Phytomedicinal and food value contributions of selected indigenous Aro plants to other Igbo and southweastern Nigerians

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Selected instances of interesting and significant contributions of indigenous Aro plants to the food culture and traditional medicine practices of the South-Eastern Nigeria geographical zone have been highlighted. Among the popular food items are vegetables such as adudu (oha), ahuji (nchanwu) and the food condiment evoro (ehuru), while the significant medicinal contributions include anti-cancer agents from akarinu (akilu) and ugba (ukpaka) as well as anti-HIV-1 agents from okazi (ukazu) and evoro (ehuru). Such instances are only representative of the abundant plant-based resources available from other Aro plants, many of which are equally listed for subsequent investigation.

Author: Joseph O. Nwankwo, D Phil (Oxon)
Professor, Department of Medical Biochemistry
Faculty of Basic Medical Sciences ,College of Medicine
Alex Ekwueme Federal University Ndufu-Alike, Ebonyi State
Phone: +234 706 267 7888 Email: joseph.nwankwo@funai.edu.ng; jonwankwo@yahoo.com

INTRODUCTION

The impact of the Aro trade networks and settlements in the former Eastern Nigeria and beyond was largely beneficial as such early contact was instrumental to thedynamic cultural exchangesand subsequent developmental strides which swept across the region in the wake of such interactions. It is to be expected that the widespread settlements and infiltration of novel communities by the Aro would lead to the impartation of peculiar cultural traits, food habits and useful plants to the host communities. Three instances exemplifying this trend may be found in the appendage of the suffix “Aro” to plant names to indicate their place of origin as in “Ede Aro” for a genus of the cocoyam(Xanthosomasagittifolium); “AchiAro” (Gossweilerodendronbalsamiferum) for the West African Tropical Rain Forest tree; both designations found in other parts of Igboland, particularly in the Owerri area (Nwankwo, 2011); thirdly, the Castor oil plant (Riccinuscommunis Linn) is known as “OgiriAro” (also “ogiriisi” and “ogiriugba”) in many parts of Igboland (Okujagu et al, 2008).

The widespread Aro settlements in Igboland and beyond could also explain the existence of certain common food sources in the region. A consequential implication of such cultural exportwould be the inference that the existence of specificAro names for certain plants different or varying from those used by other Igbos, is suggestive of the Aro origin of such plants. Further support for such an assumption is the fact that majority of plant names are the same and common to all Igbo, including the Aro, thus the few differences where they exist could be a signal to an earlier occurrence of the item in Aro society. This viewpoint, in the absence of credible evidence to the contrary, hereinsubsists and is employed in the ensuingdiscussion. A few examples of such differences are here given as “adudu” in Arofor a vegetable known as “oha” (Pterocarpussoyauxii; P.Mildbraedii)in other Igbo societies; similarly “ahuji” for “nchanwu” (Ocimumbasilicum) which leaves serve as food spice and medicinal agent; and “enini” for “egusi” (Citrullus vulgaris), a soup ingredient which may also be eaten as a cake snack. More cases are summarized in tabular form at the end of this presentation, to which the reader is referred.The food and medicinal values of a selected number of such plants are here profiled, to underscore the significance of their contributions to the health and general well-being of this geographical zone.

FOOD VALUES

The Igbo and neighbours in the South-Eastern region are familiar with the food values and uses of the plants discussed herein and so, only brief mentions of these shall be made. These are described in alphabetical order as follows:

Adudu (oha): African coralwood; PterocarpussoyauxiiThe tree is commonly grown in family compounds or around semi-developed living quarters and the yellowish-green, young leaves serve as a vegetable in soups.

Ahuji (nchanwu): Scent leaf; OcimumbasilicumThis is a shrub cultivated around family homes which leaves are very much valued for their food and medicinal uses. For food uses, the leaves provide a distinctive flavor to food, especially pepper soups and meat or fish salads where in the latter, sliced leaves are sprinkled on the meat or fish as a taste-enhancer.

Evoro (ehuru). African Nutmeg: Monodoramyristica.From the green fruits of this tree are obtained brownish seeds used as condiment to flavor many dishes and sauces. It is also a special ingredient in the popular “Isi-Ewu” meat dish, a specialty of the Igbo.

Ibaa (ukpo):Mucunasloanei.A climbing shrub with twinning stems and irritant hairs on the seedpods.Cultivated in farms and gardens alike. The dried seeds are hard and blackish in colour. They are boiled to remove the hard covering, then pulverized to produce a whitish-grey powder used to thicken soups.

Okazi (ukazu):Gnetumafricanum.Okazi is a climbing liana of tropical forests but has now been domesticated and cultivated in local environments of living quarters. The green leaves sliced, constitute a popular vegetable in soups and are also eaten as a salad with a sauce of red palm oil and potash. The salad may be garnished with sliced onions, pieces of meat, dried fish or stockfish. The most popular type of okazi soup is that mixed with water-leaf and served at home and restaurants.

