Assessment of Adaptogenic Potential of Tecoma stans

Introduction

Stress is a sensation of emotional and physical tension everyone experiences. When emotional and physical tension becomes extreme, it harms the body and must therefore be cured. The excitement and physical stress are involved in the pathogenesis of various diseases including ulcer, hypertension, immunodepression, reproductive problems and behavioral problems.¹ Evidence indicates that pressure impairs mastering and memory and encounters several disorders including anxiety and depression.² A drug with anti-stress properties stimulates nonspecific resistance to stressful conditions.

The experiential use of plant-based drugs has been far and wide used traditionally to cure wide range of diseases. Over the decades, awareness in substitute therapies has increased extensively worldwide.³ Drugs obtained from natural plant sources are promising as alternative remedies in the psychiatric treatment.⁴ Medicinal plants from the natural origin plays a very significant role in the novel pharmacotherapy to treat psychiatric disorders. Medicinal plants are always a classical source of medicines and many available medicines have been derived indirectly/directly from them.⁵

Drugs such as benzodiazepines, caffeine, amphetamines and anabolic steroids are classically used by people to relieve anxiety and tension. The incidence of toxicity and addiction has restricted the therapeutic utility of these drugs.⁶ Alternative drugs are obviously necessary because of the incapability of the modern therapies to control disease condition. The initial medications used to treat pathologic conditions of the CNS were based on innate resources.⁷ People from diverse areas of world used herbal remedies to alleviate affective disorders.⁸ The herbal preparations claiming to develop physical endurance, mental functions and nonspecific resistance in the body are called adaptogens.⁹ They are using a variety of plants in complementary and alternative medicines to manage stress. It is reported that the possible use of herbal medicines as anti-stress agents is safer and cheaper, since stress can survive without changing the physiological functions of the body.

Tecoma stans Linn is an erect shrub found in India, belonging to the family Bignoniaceae. The   shrub has some common names in different native Indian languages. Tecoma stans Linn, is commonly recognized as yellow bells, old yellow, trumpet flower in English and piliya in Hindi. Tecoma stans Linn is an important medicinal plant. It is reported to exhibit anticancer,¹⁰ antioxidant and antimicrobial,¹¹ anti-proliferative¹² properties. Tecoma stans is usually planted as an ornamental plant in warmer climates around the world because of its yellow bells and pinnate foliage.¹³

In the traditional therapeutic method, different parts of Tecoma stans have been mentioned to be helpful in a variety of diseases. All parts of the plants contain more amount of alkaloids called tecomine and tecostamine.¹⁴ However, anti-stress (Adaptogenic) activity of flowers of Tecoma stans has not been scientifically validated to date. Therefore, the investigation of extract of Tecoma stans flowers was undertaken in experimental animals.

Material and Methods

Plant material

The flower of Tecoma stans was identified and authenticated by Mrs. Gangambika Biradar, Professor & HOD, Dept. of Botany, S.B Arts & KCP Science College, Vijayapur, Karnataka. Then sufficient amounts of Tecoma stans flowers were collected from the gardens of Vijayapur city in the month of September.

Flower extract

The flowers were dried in shade at room temperature, made a course powder and then extracted with methanol by Soxhlet’s extraction process. The yield of the methanol extract of Tecoma stans flowers (METSF) was 20.8%. Further the crude extract was preserved in air tight vessel in fridge for further studies.

Phytochemical analysis

Phytochemical analysis of crude extract was carried out for the determination of phytoconstituents by reported methods in the literature.¹⁵

Acute toxicity study (LD50)

Acute toxicity study of Tecoma stans flowers extract was carried out on female albino mice weighing 20- 30 g. The mice were not given food overnight prior to the experiment. Guideline No.423 of Organisation for Economic Co-operation Development (OECD) was adapted for acute toxicity studies. 1/20^th, 1/10^th and 1/5^th (125, 250 and 500 mg) LD₅₀ cut of value of the extract were selected as screening doses for the adaptogenic activity.¹⁶

Anoxia Stress Tolerance Test¹⁷

Albino mice 20-30 g of both the sexes were chosen and segregated into five different groups (G) of six each.

