Botanical pentacyclic triterpenes possessed a broad range of pharmacological activities such as anti-oxidant, anti-tumor, anti-microbial and anti-inflammatory activities. It is believed that the mechanisms involved in these bioactivities are due to the modulation of immune system. Recently, the pharmacological validation on immunomodulatory of pentacyclic triterpenes derived from higher plants is very limited and several existence review papers related for this group of compound have not been focused for this activity. In this review, we have highlighted several studies on immunomodulatory potential of botanical pentacyclic triterpenes isolated from wide array of different species of medicinal plants and herbs based on various preclinical in vitro and animal models. This review also attempts to discuss on bioactivities of compouns related with their structure-activity relationship. Hence, the evaluation of pentacyclic triterpenes offers a great opportunity to discover adjuvants and novel therapeutic agents that presented beneficial immunomodulatory properties.

Centella asiatica (Linn.) Urban (Umbelliferae) which is also known as ‘pegaga’ is highly consumed and eaten raw as ‘ulam’ in Malaysia. C. asiatica is used in traditional medicines to treat various health conditions such as rheumatism, inflammation, syphilis, skin diseases and diarrhoea. Various reports exhibited that the crude extracts and isolated bioactive compounds of C. asiatica possessed a broad range of pharmacological activities such as anti-oxidant, anti-diabetic, anti-tumor, wound healing, anti-microbial, anti-inflammatory, immunomodulatory, hepatoprotective and memory enhancing properties. The pharmacological validation on anti-microbial and immunomodulatory of C. asiatica is very limited and several existence review papers related for this plant had not been focused for both activities. This review therefore attempts to combine the existing literature to offer immense scope for researchers engaged in validation of the traditional claims and bioactivities of this plant related with anti-microbial and immunomodulatory potential.
Centella ; Complex Mixtures ; Inflammation ; Malaysia ; Memory ; Plants ; Rheumatic Diseases ; Syphilis, Cutaneous ; Wound Healing

Objective: To investigate the effects of 20 methanolic extracts from Malaysian selected plants on CD18/11a expression and phagocytosis activity of leukocytes using flow cytometry analysis. Methods: The effects of methanolic extracts on CD18/11a expression and phagocytosis of leukocytes were measured by labelling the cells with CD18-fluorescein isothiocyanate and ingestion labelled with Escherichia coli-fluorescein isothiocyanate and then analyzed using flow cytometer. Results: About 12 out of 20 methanolic extracts of selected Malaysian medicinal plants significantly (P≤0.05) inhibited the CD18/11a expression of leukocytes at both concentrations of 6.25 μg/mL and 100 μg/mL in dose dependent manner. The most active inhibitory was shown in Citrus aurantifolia (Christm.) Swingle and Alpinia galangal (L.) Willd. at dosage 100 μg/mL. Moreover, the Orthosiphon aristatus (Blume) Miq (O. aristatus). showed the highest stimulatory activity at the concentration of 100 μg/mL. Other than that, four plant extracts significantly (P≤0.05) rose the phagocytosis activities of leukocytes in dose dependent manner. However, Annona muricata L. and O. aristatus showed the highest stimulated activities at the 100 μg/mL concentration. Conclusions: The results suggest that methanolic extracts of Citrus aurantifolia, Alpinia galangal, O. aristatus and Annona muricata are able to modulate innate immune system and can potentially be recognized as therapeutic agents for modulating immune system.