In Vitro Anti-inflammatory and Anti-bacterial Activities of Extracts from Three Phlai Species Using an Adapted Traditional Thai Medicine Extraction Method

Abstract

Phlai is a widely utilized medicinal herb in Thailand, particularly in traditional Thai medicine and the health industry. It comprises several species, including Yellow Phlai (Zingiber cassumunar Roxb.), Black Phlai (Z. ottensii Valeton), and White Phlai (Z. kerrii Craib). While these species exhibit distinct physical characteristics and biological activities, they share similar medicinal properties, such as anti-inflammatory, anti-oxidant, and anti-microbial effects. This study aims to develop an optimized extraction method for bioactive compounds from the three Phlai species by incorporating traditional Thai medicinal techniques, specifically decoction and oil extraction. These methods were adapted for laboratory use through reflux extraction, employing water and palm oil as solvents with an extraction duration of three hours. This process yielded six extract samples, consisting of three oil extracts (BOE, YOE, WOE) and three water extracts (BWE, YWE, WWE). The extracts were evaluated for in vitro anti-inflammatory activity and anti-bacterial activity against Streptococcus mutans. The results demonstrated the potential of the Phlai extracts in inflammation inhibition. Specifically, the oil extracts from Black Phlai (BOE), Yellow Phlai (YOE), and White Phlai (WOE) exhibited significant anti-inflammatory activity. Meanwhile, the water extracts from Black Phlai (BWE) and White Phlai (WWE) also showed anti-inflammatory effects, whereas no such activity was observed in the Yellow Phlai water extract (YWE). The anti-inflammatory potential of these extracts was assessed in comparison to Diclofenac diethylammonium, a standard pharmaceutical anti-inflammatory agent. Among the tested samples, Black Phlai oil extract (BOE) and Black Phlai water extract (BWE) displayed the strongest anti-inflammatory effects, with IC₅₀ values of 5.21 ± 0.33 mg/ml and 3.72 ± 0.11 mg/ml, respectively. Conversely, none of the six Phlai extracts exhibited anti-bacterial activity against S. mutans, as determined by the disc diffusion method, when compared to the standard antibiotic Erythromycin. The experiment demonstrated that applying Thai traditional medical wisdom through the reflux extraction technique resulted in effective extracts. The well-defined extraction process allowed for the development of high-quality herbal extracts, which can be further used in the development of health products for use in Thai traditional medicine.