Okwukwa (ogbono): African mango;Irvingiagabonensis.A tree whose fruits resemble the mango fruit, hence the name. The fruits are smaller than the average mango fruit and are equally yellowish in colour, when ripe. The fruit has a slightly bitter taste and the seeds from the ripe fruits are dried and used to thicken soups to give a thick, slimy consistency. 

Ugba (ukpaka):  Oil bean seed;Pentaclethramacrophylla.A tree found in bushes of local villages and sometimes cultivated near homes. The oil bean seeds are expelled from the pods when these desiccate sufficiently and while on the trees as flat, dark-brown beans of about six centimeters average diameter size. Cooked, sliced and fermented beans constitute the delicacy known as “ugba” which may be eaten in various forms as salads, soups or mixed with starchy staples such as yam in porridges.

GENERAL MEDICINAL PROPERTIES

Detailed medicinal properties of these plants and more, may be obtained from specialized text books such as that edited by the Nigerian Natural Medicine Development Agency, 2008 (Okujagu et al, 2008),to which the reader is referred, as such a treatment is beyond the scope of this brief presentation. For our present purposes however, the effort is limited to identifying specific and significant pharmacotherapeutic values for a few interesting plants and affecting intractable health conditions such as cancer and pandemic viral diseases. Two examples each for anticancer (cancer chemopreventive and cancer chemotherapeutic) and antiviral (anti-HIV-1) phytochemicals obtained from relevant indigenous Aro-Igbo plants shall therefore be discussed as given hereafter:

ANTICANCER ACTIVITIES

CANCER CHEMOPREVENTION

Cancer chemopreventive agent from “akarinu”(Bitter kola)

From Bitter kola (Garcinia kola), (akarinu, akilu),  a mixture of three biflavonoid compounds(GB1, GB2 and KF) named kolaviron(KV), (Figure 1) was isolated and deployed successfully to prevent or reduce liver toxicity states in animal studies (Iwu et al, 1987).

Figure 1: Kolaviron (KV)

GB1 (Rl = R2 = R3 = R5 = H, R4 = OH)        GB2 (Rl = R2 = R4 = R5 = H, R3 = OH)   KF   (R3 = R5 = H, Rl = R4 = OH, R2 = OCH3)

A pioneering investigation (Nwankwo et al, 2000) was later initiated to ascertain the potential of KV as a chemopreventive agent against human liver cancer. This consisted of studies into the molecular mechanisms of KV’s mode of action, by determining the potential of KV to inhibit the hepatotoxic and genotoxic actions of the potent liver toxin and human hepatocarcinogen, aflatoxin B1 (AFB1), in a human liver-derived cell line, HepG2. Results demonstrated that KV significantly regulated the expression of major genes involved in human AFB1 metabolism and enhanced the latter’s detoxication, thus potentially preventing AFB1-induced hepatocarcinogenesis (Nwankwo et al, 2000).

Hepatocellular carcinoma (HCC) is thefourth most prevalent malignancy in Africa and accounts for the second highest cancer-related deaths in African men (Ndom, 2019).Prevalence of this malignancy has been exacerbated by its etiology of chronic liver damage sustained from hepatitis B and C virus infection,AFB1 contamination from mouldy grains such as garri, groundnuts, etc, and alcoholism (Fitzmaurice et al, 2017)

Human HCC is one of the intractable malignancies with very little treatment options especially for patients with locally unresectable or metastatic disease. For instance, chemotherapy is largely ineffective for this disease, with response rates of only 20% and no improvement in survival (Di Bisceglie et al., 1998). There is therefore a need for improved pharmacological intervention alternatives or better still, a shift in focus to chemopreventive strategies as could be afforded by this report of a locally available, edible and potentially effective chemopreventive agent (KV) against AFB1-induced human HCC.

In view of the promise observed for KV as a potential cancer chemopreventive agent in the above-mentioned study, a follow-up investigation was designed to explore the potentials of KV in regulating other hepatoprotective genes against hepatocarcinogen assault (Nwankwo, 2017). This study employed gene expression analysis (microchip gene array) of human hepatocytes exposed separately to the potent hepatocarcinogen AFB1 and KV, then pretreatment with KV before AFB1, to obtain a retinue of new genes so regulated.(Nwankwo, 2017).

