Are You Using the Correct Fang Ji?
Are You Using the Correct Fang Ji?
by Eric Brand
Obviously I’ve been having fun with my new camera the past few days. This photo shows a mixed sample of Fang Ji. Can you differentiate the safe herb Han Fang Ji (Stephaniae Tetrandrae Radix) from the dangerous herb Guang Fang Ji (Aristolochiae Fangchi Radix) in this photograph? It isn’t easy unless you know what to look for!
Guang Fang Ji is a common adulterant of Han Fang Ji. In the past, the two were regarded as interchangeable medicinals, two regional variants of Fang Ji. Their TCM actions were traditionally regarded as the same, but they differ significantly in their chemical constituents. Han Fang Ji (also called Fen Fang Ji or simply Fang Ji) contains an important active constituent called tetrandrin, while Guang Fang Ji contains the nephrotoxic and carcinogenic chemical aristolochic acid (AA).
AA is a major concern for Chinese medical practitioners because it is associated with serious adverse events. AA has been implicated in some high-profile cases of adverse events with Chinese herbs, and as a whole our community remains undereducated on this important issue. Like the aerial portions of Xi Xin, Guang Fang Ji is no longer considered safe for use (for example, it was banned from use in Hong Kong in 2004, and is not allowed in the USA as well). Therefore, practitioners should learn how to differentiate Han Fang Ji from Guang Fang Ji so that the latter can be avoided.
The similar appearance, similar Chinese names, and traditionally interchangeable use of these two items cause them to be easily confused. In fact, they are sometimes mixed together, as in the sample shown here (taken from a clinic in the USA). For this reason, many regions have very strict regulations when it comes to manufacturing products that contain Fang Ji; for example, Taiwanese granule companies are required to use microscopy and TLC testing from several different parts of each batch of raw herbs before the product can be made. This allows the batch to be definitively identified as Han Fang Ji and verifies that it lacks contamination from Guang Fang Ji.
In the absence of chemical testing, the two can be assessed based on their gross appearance if one knows what to look for. Han Fang Ji is powdery to the touch (its alternate name Fen Fang Ji literally means “powdery fang ji”). Guang Fang Ji is less powdery, it feels coarser to the touch. This is particularly noticeable if you break the slice and touch the broken area. Additionally, Guang Fang Ji has more defined and numerous striations, which look like spokes on a bicycle wheel. By contrast, Han Fang Ji has sparse radial striations and its broken surfaces are more even and less rough.
In this photograph, the two pieces at the center of the bottom row are characteristic of the appearance of Han Fang Ji, while most of the other slices are more characteristic of Guang Fang Ji.
Generally I would say that Mayway and Nuherbs are good about providing the correct medicinals. Spring Wind is also a good source. I've never done a comprehensive review of the products from these brands, but most examples I've seen have been the authentic items. Each of these companies has a relatively good handle on the issues involved.
Do you think that during the Han dynasty the Xixin and Fangji being used had levels of AA which today we would consider dangerous?
Several materia medica scholars that I have spoken with believe that the part of the plant used for Xi Xin in Shang Han Lun times was the root rather than the aerial portion. Since only the aerial portion is considered to be problematic, this view would suggest that the Han dynasty Xi Xin would be basically safe on the AA issue (it is still toxic, but that is a separate issue from AA).
As for Fang Ji, it is not clear exactly which species was used in Han dynasty times (some sources indicate that it was a different plant altogether, now known as Han Zhong Fang Ji). Regardless of the time period, substitution between Guang Fang Ji and Han Fang Ji was going on for a long time before the AA issues were discovered. Most likely AA was not a big issue because the herbs were decocted in water (some sources indicate AA is not very water-soluble) and were given for relatively short periods of time. AA really blew up after the use of substitute herbs taken as a crude powder with a blend of pharmaceutical drugs caused nephrotoxicity and deaths in Belgium. After that, AA was researched more extensively and it is indeed dangerous, but AA-containing plants had a long history of use before the dangers were discovered.
So.. you say above that xi xin is still toxic in the root, though not d/t AA. What is that toxicity?
Thanks for your comments. I'd also like to take this chance to thank you for the great contribution you've made to the herbal field in the area of adulterants. I've been visiting many school pharmacies lately and invariably the ones that have correctly identified specimens on the commonly confused substances have the right items because they order from your company Spring Wind. In many instances, the reason the pharmacy managers even know about the issues involved is directly related to your efforts.
In this blog, I wasn't trying to suggest that visual identification alone is sufficient for differentiating Han Fang Ji and Guang Fang Ji. As I understand it, some specimens do not have a very textbook appearance and microscopy and chemical testing is ultimately the only way to conclusively confirm the identity.
Furthermore, as you mentioned, different cuts make differentiation more difficult, and often the whole roots are harder to tell apart.
That said, we need more general awareness of the issues involved, and for the average practitioner that doesn't have TLC and microscopy available, the basic rules of thumb can be used to identify whether a specimen is clearly safe or is somewhat suspicious. Beyond the visual assessment, the tactile sensation of the powdery nature of Han Fang Ji is extremely important (I believe I mentioned this in the blog).
I wasn't trying to suggest that the info in this blog offered a definitive means of differentiating the two, it is just meant to be a starting point to illustrate the general issues to watch out for. I agree that visual assessment alone is insufficient, but I also know that experts such as Zhao Zhongzhen at HKBU use these basic criteria when assessing any given specimen, and in many cases the specimens can be differentiated in the field with the naked senses.
Comments are not allowed from anonymous visitors.