The menace of cancer and the nightmare of complications of cancer chemotherapy have driven researchers to explore simple but efficient combination therapy that includes antioxidants, in cancer therapy. The ability of gallic acid to correct the toxic complication of Vincristine was investigated.

Twenty adult male rats of the Wistar strain were grouped into four, randomly, consisting of five rats each. The untreated control (group A) was given only distilled water, groups B and C 0.025 mg/kg Vincristine sulfate intraperitoneally once a week for two weeks. Group C rats were thereafter administered 100 mg/kg gallic acid daily by gastric gavage for 14 days. At 14 days, blood pressure and ECG were measured in the rats, then blood samples were obtained via the retrorbital venous plexus for determination of haematological parameters and plasma biochemistry. They were then euthanized through cervical dislocation, under ether anaesthesia, and liver, kidneys, heart, and brain samples were collected, weighed, and stored for determination of marker of oxidative stress in the post mitochondrial fractions of each organ.

Results of the study showed that rats in group B had hypertension as evidenced by elevated diastolic and systolic as well as mean arterial pressure while QT interval and corrected QT were slightly elongated. They also had lowered RBC, WBC, and granulocyte counts. Markers of oxidative stress, GSH, and SOD were also depleted while H2O2 generation increased in this group, whereas all the observed anomalies were corrected in the group C rats that were administered both Vincristine and gallic acid. This study further showed that Vincristine, at normal recommended therapeutic dosage is toxic, causing anaemia, panleucopenia, and cardiovascular anomalies via oxidative stress and generation of hydroxyl radicals. These were however corrected by concurrent administration of gallic acid


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Cancer is probably the foremost cause of death throughout the entire world. It was reported to cause about 9.6 million deaths in 2018 alone [1]. Meanwhile, the treatment of cancer, irrespective of the mode employed is also a challenging feat. This ranges from the invasive nature of surgery to the damaging effect of ionizing radiation on tissues during the use of irradiation therapy; to the toxicity of chemotherapeutic agents that are used for cancer treatment. These effects have led to the development of novel and innovative concepts, such as the use of designer nanoparticles, liposomes, and other materials for direct delivery of drugs into cancerous tissues to prevent damage to healthy cells [2]. By nature however, most anticancer chemotherapeutic drugs are toxic to cells, affecting both cancerous and normal cells [3], including the rapidly dividing myeloid cells [4] immune cells in lymph nodes and other lymphoid tissues [5], and the GIT. Myelosuppression (with anaemia and panleucopenia) and GIT toxicity signs including anorexia, nausea, diarrhoea, and vomiting, are usually the early signs associated with toxicity of cancer therapy. Anaphylactic reactions, skin damage, cardiopulmonary pathologies, toxicity to the pancrease, nervous system, liver, and kidneys have been widely reported [6], [7].

In a bid to reduce the side effects of chemotherapy, clinicians and oncologists have embarked on combination therapy that includes antioxidants. Several studies have evaluated the role of antioxidants and medicinal plants with antioxidant potential on complications and side effects of anticancer drugs such as Methotrexate [8], Doxorubicin [9], [10], Cisplastin [11]. In a randomized study that evaluated the use of antioxidants therapy combined with anti-cancer drugs, it was reported that about 87% of cancer chemotherapy included one antioxidant or the other. This idea reportedly increased the efficacy of the anticancer drugs, reduced the side effects considerably, and improved the well being of affected individuals [7].

Vincristine is a vinca alkaloid synthesized from Japanese periwinkle (Vinca rosea). The vinca alkaloids generally bind to tubulin of mitotic spindle to halt cell division. Despite the popular use of vincristine in humans, leukemia in pediatric cancer patients, and transmissible venereal tumour (TVT) in dogs, there is paucity of information on the combination of vincristine with antioxidant therapy to reduce the side effects. Several antioxidants and medicinal plants with antioxidant properties have been used to ameliorate toxic effects of anticancer drugs. Notable among these antioxidants is gallic acid—a phenolic compound found in tea, especially green ones, grapes, red wine, and nuts. It can also be found as hydrolysable tannins in woody perennial plants generally [12].

However, there is paucity of information on the clinical combination of antioxidants in the use of Vincristine, especially when used in small animals. This paucity may be due to a lack of studies on the modulatory effects of antioxidants on Vincristine toxicity and side effects. This study was therefore tries to elucidate the role of the antioxidant gallic acid as it affects the toxic side effects of Vincristine Sulfate at its normal recommended therapeutic dosage.

Materials and Methods

Twenty adult male Wistar rats (130–150 g) were used in the study. The rats were housed under standard conditions of 12-hour daylight cycle and fed with normal rat chow, in the Experimental Animal Unit of the Department of Veterinary Physiology and Biochemistry, University of Ibadan. They also had access to clean potable water ad libitum. The rats were settled in, for two weeks and then divided into four groups A–D. Group A, which serve as the control was not exposed to Vincristine but given only water, group B and C were given a single weekly dose of Vincristine Sulfate at 0.025 mg/kg intraperitoneally once in a week for two weeks, while group B was given distilled water, group C was given 100 mg/kg gallic acid by gastric gavage daily for fourteen days. Group D on the other hands received only gallic acid (100 mg/kg) by gastric gavage daily for 14 days.