CANCER CHEMOTHERAPY

Cancer chemotherapeutic agent from “ugba” (Oil bean seed)

Gamma-linolenic acid:(γ-linolenic acid: GLA:octadeca-6, 9, 12-trienoic acid,Figure 2) is an essential polyunsaturated fatty acid (PUFA)present in large amounts (46% of fatty acids content), as its biochemical precursor, linoleic acid, in the commonly eaten (South-Eastern Nigeria) oil bean seed Pentaclethramacrophylla(ugba,upkaka), (Onwuliri et al, 2004).Patients with malignant primary gliomas or mammary adenocarcinomas have a poor prognosis as common therapeutic approaches are relatively ineffective. Interestingly, GLA was found to be selectively cytotoxic to gliomas and other tumor types (Horobin, 1989; Jiang et al, 1998), while normal cells are largely unaffected.


Figure 2: GLA:octadeca-6, 9, 12-trienoic acid

Subsequently, a hypothesis wasproposed to account for the mechanismof GLA-induced cytotoxicity to tumor cells, particularly gliomas and mammary adenocarcinomas (Nwankwo, 2001). About four years later, workers in another laboratory (Menendez et al, 2005) independently provided corroboratory experimental support for this hypothesis, thus strengthening the theory and conferring scientific legitimacy on the postulate. There is hope that this postulate would serve as a basis for the design of new therapeutic derivatives of GLA against the dreaded gliomas and metastatic mammary carcinomas.

In a related investigation, the molecular mechanisms regulating transcriptional expression of the human gene (FADS2) for biosynthesis of GLA from linoleic acid, were revealed (Nwankwo et al, 2003) and this novel finding could pave a way for effective design of gene therapy approach against gliomas and other cancers susceptible to GLA treatment.

ANTIVIRAL AGENTS


Anti-HIV-1 agent from “Okazi
Apigenin-7-O-β-D-(4′-caffeoyl)-glucuronide, was isolated from Chrysanthemum flowers as a new flavonoid glucuronide (Lee et al, 2003). The new compound exhibited strong HIV-1 integrase inhibitory activity, with IC50 value of about 7.2 µg/mL, as well as HIV-inhibitory potentials in a cell culture assay, employing the HIV-I (IIIB) infected MT-4 cells (Lee et al, 2003).


Figure 3: Apigenin (5, 7, 4 – trihydroxyflavone; R = H)

It is noteworthy that apigenin(Figure 3) derivativesknown as isoswertisins, were isolated from the leaves of an indigenous plant which serves as a popular local vegetable in Igboland, (Ouabonzi et al, 1983). The plant, Gnetumafricanum (okazi, ukazu), is a vine of tropical rain forests, and the leaves are a delicacy, consumed both as a vegetable in soups, and alone as a salad, in most parts of eastern Nigeria. High concentrations of the apigeninderivatives, may therefore be administered to patients with HIV infection and recommended to be ingested in high quantities as meals, to augment any orthodox therapeutic regimens, if these compounds should possess anti-HIV activities as described (Nwankwo, 2011). It should be emphasized however that such prescriptions should be enabled only after initial animal and subsequent relevant human Phases trials have been performed.

Anti-HIV-1 agent from “evoro” (African nutmeg)

A lignan, 3′-O-methyl nordihydroguaiaretic acid (3′-O-methyl NDGA: Figure 4), isolated from Larreatridentata, was shown to inhibit the human immunodeficiency virus (Gnabre et al, 1995).

Figure 4: NDGA       

The range of anti-HIV activities of this compound was reported to include: dose-dependent inhibition of HIV Tat-regulated transactivation in vivo; induction of protection for lymphoblastoid CEM-SS cells from HIV (strain IIIB) killing; and suppression of the replication of five HIV-1 strains (WM, MN, VS, JR-CSF, and IIIB) in mitogen-stimulated peripheral blood mononuclear cells (Gnabre et al, 1995).

A derivative of NDGA, described as a new lignan and named macelignan (2R,3S)-1-(3,4-methylenedioxyphenyl)-2,3-dimethyl-4-(4-hydroxy-3-methoxyphenyl)-butanewas isolated from the fruit aril of the Igbo medicinal plant and food condiment, Myristicafragrans (evoro, ehuru), otherwise known as the edible African nutmeg (Woo et al, 1987). The only structural difference between macelignan and the active 3′-O-methyl NDGA is in the 3,4-catechol groupbeing replaced by a 3,4-methylenedioxy one (Nwankwo 2011). The influence of this minor substitution on the anti-HIV activity of the original compound, remains to be experimentally determined. Chances are that macelignan could prove to be even more anti-HIV active than the reported 3′-O-methyl NDGA compoundand that would be a welcome development indeed!

SUMMARY

This brief summary of medicinal and food value contributions of selected Aro plants to the peoples of South-Eastern Nigeria geographical area, is by no means comprehensive but mostly a highlight of a few interesting instances, in an attempt to emphasize the significance of such contributions. Many more similar examples may be obtained from other such plants, some of which are summarized in Table 1 below. Finally, we must discourage deforestation to save our tropical rain forests which are fast depleting! Two drastic consequences of our disappearing rain forests immediately come to mind: the first is the damaging effect of climate change brought about by the loss of vegetation in the tropics, which is already being felt; secondly, many important, life-saving plants may be lost forever unless we act now!!!

