Strobilanthes anamallaica (Acanthaceae) is an endemic plant of South-Western Ghats, Kerala, India. Cytogenetical characterisation from the root meristem revealed exhibition of mixoploidy, i.e. three chromosome counts, 2n = 10, 20 and 30, within the same tissue. Three different euploid linkage sets corresponding to hypoploid, diploid and hyperploid cells could be differentiated. Although it is difficult to ascertain true paired sets, but a close look at the karyomorphology led to deduce karyotype formulae as 2nsm(-) + 8 nm; 2 M + 18 nm; and 30 nm, respectively (nsm = nearly submedian, nm = nearly median, M = median). The centromere position of chromosomes was predominantly nearly median with a few median ones. The karyotype details and incidence of mixoploidy is the first report for this endemic species. The karyotype is symmetric and primitive in nature. Occurrence of mixoploidy is suggested as an adaptation measure for the species.

The artificial colorants act as a potent cytotoxic agent at the consumer level, whose analysis is inevitable. The investigation is mainly focused to analyze the toxicity of two commonly used synthetic food colorants (Brilliant blue and Fast green) with the help of Allium cepa root tip assay. The frequency of aberrations and the concentrations of both the colorants were found to be positively correlated in the chromosome studies. The integrity of the cell membranes, which is a potent parameter to detect cellular damage was detected using Evan’s blue staining. 2,3,5-triphenyl tetrazolium chloride (TTC) method was also adopted to determine the damaging effects of the synthetic molecules on the mitochondrial oxidative properties in the root tip cells. Both food colorants showed prominent membrane damage and mitochondrial activity reduction in the test material.

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The mixoploid karyotype found in the garden plant, Strobilanthes hamiltoniana, is a new record of chromosome count to the contemporary knowledge. The detailed karyomorphometrical analysis of the plant revealed a symmetric karyotype which is primitive. A hypoploid variant along with the normal chromosome complement was recorded within a root meristem with karyotype formulae as 10 nm and 20 nm respectively. In the diploid cells two pair of chromosomes have secondary constriction with an average chromosome length of 1.81 μm. The high values of symmetric indices and low values of asymmetric indices proved the primitive nature of the karyotype.

Modern food habits in humans have increased the frequency of diseases especially colon cancer. The present findings suggest the potential efficacy of two endemic Strobilanthes species of Southern Western Ghats. The shoot extract of the plants showed high radical scavenging activity in hydroxyl scavenging assay at an half maximal inhibitory concentration of 375.24±2.03 and 375.24±2.03 µg/ml against gallic acid for Strobilanthes anamallaica and Strobilanthes virendrakumarana respectively. Their activity in the superoxidefree radical assay was moderate when compared with the standard. Among the two species, Strobilanthes virendrakumarana highly impacted colon cancer cells (DLD1) with an Lethal concentration 50 of 111.99±4.91 µg/ml. These concentrations do not affect the normal cell line L929 under consideration. Hence, the endemic plant of Southern-Western Ghats, viz., Strobilanthes virendrakumarana is a promising candidate against colon cancer cells.