Insight into Therapeutic Role of Plant-derived Medicines in Thyroid Dysfunction

Abstract

Endocrine disorders are very common in Asia of which the thyroid dysfunction (TD) represents a major subset. The prevalence of TD is rising to an alarming rate. The thyroid gland (TG) is morphologically a butterfly-shaped organ, located anterior to the trachea, just inferior to the larynx and flanked by wing-shaped left and right lobes with the medial region called isthmus. TG produces thyroid hormones (TH), mainly triiodothyronine (T3) and thyroxine (T4). TH action is mediated by multiple TH receptors belonging to a nuclear receptor superfamily that also includes receptors for other small lipophilic hormones. TH receptors function by binding to specific TH-responsive sequences in promoters of target genes and by regulating transcription. Regulation of TH is followed by the hypothalamic-pituitary-thyroid axis. TD can be due to overproduction or under production of TH; i.e. hyperthyroidism and hypothyroidism respectively. Hyperthyroidism is characterized by weight loss, heat intolerance, palpitation, increased sweating, warm soft skin, increased heart rate and blood pressure. Whereas; in hypothyroidism, the facial expressions become dull, the voice becomes husky, speech is slow, the eyes and face become puffy. Hormone replacement therapy has been a standard approach to TD. However, herbal approach for the treatment of thyroid dysfunction is gaining popularity as it is proved to be effective, safe and devoid of any or at least lesser side effects. According to the world health organization (WHO), about three-quarters of the world population depends upon natural remedies, including herbal medicine. Plants possess several secondary metabolites like phenols, phenolic acids, flavonoids, alkaloids, tannins, quinones, coumarins, saponins, terpenoids, triterpenoids, glycosides and organic acids, which affect thyroid dysfunction by different mechanisms. Therefore, this review aims to provide comprehensive information regarding various herbal drugs used in the management of thyroid dysfunction.