% of free radical were

324 scavenged was 10.3µg/ml. This was followed by Monodora myristica (72.0%) with EC50 of

325 10.58µg/ml. Ricinodendron heudelotii had the least DPPH scavenging ability (56.1%) with EC50

326 of 12.81µg/ml. Using the classification of Kaur & Kapoor (2002), Aframomum citratum and

327 Monodora myristica had high antioxidant activity (>70%), Afrostyrax lepidophllus had medium

328 and Ricinodendron heudelotii low (,< 60%) antioxidant activity.

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329 The high DPPH of A. citratum could be attributed to its higher amounts of phenolic acid

330 and flavonoids compared to the other spices. Phenolic acids and flavonoids have been shown to

331 be very important group of bioactive compounds in plants that have natural antioxidants

332 important in human health (Kim, Jeond, & Lee, 2003; Dai & Mumper, 2010). M. myristica

333 exhibited high antioxidant activity using both DPPH and FRAP as parameters. In addition to

334 having substantial amount of phenolic acids, it had the highest amount of vitamin C which is also

335 known to be a potent antioxidant. Ricinodendron heudelotii, with the lowest amount of phenolic

336 acid and vitamin C had the lowest DPPH and FRAP ability despites the fact that its flavonoid

337 content was second to that of Aframomum citratum. It has been shown that the capacity of

338 flavonoids to act as powerful antioxidant and free radical scavenger will depend on the position

339 of the hydroxyl groups and other features in the chemical structure (Formica & Regelson, 1995).

340 These may include liquid/aqueous phase partitioning properties of the oxidation condition and

341 the physical state of the oxidation substrate or of the antioxidant (Frankel & Mayer, 2000). This

342 may also account for the high FRAP value obtained from Afrostyrax lepidophyllus despite its

343 low flavonoid content. Fogang et al. (2014) have also reported a good DPPH (.) and ABTS (+)-

344 scavenging activity of the oil of Afrostyrax lepidophyllus.

345 Aqueous extracts were deliberately used in this study rather than methanoic extracts in

346 order to mimic their use in human nutrition. Several authors have also used aqueous extract and

347 found them containing potent bioactive compounds. Onyenibe et al. showed that aqueous extract

348 of Monodora myristica had the ability of significantly reducing total cholesterol (TC),

349 triglycerides (TG) and low-density lipoprotein–cholesterol (LDL-C) and increased high-density

350 lipoprotein cholesterol (HDL-C) in Wistar rats. Dada, Ifesan & Fashakin (2013) working with

351 five local spices found that water extracts (58-77.5%) yielded the highest DPPH scavenging

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352 activity followed by hexane extracts (44.5-74%) and ethanol extracts (23-47%) and therefore

353 suggested that water extracts of the spices studied may be good antioxidants, while ethanol

354 extracts may be better antimicrobial agents. Furthermore, Etoundi et al. (2010) also suggested

355 that aqueous extract of A. citratum and other spices studied could be offered as teas, foods and/or

356 dietary supplements because of the anti-enzymes (amylase and lipase) activities which could be

357 exploited in the management of chronic diseases, e.g., diabetes mellitus. The aqueous extracts

358 were also found to have high antioxidant activities.

359 3.3 Conclusion

360 Although these spices are consumed in small quantities, they could make substantial

361 contribution to nutrient intake if used more frequently. Mild flavoured spices like R. heudelotii

362 could be exploited for other uses. The high antioxidant and free radical reducing abilities of the

363 spices justify their use for medicinal purposes. Proper description and classification of Nigerian

364 foods is still a major challenge. Awareness of their availability, nutritional and medicinal values

365 needs to be created among the Nigerian population. This is why they should be included in the

366 national FCT/database. More research efforts are needed in this area so that they can be

367 appropriately exploited for use in solving nutritional problems in the society

368 References

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414 Faleyimu, O. I. & Oluwalana, S. A. (2008). Proximate analysis of Monodora myristica
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481 content of some Nigerian spices. International Journal of Nutrition and Metabolism, 3
482 (6): 72-76.
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484 Tetrapleura tetraptera (Schum & Thonn) Taub. Accessions from Cross River State,
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489 Weaver, C. M. (2013). Potassium and Health. American Society for Nutrition, Advances in
490 Nutrition: An International Review Journal, 4(3): 368S-377S.

491

492
493

494

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495 Caption
496 Table 1: Proximate (%), energy value (KJ/Kcal) content of spices consumed in Nigeria.