Determination of Blood Pressure

On day 14 of the study, diastolic and systolic blood pressure and mean arteria blood pressure were measured in awake rats by tail cuff plethysmography with automatic blood pressure monitor.

Electrocardiograph (ECG) Determination

The ECG was also measured in the rats using 7-lead EDAN VE-1010, ECG. From the results, heart rate, P-wave, QRS duration, PR-interval, amplitude for R, QT segment and Bazett’s correction of the QT interval (QTc) were evaluated.


At the conclusion of the experimentation, 5 ml of blood samples was collected from each rat using the retro-orbital venous plexus into tubes containing anticoagulant for determination of haematological parameters. Blood samples were spun at 4000 rev/min for 10 minutes and the plasma collected for plasma biochemistry. From the blood samples collected were determined, the packed cell volume (PCV) using the microhaematocrit method, haemoglobin concentration (Hb) by spectrophotometric method, red and white blood cell counts using the improved Neubauer’s slide while differential white blood cell count were determined in Giemsa stained slide. Erythrocytic indices–mean corpuscular haemoglobin (MCH), mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCH) were calculated using standard erythrocytic parameters above. Erythrocyte osmotic fragility was determined according to the method described by Azeez et al. [13], in varied phosphate-buffered sodium chloride concentrations.

Plasma Biochemistry

Sodium and potassium serum levels were determined using Flame Photometery while Cl- and HCO3- were measured according to the methods of Schales and Schales. Urea and creatinine were determined by spectrophotometery. Alkaline phosphatase (ALP) levels were measured by the method of Bessey while ALT and AST were determined by the method of Reitman and Frankel as previously described by Oyagbemi et al. [14]. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) were all measured by spectrophotometry using kits for Cobas Integra 400 plus Autoanalyzer.

Determination of Indicators of Oxidative Damage

The rats were thereafter sacrificed under ether anaesthesia whilst the kidney, liver, heart, testes and brain samples were harvested. The organs were quickly removed, cleaned in cold normal saline, blotted with filter paper and weighted for determination of the relative organ weight; then stored at −20 °C till the time of homogenization. At the time of homogenization, the organs were thawed, cut into bits and homogenized in twenty volumes of 0.1M phosphate buffer at pH 7.4 (PHD 710, New Jersey, US). The products were then centrifuged at 10,000 revolution per minute for 10 minutes with ultra centrifuge (80–2, Lemfield medical, UK) at −4 °C. The supernatant was decanted and used for determination of indictors of oxidative stress. From the homogenates of heart, liver, kidney, testes and brain tissues were determined, total protein by Biuret method, H2O2 generation, GSH and Superoxide dismutase (SOD) were determined as previously reported, see Oyagbemi et al. [14].

Statistical Analysis

Data are computed as mean and SD and compared with One-way ANOVA as well as Tukeys post-hoc test using GraphPad 9.00 (https://graphpad-prism.software.informer.com/2019). The Probability value <0.05 at 95% CI was taken to be significant.


Relative Organ Weights

The effects of vincristine treatment on the relative organ weight are shown in Table I. Relative organ weight progressively increased in the rats treated with vincristine. For example, relative weight observed for kidney, liver, liver heart, brain, and testes were slightly higher in group B that received vincristine only, though non significantly. However, group C rats that received vincristine and gallic acid had higher (P < 0.05) relative organ weight in the kidney, heart, and brain than the values in the control (A). It was also higher in the heart and brain (P < 0.05) than the values in those treated with gallic acid only (group D). The relative weight of these parenchymatous organs in group D was also similar to those of the untreated control.

Organ Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
Kidney (% bw) 0.47 ± 0.05a 0.61 ± 0.05 0.74 ± 0.13a 0.49 ± 0.13
Liver (% bw) 0.87 ± 0.13 1.23 ± 0.08 1.21 ± 0.18 0.79 ± 0.12
Heart (% bw) 0.21 ± 0.03 0.28 ± 0.03 0.31 ± 0.07a 0.19 ± 0.03a
Brain (% bw) 0.42 ± 0.11a 0.60 ± 0.12 0.72 ± 0.10ab 0.46 ± 0.02b
Testes (% bw) 0.64 ± 0.08 0.75 ± 0.36 1.07 ± 0.02 0.79 ± 0.12
Table I. Relative Organ Weight as Influenced by Vincristine Administration on Wistar Rats

Effects of Vincristine Administration on the Blood Pressure Parameters

Table II shows the blood pressure parameters of the Wistar rats following exposure to vincristine only or when combined with gallic acid therapy. The diastolic, systolic pressure as well as MAP pressure, and volume of blood flow in the cuff were elevated significantly (P < 0.05) in the vincristine only treated group (group B) than those of the untreated control (group B). The diastolic Bp, heart rate and blood volume were also elevated significantly (P < 0.05) in group B than the values observed in the group D rats that received only gallic acid. The heart rate in group C (vincristine + gallic acid) was also higher than that of group D significantly.