Table 1: Some Aro-Igbo plant names and their synonyms in the general Igbo language.

Aro-Igbo General Igbo Common Scientific Uses*
Adudu Oha African coralwood Pterocarpussoyauxii F, M
Ahuji Nchanwu Scent leaf Ocimumbasilicum F, M
Akarinu Akilu Bitter kola Garcinia kola M
Asiboko Ahuekere Groundnut Arachis hypogea F
Enini Egusi Melon Citrulus vulgaris F
Evoro Ehuru African nutmeg Monodoramyristica F, M
Ibaa Ukpo   Mucunasloanei F, M
Ichiara Ijikere Hog plum Spondiasmombin M
Mgbapa Ebele Calabash Lagenariasiceraria M
Mgbi-mgbi Okwurubekee Paw-paw Caricapapaye F, M
Nkasi Ede Cocoyam Xanthosomaspp F, M
Mkpochara Otosi Bamboo Oxythenantheraabyssinica  
Okazi Ukazu   Gnetumafricanum F, M
Okpoto Opete Bush cane Costusafer F, M
Okwukwa Ogbono African mango Irvingiagabonensis F, M
Ugba Ukpaka Oil bean Pentaclethramacrophyla F
Ukubia Icheku Velvet tamarind Dialiumguineense F

*F and M represent Food and Medicinal uses respectively.

REFERENCES

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Fitzmaurice C, Akinyemiju T, Abera S, et al. (2017). The burden of primary liver cancer and underlying etiologies from 1990 to 2015 at the global, regional and national level.JAMA Oncol. doi:10.1001/jamaoncol.2017.3055.

Gnabre JN, Brady JN, Clanton DJ. (1995).Proc. Natl. Acad. Sci. USA. 92:11239-11243.

Horobin DF (1989). In: Abraham S (editor) Carcinogenesis and dietary fat. Kluwer Academic Publishers: Boston; pp: 247-262.

Iwu MM, Igboko OA, Onwuchekwa UA, Okunji CO. (1987). Evaluation of the anti-hepatotoxic activity of the biflavonoids of Garcinia kola seed.J. Ethnopharmacol. 21: 127-138.

Jiang WG, Bryce RP, Horrobin DF (1998) Essential fatty acids: molecular and cellular basis of their anti-cancer action and clinical implications. Crit Rev OncolHematol 27:179-209.

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Menendez JA, Colomer R, Lupu R (2005). Inhibition of fatty acid synthase-dependent neoplastic lipogenesis as the mechanism of γ-linolenic acid-induced toxicity to tumor cells:an extension to Nwankwo’s hypothesis. Med Hypotheses 64: 337-341.

Ndom P. (2019). Cancer prevention in Africa: Liver cancer. eCancer Medical Science. 2019, 13:950. DOI: https://doi.org/10.3332/ecancer.2019.950.

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Nwankwo JO.(2001). Repression of cellular anaplerosis as the hypothesized mechanism of gamma- linolenic acid-induced toxicity to tumor cells.Med Hypotheses 56: 582-588.

Nwankwo JO, Spector AA., Domann FE. (2003). A nucleotide insertion in the transcriptional regulatory region of FADS2 gives rise to human fatty acid delta-6-desaturase deficiency. J. Lipid. Res. 44: 2311-2319.

Nwankwo JO. (2011). In: “Potential anticancer and antiviral agents from West African phytochemicals”, pp. 159, 162; 75; 92. ISBN: 978-978-53040-4-6. University of Nigeria Press,

Nwankwo J.O. (2017). Anticancer potentials of phytochemicals from some indigenous food and medicinal plants of West Africa.Adv Cancer Prev. 2:124-130. doi: 10.4172/2472-0429.1000124.

Okujagu TF. (2008). Medicinal plants of Nigeria: South-East Nigeria. Vol 1.Nigeria Natural Medicine Development Agency.Federal Ministry of Science and Technology.ISBN 978-978-088-434-5 Lisida Consulting Publishers. Lagos, Nigeria.

Onwuliri VA, Attah I, Nwankwo JO. (2004). Anti-nutritional factors, essential and non-essential fatty acids composition of Ugba (Pentaclethramacrophylla) seeds at different stages of processing and fermentation J Biol Sci. 4: 671-675.

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1 comment

  1. Kelechi Orieh 23 March, 2020 at 18:20 Reply

    Quite enlightening research based write up. Plant names indigenous to Aro and their medicinal efficacy. Much appreciate.

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