Chinese Herbal Medicine (CHM) is a popular form of complementary and alternative medicine worldwide. Despite the numerous studies on the chromatographic fingerprinting, advanced extraction techniques and process development, the lack of a fundamental understanding of traditional manufacturing process has impeded the development of consistent and high quality CHM product. A traditional recipe based processing method for CHM consists of two main steps: maceration and extraction. A fundamental understanding of the traditional aspect for these two steps is of great importance for the quality assurance of CHM production.

Maceration is generally utilized as a basic step before extraction in traditional recipe method for processing CHM. However little has been done to verify the eff...[ Read more ]

Chinese Herbal Medicine (CHM) is a popular form of complementary and alternative medicine worldwide. Despite the numerous studies on the chromatographic fingerprinting, advanced extraction techniques and process development, the lack of a fundamental understanding of traditional manufacturing process has impeded the development of consistent and high quality CHM product. A traditional recipe based processing method for CHM consists of two main steps: maceration and extraction. A fundamental understanding of the traditional aspect for these two steps is of great importance for the quality assurance of CHM production.

Maceration is generally utilized as a basic step before extraction in traditional recipe method for processing CHM. However little has been done to verify the effect. In order to understand the rationale behind it, different parts of herbs from herb plants, namely seed, stem, stem bark, root, root bark, flower and fruit, were used to study the maceration effect. It was found that maceration process could not affect the extraction yield of dashensu from Salviae Miltiorrhizae Radix (root) even though it caused swelling of the herbal tissue. Nevertheless, extraction yield of chrysophanol in Cassiae Semen (seed) was increased with an increase in maceration time. Decomposition of chemical marker was found in the extraction Lonicerae Flos (leaf) and Eucommiae Cortex (Stem bark) caused by hydrolysis of chlorogenic acid and pinoresinol diglucoside, respectively, during maceration. With an understanding of the plant physiology and anatomy, the relationship between extraction yield and herbal structural characteristics was revealed.

On the other hand, herbs are usually sold in the herbal market in the form of slices instead of the raw herbs or powder form. However, difference of extraction performance in slice and powder form is often overlooked in the domestic and pharmaceutical industrial production. Therefore, by treating the herbal slice as slab form, the extraction behavior for the herbal slices was investigated and a one-dimension mass transfer model with internal diffusion controlled transport was proposed based on the physicochemical diffusion phenomena of herbal extraction. Herbal slice Astragali Radix with marker calycosin-7-O-beta-D-glucoside was selected as an example to demonstrate how to apply the model. Model parameters D’ was obtained by curve fitting and the calculated value was 4.0313×10^-10 m²/s. The overall objective of the thesis was to improve the traditional manufacturing process with an understanding of the herbal structural characteristics and intra-particle diffusion process for conventional extraction of phytochemicals from CHM. It is believed that it could improve the current CHM production process and present a modern engineering view on the traditional recipe method.