Phytochemical research related to secondary metabolites contained in kratom has been started for a long time. Based on several research results, it can be concluded that kratom has 57 compounds, 40 of which belong to the group of alkaloid compounds (Meireles et al., 2019).
The chemical content of kratom which we will discuss this time is a chemical content that has a very dominant role in providing benefits to humans, especially if we examine the study of kratom to treat acute diseases. The eight chemical compounds owned by kratom include; alkaloids, flavonoids and polyphenols, triterpenoids and triterpenoid saponins, other minor compounds.
1. ALKALOID
There are various methods of extraction, isolation and purification of kratom alkaloids. The most popular extraction methods use alcohol group filters, such as methanol, ethanol, isopropanol and n-butanol or through an alcohol-water mixture with maceration, sonication or sokhlet techniques. Furthermore, the crude extract was carried out by acid-base extraction to obtain the yield of the alkaloid fraction. Other popular methods for the extraction of kratom alkaloids are ultrasound assisted extraction (UAE), microwave-assisted extraction (MAE), and supercritical carbon-dioxide extraction (SFE-CO2). The three methods are known to be able to increase the concentration of the resulting alkaloid fraction (Orio et al., 2012).
The types of alkaloids that have been isolated generally include the indole and oxindole alkaloids. Mitraginin and 7-hydroxymitraginine are the two main indole alkaloid compounds that can be found in kratom, especially the leaves. Mitraginine makes up about 66% while 7-hydroxymitraginine makes up 2% of the total alkaloids. Other alkaloid compounds that are quite dominant include paynanthein, speciogynin and speciociliatin, each with levels of 9%, 7% and 1% of the total alkaloids. Meanwhile, mitraciliatin, corynantheidin and 9-corynantheidin compounds are also often found with levels of no more than 1% of total alkaloids (Rybarczyk, 2019). In addition, there are other alkaloid compounds that have been isolated from kratom leaves, such as 3-isocorynantheidine, corynantheidalinic acid,
isopaynantheine, 3-dehydromitraginine, mitragunalinic acid, mitralactonal, mitralactonin, 9-methoxymitralactonin and sulfonated mitrasulginine derivatives. Compounds 7-hydroxyspeciosiliatin and 7-hydroxymitraginine isomers have also been isolated from kratom fruit from Malaysia (Kitajima et al., 2006).
Kratom that grows in America has more content of oxindole alkaloid compounds in the form of mitrafilin with levels of 45% of the total alkaloids. Leon et al. (2009), revealed that kratom originating from America has different chemical properties from kratom originating from the Southeast Asian region. and oxindole alkaloid compounds that are also found in kratom, including isomitraphylline, speciophylline, speciofoline, isospeciofoline, mitrafoline, isomitrafoline, rotundifoleine, isorotundifoleine, ciliaohylline, rhynchociline, specionoxeine, iso specionoxeine, corhyynoxeline, isocrynoxophylline. While alkaloid compounds with heteroyohimbine type are not commonly found in kratom. Ajmalicine
or better known by the trade names circolene and lamuran is one of the compounds that has also been isolated from kratom.
2. FLAVONOIDS AND POLYPHENOL
These compounds function as -adrenergic receptor antagonists. Mitraginin levels in young and old plants vary widely, generally old plants have a higher percentage of mitraginin than young plants. Differences in mitraginin levels can also be caused by other factors, one of which is the environmental factor in which it grows. In addition, the levels of alkaloids in one plant can also experience differences between one month and the next.
Phenolic compounds including flavonoids can also be found in kratom leaves, but information regarding this is still very limited. The flavonoid groups that can be isolated and identified include apigenin and other 7-glycosides including derivatives of flavonol compounds such as quercetin and its glycosides (quercitrin, rutin, isoquercitrin, hyperoside, quercetin-3-galactoside-7-
3. TRITERPENOID AND TRITERPENOID SAPONIN
Triterpenoid compounds isolated from kratom specimens, including roots infected by Agrobacterium rhizogenes, were found to contain ursolic acid and oleonic acid. In fact, plants infected with the bacteria are known to have mitraginin content about three times higher than normal plants. Kratom leaves, which are located in America, are known to contain triterpenoid saponins in the form of 3-O-β quinovopyranoside quinovic acid and 3-O-β-glucopyranoside quinovic acid. Similar to flavonoid and phenolic compounds, the content of triterpenoid compounds in kratom has not been studied much so that not much has been revealed (Gogineni et al., 2014).
4. OTHER MINOR COMPOUNDS
Kratom also contains other compounds whose levels are very minor, such as 3-oxo-α-ionyl-O-β-D-
