Hibiscus sabdariffa Linn. (roselle) is a polyphenol rich fruit. This study aimed to identify the neuroprotective effect of roselle on LPS-induced cell proliferation and nitric oxide-induced free radical in microglia and neuroblastoma cells. MTT assay was used to identify the appropriate concentration of roselle and LPS for microglia and neuroblastoma cells proliferation study. Griess assay were used to determine the level of nitric oxide accumulated based on the reaction of Griess to estimate the activity of iNOS in nitric oxide production. The results showed that roselle at the concentration of 50 μg/mL and 100 μg/mL and LPS at concentration of 1 μg/mL does not give cytotoxic effect towards microglia C8-B4 and neuroblastoma LN18 cells. The roselle treatment at 50 μg/mL and 100 μg/mL showed a protective effect on LPS-induced microglia C8-B4 cells. However, in neuroblastoma LN18 cells, no protective effect was seen on both 50 μg/mL and 100 μg/mL of roselle treatment following induction with 1 μg/mL of LPS. On the other hand, the production of nitric oxide (NO) was reduced when LPS-induced microglia C8-B4 cells were treated with 50 μg/mL of roselle. Treatment of roselle at concentration 100 μg/mL on LPS-induced neuroblastoma LN18 cells also reduced the production of nitric oxide. As a conclusion, roselle had the ability to give neuroprotective effect by the inhibition of LPS induction activity on microglia activation for normal and cancer cells at different concentrations.
Hibiscus

Clinacanthus nutans (C. nutans) leaf extracts have been widely used by cancer patients in Malaysia and local practiceclaims a cure to cancer. There were several studies done to determine the cytotoxicity potency of C. nutans extracts onvarious types of cells. However, there is still lacking on the knowledge regarding the combination effect of C. nutanswith anticancer drugs. Thus, the study was carried out to determine the cytotoxicity potency of C. nutans extracts andpaclitaxel (PTX) alone and, in combination on MDA-MB-231 cells. The cells were treated with 100% ethanol extract ofC. nutans (CNE) and water extract of C. nutans (CNA), PTX and combination of both extracts and PTX for 72 hours andthe cytotoxic activity was determined using SRB assay. Result showed that CNE had little cytotoxic activity, whereas CNAshowed no cytotoxic activity on MDA-MB-231 cells. For combination treatment of C. nutans extracts and PTX, only CNEshowed significant enhanced PTX-induced cytotoxicity (p < 0.05), meanwhile CNA inhibited PTX-induced cytotoxicitysignificantly (p < 0.05). As a conclusion, CNE was able to increase PTX potency to inhibit the viability of MDA-MB-231cells.