A REVIEW ON GONGRONEMA LATIFOLIUM, AN EXTREMELY USEFUL PLANT WITH GREAT PROSPECTS

Gongronema latifolium is a plant that has a wide range of nutritional and ethnomedical uses in different tropical African communities. Scientific reports on the chemical composition and bioactivity (anti-inflammatory, antimicrobial, antidiabetic, antioxidant, anticancer and allelopathic properties) of the plant material by different authors were discussed in this review. Future prospects of the plant extracts in the areas of herbal formulations, food preservation, alcoholic fermentation and beer production, drug discovery and allelopathy were also highlighted.


Figure 2: Basic sapogenin structure
Flavonoids are widely distributed and form major colouring components of plants. They large group of phenolic compounds and are responsible for a variety of pharmacological activities [21][22][23]. They exist as aglycones, glycosides and methylated deriva further divided into different groups like the flavones, flavon plant flavonoids have been shown to exhibit protective effects against infectious, cardiovascular, carcinogenic and age  [22,23].

phenyl-1,4-benzopyrone)
are large polyphenolic compounds that contain many hydroxyl and other groups, such as carboxyls, which usually form strong complexes with various macromolecules. Tannins medicinal properties [24]. The structure of tannic acid, a Flavonoids are widely distributed and form major colouring components of plants. They are a large group of phenolic compounds and are responsible for a variety of pharmacological tives and can be ols and flavanones [21]. Some plant flavonoids have been shown to exhibit protective effects against infectious, are large polyphenolic compounds that contain many hydroxyl and other groups, such as carboxyls, which usually form strong complexes with various macromolecules. Tannins e of tannic acid, a tannin, is It is hoped that in future the actual saponins, flavonoids and tannins present in leaves would be isolated, purified, characterized and subjected to bioactivity evaluations.
Eleyinmi [26] did nutritional analysis of the protein content was 27.2 %, dry weight, while the lipid extract, ash, crude fibre and nitrogen free extractives were 6.07%, 11.6%, 10.8%, and 443.3% dry matter, respectively. that leucine, valine, phenylalanine, the plant material, with aspartic acid, glutamic acid and glycine having 10.3%, respectively of the total amino acid composition. Likewise, saturated and unsaturated 6 Sitosterol is a plant sterol (phytosterol). Phytosterols are known to have beneficial effects in helping to reduce cholesterol absorption in the intestines [25].

Figure 5. B-Sitosterol
It is hoped that in future the actual saponins, flavonoids and tannins present in ified, characterized and subjected to bioactivity evaluations. did nutritional analysis of the G. latifolium leaves and reported that the crude protein content was 27.2 %, dry weight, while the lipid extract, ash, crude fibre and nitrogen ee extractives were 6.07%, 11.6%, 10.8%, and 443.3% dry matter, respectively. leucine, valine, phenylalanine, aspartic acid, glutamic acid and glycine were the plant material, with aspartic acid, glutamic acid and glycine having 13.8%, 11.9%, and 10.3%, respectively of the total amino acid composition. Likewise, saturated and unsaturated are known to have beneficial effects in It is hoped that in future the actual saponins, flavonoids and tannins present in G. latifolium ified, characterized and subjected to bioactivity evaluations. leaves and reported that the crude protein content was 27.2 %, dry weight, while the lipid extract, ash, crude fibre and nitrogen ee extractives were 6.07%, 11.6%, 10.8%, and 443.3% dry matter, respectively. He reported aspartic acid, glutamic acid and glycine were abundant in 13.8%, 11.9%, and 10.3%, respectively of the total amino acid composition. Likewise, saturated and unsaturated fatty acids were 50.2% and 39.4% of the oil, respectively. He also reported occurrence of minerals in the plant material [26].
latifolium. Both aqueous and methanolic extracts of the leaf significantly (P=0.05) inhibited the carrageenan-induced rat paw oedema in a dose-related manner [27]. The extracts also significantly inhibited the acetic acid-induced vascular permeability and the leukocyte migration assay conducted on experimental mice. The carrageenan-induced rat paw oedema test is an established protocol to test for acute inflammation [30, 31 while the leucocyte migration assay and acetic acid-induced vascular permeability experiments are additional established antiinflammatory tests [32,33]. Morebise et al [28] also reported that the methanolic extract of the plant leaf material significantly inhibited the nystatin-induced rat paw oedema and also significantly stabilized erythrocyte membrane subjected to heat-and hypotonic solutioninduced lyses.
To test for possible anti-inflammatory property of the plant in chronic inflammatory conditions, arthritis was induced in experimental rats and G. latifolium extracts were found to significantly and dose-dependently inhibit the arthritis formation and to lower the serum levels of Gammaglutamyl transferase, alanine aminotransferase and aspartate aminotransferase [29]. The total serum protein and the globulin fraction were significantly (P=0.05) raised while the albumin fraction and the serum glucose were significantly reduced [29].

