## 3 Results and Discussion
### Phenolic Compound Profile of Leptadenia pyrotechnica Stem  
Due to different botanical and regional sources, the phenolic compounds differ between samples. The phenolic substance type and concentration are responsible for the biological activities and rely on the source of the sample [34; 35]. The qualitative and quantitative analysis of tann acid, chlorogenic acid, caffe acid, vanillin, acetylsalicylic acid, salicylic acid, and quercetin in _L. pyrotechnica_ using HPLC is reported in Table 1. All the samples contained five phenolic compounds. The range of the detected phenolic compounds in the control sample was 2.00-43.95 mg/100 g DW; for the microwave-treated samples, it was 1.52-49.08 mg/100 g DW, and for the hot-air heated samples, it was 1.06-41.98 mg/100 g. Acetylsalicylic acid was the highest (119.08 mg/100 g DW) phenolic compound, while vanillin (1.61 mg/100 g) was the lowest in the 5 min microwave-heated sample. Tannic acid was the highest (116.06 mg/100 g), whereas vanillin (1.65 mg/100 g DW) was the lowest  
Figure 5: Effect of microwave heating (MW) and hot-air heating (HA) methods on the reducing power of _Leptadenia pyrotechnica_ stem samples. MD. The bars for the treatments bearing different letters are significantly different from each other at \(p<0.05\).  
in the 8 min microwave-treated sample. For the 10 min microwave-treated sample, tann acid was the highest (77.30 mg/100 g DW), while caffeic acid (1.52 mg/100 g DW) was detected at its lowest amount.  
The results of the hot-air treatment revealed that vanillin was the lowest compound (1.06 mg/100 g DW), while tannic acid was found to be the highest one (28.12 mg/100 g DW) when samples were treated for 60 min. The caffeic acid (3.54 mg/100 g DW) was the lowest, and acetylsalicylic acid (25.82 mg/100 g DW) was the highest in the 120 min hot-air dried sample. In contrast, for the 180 min treatment, vanillin (1.17 mg/100 g DW) was the lowest and tannic acid (41.98 mg/100 g DW) was the highest phenolic compound.  
These results reveal that the total phenolic compounds were higher in microwave-heated samples than in the hot-air treated samples. The range of total detected phenolic compounds for the microwave treatment was 95.43-214.66 mg/100 g DW compared to 68.90-82.47 mg/100 g DW for the hot-air treatment. [PERSON] et al. [3] reported the phenolic compounds in _L. pyrotechnica_ with different solvent extractions. The results showed that ethyl acetate extraction had a higher caffeic acid content, 0.78 mg/g, whereas n-butanol extract had the lowest amount of caffeic acid, 0.23 mg/g. The amounts of vanillic acid and gallic acid were found to be 1.2 and 0.42 mg/g, respectively; in water extraction, they were found to be in minute concentrations. [PERSON] and [PERSON] [2] reported the phenolic compounds in Indian _L. pyrotechnica_, in which caffeic acid was the most abundant, 3.305%. [PERSON] et al. [36] reported the total tann content in the _L. pyrotechnica_ aerial part and root as 154.96 and 62.71 mg/100 g, respectively. The sharp reduction in the acetylsalicylic acid content after microwave treatment for more than 5 min might be due to the increase in the temperature during the treatment. It has been stated that acetylsalicylic acid begins to significantly decrease at high temperatures above 150 \({}^{\circ}\)C [37]. Our study showed an improvement in the phenolic compound content due to heating at a particular time, and it was more evident for the microwave-treated sample; this might contribute to the antioxidant activity of _L. pyrotechnica_. [PERSON] et al. [38] reported a weak correlation between the free radical scavenging antioxidant activity and the total phenolic content. They have suggested that phenolic compounds could not be the main components responsible for free radical scavenging ability.