A traditional method of Cinnamomum carolinense preparation eliminates safrole from a therapeutic Pohnpean tea

Traditional preparation of Phaleria nisidai, a Palauan tea, reduces exposure to toxic daphnane-type diterpene esters while maintaining immunomodulatory activity

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Phaleria nisidai Kaneh. (Thymelaeaceae) are brewed into a tea commonly used as a tonic, strengthening beverage and immune enhancer in Palau, Micronesia. Recently, the leaves of P. nisidai have been shown to contain toxic daphnane diterpene esters which may pose a public health threat to Palauans.

AIMS OF THE STUDY

This project documents the use frequency, preparation and side effects of P. nisidai. The content of daphnane diterpene esters in aqueous and methanol extracts and infusions prepared by healers in Palau is compared to assess the risk of daphnane ingestion associated with traditional consumption. Quantitative results are correlated with an in vitro assessment of the immunomodulating activity of the extracts.

MATERIALS AND METHODS

Research participants, comprising traditional healers and laypeople, were interviewed concerning use patterns and side effects of P. nisidai. Several traditional healers prepared and provided boiled tea samples for chemical analysis. Leaves were collected and methanolic and aqueous extractions were prepared in the laboratory. Peripheral blood mononuclear cells (PBMCs) were cultured with various concentrations of methanol and aqueous leaf extracts and their output of IFNγ was measured using ELISA. Cell proliferation was also assessed using the MTT assay. The concentration of selected daphnane diterpene esters in healer-prepared infusions, lab methanol and lab aqueous extracts was quantified using ultraperformance liquid chromatography-mass spectrometry-triple quadrupole detection (UPLC-MS-TQD).

RESULTS

Through structured interviews it was determined that P. nisidai tea was used frequently, with many participants drinking it daily. The reported side effects were mild, and with the exception of diarrhea (n=2), no side effect was mentioned more than once. Methanol extracts contained 4.0μg simplexin, 17.6μg acetoxyhuratoxin and 2.3μg huratoxin per g dry leaf material. In traditional water infusions provided by healers and in standardized lab-prepared aqueous extracts all three compounds were below the limit of detection (16.3ng/mL) using our UPLC-MS-TQD method. Methanol and aqueous extracts increased the release of IFNγ by PBMCs (p<0.05); however, methanol extracts were significantly more active than aqueous extracts (p<0.05). Methanol and aqueous extracts significantly increased proliferation of PBMCs, causing at least 60% more cell proliferation than negative control (p<0.05).

CONCLUSIONS

The presence of daphnane diterpene esters in a frequently consumed traditional beverage was initially viewed as a public health concern, though interview data reveal that Palauans do not observe toxicity or side effects associated with their use of P. nisidai tea. Concurrently, daphnanes are present in methanolic extracts but not detected in aqueous preparations indicating that the traditional method of preparation avoids the extraction of these potentially toxic compounds, while still maintaining immunostimulant activity.

Science Across Borders: 5th Annual Natural Health Product Research Conference—March 26–29, 2008, Toronto, Canada

Canada is experiencing a growing interest in the use of alternative therapies and products particularly natural health products (NHP). In 1997, Canadians spent around C$ 2 billion on NHP. In an attempt to catch with this popularity of NHP use, Canadian researchers and administrators from academia, industry and government jointly established the Natural Health Product Research Society of Canada (NHPRS). Since its formation, NHPRS has been organizing an annual meeting which brings together world renowned researchers and experts in the area of NHP research. For 2008, the annual NHPRS meeting took place in Toronto from the 26th to 29th of March with a focus on ‘Science Across Borders: Global Natural Health Products Research’. The scientific program was spread into three days of plenary lectures and oral presentations. The different sessions containing these talks were on: ethnobotany around the world; chemical analysis of NHP; product standards and quality control; ethnomedicine; novel analytical approaches; systemic research, nutrisciences and molecular medicine; and drug development from NHP. The meeting proved to be a great success in terms of the speakers that were invited and based on the data that was presented which highlighted recent research taking place in the field of NHP not only in Canada but from many parts of the world.