Werayut Pothitirat

Comparison of bioactive compounds content, free radical scavenging and anti-acne inducing bacteria activities of extracts from the mangosteen fruit rind at two stages of maturity.

Contents of bioactive components, free radical scavenging and anti-acne producing bacteria activities of young and mature fruit rind extracts of mangosteen were compared. The young fruit rind extract contained significantly higher contents of phenolics and tannins and promoted higher free radical scavenging activity than the mature fruit rind extract, while the later extract contained higher contents of flavonoids and alpha-mangostin xanthone and gave higher anti-acne producing bacteria activity than the young fruit rind extract. Thus, the young and mature stages of mangosteen fruit rind should be beneficial for further development of antioxidant and anti-acne pharmaceutical preparations, respectively.

Free radical scavenging and anti-acne activities of mangosteen fruit rind extracts prepared by different extraction methods.

The ethanol extracts of mangosteen fruit rinds prepared by several extraction methods were examined for their contents of bioactive compounds, DPPH-scavenging activity, and anti-acne producing bacteria against Propionibacterium acnes and Staphylococcus epidermidis. The dried powder of the fruit rind was extracted with 95% ethanol by maceration, percolation, Soxhlet extraction, ultrasonic extraction, and extraction using a magnetic stirrer. Soxhlet extraction promoted the maximum contents of crude extract (26.60% dry weight) and α-mangostin (13.51%, w/w of crude extract), and also gave the highest anti-acne activity with MIC 7.81 and 15.63 μg/mL and MBC 15.53 and 31.25 μg/mL against P. acnes and S. epidermidis, respectively. Ethanol 70% and 50% (v/v) were also compared in Soxhlet extraction. Ethanol 50% promoted the extract with maximum amounts of total phenolic compounds (26.96 g gallic acid equivalents/100 g extract) and total tannins (46.83 g tannic acid equivalents/100 g extract), and also exhibited the most effective DPPH-scavenging activity (EC50 12.84 μg/mL). Considering various factors involved in the process, Soxhlet extraction carried a low cost in terms of reagents and extraction time. It appears to be the recommended extraction method for mangosteen fruit rind. Ethanol 50% should be the appropriate solvent for extracting free radical-scavenging components, phenolic compounds, and tannins, while 95% ethanol is recommended for extraction of α-mangostin, a major anti-acne component from this plant.

Anti-Acne-Inducing Bacterial Activity of Mangosteen Fruit Rind Extracts

Objective: The aims of this study were to determine the most effective solvent extract of mangosteen, anti-acne- inducing bacterial activity and the amount of α-mangostin, a major active component in each mangosteen fruit rind extract, using high-performance liquid chromatography (HPLC). Materials and Methods: The fruit rinds of mangosteen were extracted with hexane, dichloromethane, ethanol and water. The extracts were tested for antibacterial activity against bacteria that induce acne, including Propionibacterium acnes and Staphylococcus epidermidis. Thin-layer chromatographic autobiography against these bacteria was also performed for each extract, while the α-mangostin content was analyzed using a validated HPLC method. Results: The dichloromethane extract exhibited the strongest antibacterial effect with minimum inhibitory concentration values for both bacterial species at 3.91 µg/ml, while the minimum bactericidal concentration values against P. acnes and S. epidermidis were 3.91 and 15.63 µg/ml, respectively. Thin-layer chromatographic autobiography indicated that α-mangostin was present in all extracts, except the water extract, and is a major active component against both P. acnes and S. epidermidis. Using HPLC, the dichloromethane extract yielded the highest content (46.21% w/w) of α-mangostin followed by the ethanol extract (18.03% w/w), the hexane extract (17.21% w/w) and the water extract (0.54% w/w). Conclusions: Dichloromethane extract exhibited the strongest anti-acne-inducing bacterial effect and this extract yielded the highest amount of α-mangostin.