**2.7** *Cordyceps sinensis*

This species is commonly called the Caterpillar Fungus and is probably the most extensively studied species. It is a parasitic species with the caterpillar as its primary host [19]. *C. sinensis* is also included in some food recipes in addition to its medicinal *Medicinal Mushroom of Potential Pharmaceutical Toxic Importance: Contribution… DOI: http://dx.doi.org/10.5772/intechopen.103845*

**Figure 6.** Boletus edulis *(Cepe or King Bolete) [37].*

use. It has activities similar to ginseng, antioxidant, anti-inflammatory, and very potent. The first documented use of *C. sinensis* was in 620 AD, during the Tang Dynasty, used for strengthening of the body after exhaustion or long term illness, impotence, backaches, and an antidote for opium poisoning [56]. Cordycepin is the active molecule in *C. sinensis*, as illustrated in **Figure 7**. Cordycepin or 3′-deoxyadenosine, is a derivative of the nucleoside adenosine. It was initially extracted from the fungus *Cordyceps militaris* [9], but is now produced synthetically. It is also found in other *Cordyceps* species as well as *Ophiocordyceps sinensis* [27].

Based on the similarity of cordycepin to adenosine acting as an analog, some enzymes have affinity but cannot discriminate between the two bioactive compounds [57]. Cordycepin can participate in some biochemical reactions like, 3-dA for example, can provoke the premature termination of mRNA synthesis [34, 58], by acting as an adenosine analog [59]. Cordycepin has been shown to produce rapid, strong imipramine-like antidepressant effects in animal models of depression, and these effects, similar to those of imipramine, are dependent on the enhancement [60]. A photo of a mature *Cordyceps sinensis* in its natural habitat is illustrated in **Figure 8**. The AMPA receptor (AMPA-R) is a subtype of the ionotropic glutamate receptor coupled to ion channels that modulate cell excitability by gating the flow of calcium and sodium ions into the cell [61].

Many studies have been done on this fungus but with little confirmatory result [62]. In traditional Chinese medicine, Cordyceps has been used in the treatment of respiratory and pulmonary diseases, such as renal, liver, and cardiovascular diseases [3, 29]. It has been used in the treatment of immune disorders in association with cancer chemotherapy treatments and surgery [9]. It is also used as a remedy for impotence, fatigue and as a "rejuvenator" for the increase in energy [57]. Successful

**Figure 7.** *Structure of cordycepin.*

**Figure 8.** *A mature* Cordyceps sinensis *in its natural habitat [39].*

treatment for impotence, acting as an aphrodisiac has also been reported in clinical trials testing. This fungus is considered to be a miracle mushroom [19].