G 1 - Vehicle control, administered vehicle only

G 2 - Received standard drug (Withania somnifera 100 mg/kg)

G 3 -  Received 125 mg/kg of METSF G 4   - Received 250 mg/kg of METSF G 5 - Received 500 mg/kg of METSF.

The animals were administered vehicle, standard and different doses of test extract for three weeks orally. On 1^st, 2^nd and 3^rd week i.e. on 7^th, 14^th, and 21^st day, 1 hour after the standard drug and test extract administration, individually each mouse was placed in the airtight container of 300 mL capacity to induce stress in all the groups of animals to record anoxia stress tolerance time. The animals that showed the first convulsions were taken out immediately from the container. The time period of mouse entry into the airtight container and the occurrence of the first convulsions were recorded as anoxic stress tolerance time.

Swimming Tolerance Test

The Swiss albino mice 20-30 g of both sex were divided into five groups containing six mice each.

G 1 -    Vehicle control, administered vehicle only

G 2 -    Received standard drug (Withania somnifera 100 mg/kg, p.o.)

G 3 -   Received 125 mg/kg of METSF G 4 - Received 250 mg/kg of METSF G 5 - Received 500 mg/kg of METSF

The administration of vehicle, standard and different doses of test extract was done to mice for seven days orally. On the seventh day, 1 hour after the treatment, all the mice (excluding G 1) were placed one by one in the swimming tank to swim. The termination point was taken when the mouse remained at the bottom of water tank for 10 sec. The mean swimming time for each group was calculated.

Immobilization Stress Method¹⁸

Male albino rats of 150-200 g were chosen and divided

into six groups (G) containing six animals each

G 1 - Normal control, no treatment

G 2 - Stress control, administered vehicle only

G 3 - Standard, received Withania somnifera 100 mg/ kg p.o.

G 4   -    Received 125 mg/kg of METSF G 5 - Received 250 mg/kg of METSF G 6 - Received 500 mg/kg of METSF

One hour before the exposure of stress, the treatment was continued for ten days. The rats were immobilized by keeping head down in a supine position (angle 60⁰) two hours daily for ten days. On the last day, rats were euthanized for the collection of blood for the determination of serum cholesterol, glucose, triglycerides and blood, urea, nitrogen (BUN). Glands like spleen, liver and adrenal glands were isolated and their weight was recorded.

Statistical analysis

The results obtained from the study were expressed in mean ± Standard Error of Mean (SEM). All data were subjected to One way ANOVA test followed by Dunnet’s multiple comparison tests by using Prism Pad 8 software.

Results

Analysis of phytochemicals

The phytochemical investigation of methanol extract of Tecoma stans flowers exhibited the presence of flavonoids, tannins, alkaloids and carbohydrates.

Acute toxicity study

The METSF was studied in female albino mice at dose 2000 mg/kg (i.p.). The METSF did not cause any mortality of the mice at dose 2000 mg/kg, even after repeated dose. Hence, 2500 mg/kg was taken as LD₅₀ cutoff value. The different doses chosen for the adaptogenic activity were:

125 mg/kg - 1/20^th of 2500 mg/kg b.w. 250 mg/kg - 1/10^th of 2500 mg/kg b.w. 500 mg/kg - 1/5^th of 2500 mg/kg b.w.

Effect of METSF in Anoxia Stress Tolerance Test

The different doses of the METSF exhibited significant adaptogenic activities on first, second and third weeks compared to diseased animals. The outcomes are presented in Table 1.

Effect of METSF in Swimming Tolerance Test

The dose dependent escalation in swimming performance time was identified in METSF treated groups. The results are summarized in Table 2.