Blood pressure indices Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
Systolic BP (mm/Hg) 105.60 ± 8.67a 135.00 ± 16.95a 117.00 ± 13.01 112.42 ± 21.91
Diastolic BP (mm/Hg) 77.47 ± 9.47a 101.75 ± 10.83ab 81.21 ± 9.54 76.63 ± 14.82b
MAP (mm/Hg) 87.65 ± 10.01a 114.42 ± 18.99a 93.35 ± 9.82 88.26 ± 16.73
Rate (Beats/min) 360.00 ± 65.52a 422.50 ± 68.52b 355.75 ± 24.27c 167.83 ± 40.76abc
Flow rate 14.60 ± 7.48 25.52 ± 12.48 16.85 ± 7.11 9.61 ± 5.65
Blood volume 29.45 ± 13.64a 140.03 ± 39.51ab 58.91 ± 7.11 40.53 ± 12.57b
Table II. Blood Pressure Parameters of Wistar Rats Following Exposure to Vincristine Only and Combined with the Antioxidant, Gallic Acid

Effects of Vincristine on ECG Indices

As shown in Table III, the heart rate in the control that was not given any drug was lower significantly (P < 0.05) than that of group B, C or D. The P wave was lower in the vincristine treated groups (B and C), although non-significantly than the value in the untreated control while the QRS complex in the gallic acid only treated group was significantly lower (P < 0.5) than value seen in the control. It also showed marginal decrease when compared to the values obtained in groups B and C. The QTc value on the other hand was elevated in groups B and C, although only the QTc value in group C was more than those of either the control or even the gallic acid only treated groups.

ECG parameters Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
Heart rate 242.40 ± 11.59abc 290.00 ± 27.27a 300.20 ± 14.42b 303.00 ± 14.16c
P wave 29.60 ± 11.80 21.00 ± 4.85 21.60 ± 6.19 24.00 ± 5.79
PR 48.40 ± 7.47 49.25 ± 4.27 49.67 ± 6.42 52.00 ± 6.00
QRS 16.80 ± 1.64a 15.00 ± 1.41 15.60 ± 1.67 12.80 ± 1.64a
QT 50.60 ± 10.50 60.80 ± 12.81 66.20 ± 9.26 52.40 ± 8.62
QTc 101.40 ± 22.15a 141.75 ± 21.38 156.50 ± 13.30ab 122.25 ± 20.71b
QRS 77.50 ± 17.68 64.00 ± 14.66 48.25 ± 19.82 53.20 ± 10.52
Table III. ECG Parameters in Adult Male Wistar Rats that were Adminsitered Vincristine Only or Combined with the Antioxidant, Gallic Acid


The erythrocyte and leucocyte indices as influenced by vincristine administration are shown in Tables IV and V, respectively. In a manner consistent with the observations on the ECG and blood pressure parameters above, there was observed a decline in PCV and haemoglobin concentration values in the vincristine treated groups (groups B and C). Similarly, RBC was lower significantly in group B, (vincristine only) than the values obtained in the gallic acid treated (group D) and group C (vincristine + gallic acid). The RBC count in group D (gallic acid only-treated) rats was also higher than that of the unexposed control (group A). Furthermore, the corpuscular volume in group B was found to be significantly higher (P < 0.05) than those of groups A, C, and D while the MCH value in this group (B) was also higher than that of groups C and D. Meanwhile, the MCH in group A was higher than that of the gallic acid treated group while MCHC appears similar across the four groups.

Erythrocytic parameters Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
PCV (%) 45.80 ± 2.59 43.40 ± 1.14 43.8 ± 3.03 47.00 ± 3.39
RBC (x 106/μL) 5.07 ± 0.71a 4.18 ± 0.39bc 5.98 ± 0.70b 7.04 ± 0.70ac
Hb (g/dl) 14.32 ± 2.45 13.18 ± 1.40 12.32 ± 3.24 12.52 ± 1.70
MCV (fl) 80.18 ± 11.77a 100.06 ± 8.14abc 69.32 ± 6.85b 67.21 ± 7.17c
MCH (ρg) 28.64 ± 5.93a 31.77 ± 4.70bc 20.86 ± 6.19b 18.03 ± 3.62ac
MCHC (g/dl) 31.28 ± 5.10 30.44 ± 3.93 28.21 ± 7.41 26.76 ± 4.27
Table IV. Erythrocyte Parameters of the Adult Male Wistar Rats Following Exposure to Vincristine Only or Combined with the Antioxidant, Gallic Acid
Leucocytes Parameters Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
WBC (x 103/μL 16.16 ± 3.21ab 9.52 ± 2.26a 10.14 ± 2.16b 12.73 ± 2.36
Neutr (x 103/μL) (%) 5.62 ± 1.14ab (34.8 ± 3.11a) 2.16 ± 0.62a (22.6 ± 3.51a) 3.14 ± 0.91b (30.6 ± 2.41) 4.11 ± 1.87 (31.0 ± 9.7)
Lymph (x 103/μL) (%) 7.27 ± 1.29a (45.2 ± 2.28a) 6.19 ± 1.50 (65.2 ± 4.32abc) 4.74 ± 0.89a (47.2 ± 5.45b) 5.77 ± 0.77 (45.8 ± 3.96c)
Eosino (x 103/μL) (%) 0.64 ± 0.34 (4.0 ± 1.87) 0.29 ± 0.17a (3.0 ± 1.58a) 0.37 ± 0.09b (3.8 ± 1.30) 0.83 ± 0.31ab (6.6 ± 2.30a)
Mono (x 103/μL) (%) 2.37 ± 0.93a (14.2 ± 4.15) 0.76 ± 0.32a (7.8 ± 1.79a) 1.66 ± 0.56 (16.2 ± 3.96a) 1.79 ± 0.53 (14.8 ± 5.97)
Baso (x 103/μL) (%) 0.27 ± 0.18 (1.8 ± 1.48) 0.11 ± 0.08 (1.4 ± 1.14) 0.23 ± 0.11 (2.2 ± 0.83) 0.23 ± 0.13 (1.8 ± 0.83)
Table V. Leucocyte Parameters of the Adult Male Wistar Rats Following Exposure to Vincristine Alone or Combined with Gallic Acid

