Abstract:
Ethyl acetate extract of the aerial part of Centella asiatica (L.) Urban (CA) was
found to possess the anticonvulsant activity in the PTZ test model. Using the fractionation
of the extract by conventional chromatographic technique together with the standard PTZ
antiepileptic screening model, it was found that saturated very long-chain fatty acids
(VLFAs) were the active principle in CA. Spectroscopic techniques were used to elucidate
the chemical structure, IR and NMR data confirmed that active principle are VLFAs with
the GC-MS technique to analyze the composition of the VLFAs, revealed that the sample
contain C12 C28 chain length acids, which contain C16 and C28 chain length acids as main
component.
A thin-layer chromatographic (TLC) method was developed to determine VLFAs
by using silica gel plate GF254 as stationary phase and hexane: ethyl acetate: glacial acetic
acid (14:6:1) as developing solvent, oleanolic acid as internal standard. The detection of
the TLC spot was developed by spraying with 3% phosphomolybdic acid in methanol and
scanned with densitometer at wavelength 550 nm. This method was validated according to
ICH guideline. The percentage recovery was in the range of 98.68-102.99 and percentage
of RSD was not more than 2.
The developed method was applied to analyze the CA that collected from 12
locations of Thailand, such as Prachin Buri, Nakhon Si Thammarat (Ban Bo Lo local
growth and Ban Bo Lo trade), Ubon Ratchathani, Trat, Rayong, Chon Buri, Nakhon
Ratchasima, Sukhothai, Chiang Mai (green petioles), Chiang Mai and Phitsanulok. The
maximum content of VLFAs was founded 0.27% w/w (Rayong), 0.24% w/w (Sukhothai
and Nakhon Ratchasima). Furthermore, the content of those compounds in CA that
collected from the commercial crops of Nakhon Pathom, Ubon Ratchathani and Nakhon
Si Thammarat provinces. The maximum VLFAs of CA in sample collected from Nakhon
Pathom province was observed also annually determine in November, from Ubon
Ratchathani in September and from Nakhon Si Thammarat province was observed in
May. Information obtained may be utilized as criteria for plant varieties selection and
breeding programs for commercial cultivars of optimal VLFAs content for further
isolation of pure VLFAs.