Immunomodulatory Effects of Premna tomentosa (L. Verbenaceae) Extract in J 779 Macrophage Cell Cultures Under Chromate (VI)-Induced Immunosuppression

Ethnomedicinal uses, phytochemistry and pharmacological aspects of the genus Premna: a review

CONTEXT

The genus Premna (Lamiaceae), distributed throughout tropical and subtropical Asia, Africa, Australia and the Pacific Islands, is used in folk medicine primarily to treat inflammation, immune-related diseases, stomach disorders, wound healing, and skin diseases.

OBJECTIVES

This review exhaustively gathers available information on ethnopharmacological uses, phytochemistry, and bioactivity studies on more than 20 species of Premna and critically analyzes the reports to provide the perspectives and directions for future research for the plants as potential source of drug leads and pharmaceutical agents.

METHODS

A literature search was performed on Premna species based on books of herbal medicine, major scientific databases including Chemical Abstract, Pubmed, SciFinder, Springerlink, Science Direct, Scopus, the Web of Science, Google Scholar, and ethnobotanical databases.

RESULTS

More than 250 compounds have been isolated and identified from Premna species, comprising of diterpenoids, iridoid glycosides, and flavonoids as the most common secondary metabolites, followed by sesquiterpenes, lignans, phenylethanoids, megastigmanes, glyceroglycolipids, and ceramides. Many in vitro and in vivo studies have been conducted to evaluate the biological and pharmacological properties of the extracts, and isolated compounds of Premna species with antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, antihyperglycaemia, and cytotoxic activities.

CONCLUSION

The bioactive compounds responsible for the bioactivities of most plants have not been well identified as the reported in vivo pharmacological studies were mostly carried out on the crude extracts. The isolated bioactive components should also be further subjected to more preclinical studies and elaborate toxicity study before clinical trials can be pursued.

New cytotoxic clerodane diterpenes from the leaves of Premna tomentosa

Bio-activity directed investigation of hexane extract from the leaves of Premna tomentosa led to the isolation of three new clerodane diterpenes (1-3) along with four known compounds (4-7). The structures of new compounds were established using IR, MS, 1D, and 2D NMR techniques. The in vitro cytotoxicity of the crude hexane extract and the isolated compounds were evaluated against seven human cancer cell lines and results indicated that compounds 2 and 4 depicted significant cytotoxicity against hepatocellular carcinoma cell line.

Modulating effect of Leptadenia reticulata (Retz) Wight & arn against chromate (VI)-induced immunosuppression and oxidative stress on mouse splenic lymphocytes and bone marrow derived macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Leptadenia reticulata (Retz) Wight & arn is mentioned in the ancient ayurvedic literature as an immune booster and rejuvenator.

AIMS OF THE STUDY

To investigate, the effects of different forms of the extract of Leptadenia reticulata [Aqueous extract (JAE), Padavashesha kashaya (JPK) and Tarpana kashaya (JTK)] to alleviate the experimental immunosuppression induced by the immunotoxicant chromate (VI) in vitro.

MATERIALS AND METHODS

Standard cell proliferation and cytotoxicity assays like MTT assay, trypan blue dye exclusion test, neutral red dye uptake test, NBT reduction test, determination of percentage cell survival and estimation of markers of oxidative stress were performed in the study. The study was conducted on primary cultures of mouse splenic lymphocytes and bone marrow derived macrophages.

RESULTS AND CONCLUSIONS

Treatment with all the three forms of the extract used in the study offered protection against chromate (VI)-induced immunosuppression and the overall protective effect was found to be superior in the case of the aqueous extract of Leptadenia reticulata (JAE). These results confirm that Leptadenia reticulata acts as a modulator and alleviates the immunosuppressive conditions induced by chromate (VI).

Cytotoxic clerodane diterpenoids from the leaves of Premna tomentosa

Three clerodane diterpenoids, premnones A-C (1-3), were isolated from a chloroform-soluble fraction of Premna tomentosa along with four known flavonoids and three known triterpenoids. Among these isolates, premnones A-C exhibited cytotoxic activity when evaluated against a small panel of tumor cell lines. However, premnone A was found to be inactive when evaluated in a follow-up in vivo hollow fiber assay at the highest dose tested (50mg/kg), using LNCaP, Lu1, and MCF-7 cells.

Protective effect of Premna tomentosa extract (L. verbanacae) on acetaminophen-induced mitochondrial dysfunction in rats

Allurement of herbs as health beneficial foods (physiologically functional foods) and as a source material for the development of new drugs, has led to greater furtherance in the study of herbal medicines during recent years. Plant extracts are being utilized to treat a wide variety of diseases like hepatotoxicity. Premna tomentosa is one such medicinal plant used widely in Indian ayurvedic medicine for the treatment of liver disorders. This study appraised the effectiveness of P. tomentosa leaf extract in protecting the liver against mitochondrial damage induced by acetaminophen, since mitochondrial injury has been investigated as a potential initiator of hepatotoxicity. Normal Wistar strain rats were pre-treated with P. tomentosa extract (750 mg/kg, orally) for 15 days and then intoxicated with acetaminophen (640 mg/kg, orally). Mitochondria were isolated from liver of experimental animals and assessed for the levels of lipid peroxide products, GSH and mitochondrial enzymes (isocitrate dehydrogenase, alpha-keto glutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, NADH dehydrogenase and cytochrome-C-oxidase). The levels of Lipid peroxidation products were increased and the levels of the other assessed parameters were significantly decreased in hepatotoxicity induced animals. Whereas, the levels were brought back to normal in P. tomentosa pre-treated rats, which shows the protective effect of the extract against mitochondrial damage. Presence of anti-oxidant compound D-limonene (58%) in P. tomentosa leaves, which is known to enhance conjugation of toxic metabolites by maintaining liver GSH concentrations may explain the hepatoprotective property of the extract.