Safety assessment of HEA-enriched Cordyceps cicadae mycelia on the central nervous system (CNS), cardiovascular system, and respiratory system in ICR male mice

Abstract

Cordyceps cicadae, an entomopathogenic fungus, is a source of traditional Chinese medicine in China. Due to the low yield of wild C. cicadae, artificial cultivation approaches will be needed to meet the increasing market demand. Using bioreactor culture can increase mass production and the abundance of the active component, N6-(2-hydroxyethyl)-adenosine (HEA). Here, we describe a safety assessment for a novel mycelium preparation method. Many studies have confirmed the safety of C. cicadae mycelia. However, the acute safety pharmacology of the C. cicadae enriched with the high HEA (3.90 mg/g) compound has not been evaluated. This study evaluated the central nervous system (CNS), cardiovascular system, and respiratory system in ICR male mice via oral gavage administration. For each requested item, two batches of eight mice tested on a vehicle (0.5% carboxymethyl cellulose, CMC) and C. cicadae mycelia (1,000 mg/kg) were performed. The heart rate at 60 min for the vehicle and C. cicadae mycelium treatment was 700.3 ± 55.4 and 603.0 ± 42.3 bpm, respectively (p = .4279). For echocardiographic analysis, the LV mass of the vehicle and drug treatment was 86.7 ± 6.4 and 80.2 ± 7.7, respectively (p = .0933). In the respiratory test, the tidal volume of the vehicle and drug treatments was 0.11 ± 0.01 and 0.14 ± 0.01 at 60 min, respectively (p = .4262). These results demonstrate that the oral administration of HEA-enriched C. cicadae mycelia is safe for the CNS, cardiovascular, and respiratory systems.

Keywords: Cordyceps cicadae mycelia; Liquid fermentation; N6‐(2‐hydroxyethyl) adenosine; safety assessment.

FIGURE 1

Time course of pH, biomass, residue glucose, HEA, and adenosine contents under 5‐ton liquid fermentation of C. cicadae

FIGURE 2

HPLC analysis in C. cicadae mycelium and fruiting body. Patterns (a) and (b) were nymph and stroma of wild fruiting body, respectively. (c) The source from the artificial fruiting body and (d) C. cicadae mycelium produced from a 5‐ton fermenter

FIGURE 3

Effects of vehicle (0.5% CMC) and C. cicadae mycelia (1,000 mg/kg) on home‐cage activity in ICR mice, (a) including distance traveled, (b) walking, (c) drinking, (d) feeding, (e) grooming, (f) hanging, (g) rearing up, (h) resting, (i) twitching, and (j) awakening. Data are presented as mean ± SEM (n = 8)

FIGURE 4

Effects of core body temperature in ICR mice. Data are presented as mean ± SEM. versus. vehicle (0.5% CMC, n = 8; C. cicadae mycelia 1,000 mg/kg, n = 8)

FIGURE 5

Effects of telemetry ECG in ICR mice. ECG recording of (a) RR interval, (b) heart rate, (c) PR interval, (d) P duration, (e) QRS interval, (f) QT interval, and (g) corrected QT. Statistically, repeated‐measures two‐way ANOVA was used to compare between groups. The post‐Bonferroni analysis presented in the figure of A, B and C, * and *p <.05, ** and **p <.01, and *** and ***p <.001 compared with basal level of predrug. Data are presented as mean ± SEM. (vehicle, n = 8; C. cicadae mycelia 1,000 mg/kg, n = 8)

FIGURE 6

Systolic (a) and diastolic (b) blood pressure and heart rate (c) in vehicle‐ and C. cicadae mycelium‐treated mice were measured by a tail‐cuff method. Data are mean ± SEM of eight mice (five recording sessions each) per group. bpm indicates beats per min

FIGURE 7

Transthoracic echocardiography evaluating the left ventricular structure and function of mice following vehicle and C. cicadae mycelium treatments. (a) Representative M‐mode recordings of echocardiography. (b‐e) Quantitative analysis of the ejection fraction (EF), fraction shortening (FS), left ventricular mass (LV mass), and the diastolic and systolic left ventricular volume (LV Vol; d and LV Vol; s) of ICR male mice by echocardiography following vehicle and C. cicadae mycelium treatments. Values are means ± SEM

FIGURE 8

Effects of C. cicadae mycelia on lung function in ICR mice. The following parameters were assessed: (a) frequency (f), (b) tidal volume (TVb), (c) minute volume (MVb), (d) respiration resistance (Penh), (e) inspiratory time (Ti), and (f) expiratory time (Te). Data are presented as mean ± SEM (vehicle, n = 8; C. cicadae mycelia, n = 8)

FIGURE 9

Plasma concentration–time curves of HEA in rats after intravenous administration of HEA at 3.0 mg/kg. Values are means ± SD (n = 3)

FIGURE 10

Brain biodistribution at time 0, 30, 60, and 1,440 min of HEA in rats after intravenous administration of HEA at 3.0 mg/kg. Values are means ± SD (n = 3)