Antioxidant activity of honey with Star fruit concentrated product and its effects combined with exercise on oxidative stress and physical function in healthy elderly.

Abstract

Star fruit (Averrhoa carambola L.) is a seasonal fruit found in Thailand that contains antioxidative compounds, such as phenolics, saponins, flavonoid C-glycosides, tannin, and L-ascorbic acid (Vitamin C), especially sour type. In Thailand, there is also a sweet-type of star fruit (SF) that is popularly grown and sold in the market, yet it remains uncharted in terms of reported or researched in terms of comparing the differences between the two types of SF. Therefore, this study has the objective (1) to study the active compounds and anti-oxidant activity in sweet- and sour-type SF extracts in vitro and (2) to evaluate the antioxidant activity and physical capacity of elderly individuals through the combined supplementation of a sweet-type SF and honey product, along with a home-walking exercise. The study is focused on evaluating the amount of various active compounds including total phenolics, total flavonoids, and Vitamin C (Vit C), anti-free radicals, and anti-oxidant activities between two types of SF. Subsequently, the sweet SF was developed into an industrial pilot model of SF juice mixed with honey, in order to investigate its effectiveness among elderly participants, with an average age range of 60 to 70 years. The study is divided into four groups: the supplement and walking exercise group (S+WG) (n = 11) was compared with the supplement group (SG) (n = 11), the walking exercise group (WG) (n = 12), and the control group (CG) (n = 12). The dosage of the supplement was designed at 20 g in 150 mL of warm water which was administered twice daily for 4 weeks. Whereas exercise was a prescribed moderate-intensity walking exercise for 30 minutes, 3 days per week. Before and after the 4-week trial, blood oxidative stress status such as glutathione (GSH), Vit C, total antioxidant capacity (TAC), malondialdehyde (MDA), and 6-minute walking distance (6MWD) were assessed. The findings indicated that the sour-type SF extract exhibited elevated levels of total phenolics, total flavonoids, and Vit C compared to the sweet-type, as well as scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO). However, sweet-type SF showed higher activity in scavenging the 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS˚+). Moreover, the sweet-type SF displayed superior protective effects against the oxidation of GSH, protein carbonyl, and lipid peroxide formation. Conversely, higher doses of sour-type SF extract triggered pro-oxidant activity by escalating GSH oxidation, protein carbonyl, and lipid peroxide formation in vitro with dose-response. For the study involved elderly participants in four groups, notable differences became evident following the 4-week intervention. In the WG, GSH and Vit C levels decreased, while TAC, MDA, and 6MWD significantly increased when compared to baseline measurements. The SG resulted in elevated plasma Vit C and TAC levels, as well as a reduction in MDA levels, with no significant changes in GSH and 6MWD. Lastly, the S+WG led to a decrease in both GSH and Vit C levels, a slight reduction in MDA levels, and a significant increase in TAC and 6MWD. Conversely, the CG showed no statistically significant changes in any of the measured parameters. In conclusion, this study demonstrates that the supplementation of products containing sweet-type SF mixed with honey effectively enhances antioxidant activity, Vit C, and TAC levels, while concurrently reducing lipid oxidation. Furthermore, the combination of this product into a regular home-walking exercise regimen proves to be beneficial in improving the walking capacity of elderly individuals.