Identification of the protein components displaying immunomodulatory activity in aged garlic extract

Ethnopharmacological relevance: Traditionally, garlic (Allium sativum L.; Alliaceae) has been knownto boost
theimmunesystem. Aged garlic hasmore potent immunomodulatory effects than rawgarlic. These effects
have been attributed to the transformed organosulfurcompounds; the identity of the immunomodulatory
proteins in aged garlic extract (AGE) is not known.
Aim of the study: The major aims are to examine the changes occurring in the protein fraction during
ageing of garlic and to identify the immunomodulatory proteins.
Materials and methods: Changes occurring in garlic during ageing have been examined by protein quantitation
and gel electrophoresis. Purification and identification of the immunomodulatory proteins have
been achieved by Q-Sepharose chromatography and mitogenic activity.
Results: Only twomajor proteins (12–14 kDa range by SDS-PAGE) are observed in AGE. The purified protein
components QA-1, QA-2, and QA-3 display immunomodulatory and mannose-binding activity; QA-2
shows the highest mitogenic activity. The identity of QA-2 and QA-1 proteins with the garlic lectins ASA
I and ASA II, respectively, has been confirmed by hemagglutination analysis. QA-3 exhibits mitogenic
activity, but no hemagglutination activity.
Conclusions: The immunomodulatory activity of AGE is also contributed by immunomodulatory proteins.
The major immunomodulatory proteins have been identified as the well-known garlic lectins.