Speaker: Prof. Pharkphoom Panichayupakaranant, Director of Phytomedicine and Pharmaceutical Biotechnology Excellence Center, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Thailand

Time: Oct 10^th, Thursday, 9:00am

Venue: Building 24#-C406

Host:  Prof.Haixia Chen

Abstract:  

Industrial regulations require a diminished consumption of petrochemical and volatile organic solvents. The safety of the chemicals used and the absence of risk during extraction process are a major concern and have drawn attention towards the need to use green solvents¹. Nowadays, various alternative green solvents, with high extraction capacity, biodegradable, low toxicity and low flammability have been reported^2,3. In addition, microwave-assisted extraction (MAE) is an extraction method that combines microwave and solvent extraction. MAE is on the basis of application of microwaves for heating the solvents and plant tissues in an extraction process that increases the kinetic of extraction, and has a number of advantages, such as reduced extraction time, less solvent use, higher extraction rate, and reduced cost of extraction, over traditional methods of extraction of compounds from herbal materials⁴.  

Mangosteen pericarps are a by-product of the mangosteen juice factory. The pericarp extracts are enriched in xanthones, particularly a-mangostin, which has been used as a marker for their standardization⁵.  Extracts from mangosteen pericarps have been reported to have various pharmacological activities, including antimicrobial, anti-inflammatory, antioxidant, and wound healing properties, and have therefore been used in several commercial pharmaceutical products and cosmetics. It has been reported that dichloromethane was the most suitable solvent for extraction of a-mangostin⁶. However, the use of dichloromethane as a solvent for extraction is restricted due to its toxicities. The absence of risk during extraction and the safety of the ingredients used are a major concern and have drawn attention towards the need to use a greener solvent. The present studies have focused on investigating the use of excipients for topical formulation that has including isopropyl myristate and cetyl alcohol as alternative green solvents for extraction using a microwave assisted green extraction method⁷. These solvents have similar polarities to dichloromethane, but they are considered to be safer and cheaper. The obtained extracts contained a-mangostin of not less than 2.0% w/w and can be used directly for topical formulations without the step of solvent evaporation and have resulted in a reduced cost of production. The medicinal creams and gels containing of 0.1% w/w a-mangostin were then formulated using these extracts⁸.

Garcinia cowa is an edible plant commonly known in Thai as “Chamuang”. We have recently isolated a new polyprenylated benzophenone, namely “chamuangone” from G. cowa leaves. Chamuangone possessed a significant cytotoxic activity against lung adenocarcinoma (SBC3 and A549) and leukemia (K562, and K562/ADM) cells with IC₅₀ values of 6.5, 7.5, 3.8, and 2.2 µM, respectively, as well as antibacterial activity against Streptococcus pyogenes (MIC 7.8 µg/mL), S. viridans and Helicobacter pylori (MICs 15.6 µg/mL), and Staphylococcus aureus, Bacillus subtilis and Enterococcus sp. (MICs 31.2 µg/mL)^9-10. Therefore, G. cowa leaf extracts containing chamuangone may be potentially used as a dietary supplement for prevention of cancer. Thus, a suitable extraction method as well as a standardization process for preparation of G. cowa leaf extracts containing chamuangone should be optimized in order to get a consistently high-quality extracts that can be effectively used in nutraceutical applications. A method for quantitative analysis of chamuangone in G. cowa leaf extracts has been established using a reversed-phase HPLC. In addition, hexane was a suitable solvent for extraction of chamuangone from G. cowa leaves using a microwave assisted extraction¹⁰. However, the use of hexane as a solvent for extraction is restricted due to its toxicities. Therefore, the present studies have focused on investigating the use of vegetable oils as the alternative green solvents for extraction of chamuangone from G. cowa leaves^11-12. A nutraceutical, soft gelatin capsule containing G. cowa leaf extract (500-1000 mg) that extracted with rice bran oil has been prepared using a green extraction method. The extracts are standardized to contain chamuangone of 1.9 mg/mL. The rice bran oil extract of G. cowa leaves exhibited satisfactory anticancer activities against human colorectal adenocarcinoma (HT‑29), breast adenocarcinoma (MCF-7) and lung adenocarcinoma (A549) cells with IC₅₀ values of 12 - 16 µg/mL, and no toxicity to normal cells.