Looking at the leucocyte indices, there were generalized and considerable decreases (P < 0.05) in the WBC count, absolute and differential neutrophil, eosinophil, and monocyte counts when compared with the unexposed control (group A), while the differential lymphocyte count was more than the values in groups A, C and D. The total WBC, absolute neutrophil and lymphocyte counts in group C were lesser in values (P < 0.05) than in the control. However, the absolute eosinophil count in group C was lower than eosinophil count observed in group D rats. The erythrocyte osmotic fragility, Fig. 1 on the other hand did not show any serious variation across the group when placed beside the vincristine treated or the control groups.

Fig. 1. Erythrocyte osmotic fragility of adult male wistar rats following exposure to vincristine treatment only or combined with the antioxidant, gallic acid. Each point is the mean and vertical bars, S.D. Number of animals is 5 per group.

Plasma electrolytes Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
Na+ (mmol/L) 139.6 ± 1.14 136.4 ± 2.30 139.2 ± 1.92 140.33 ± 0.58
K+ (mmol/L) 3.94 ± 0.19 3.70 ± 0.24 4.04 ± 0.15 3.97 ± 0.42
Cl- (mmol/L) 107.00 ± 2.74 96.00 ± 2.74 107.20 ± 2.73 106.66 ± 5.77
HCO3- (mmol/L) 31.60 ± 1.34 24.00 ± 1.58 22.60 ± 2.07 21.66 ± 1.53
Table VI. Plasma Electrolytes of the Wistar Rats After Exposure to Vincristine Only or Combined with the Antioxidant, Gallic Acid
Plasma protein and metabolites Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
Total protein (g/dl) 6.88 ± 0.22 6.36 ± 0.23 7.04 ± 0.23 7.10 ± 0.20
Albumin (g/dl) 3.78 ± 0.25 3.58 ± 0.29 4.06 ± 0.11 4.06 ± 0.11
Globulin (g/dl) 3.1 ± 0.17 2.73 ± 0.32 3.03 ± 0.15 3.03 ± 0.12
Urea (mg/dl) 28.4 ± 2.41 23.8 ± 1.92 28.6 ± 3.05 29.67 ± 2.08
Creatinine (mg/dl) 0.66 ± 0.05 0.54 ± 0.05 0.70 ± 0.07 0.73 ± 0.06
Total Bilirubin (mg/dl) 0.54 ± 0.18 0.64 ± 0.23 0.58 ± 0.28 0.53 ± 0.21
Conjugated Bilirubin (mg/dl) 0.30 ± 0.12 0.36 ± 0.17 0.32 ± 0.08 0.23 ± 0.06
Table VII. Plasma Protein and Metabolites of the Wistar Rats After Exposure to Vincristine Only or Combination with the Antioxidant, Gallic Acid

Plasma Biochemistry

The plasma biochemical parameters consisting of plasma electrolytes, protein and metabolites, liver enzymes, and lipid profiles are shown in Table IX. Although many of the parameters did not show statistically significant variations, the marginal variations observed must be mentioned because of their clinical significance. For example, there was consistently lower sodium, potassium, chloride and bicarbonate values in group B, which was corrected in group C and D except plasma bicarbonate ion. Similar trend can also be observed in the total protein, albumin, globulin, urea or creatinine values whereas, total and conjugated bilirubin was slightly higher. Meanwhile, the liver ALT and GGT were slightly elevated in group B than were the control, group C and D, although non-significantly. But the plasma ALP was higher in the vincristine only treated group (P < 0.05) than the values from the control, group C and D (Table VIII). Meanwhile, lipid profile appeared relatively similar across the groups (Table IX).

Liver enzymes Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
AST (IU/L) 15.2 ± 2.05 14.4 ± 3.13 15.2 ± 4.43 13.33 ± 1.53
ALT (IU/L) 11.4 ± 1.67 14.2 ± 2.49 11.8 ± 3.03 9.66 ± 0.57
GGT (IU/L) 8.4 ± 1.81 12.6 ± 2.70abc 8.2 ± 2.77 6.00 ± 2.00
ALP (IU/L) 39.2 ± 8.92a 44.8 ± 0.52abc 37.00 ± 9.97b 38.00 ± 7.00c
Table VIII. Liver Enzymes Rats After Exposure to Vincristine Only or Combined With the Antioxidant, Gallic Acid
Lipid profiles Group A (Control) Group B (Vincristine only) Group C (Vincristine + Gallic acid) Group D (Gallic acid only)
Total Cholesterol (mg/dl) 161.8 ± 11.69 161.4 ± 20.33 160.4 ± 12.62 155.33 ± 6.51
Triglyceride (mg/dl) 62.8 ± 12.23 60.4 ± 23.31 66.00 ± 14.37 60.67 ± 7.51
HDL (mg/dl) 43.4 ± 4.03 41.00 ± 10.95 41.60 ± 5.55 41.67 ± 5.13
LDL (mg/dl) 129.40 ± 12.74 124.80 ± 26.43 126.8 ± 13.94 123.33 ± 8.02
Table IX. Lipid Profile of Adult Male Wistar Rats After Exposure to Vincristine Only and in Combination with Gallic Acid

