Change in the active component of processed Tetradium ruticarpum extracts leads to improvement in efficacy and toxicity attenuation

Ethnopharmacological relevance: The dried and nearly ripe fruits of Tetradium ruticarpum (A. Juss.) T.G. Hartley (TR) have long been used in treating headache and gastrointestinal disorders in oriental medicine. TR is usually processed by stir-frying with licorice extract before use. Although processing procedure is considered as the way to relieve pungent smell, reduce toxicity, and improve efficacy, its effects on TR's toxicity and efficacy and bioactive compound profiles are largely unknown.

Aim of the study: The purposes of the study are to evaluate the acute toxicity, efficacy and variation of toxic and effective components of TR before and after processing, and to explore the possible mechanism of how the processing procedure affect the quality of TR as a herbal medicine.

Materials and methods: Volatile oil, aqueous extract and ethanol extract of raw and processed TR were tested for their acute toxicity, analgesic, and anti-inflammatory effects in mouse models, respectively. To identify potential toxic and effective components, the extracts were analyzed with gas chromatography-mass spectrometry and ultra-performance liquid chromatography - quadrupole time-of-flight mass spectrometry, followed by fold-change-filtering analysis.

Results: LD₅₀ and LD₅ tests indicated that although the aqueous extract has higher toxicity than volatile oil and ethanol extract, the use of TR is safe under the recommended does. The processing procedure could effectively decrease the toxicity of all three extracts with the largest decrease in volatile oil, which is likely due to the loss of volatile compounds during processing. Analgesic and anti-inflammatory studies suggested that volatile oil and ethanol extract of TR have better efficacy than the aqueous extract and the processing procedure significantly enhanced the efficacy of these two former extracts, whereas processing showed no substantially effects on the bioactivities of aqueous extract. Integrated analysis of animal trial and chromatographic analyses indicated that indole and quinolone type alkaloids, limonoids, amides and 18β-glycyrrhetinic acid were identified as the potential main contributors of TR's efficacy, whereas hydroxy or acetoxy limonoid derivates and coumarins could be the major causes of toxicity. Moreover, the reduced toxicity and improved efficacy of the processed TR are liked due to the licorice ingredients and altered alkaloids with better solubility.

Conclusions: In summary, the integrated toxicity and efficacy analyses of volatile, aqueous and ethanol extracts of TR indicated that the processing procedure could effectively reduce its acute toxicity in all three extracts and enhance its analgesic and anti-inflammatory effects in volatile and ethanol extracts. The promising candidate compounds related to the toxicity and efficacy of TR were also identified. The results could expand our understanding of the value of the standard processing procedure of TR, be valuable to the quality control of TR manufacturing and administration, as well as support clinical rational and safety applications of this medicinal plant.

Keywords: Processing; Tetradium ruticarpum; acute toxicity; bioactive components; efficacy.