497 Table 2: Mineral composition of the spices consumed in Nigeria (mg/100g)

498 Fig 1: Pictorial presentation of the spices consumed in Nigeria.

499 Fig 2: Vitamin C, total phenol and flavonoid content of selected spices consumed in
500 Southern Nigeria.

501 Fig 3: Ferric reducing antioxidant power (FRAP) of selected spices.

502 Fig 4: DPPH radical scavenging ability of the selected spices.

503

504

505

506

507

21
508

509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545 Fig. 1.
546
547
548
549
550

551

22
 16

Total phenol content(mg

14
12
10

GAE/g)
8
6
4
2
0
Aframomum Afrostyrax Ricinodendron Monodora
citratum lepidophyllum heudelotii myristica
Various Spices
552

553

2
Total flavonoid (mg QE/g)

1.5

0.5

0
Aframomum Afrostyrax Ricinodendron Monodora
citratum lepidophyllum heudelotii myristica
Various spices
554

555

556

8
Vitamin C (mg AAE/g)

6
4
2
0
Aframomum Afrostyrax Ricinodendron Monodora
citratum lepidophyllum heudelotii myristica
Various spices
557

558

559 Fig 2.

560

23
 10

Ferric reducing antioxidant

8
6

(mg AAE/L)
power
4
2
0
Aframomum Afrostyrax Ricinodendron Monodora
citratum lepidophyllum heudelotii myristica
Various spices
561

562

563 Fig. 3:

564
565

566

24
 80 Monodora myristica A. lepidophyllum

DPPH radical scavenging ability(%)

70
60
50
40
30
20
10
0
0 5 10 15 20
567 Concentration of extracts (μg/ml)

568

569

570 Fig. 4

571
572

573

25
574 Table 1: Proximate (%), energy value (KJ/Kcal) content of spices consumed in Nigeria.

Spice Moisture Protein Fat Ash Fibre Total Energy

CHO* kJ/Kcal
Monodora myristica: 6.9 13.3 13.1 2.0 8.2 64.7 1810/433
“ehuru”
Monodora spp.: “ehu” 9.1 11.1 9.0 3.6 10.3 67.8 1674/400
Afromomum citratum: 9.2 9.2 9.6 3.4 7.4 68.6 1678/401
“mfong/olima”
Afrostyrax lepidophyllus: 7.8 7.7 13.2 3.0 4.4 68.3 1780/426
“oyim efik”
Ricinodendron heudelotii: 7.2 30.6 24.5 3.6 9.5 34.1 2006/480
“njangsang”
Piper guineense: 8.8 5.0 8.8 4.9 4.5 72.4 1642/393
“Uziza/odusa”
Tetrapleura tetraptera: 13.5 10.5 8.5 3.4 7.5 64.1 1583/379
“uyayak”
575 CHO*= Total Carbohydrate calculated by difference with crude fibre included: 100 – (moisture +protein +lipid + ash);
576
577
578
579

580

581

582

583

584

585

26
586 Table 2: Mineral composition of the spices consumed in Nigeria (mg/100g)

Spice Ca K P Na Mn Mg Fe Cu Zn Se I
Monodora 590 310 680 254 7.14 540 11.79 1.07 3.09 0.06 2.35
myristica: “ehuru”
Monodora spp.: 660 715 ND 225 5.85 ND 20.20 1.19 4.84 0.09 3.68
“ehu”
Afromomum 495 550 690 264 19.5 690 19.76 0.99 6.78 ND ND
citratum:
“mfong/olima”
Afrostyrax 415 710 230 323 7.77 230 24.26 1.71 5.65 0.01 2.86
lepidophyllus:
“Oyim efik”
Ricinodendron 627 645 460 210 10.29 460 15.28 3.22 5.79 0.02 2.18
heudelotii:
“njangsang”
Piper guineense: 445 220 ND 280 9.9 ND 16.25 1.49 4.98 ND ND
“Uziza/odusa”
Tetrapleura 24 ND 130 18 3.68 180 2.32 0.93 6.78 0.16 1,74
tetraptera:
“uyayak”
587 ND = Not determined

588

589
590
591

592

27
593 Chemical composition and antioxidant activities of some indigenous spices consumed in Nigeria
594

595 Highlights

596

597 1. Aqueous extract of most spices contain potent bioactive compounds

598 2. Frequent consumption of spices can contribute to adequate nutrition and good health
599 3. Spices (e.g., Ricinodendron heudelotii) can be exploited as functional food
600 4. Awareness of nutrient potentials and health benefits of local spices is needed

601

602

603

604

28