Markers of Oxidative Stress

The impacts of vincristine administration on the indicators of oxidative stress, vis a vis hydrogen peroxide generation (H2O2), glutathione (GSH), total protein, and superoxide dismutase (SOD) in post mitochondrial fractions in the liver, kidney, heart, testes and brain samples were also investigated, as shown in Figs. 25, in that order. As shown in Fig. 2, the total protein and GSH values were depleted in group B (vincristine only), while H2O2 was elevated, but the parameters were restored to normal values in group C and D, although the decreases were not statistically significant. A similar reduction was also observed in the SOD value in group B, but the values were not restored to the observed SOD value in the normal untreated control.

Fig. 2. Oxidative stress markers from post mitochondrial fraction in the kidney of adult male Wistar rats following exposure to Vincristine only or combined with the antioxidant, gallic acid. Values are shown as means; error bars indicate the standard deviation. Number of animals is 5 per group.

Fig. 3. Oxidative stress markers from post mitochondrial fraction in the liver of adult male Wistar rats following exposure to Vincristine only or combined with the antioxidant, gallic acid. Values are shown as means; error bars indicate the standard deviation. Number of animals is 5 in each group. Values with connected lines are significantly different @ P < 0.01.

Fig. 4. Oxidative stress markers from post mitochondrial fraction in the heart of adult male Wistar rats following exposure to Vincristine only or combined with the antioxidant, gallic acid. Values are shown as means; error bars indicate the standard deviation. Number of animals is 5 in each group. Values with connected lines are significantly different @ P < 0.01.

Fig. 5. Oxidative stress markers from post mitochondrial fraction in the brain of adult male Wistar rats following exposure to Vincristine only or in combination with antioxidant, gallic acid. Values are shown as means while error bar indicates the standard deviation. Except otherwise stated, number of animals is 5 per group.

In the liver samples, the GSH values in the vincristine treated groups B and C were lower significantly (P < 0.05) than the values unexposed group A, despite the treatment of the rats in group C with gallic acid. The GSH value in gallic acid only treated group (group D) was also lower (P < 0.05) than the values obtained in the control. The quantity of H2O2 generated in the liver of the vincristine only treated also followed the pattern observed in the kidney. There was an elevation of H2O2 in this group but the values in group C and D were similar to that of the control. As observed for GSH, the SOD was depleted in group B while group C and D showed slight elevations (See Fig. 3). A clearer picture of the effects of vincristine administration was observed in the heart, see Fig. 4. We also saw considerably significant decreases in the GSH and total protein while H2O2 was significantly elevated in group B when placed side by side with the control (GSH and H2O2) as well as the other groups C and D (H2O2). Whereas, the SOD value was only slightly reduced in the vincristine treated groups. The testes on the other had depleted total protein in group C (vincristine + gallic acid) while the other parameters, H2O2, GSH and SOD followed the pattern observed in the kidney, liver and heart, although non significantly. Finally, the indicators of oxidative stress evaluated in the brain did not follow the pattern observed in the other organs (Fig. 5). For example, SOD and GSH values were elevated in groups B and C but total protein did not show any observable difference, whereas the H2O2 was slightly elevated in the vincristine only treated group (B).


Cancer chemotherapy as promising as it is, is bedeviled by complications associated with its cytotoxicity, not only to the cancerous cells but also to other cells, especially rapidly dividing myeloid cells, lymphoid tissue and cells in the GIT. Thus leading to significant complications that could hamper survival of the affected patients [6]. These anticancer drugs are mostly nonselective because they kill both rapidly dividing neoplastic tissues and those of the host. They also have low therapeutic index. A general reflection of this observation was observed in the current study on the toxic side effects of Vincristine Sulfate at normal recommended therapeutic dosage utilized in this study.

Relative Organ Weight

A generalized increase in the relative organ weight was observed in all the parenchymatous organs—kidney, liver, heart, testes, and brain that were evaluated as a result of Vincristine administration. This observed increase in relative organ weight appears to be an inflammatory response. Inflammation may have resulted in cellular infiltration as a result of the toxic effect of vincristine, in the form of acute phase reaction to tissue damage [15]. In the presence of destructive endogenous and exogenous stimuli, the body produces several cytokines and other chemokines induced by inflammatory responses, some of which include cortisol, bradykinin, prostaglandin, etc. This is closely followed by mobilization and activation of inflammatory cells like macrophages, mast cells, and neutrophils which will also promote the acute phase reaction at the site. Because inflammatory response is a critical side effect of cancer therapy, it is a common and necessary practice to incorporate drugs with anti-inflammatory effects and opioids as an adjunct to cancer chemotherapy [16].

Cardiovascular Functions

In this study, we observed a slightly elevated QT interval while the corrected QT (QTc) was significantly higher in vincristine treated groups. Generally, by way of definition, the QT interval in an ECG is the time between depolarization of the ventricular muscle denoted as “QRS complex” and its repolarization or “T wave”. When QT is prolonged, it is a key risk factor in the pathogenesis Torsades de Pointes—a potentially deadly cardiac dysarrhythmia [17]. Wedam et al. [18] had earlier reported that prolongation of QT interval might be an indicator of cardiac toxicity from xenobiotics or an undiscovered cardiac problem or disease. Since apparently healthy rats were used for the study, these observed changes in the QT interval and QTc must have resulted from the vincristine administration.

