Secologanin is a monoterpene that has been found in V. rosea and is an intermediate in the synthesis of monoterpene indole alkaloids from geraniol. [1][2] It is a metabolite of loganin formed by the cytochrome P450 (CYP) isoform CYP72A1, also known as secologanin synthase.[3]

Reference:
[1]. Battersby, A.R., Burnett, A.R., and Parsons, P.G. Alkaloid biosynthesis. XIV. Secologanin: Its conversion into ipecoside and its role as biological precursor of the indole alkaloids. J. Chem. Soc. C Organic 8, 1187-1192 (1969).
[2]. Miettinen, K., Dong, L., Navrot, N., et al. The seco-iridoid pathway from Catharanthus roseus. Nat. Commun. 5:3606, (2014).
[3]. Irmler, S., Schroder, G., St-Pierre, B., et al. Indole alkaloid biosynthesis in Catharanthus roseus: New enzyme activities and identification of cytochrome P450 CYP72A1 as secologanin synthase. Plant J. 24(6), 797-804 (2000).