There was a study comparing the amount of Mitragynine in Kratom leaves from Thailand and Malaysia. It was found that the Mitragynine content of Thailand was approximately 5 times higher than Malaysia.
A study compared the content of Mitraginine in thatch leaves between Thailand and Malaysia and found that the content of Mitraginine in Thailand was approximately higher than that in Malaysia. 5x
The content of mitramycin in leaves of Mangosteen in Thailand and Malaysia was compared. It was found that the content of mitramycin in leaves of Mangosteen in Thailand was about 5 times higher than that in Malaysia.