Meanwhile, the blood pressure result also showed that there was a significantly higher blood pressure in the rats treated with vincristine only. These parameters were however corrected in the rats administered with gallic acid. The heart rate and the blood volume that traverse the cusp were also higher in this group. This shows that administration of vincristine in cancer therapy has the potential to cause hypertension and cardiac toxicity. Although the most common side effect of Vincristine is peripheral neuropathy [19], we can see the potential cardiac effects of the drug in the present study. However, drug induced hypertension is a common side effect of many anti cancer drugs, but hypertension in vincristine is not a prominent observation [20] unlike the one observed in the present study.


Vincristine administration in rats in the present study to macrocytic normochromic anaemia when compared with untreated control. It also resulted in panleucopenia, in rats with significant neutropenia, eosinopenia, and monocytopenia being very prominent. However, percentage of differential lymphocytes appears higher, that is more lymphocytes were produced than neutrophils in the exposed rats. No significant changes were however noticed in the erythrocyte osmotic fragility in this study. These complications were however corrected in the rats treated with gallic acid. Our observations agree with previously documented effects of vincristine as a result of myelosuppression and disruption of rapidly dividing cells [21], [22] Vincristine acts by binding to tubulin in the mitotic spindle to prevent cell division during metaphase. It has been reported to be active in the G2 and M phases of the cell cycle, causing depolymerization of microtubules. Vincristine binding to spindle proteins also disrupts the formation of the mitotic spindle, thereby preventing alignment and segregation of chromosomes during anaphase. This singular action prevents tumour cell development during metaphase [21]. Vincristine is also known to disrupt nucleic acid and protein synthesis through prevention of the use of glutamic acid [22]. The side effect of all these activities is that the binding of vincristine to mitotic spindles and blockage of protein synthesis is not specific to tumour cells only. As stated by Fuchs-Tarlovsky [23], the haematological toxicity of antimitotic drugs generally shows in the form of leucopenia and thrombocytopenia. In fact, accumulation of these drugs in the bone marrow usually leads to destruction of myeloid cells to prevent their division and maturation. Anaemia, general myelosuppression, and neutropenia have also been widely reported in vincristine therapy in dogs [24]. Pancytopenia and desquamation of rapidly dividing cells in the GIT usually lead to death as a result of invasion of bacteria through the GIT and life threatening septicaemia following granulocytopenia in affected patients unless the patient is treated appropriately.

Gallic acid reversal of anaemia and panleucopenia in the present study, being an antioxidant has also laid credence to the oxidative effects of vincristine. Although some authors have reported that vincristine causes oxidative stress [22] its activities have been limited to its antimitotic effects mentioned earlier. Our findings as we shall soon discover also showed that vincristine administration results in significant oxidative stress, which was corrected in the rats treated with the antioxidant—gallic acid. Gallic acid is a 3,4,5-trihydroxybenzoic acid, a polyphenol widely found in nuts, green tea, hops, grapes, red wine etc. It can be said that gallic acid is one of the main plant derived phenolic compounds. Gallic has been reported to show several pharmacological properties, including antioxidant and anti-inflammatory effects, through decreased expression of cytokines and anticancer effects [8].

Plasma Biochemistry

We also evaluated the effects of vincristine administration on plasma electrolytes, plasma protein and metabolites, liver enzyme, and lipid profile in the Wistar rats. However, besides mild reduction in the electrolytes—sodium, potassium, and bicarbonate ions; total protein, globulin, urea, and creatinine, only the enzyme GGT and ALP showed some degree of elevation in the vincristine treated rats. Although many of these parameters did not show statistical significance, they are important clinically as early pointers of hepatic damage and kidney dysfunction. Because anticancer drugs follow the first-order kinetics [6] they show considerable toxic effects on the liver [25] and kidneys [26] which were corrected by antioxidants co-administration as observed in those rats administered with gallic acid in the present study. Non-catalytic enzymes such as ALT and AST, localized within the cells of numerous organs, including the liver act as a significant indicator for evaluation of kidney and liver status and tissue injury or organ dysfunction [27]. Damage to the liver kidney and other parenchymatous organs by vincristine and other anti cancer drugs have been linked to their ability to produce oxidative stress and mediators of inflammation [22].

Oxidative Stress

Vincristine administration resulted in oxidative stress as seen in elevated H2O2 generation while GSH, SOD, and total protein values were depleted in the vincristine only group. These anomalies were however corrected with concurrent administration of gallic acid. Gallic acid demonstrated its reported effects as are free radical scavengers, reducing lipid peroxidation [28]. It could also potentiate the activities of other endogenous antioxidant agents such as SOD, CAT, endothelial nitric oxide synthase and prostaglandin E2 through reduction of the expression of pro-inflammatory mediators like TNFα and inducible nitric oxide synthase, up-regulation of the pro-angiogenesis factors and inhibition of caspase-3 and 9 [29]. Some other authors have also reported that gallic acid disrupts intra-cellular inflammatory pathways by inhibiting the expression of nuclear transcription factors such as NFκB, STAT3, cyclooxygenase (COX)-2, and also prevent neutrophils infiltration during inflammation [30]. In some of the studies in our laboratory, gallic acid has been observed to ameliorate the hepatotoxic effects of xenobiotics by acting as an antioxidant compound that scavenges free radicals and ROS, and improve in rats [31].

