Among athletes, endurance is one of the key elements to victory. In addition to
training, athletes normally used supplement to prevent fatigue during the event. With
prolonged and intense activity, our body started to experience decrease in muscle
performance due to several factors such as oxidative stress, dehydration and
accumulation of lactic acid in the body fluids. The free radicals generated during
intense exercise will expose the cells to oxidative damages. In the event of
dehydration, there will be significant losses of water and functional electrolytes during
intense exercise which affected the body fluid balance. Fatigue will also occur during
reduced oxygen in aerobic metabolism which later caused accumulation of lactic acid
in the muscle. This will change the pH balance toward more acidic and caused the
muscles to lose contractile efficiency. In addition, fatigue can also be studied using rats
as model organism. Results from this activity can be useful to analyse cellular
metabolism and physiology effects of the tested rats toward physical exercise.
Therefore, this review aims to discuss the causes of fatigue through oxidative stress,
dehydration and lactic acid accumulation. In addition, the effectiveness of using rats as
a model system in measuring fatigue is also included in illustrating examples on fatigue
assessment in vivo.
Introduction: There are numerous studies on the therapeutic properties of Artocarpus heterophyllus. However, stud- ies on the aqueous extraction of A. heterophyllus leaves are limited. This present study was conducted to optimize the extraction conditions of A. heterophyllus leaves to yield the highest phenolic, flavonoids and antioxidant contents. Methods: Response surface methodology (RSM) was employed to obtain a higher phenolic extraction parameter(s) of A. heterophyllus leaves using Central Composite Design (CCD). The antioxidant activity was then determined via ABTS (2,29-azinobis (3 ethylbenzothiazoline-6-sulfonic acid)) and DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay and analysis of the individual phenolics was performed by high performance liquid chromatography (HPLC). Results: The optimum extraction conditions with higher phenolics content and antioxidant activity was achieved at 81°C, 100 min and 40 mL/g sample with a good desirability value of 0.87. Under these optimized parameters, total phenolics and flavonoids were 174.48 ± 4.05 mg GAE/g sample and 21.44 ± 0.05 mg RE/g sample, respectively. Meanwhile, antioxidant activity via ABTS and DPPH assays were 90.88% ± 0.09 and 87.22% ± 0.62, respectively. Finally, under optimal extraction conditions revealed 4 compounds identified as chlorogenic acid, quercetin, rutin and kaempferol. Conclusion: The optimisation are promising to improve phenolic yield and antioxidant activity in A. heterophyllus leaves. It also proved that A. heterophyllus leaves can be used as an alternative natural antioxidant especially in medicinal applications since all identified compound possess significant biological activities for human health.
In the present work, aqueous ethanolic (60% ethanol) extracts from selected Malaysian herbs
including Murraya koenigii L. Spreng, Lawsonia inermis L., Cosmos caudatus Kunth, Piper
betle L., and P. sarmentosum Roxb. were evaluated for their ergogenic, anti-diabetic and
antioxidant potentials. Results showed that the analysed herbs had ergogenic property and
were able to activate 5'AMP-activated protein kinase (AMPK) in a concentration dependant
manner. The highest AMPK activation was exhibited by M. koenigii extract which showed no
significant (p > 0.05) difference with green tea (positive control). For anti-diabetic potential,
the highest α-glucosidase inhibition was exhibited by M. koenigii extract with IC50 of 43.35
± 7.5 µg/mL, which was higher than acarbose (positive control). The determinations of free
radical scavenging activity and total phenolics content (TPC) indicated that the analysed herbs
had good antioxidant activity. However, C. caudatus extract showed superior antioxidant
activity with IC50 against free radical and TPC of 21.12 ± 3.20 µg/mL and 221.61 ± 7.49 mg
GAE/g, respectively. RP-HPLC analysis established the presence of flavonoids in the herbs
wherein L. inermis contained the highest flavonoid (catechin, epicatechin, naringin and rutin)
content (668.87 mg/kg of extract). Correlations between the analyses were conducted, and
revealed incoherent trends. Overall, M. koenigii was noted to be the most potent herb for
enhancement of AMPK activity and α-glucosidase inhibition but exhibited moderate antioxidant activity. These results revealed that the selected herbs could be potential sources of
natural ergogenic and anti-diabetic/antioxidant agents due to their rich profile of phenolics.
Further analysis in vivo should be carried out to further elucidate the mechanism of actions of
these herbs as ergogenic aids and anti-diabetic/antioxidant agents.