O. smaragdina, the weaver ant when required leafy nests that the ants construct are plucked from their host tree for consumption after sorting them out from the nest. Both larval and adult stages are preferred and are eaten either raw or turned into “chutney” by mixing them with spicy ingredients. On the other hand, Odontotermes sp. usually collected when it is abundant i.e.; during swarming phase during rainy season and is eaten either raw or roasted. Therefore, it is evident that compounds meant for antioxidant capacity are consumed without any loss of activity when consumed as fresh/raw. Our results (Table 1Figure 1 to 4) show that the antioxidant pattern of studied insects varied according to taxonomy and life stages.
Table 1
ABTS•+, DPPH• free radical scavenging activity (IC50 µg/ml), ferric-reducing power (α-TPEE µg/g), total flavonoids content (mg RTE/100g) and phenolic content (mg GAE/100g) of weaver ant and termite. Values are presented as mean±SD (n=3) for each dataset.
species
|
Edible Stages
|
ABTS•+
Radical Scavenge
(IC50 µg/mL)
|
DPPH• Radical Scavenge
(IC50 µg/mL)
|
Ferric-Reducing Power
(µg TPEEq /g)
|
TPC
(mg GAEq/100g)
|
TFC
(mg RTEq/100g)
|
O. smaragdina
|
Adult
|
52.57±0.99
|
59.55±1.02
|
14.39±0.76
|
369.69±3.93
|
663.4±20.8
|
O. smaragdina
|
brood
|
33.34±0.89
|
60.93±1.03
|
10.62± 0.59
|
486.04±3.99
|
387.2±22.6
|
Odontotermes sp.
|
Adult
|
18.70±0.7
|
66.38±1.05
|
36.60±0.51
|
626.92±2.83
|
58.0±5.2
|
*(ABTS•+): 2, 2-azinobis-3-ethylbenzothiazoline-6-sulfonate; (DPPH•): 2, 2-Diphenyl-1-picrylhydrazyl; α-TPEE: α-Tocopherol equivalent/g; GAE: Gallic Acid equivalent/100g; RTE: Rutin equivalent/100g
*FRP assays were 500 µg/ml
|
From the analysis Table 1 and Figure 1, it appears that termite better inhibit free radicals with low inhibitory concentrations (IC50) of 18.70 for ABTS followed by ant brood (33.34) ant adult 52.57. In turn antiradical activity against DPPH was noted in ant adult and its brood (59.55 and 60.93) with slightly lower in termite (66.38). These values are either superior or similar to some edible insects, common fruits and vegetable, though, in some cases better scavenging activity could be noticed (Fig. 2 & 3). Differences in radical scavenging activity between ant and termite in the present study and other reports from edible insects might be for their protein quality in respective species. Chatsuwan et al [20] postulated that protein from different species might give different scavenging activity on DPPH and ABTS. The strong inhibition of free radicals could be justified by the relatively high concentrations of total phenols and flavonoids quantified in this study. Phenolic compounds are known to be powerful compounds with ability to reduce free radicals. [22]
TFCS (Fig. 4) in the weaver ant adult was significantly (P<0.05) higher in adult (663.4) than its brood (387.2) while least was observed in the termite species (58.0 mg RTE/100g). These values (Fig, 2), except for termite, are higher than or similar to most of the fruits and vegetable with few exception. [25] Nevertheless, with the value 58.0, flavonoid content in termite is higher than vegetables like Amaranthus, S.nigram, B.campestris S. oleracea (values between 27.52 to 59.70) and fruits (A. gigantum, A. muricata, A. gensis, A. alboviolaceum, F. capensis, values between 23.36 to 36.86) reported by Tsiba et al [22].
TPC (mg GAE/g) (Fig. 5) was significantly higher (P<0.05) in the termite species (626.92) followed by the ant brood (486.04) and its adult (369.69).These values are superior to as reported for few edible insects and comparable to most of the fruits and vegetables, except for few.
The results obtained advocate that O. smaragdina and Odontotermes sp. can both be recommended as a source of natural antioxidants on par with or superior to conventional fruits and vegetables to avoid oxidative stress such as degenerative diseases [28] and provide protection against oxidation at the cellular level by interfering in enzyme activity.[29]