Catharanthus roseus belonging to the Apocynaceae family synthesizes indole alkaloids like vinblastine and ajmalicine which are used in cancer treatment and for decrease high blood pressure, respectively. However, these compounds with a high value added are accumulated at low level in the plants. For the first time, endophytic fungi isolated from leaves (Stemphylium amaranthi) and roots (Gliomastix masseei) of C. roseus cv. Icy Pink were used as fungal elicitors to improve the biomass of C. roseus callus culture as well as the accumulation of indole alkaloids in the calli. Polyphenols and the antioxidant activity of endophytes extracts were examined. The ethyl acetate extract of S. amaranthi showed the maximum scavenging activities in 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. The maximum amount of total flavonoid and total phenol content were found in S. amaranthi (18.29 ± 0.03 mg gallic acid equivalents.g−1 and 0.117 ± 0.00001 mg quercetin equivalents.g−1, respectively). Also 5% cell extract and 5% culture filtrate extract of this endophytic fungus during 7 days of calli culture led to the highest contents of ajmalicine (0.735 μg.g −1 fresh weight) and vinblastine (0.059 μg.g −1 FW) respectively. Thus, endophytic fungi isolated from C. roseus could be used as fungal elicitor to improve the indole alkaloid production.

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