The plant commonly known as African chewing gum, locally known in northern Nigeria as 'Goron tula' and scientifically known as Azanza garckeana belongs to a family of angiosperm known as Malvaceae. It is widely distributed locally in Nigeria, specifically in Tula, Kaltungo Local Government Area of Gombe State, and in Michika in Adamawa State. ref. Beyond the shores of the country, Goron tula grows from Sudan down to South Africa and the local name given to the plant varies accordingly. ref
The plant grows as a small drought-resistant shrub or semi-deciduous tree of 3 to 10 m in height, produces simple lobed leaves, and produces yellow-petaled flowers between December and May of the following year. The fruits of Azanza garckeana, which is perhaps the most important part of the plant in terms of its usefulness to man are hard and hairy with splittable 5 lobes and the entire fruit measuring between 20 to 50 millimeters in diameter. ref
The leaves, fruits, barks, and roots of A. garckeana has found a wide variety of usage among the locals. The slimy flesh of the young fruits of the plant forms a palatably sweet snack and a decoction of the root is often taken to for relief from cough, chest, and menstrual pains. ref Apart from the ample anecdotal evidence of the effectiveness of the infusion/decoction/concoction of different parts of the plant in the treatment against a wide range of pathogenic diseases, several scientific investigations have also reported the antibacterial, antifungal, as well as antiviral activities of the extracts of the plants. ref
In Nigeria, there are huge claims among the locals that the fruits of Goron tula is the next best thing in town in terms of its effectiveness against a wide range of ill-health such as malaria, sexually transmitted infections, body pains, erectile dysfunctions, etc. The therapeutic effects come from the chewing of the fruits, as they claimed. If this were to be so, perhaps an investigation into the phytochemical contents of the fruits can give an insight into its usefulness against such diseases.
Hence, this study was set up to qualitatively determine the presence of major phytochemicals that confer medicinal properties on plants in the ethanolic extract of the fruits of A. garckeana.
Collection and Treatment of Fruit Sample
Samples of the fruits of Azanza garckena were obtained from the Northern region of Nigeria where the plant grows. The semi-dry fruits were sent from Abuja via dispatch to Oduduwa University Ipetumodu, Osun State in southwestern Nigeria. Upon reception, the fruits were taken to the Faculty of Pharmacy in Obafemi Awolowo University, Ile-Ife, within the same state where they were opened up to reveal flesh mesocarp and stony endocarp. The opened fruits were then placed on smooth papers and allowed to dry under natural air in the screen house for up to 6 months. Air-dried fruits were then grounded to powder in the mill house and stored prior to extraction.
Preparation of Extract
The phytochemical compounds in the grounded sample of the fruits were extracted using ethanol in a process known as cold extraction. The sample was carefully transferred into a big glass jar. Two liters of ethanol was initially added and the glass jar was shaken vigorously. Thereafter, another one-liter ethanol was added to make three liters in all. The mixture was shaken for a few minutes and then allowed to stand for up to 72 hours with foil paper covering to prevent the evaporation of the ethanol.
After 72 hours, the mixture was filtered through a cotton plug into a 2.5-liter glass jar using a funnel. The filtrate was collected and the shaft discarded. The collected filtrate was then concentrated using a rotary evaporator.
Phytochemical screening of the extract
A measured amount of the concentrated extract was reconstituted by weighing 13 g of the extract and dissolving it in 13 mL methanol. The reconstituted mixture was then used to qualitatively test for the presence of different phytochemicals using established methods.
For the detection of tannin, 2 drops of Iron (III) chloride solution was added to 1 mL of the reconstituted extract. The formation of a dirty green precipitate gave an indication of the presence of tannin in the extract.
For qualitative determination of glycosides, 1 mL of 50% sulphuric acid was added to 0.1 mL of the reconstituted extract in a test tube. The mixture was boiled for about 5 minutes using a water bath after which 5 mL each of Fehling solution A and B was added and then boiled again over a water bath. The formation of brick red precipitate gave a positive indication of the presence of glycosides in the extract.
In order to qualitatively determine the presence of resin in the reconstituted extract, 0.25 mL standardized copper sulfate solution was added to 0.25 mL of the extract. The appearance of a green precipitate indicated the presence of resin.
About 1 mL of the reconstituted extract was pipetted into a test tube and vigorously shaken for about 2 minutes. The formation of a few centimeter froth layer is an indication of the presence of saponin
To 0.5 mL of the reconstituted extract in a test tube, 1 mL concentrated sulphuric acid was added slowly and alongside the test tube. Observation of colour change gave an indication of the presence of sterols in the extract.
In order to detect phenol, an equal volume of the reconstituted extract and a solution o iron (III) chloride were mixed in a test tube. A colour change to deep bluish-green gave an indication of the presence of phenolic compounds in the extract.
To detect the presence of alkaloids in the extract, 1.5 mL of the reconstituted extract was dispensed into a test tube and 0.5 mL conc. Sulphuric acid was added. A few drops of Wagner’s reagent were then added into the mixture. A positive test is indicated by the formation of a reddish-brown precipitate.
About 0.2 mL of the extract was dispensed into a test tube and was mixed with 2 mL chloroform and 3 mL conc. Sulphuric acid respectively. A colour change to reddish-brown would be an indication of the presence of terpenoids.
To test for phlobotanin, an equal volume of the reconstituted extract and distilled water were mixed and then boiled with 1% hydrochloric acid for about 2 minutes. The formation of a deep green precipitate indicated the presence of the compound.
To qualitatively detect the presence of flavonoids, 1 mL of the reconstituted extract was boiled with 5 mL ethyl acetate solution. The mixture was then allowed to cool and a red colour formation indicates the presence of flavonoids.
To check for the presence of carbohydrates, 5 mL each of Fehling solution A and B were added to 2 mL of the reconstituted extract in a test tube. The formation of red colouration is an indication of the presence of carbohydrate compounds in the extract.
The phytochemical screening of the ethanolic extract of the fruits of A. garckeana revealed a mix of results ranging from the absence of some phytochemicals to just the presence of some, and the abundance of others. The result is presented in the table below:
NOte: +++ = abundance, + = detectable, - = not detected
The result showed that the ethanolic extract of the fruits has an abundance of tannins, a compound that has been reported to confer antibacterial as well as antifungal properties on plants. ref This might be the reason the extracts from the tissues of the plant have been reported to have anti-pathogenic properties. Terpenoids, alkaloids, phenols, resins, saponins, phlobatannins, etc, were also present in detectable amounts and these compounds have different significance against various ailments when consumed.
The investigation revealed the presence of important phytochemicals that have health implications and this might be the reason the fruits of the plant of A. garckeana has been locally reported to be effective against a wide range of ailments. A further research into some of the specific claims is recommended.