**3. Turmeric (***Curcuma longa)*

It is one of the most useful herbal medicinal plants which belongs to Zingiberaceae family (**Figure 3**). It is known for its medicinal properties for 4000 years [25].

It is used widely as a spice all over the world but mostly in eastern region. It is broadly cultivated in Asian countries like India and China. In ancient times, it was used in many ways including its presence in ointments due to its great healing properties, it is used to improve digestion, intestinal problems, to strengthen organs such as gall bladder and liver [26]. In 1870s, chemists found that the yellow-orange color of turmeric changes to reddish brown in alkaline medium. This led to the formation of turmeric paper which is used to test alkalinity [9].
