The aromatic herb can be found around the globe, and the researchers reported that it is a popular ingredient in traditional medicine cultures of Asia, Africa, and South America "to treat respiratory illness, skin disease, and gastrointestinal disorders," they wrote in their study, published in the journal Food Chemistry.
Observations have been made on the herb’s seed’s mucilage being rich in neutral and acidic polysaccharides galactose, glucose, mannose, fucose, xylose, and 4-O-methylglucuronic acid—the kinds that may act as prebiotics, an ingredient that results in specific changes in the composition and activity of the gastrointestinal microbiota.
“The aim of this study was to determine the prebiotic potential of poly- and oligosaccharides isolated from the seed mucilage of H. suaveolens by investigating the impact of separation into acidic and neutral fractions and the effect of enzymatic treatment,” the researchers wrote.
Preparing H. suaveolens mucilage and extracting polysaccharides
The main study design was observation of probiotic growth in the presence of total acidic or neutral polysaccharides and oligosaccharides using turbidity (cloudiness) measurements.
Mucilage from H. suavoeolens seed used in this study was prepared in conjunction with the Chiang Mai University of Thailand. Mucilage was extracted using cold water, then purified and dried at a low temperature.
The total soluble polysaccharides (TPS), the fraction of neutral polysaccharides (NPS), and the fraction of acidic polysaccharides (APS) were extracted from finely milled mucilage treated with 4 M sodium hydroxide solution for 24 hours at 70 degrees Celsius, which had its insoluble parts removed through centrifugation. Potato galactose was used as a control.
Determining the prebiotic effect
Researchers looked at the growth curves of the probiotic strains in the presence of standard compounds and different fractions from H. suaveolens using Bioscreen C. The method entailed looking at the change of cloudiness as a marker of bacterial growth.
Twelve probiotic strains were used in the study: Lactobacillus (L.) paracasei ssp. paracasei CRL 431 (ATCC 55544), L. paracasei ssp. paracasei DN114001, L. paracasei ssp. paracasei DSM 20312, L. rhamnosus GG (ATCC 53103), L. reuteri (ATCC 55730), L. acidophilus LA-5(DSM 13241), B. animalis ssp. lactis BB12(DSM 15954), B. longum ssp. infantis, L. plantarum (ATCC 15697), L. brevis (ATCC 367), L. bulgaricus (DSM 20081), Lactococcus (Lc) lactis ssp. lactis (SR 3.54; NCIMB 30117), L. fermentum and Streptococcus (S.) thermophilus (ATCC 19258).
Observations: ‘prebiotic potential characterized by a delayed but long lasting effect’
According to the researchers, 11 out of the 14 tested probiotic strains significantly grew in the neutral polysaccharides fraction. “The population growth with native [neutral polysaccharides] reached up to 20% when compared to the positive control (galactose) and was dependent on the probiotic strain,” the researchers wrote.
They also observed that growth is dose dependent, “thus the prebiotic potential of H. suaveolens can be increased by administering higher doses.” However, this growth was delayed compared to the same plant’s neutral oligosaccharides or to other oligosaccharides with prebiotic potential.
“Indeed combinations of different prebiotics would be ideal to obtain a fast occurring and long lasting prebiotic effect,” the researchers added. Nonetheless, they concluded that the neutral fraction of H. suaveolens enhanced the growth of various probiotic strains moderately but significantly.
“The neutral fraction of H. suaveolens may serve as a novel prebiotic source with a delayed, but longer lasting, effect,” they wrote.
Source: Food Chemistry
Published online ahead of print, http://dx.doi.org/10.1016/j.foodchem.2016.10.075
"Prebiotic potential of neutral oligo- and polysaccharides from seed mucilage of Hyptis suaveolens"
Authors: Monika Mueller, Andrea Čavarkapa, Frank M. Unger, Helmut Viernstein, Werner Praznik