3. Discussion
The plant material was yellow, with a coarse texture, a very characteristic odor, and a bitter taste. Aqueous extraction was performed as recommended by the health tradipratician. Water, the most polar solvent, was used to extract a wide range of polar compounds. It has the advantage of dissolving many substances; it is inexpensive, non-toxic, non-flammable and highly polar [
28,
29]. The lyophilizates varied in color from yellow to light yellow, depending on the mass to volume ratio, with a bitter-sweet taste, the sweetness being more pronounced in lyophilizates with a low mass to volume ratio and a fine texture. These changes in characteristics are thought to be related to extraction [
30]. Organoleptic and macroscopic characteristics are parameters used in the identification and quality control of raw materials. These data help to establish quality control and assurance standards and to define the purity of herbal or synthetic drugs [
31]. Visual assessment of appearance sometimes allows rapid identification of certain herbal drugs, checking their degree of purity according to the presence or absence of foreign elements, moulds, etc., and possibly detecting adulteration or falsification. A color change may indicate deterioration due to poor drying or storage conditions [
29,
32].
The result for the residual moisture content of the plant material was 4.84 ± 0.06. The control of this parameter reduces errors in estimating the actual weight of the plant material and guarantees the quality during the storage period [
33]. This value, below 10%, indicates that the powder is sufficiently dry and can be stored during the handling period without the development of molds or yeasts, according to the standards of the European Pharmacopoeia [
31]. In fact, too high a water content (above 10%) could promote enzymatic reactions with negative consequences on the appearance of the plant drug, its organoleptic characteristics and its therapeutic properties during the shelf life of the plant material powder. High residual moisture also favors the proliferation of microorganisms such as bacteria, yeasts and moulds. These results are similar to those obtained by Sanfo [
24], who obtained THRs below 10%, i.e. 4.26%. The RMC of lyophilisates varied from 5.11% to 7.76%, with an average of 6.65%. These lyophilises were more or less dry and could be stored without mould or yeast growth. The best yields, 35.12±1.1% and 33.54%, respectively, were obtained from extracts macerated for 12 h and 6 h at a mass/volume ratio of 5%.
The mass/volume ratio parameter has a significant effect on yield. The yield results show that increasing the solvent volume by decreasing the m/v ratio improves the extraction yield up to a ratio of 5%; in fact, the best yields are obtained with the lowest m/v ratio. This is consistent with the principle of mass transfer, which states that the driving force during extraction is the concentration gradient between the solid and the external liquid medium. This force becomes important when the liquid/solid ratio used is higher [
34]. Similar results were obtained by Cacace who evaluated the effect of the solids ratio on the extraction rates in their studies [
34]. They found that increasing the volume of solvent had a positive effect on extraction regardless of the type of solvent used.
Increasing the extraction time can often improve the extraction yield. This is mainly due to the fact that a longer contact time between sample and solvent allows a better solubilisation of the target compounds in the solvent. This more efficient solubilisation leads to a more complete extraction of the desired compounds, thus increasing the overall extraction yield [
35]. We can stated that a long extraction time would allow for good extraction and therefore good yield.
However, in this study, after 6 hours, increasing the time did not significantly improve the yield. This could be explained by the phenomenon of extraction saturation when time is extended over a long period [
36]. This result is similar to that of Tiendrebeogo who found that the time parameter alone in maceration was not sufficient to significantly improve extraction [
36]. The results of our study show that the conditions for optimal crude yield from aqueous maceration of
B. aegyptiaca seeds crush would be maceration for 6 h at a mass/volume ratio of 5%.
Phytochemical screening of the extracts by thin-layer chromatography on chromatoplates using the methods described by Wagner and Bladt revealed metabolites such as saponins and flavonoids. Saponins were the most essential compounds in the extracts, as significant precipitation reactions were obtained with appropriate reagents. Chemical screening revealed spots of equal intensity in all extracts.
Assay results ranged from 9.27±0.07 mg/g to 13.81±0.04 mg/g. Analyses show that the highest levels were obtained at the 12-hour maceration time with 13.81±0.04mg/g at 10%, 12.89±0.06mg/g at 30%, 12.59±0.02mg/g at 40%, 12.32±0.07mg/g at 5%. The most significant content obtained with 12 hours time parameters and 10% mass/volume ratio was 13.81±0.04mg/g.
The antioxidant activity results by ABTS ranged from 3.57±0.21 μg/mL to 4.82±0.10μg/mL. The most active extracts (4.82±0.10), (4.54±0.13) and (4.52±0.19) were obtained at 6 h of the 5% and 10% ratios and 12 h of the 5% ratio, respectively. The lower the concentration (IC
50), the higher the antioxidant effect [
37]. The phytochemical groups identified, namely flavonoids, tannins and saponins, are thought to be responsible for the antioxidant activity of the extracts [
38,
39].
These tests allowed us to determine the anthelmintic activity of the two
B. aegyptiaca seeds extracts with the highest yields while maintaining their physicochemical properties against
H. bakeri L
1 larvae [
40,
41]. The results obtained show an interesting larvicidal effect. Indeed, the 5% extract showed a maximum effect of 84.64% larval mortality at a concentration of 25 µg/mL, while the 10% extract resulted in 100% mortality of
H. bakeri L
1 larvae at the same concentration—also, the IC
50 (extract at 5%) < IC
50 (extract at 10%). Therefore, we can say that the 10% extract at 12h is more effective and potent than the 5% extract. The difference in the activity of the extracts tested may be due to the content of secondary metabolites, especially saponins, which are antiparasitic substances present in the extracts [
42,
43].
B. aegyptiaca has been chemically investigated for various classes of constituents. It is reported to contain several secondary metabolites and bioactive compounds, including flavonoids, alkaloids, glucosides, phenols, steroids, saponins, furanocoumarins, diosgenin, N-trans-feruloyl tyramine, N-cis-feruloyl tyramine, trigonelline, balanitol, fatty acid [
26,
44]. The 10% extract at 12 h has the highest saponins content compared to the other extracts. In
B. aegyptiaca fruits, saponins such as balanins 4, 5, 6 and 7 have been isolated.
The activity of the different extracts obtained by successive depletion of
B. aegyptiaca seeds powder was evaluated on
C. elegans. Aqueous and methanolic extracts resulted in worm mortality. However, the aqueous extract (IC
50 = 1.0 mg/mL) was much more nematocidal on
C. elegans than the methanolic extract (IC
50 = 25.3 mg/mL). Pure balanitin-7 obtained after successive column fractions showed very high nematocidal activity (IC
50 = 0.1μg/mL, expressed as aqueous extract equivalent) [
26]. Based on the results of his study, Gnoula hypothesised that the major nematocidal agent present in the seeds of
B. aegyptiaca may be balanitin-7 (Bal-7), a heteroside of the diosgenyl saponins family [
26]. Since the 10% 12 h extract is rich in saponins, we can assume that the larvicidal activity on
H. bakeri is related to the high presence of this phytochemical group.