Effect of METSF in Immobilization Stress Method

On biochemical parameters

There was a significant elevated level of serum glucose, triglycerides, cholesterol and BUN in stress control rats compared to normal controls. Rats pretreated with METSF for ten days at various doses exhibited dose reliant fall in serum cholesterol, glucose, triglycerides, and BUN as compared to the stress control rats. However, the reduction in various biochemical parameters such as glucose, cholesterol and triglyceride at dose of 125 mg/ kg monitored in METSF were found to be statistically not significant. The results are displayed in Table 3.

On weight of organs

The immobilization stress caused increase in weights of the liver and adrenal glands while there was decrease in weight of spleen in stress control rats as compared to normal control rats. The pretreatment with graded doses of METSF for ten days significantly reversed the immobilization stress induced altered organs weight. The observations are represented in Table 4.

Discussion

In the current research work, the adaptogenic activity of METSF was evaluated against Anoxia stress tolerance test, Swimming tolerance test and Immobilization stress method in experimental animals. The body functions containing cellular respiration depends on oxygen supply to them. Any deficiency of this vital element plays a major role on all the body mechanisms. Increase in adaptation during anoxic stress by any drug could be considered as its major anti- stress effect.^19,20 The results obtained on treatment with METSF exhibited significantly delayed latency of post anoxic convulsions in mice in the anoxia stress tolerance test, thereby demonstrating its adaptogenic activity.

Swimming tolerance test has been used to explore the anti-stress (adaptogenic) activity of different agents, based on the fact that swim endurance reflects physical endurance.²¹ In the present study, the results of swimming tolerance test evidently indicate that METSF exhibited anti-stress property by increasing the physical endurance as well as the overall performance in mice.

In Immobilization stress method, the rats exposed to stress exhibits hyperglycemia because in stressful situations, adrenal cortex secretes more cortisol.²² This increased secretion of cortisol maintains the internal homeostasis through the process of gluconeogenesis and lipogenesis.²³ The results of the present investigation revealed the promising effect of METSF in decreasing the increased levels of blood glucose representing the capability to prevent the alterations on adrenal cortex and helping in maintenance of homeostasis.

Stress causes over activation of hypothalamo- hypophyseal axis (HPA), which in turn rises cholesterol which is linked to the excessive release of catecholamines. These catacholamines are also responsible for increased levels of glucose and BUN.^24-26 In the present study, METSF significantly decreased the elevated levels of these serum biochemical parameters in dose dependant manner in immobilization stress model.

Stress related increase in serum cholesterol is likely to be related to the increased activity of hypothalamo- hypophyseal axis (HPA) ensuing in discharge of catecholamines and corticosteroids. This results in increase in levels of blood cholesterol, since epinephrine is known to mobilise lipids from adipose tissues. The effect of stress on serum triglycerides has been shown to be variable. The increase in discharge of catecholamines leads to high levels of glucose and BUN.^24-26 In the present study, METSF significantly decreased the elevated levels of these serum biochemical parameters in a dose dependent manner in immobilization stress model.

Stress induces adreno-medullary response in man. Adrenaline in turn excites Beta 2 receptors on the pituitary glands initiating greater release of adrenocorticotropic hormone (ACTH), which can stimulate the adrenal medulla as well as cortex that results in proliferation in the weight of adrenal glands. Cortisol increases mRNA levels in liver cells resulting in increase in weight of liver. During stress, spleen gets constricted to release more red blood cells (RBC), as a result weight of spleen also decreases.^27-28 This stress mediated changes of organs weight were significantly reversed in a dose dependent manner and thus claims the adaptogenic effect of METSF against immobilization stress model.

Earlier researchers published that the extracts of medicinal plants containing flavonoids and tannins are known to exhibit significant anti-stress activity.²⁹ Even in the present study, flavonoid and tannin contents of methanolic extract of Tecoma stans flowers may be responsible for the observed anti-stress (adaptogenic) activity.

Conclusion

The METSF exhibited dose dependent significant anti- stress (adaptogenic) activity against all the three stress induced experimental animal models tested.