adulterations of herbal drugs

3.3  DETERIORATION OF HERBAL DRUGS

Deterioration of herbal drugs in storage is another factor affecting the equality of herbal medicinal products. The storage 

conditions (light, humidity, oxygen, temperature) affect the stability of the herbs and the secondary metabolites present 

therein. Also, microbial growth in the phytopharmaceuticals tells upon the quality of the products. The primary factors 

leading to the deterioration of herbal medicines can be summarized as follows.

3.3.1 Light

Wormseed (Dysphania ambrosioides) contains Santonin as the principal constituent. When wormseed is exposed to light, 

it undergoes photodecomposition and becomes black. Similarly, Rhubarb powder undergoes decomposition in clear glass 

jars and becomes reddish. In order to prevent such phenomena, it is recommended that drugs should be stored in amber 

colored bottles or with lightproof wrapping. Similarly, the glycosides of digitalis seem to be photosensitive, particularly 

with respect to polarized and reflected light.

With an eye to these detrimental effects, the World Health Organization has recommended that photosensitive herbal 

drugs should be stored in light-resistant containers. If that is not possible, then the bottle should be stored in light-resistant 

boxes.

3.3.2 Moisture

The percent relative humidity (%RH) of the storage environment of the herbal medicinal product determines the moisture 

content, a factor affecting the stability of the herbal medicinal product. Some drugs do not tend to absorb moisture from the 

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atmosphere and are thus called air-dry. These drugs do not need to be kept in air-tight containers. Depending on the %RH, 

these drugs contain 10%–12% moisture. The presence of moisture in drugs results in reactivation of enzymes in the drug, 

resulting in decomposition of the constituents. Moisture-sensitive drugs need to be stored in the presence of siccatives, 

such as calcium chloride, calcium sulfate, or sodium sulfate. Squill powder picks up moisture from the atmosphere quickly 

and soon becomes a sticky mass. Also, a strict control of the humidity of the storage region is necessary for controlling the 

moisture content of the herbal medicinal product.