| dc.description.abstract | Diabetes mellitus (DM) is a chronic and serious metabolic disorder that is
t revalent in the world. Diabetes mellitus occurs due to insulin deficiency and inswli
resistance. This condition causes high blood glucose levels or called hYN.. rglycemia condition.
One therapeutic approach to treat diabetes is to retard the abs" tion of glucose via inhibition of
enzymes, such as a-glucosidase, in the small tinal. Inhibition of this enzyme slows the elevation
of blood glucose following
· rl:hohydrate meal. The a-glucosidase inhibitor is a bioactive compounds i8uted widely in plants
and microorganisms including actino bacteria.
}\ctinobacteria are Gram positive bacteria widely distributed in nature. They produce numerous
metabolic products, most of which are bioactive compound with applications in many therapeutic
areas. Actinobacteria are predominantly free living and are found in diverse environments including
plants tissue. Microbes that live on plant tissues without causing harmfull to the host are called
endophytes. Such icrobial endophytes are beginning to pay attention ofresearchers due to their
abilit)1 to produce various compounds of pharmacological value similar to their li.osts. Previous
reports showed that endophytic actinobacteria have a-glucosidase mhibi or activity such as
Tinospora crispa (Brotowali) and Datura stramonim L (Kecubung).
lf abat barito (Ficus deltoidea Jack) is a medicinal plant originating from Southeast Asia. In
Indonesia, tabat barito has the most distribution in Borneo island. Tabat barito was used
traditionally to treat diabetes. On another hand, several studies have shown that tabat barito has
an a-glucosidase inhibitor activity. The abilit)1of tabat barito to produce a-glucosidase
inhibitors is suggested to be related to the presence of endophytic microbes including
actinobacteria. Previous studies showed that the abundance of actinobacteria in the tabat barito
plant tissue is quite umer:ous and varied. Based on these reports, it is expected that the
capability of abat barito on producing a-glucosidase inhibitors is related to the presence of
actinobacteria.
In this study, it was proven that endophytic actinobacteria from tabat barito
<t:ould produce a-glucosidase inhibitors. Screening using a-glucosidase from rat intestine is
recommended for in vitro a-glucosidase inhibitor because the homology sequeroce of catalytic side
closer to enzymes in the human intestine. In this study endophytic actinobacterial isolates more
inhibited a-glucosidase from rat intestines according to acarbose which only inhibit mammalian
a-glucosidase. Screening of 40 enoophytic actinobacteria isolates using yeast a-glucosidase showed
that 25 sG).}ates (62%) of isolates had a-glucosidase inhibitors activity. Whereas screening msm
rat intestinal enzymes from 40 isolates, 31 isolates (77%) had a-glucosidase
lnor activity.
Aqueous extract and n-hexane ofTBL 7 isolates were the best extracts for a sidase inhibition, IC₅₀
value of 159.25 µg mL-¹ (aqueous extract) and 118.52 mIL-1 (n-hexane extract). Based on the 16S
rRNA gene TBL 7 showed was
similar to Streptomyces tendae (99.91%). The ISP 2 medium with 10 days incubation period is the
best condition to produce a-glucosidase inhibitor compound. After fractionation, AF 2 from aqueous
crude extract has ICso value of
58.8 µg mL-I, higher than acarbose as positive control (ICso = 90.4 µg mL-I). The
LC-MS analysis showed that the fraction of AF 2 had bioactive compounds similar t phenylpropynal,
butyric acid, solketal, p-coumaric acid. The butyric acid and p c u aric acid have been reported
to have a-glucosidase inhibitor activity. P c u aric acid is a pheno lie compound that has been
known to have antidiabetic a..t;ivity because of its ability to reduce glucose absorption in the
intestine. The p; esence of AF 2 in the reaction did not change the Km value of 1.38 mM. Whereas, t
e Vmax value decreased from 0.52 mM min-I to 0.40 mM min-I. Based on these r . ults, it can be
concluded that the inhibitor of the fraction is a non-competitive itili.i itor. Based on the
results of this study, endophytic actinobacterial extracts can
developed as antihyperglycemic agents. | id |