Thus, we can conveniently infer from our findings and previous studies that the modulatory activities gallic acid in the present study were due to its antioxidant and anti-inflammatory activities. A similar thing can be said concerning the cardiac anomalies in the form of hypertension and prolonged QT interval and corrected QT (QTc), because gallic acid has also been observed to decrease the harmful oxidative consequences of myocardial infarction in the context of its antioxidant potency, either by increasing the activity of antioxidant enzymes, or by potentiation of the activities of non-enzymatic antioxidant agents including GSH [31]. All the aforementioned effects of gallic acid have the propensity to ameliorate the damage associated with vincristine and toxic side effects free radicals and ROS in several sites including parenchymatous organs and bone marrow [32] as observed in this study.


The study shows that vincristine administration causes macrocytic normochromic anaemia, granulocytopenia, especially neutropenia, cardiac dysfunction via hypertension, and prolonged QT interval. This may not be unconnected to its ability to induce oxidative stress via generation of hydroxyl radical and depletion of endogenous antioxidant enzymes. These complications of vincristine were however corrected by co-administration of gallic acid. It can therefore be suggested that concurrent antioxidants therapy, especially gallic acid, combined with vincristine in the treatment of cancer will significantly reduce or totally eliminate its undesirable side effects.


  1. Tan BL, Norhaizan ME. Curcumin combination chemotherapy: the implication and efficacy in cancer. Molecules. 2019;24(14):2527.
    DOI  |   Google Scholar
  2. Navya P, Kaphle A, Srinivas S, Bhargava SK, Rotello VM, Daima HK. Current trends and challenges in cancer management and therapy using designer nanomaterials. Nano Convergence.2019; 6(1):1–30.
    DOI  |   Google Scholar
  3. Naidu MUR, Ramana GV, Rani PU, Suman A, Roy P. Chemotherapy-induced and/or radiation therapy-induced oral mucositis-complicating the treatment of cancer. Neoplasia. 2004;6(5):423–31.
    DOI  |   Google Scholar
  4. May JE, Donaldson C, Gynn L, Morse HR. Chemotherapyinduced genotoxic damage to bone marrow cells: long-term implications. Mutagenesis. 2018;33(3):241–51.
    DOI  |   Google Scholar
  5. Makker PG, Duffy SS, Lees JG, PereraCJ, TonkinRS, Butovsky O, et al. Characterisation of immune and neuroinflammatory changes associated with chemotherapy-induced peripheral neuropathy. PloS One. 2017;12(1):e0170814.
    DOI  |   Google Scholar
  6. CoutoCG. Management of complications of cancer chemotherapy. Vet Clin North Am Small Anim Pract. 1990;20(4):1037–53.
    DOI  |   Google Scholar
  7. Singh K, Bhori M, Kasu YA, Bhat G, Marar T. Antioxidants as precision weapons in war against cancer chemotherapy induced toxicity–exploring the armoury of obscurity. Saudi Pharm J. 2018;26(2):177–90.
    DOI  |   Google Scholar
  8. Safaei F, Mehrzadi S, Khadem Haghighian H, Hosseinzadeh A, Nesari A, Dolatshahi M, et al. Protective effects of gallic acid against methotrexate-induced toxicity in rats. Acta Chir Belg. 2017:118(3):152–60.
    DOI  |   Google Scholar
  9. Davies O, Azeez O. Modulatory effects of guava extract on Adriamycin (Doxorubicin) induced toxicity in Wistar Rats. Glob Vet. 2016;16:31–6.
     Google Scholar
  10. Omobowale TO, Oyagbemi AA, Ajufo UE, Adejumobi OA, Ola-Davies OE, Adedapo AA, et al. Ameliorative effect of gallic acid in doxorubicin-induced hepatotoxicity inWistar Rats through antioxidant defense system. J Diet Suppl. 2017;15(2):183–96.
    DOI  |   Google Scholar
  11. Kim YH, Choi BK, Kim KH, Kang SW, Kwon BS. Combination therapy with cisplatin and anti-4-1BB: synergistic anticancer effects and amelioration of cisplatin-induced nephrotoxicity. Cancer Res. 2008;68(18):7264–9.
    DOI  |   Google Scholar
  12. Ow YY, Stupans I. Gallic acid and gallic acid derivatives: effects on drug metabolizing enzymes. Curr Drug Metab. 2003;4(3):241–8.
    DOI  |   Google Scholar
  13. Azeez O, Olayemi F, Olanrewaju J. Age and sex influences on the haematology and erythrocyte osmotic fragility of the nigerian turkey. Res J Vet Sci. 2011;201:1.
    DOI  |   Google Scholar
  14. Oyagbemi, Adetokunbo A, Omobowale TO, Akinrinde AS, Saba AB, Ogunpolu BS, et al. Lack of reversal of oxidative damage in renal tissues of lead acetate-treated rats. Environ Toxicol. 2015;30(11):1235–43.
