Previously, the authors isolated two new alkaloids, secaclavine (alkaloid "X") and festuclavine (alkaloid "Y"), besides agroclavine and elymoclavine, from the sclerotia as well as the saprophytic culture of the Agropyrum-type ergot fungus parasitic on several plants growing in Japan, and pointed out the existence of another unknown water-soluble alkaloid "Z" in the mother-liquor. Recently, they succeeded in isolating this alkaloid ("Z") and two other unknown water-soluble alkaloids "U" and "V" from the saprophytic culture of the mentioned fungus by counter current distribution. "Z" (named pyroclavine) crystallized from ethyl acetate, benzene or methanol in needles; m.p. 204° (uncorr.), [α]D = -90°, [α]561 = -105° (c. 0.2 in pyridine). Anal. Found: C 79.71; H 8.59; N 11.87. Calcd. for C16H20N2: C 79.95; H 8.39; N 11.66%. It gave a deep blue color with Allport and Cocking's reagent and concentrated sulfuric acid, had UV maxima around 225, 275, 282 and 292 mμ (agreeing with secaclavine, festuclavine or dihydrolysergols), showed specific solubility in organic solvents and water/dilute acids, and no fluorescence. "U" (named costaclavine) crystallized from ethyl acetate, acetone, methanol or ethanol in prisms; m.p. 182° (uncorr.), [α]D = +44°, [α]561 = +59° (c. 0.2 in pyridine). Anal. Found: C 79.92; H 8.54; N 11.55. Calcd. for C16H20N2: C 79.95; H 8.39; N 11.66%. It had similar color reactions, UV spectrum (identical with "Z") and solubility properties to "Z", with higher water solubility. "V" crystallized from benzene, chloroform or ethyl acetate in prisms; m.p. 224° (uncorr. decomp.), [α]D = +109°, [α]561 = +1460 (c. 0.16 in pyridine). Anal. Found: C 75.68; H 7.21; N 10.94. Calcd. for C16H18ON2: C 75.55; H 7.14; N 11.02%. It gave a green color with Allport and Cocking's and Keller's reagents, a blue color with concentrated sulfuric acid, had UV maxima around 226, 242 and 315 mμ (matching penniclavine, triseclavine or lysergic acids), showed fluorescence in methanol/ethanol, and specific solubility. "V" was identical to isosetoclavine. Both pyroclavine and costaclavine were considered isomers of festuclavine (represented by Formula II) and produced through agroclavine. Isosetoclavine was confirmed as an isomer of triseclavine and an oxidation product of agroclavine.