Potential mechanisms of hypocholesterolaemic effect of Thai spices/dietary extracts

Abstract

Several Thai spices/dietary ingredients were previously shown to have hypocholesterolaemic effects. These studies were mostly conducted in animal models in which the mechanisms of action were not yet well-established. Therefore, this study aimed to investigate the potential mechanism of hypocholesterolaemic action of 12 selected plants, namely Hibiscus sabdariffa L., Moringa oleifera Lam., Cucurbita moschata Duchesne, Ananas comosus (L.) Merr., Zingiber officinale, Morus alba L., Camellia sinensis (L.) Kuntze, Piper nigrum L., Alpinia galanga (L.) Willd., Curcuma zedoaria Rose, Bacopa monnieri (L.) Wettst. and Piper retrofractum Vahl., widely used as spices and ingredients in various types of Thai food. The extract of P. nigrum at 100 µg mL⁻¹ was found to be the most effective cholesterol uptake inhibitor whereas those of A. galanga and C. sinensis effectively inhibited pancreatic lipase activity with IC₅₀ values of 8.99 ± 3.41 and 12.36 ± 1.23 µg mL⁻¹, respectively. The potency of extracts from H. sabdariffa, M. oleifera and C. moschata at 100 µg mL⁻¹ were found to be similar to 0.4 µg mL⁻¹ pravastatin in inhibiting HMG-CoA reductase and possibly reduced cholesterol biosynthesis. This study also demonstrated that several of the tested plants possessed multiple sites of action that were possibly responsible for their cholesterol-lowering effect in the in vivo model.

Keywords:

• cholesterol
• pancreatic lipase
• HMG-CoA reductase
• Thai spices
• dietary plant

Acknowledgements

The authors would like to thank Asst Prof. Dr Arom Jedsadayanmata for his suggestions in preparing the manuscript and Mr Wittaya Pongamornkul, from the Queen Sirikit Botanic Garden Chiang Mai, Thailand, for providing plant materials. This study was financially supported by the National Research Council of Thailand to Naresuan University (RX-AR-032/2552) and the Thailand Research Fund (MRG5180254). The graduate student was supported by the Strategic Scholarships for Frontier Research Network for the PhD Programme Thai Doctoral Degree from the Commission on Higher Education, Thailand, and the Center of Excellence for Innovation in Chemistry (PERCH-CIC).