    DOI  |   Google Scholar
  15. Slaviero KA, Clarke SJ, Rivory LP. Inflammatory response: an unrecognised source of variability in the pharmacokinetics and pharmacodynamics of cancer chemotherapy. The Lancet Oncology. 2003;4(4):224–32.
    DOI  |   Google Scholar
  16. Constance JE, Campbell SC, Somani AA, Yellepeddi V, Owens KH, Sherwin CM. Pharmacokinetics, pharmacodynamics and pharmacogenetics associated with nonsteroidal anti-inflammatory drugs and opioids in pediatric cancer patients. Expert Opin Drug Met. 2017;13(7):715–24.
    DOI  |   Google Scholar
  17. Denny JC, Miller RA, Waitman LR, Arrieta MA, Peterson JF. Identifying QT prolongation from ECG impressions using a general-purpose Natural Language Processor. Int J Med Inform. 2009;78 Suppl 1(Suppl 1):S34–S42.
    DOI  |   Google Scholar
  18. Wedam EF, Bigelow GE, Johnson RE, Nuzzo PA, Haigney MC. QT-interval effects of methadone, levomethadyl, and buprenorphine in a randomized trial. Arch Intern Med. 2007;167(22):2469–75.
    DOI  |   Google Scholar
  19. Yardim A, Kandemir FM, Ozdemir S, Kucukler S, Comakli S, Gur C, et al. Quercetin provides protection against the peripheral nerve damage caused by vincristine in rats by suppressing caspase 3, NF-κB, ATF-6 pathways and activating Nrf2, Akt pathways. Neurotoxicology. 2020;81:137–46.
    DOI  |   Google Scholar
  20. Essa H, Dobson R,Wright D, Lip GY. Hypertension management in cardio-oncology. J Hum Hypertens. 2020;34(10):673–81.
    DOI  |   Google Scholar
  21. Weber GF. Drugs that Suppress Proliferation’,Molecular Therapies of Cancer. Springer, Switzerland; 2015. 113-162.
    DOI  |   Google Scholar
  22. Martino E, Casamassima G, Castiglione S, Cellupica E, Pantalone S, Papagni F, et al. Vinca alkaloids and analogues as anti-cancer agents: looking back, peering ahead. Bioorg Med Chem Lett. 2018;28(17):2816–26.
    DOI  |   Google Scholar
  23. Fuchs-Tarlovsky V. Role of antioxidants in cancer therapy. Nutrition. 2013;29(1):15–21.
    DOI  |   Google Scholar
  24. Northrup NC, Rassnick KM, Snyder LA, Stone MS, Kristal O, Cotter SM, et al. Neutropenia associated with vincristine and lasparaginase induction chemotherapy for canine lymphoma. J Vet Intern Med. 2002;16(5):570–5.
    DOI  |   Google Scholar
  25. Harchegani AB, Khor A, Niha MM, Kaboutaraki HB, Shirvani H, Shahriary A. The hepatoprotective and antioxidative effect of saffron stigma alcoholic extract against vincristine sulfate induced toxicity in rats. Interdiscip Toxicol. 2019;12(4):186–91.
     Google Scholar
  26. Beigi Harchegani A, Sohrabiyan M, Bakhtiari Kaboutaraki H, Shirvani H, Shahriary A. The protective effects of saffron stigma alcoholic extract against vincristine sulfate drug-induced renal toxicity in rat. Iran J Pharm Sci. 2019;15(4):83–94.
    DOI  |   Google Scholar
  27. Monfared L, Ali, Tootian Z, Fazelipour S. Study of anatomical, histological and biochemical changes of liver in the mice exposed to phenol. Med Sci J Islam Azad Univ-TehranMed Branch. 2013;22(4):266–72.
     Google Scholar
  28. Kahkeshani N, Farzaei F, Fotouhi M, Alavi SS, Bahramsoltani R, Naseri R, et al. Pharmacological effects of gallic acid in health and diseases: a mechanistic review. Iran J Basic Med Sci. 2019;22(3):225.
     Google Scholar
  29. Mard SA, Mojadami S, Farbood Y, Naseri MKG. The antiinflammatory and anti-apoptotic effects of gallic acid against mucosal inflammation-and erosions-induced by gastric ischemiareperfusion in rats. In: Veterinary Research Forum: Faculty of Veterinary Medicine. Urmia, Iran: Urmia University. 305.
     Google Scholar
  30. Pandurangan AK, Mohebali N, Norhaizan ME, Looi CY. Gallic acid attenuates dextran sulfate sodium-induced experimental colitis in BALB/c mice. Drug Des Devel Ther. 2015;9:3923.
    DOI  |   Google Scholar
  31. Oyagbemi AA, Omobowale OT, Asenuga ER, Akinleye AS, OgunsanwoRO, Saba AB. Cyclophosphamide-induced hepatotoxicity in wistar rats: the modulatory role of gallic acid as a hepatoprotective and chemopreventive phytochemical. Int J Prev Med. 2016;7(51):1–8.
    DOI  |   Google Scholar
  32. Priscilla DH, Prince PSM. Cardioprotective effect of gallic acid on cardiac troponin-T, cardiac marker enzymes, lipid peroxidation products and antioxidants in experimentally induced myocardial infarction inWistar rats. Chem-BIOL Interact. 2009;179(2–3):118–24.
    DOI  |   Google Scholar