Antidiabetic activity.
There have been several reports on the antidiabetic activity of the leave extracts of G.
latifolium. In the study conducted by Sylvester et al. [36], experimental rats were subjected to Streptozotocin-induced diabetes mellitus and then treated with G. latifolium leaf extracts. They iv.

Antioxidant activity.
Numerous reports have shown that G. latifolium leaf extracts exhibit antioxidant property.
Ugochukwu and Babady [38] reported that oral administration of aqueous and ethanolic extracts of G. latifolium leaf to Streptozotocin-induced diabetic rats significantly raised the activity of superoxide dismutase, glutathione reductase, glutathione peroxidase and glucose-6phosphate dehydrogenase (G6PD). The level of reduced glutathione was increased while lipid peroxidation was decreased. They concluded that G. latifolium leaves could exert their antidiabetic activity through their antioxidant properties [38].
Nwanjo et al. [39] reported the anti-lipid peroxidative property of the aqueous extract of G.
latifolium leaves in experimental rats subjected to Streptozotocin-induced diabetes. They found out that the extract significantly increased the activity of superoxide dismutase and lowered the level of the plasma lipid peroxidation product, malondialdehyde.
Eze and Nwanguma [12] reported the antioxidant activity of the tannin extract from G. latifolium leaves on partially purified lipoxygenase from Cucumeropsis manii seeds. The inhibitory effects of the tannin extract and of two known antioxidants: ascorbic acid and propyl gallate, on the partially purified lipoxigenase was investigated. The extract significantly inhibited the lipoxygenase and this inhibitory activity compared well with those of ascorbic acid and propyl gallate. They suggested that the extract could be included in food processing to hinder the deteriorative effects of lipoxygenase [12].

v. Anticancer activity.
G. latifolium leaf extracts were reported by Iweala et al.
[40] to exhibit strong inhibitory activity against human lung carcinoma and human breast adenocarcinoma in vitro. The extracts also exhibited free scavenger scavenging activity against 1,1-Diphenyl-2-picrylhydrazyl (DPPH) in vitro. Previous reports have indicated that phytochemicals could prevent cancer and other chronic diseases by their antioxidant activity as free radical scavengers [41][42][43].
vi. Allelopathic activity. Morebise and Fafunso [4] reported the phytotoxic activity of saponin extracts from G. latifolium leaves. The saponin extract showed strong inhibitory activity against the germination of bean and maize seeds, and against the growth of their seedlings. Inhibition of root and shoot lengths was concentration-dependent and the roots were more sensitive than the shoots to the effect of the extract [4].

vii. Beer production
Adenuga et al. [44] conducted an experiment in which sorghum beer was brewed with the extracts of G. latifolium, Vernonia amygdalina and Garcinia kola to impart bitter taste and flavor as substitutes for hops used for beer production. Sensory evaluation of the beer samples was done by trained panelists. The panelists adjudged the G. latifolium flavoured beer as better than the other samples and that it compared favourably with hopped beer in terms of flavor and taste.

viii. Toxicological study
Interestingly, Sylvester et al. [36] reported that acute toxicity of the ethanolic extract of the plant on mice showed 0% lethality when administered intraperitoneally at 1000mg/kg body weight, but 100% mortality when administered at 2000mg/kg. This clearly suggests that the plant material is not toxic at the safe doses being consumed. More research is needed in this area.

GENERAL DISCUSSION
The Catharanthus roseus [49,50]. A large percentage of Orthodox drugs in clinical management of 13 cancer have their roots in plants and other natural products [51] while more than 60% of cancer patients still resort to use of herbs to manage the disease [52].

ii. Herbal Supplements/ Formulations
Researchers should look into the possibility of using G. latifolium leaf extracts as approved medicinal formulations or supplements, especially for diseases like diabetes mellitus, sickle cell disease, malaria and other disorders for which the plant is being used ethnomedically. During the past decades, the World Health Organization (WHO) and several Governments in the developing countries have campaigned for the promotion and integration of herbal remedies in healthcare delivery as supplementary contributions to modern medical facilities [53].

iii. Food Production and Preservation
Based on the research findings highlighted in this review, commercial application of G.
latifolium extracts as alternative to hops in beer production should be looked into. Also, commercial use of the extracts as food supplements or for food preservation is an interesting area which researchers can focus on.

iv. Allelopathy
Allelopathy is an emerging approach to agricultural issues like inter-cropping, pest management, crop rotation and growth enhancement [54]. A lot of research has been done to explore the inhibitory potential of different allelopathic crops and trees for weed management [55][56][57][58]. The inhibitory property of allelochemicals has been attributed to the blockage or cessation of important physiological and metabolic processes of plants [54]. Since allelochemicals do not have residual toxic effects, they are better alternatives to synthetic herbicides [59].